AbstractIn the present study, flax fiber based semicarbazide biosorbent was prepared in two successive steps. In the first step, flax fibers were oxidized using potassium periodate (KIO4) to yield diadehyde cellulose (DAC). Dialdehyde cellulose was, then, refluxed with semicarbazide.HCl to produce the semicarbazide functionalized dialdehyde cellulose (DAC@SC). The prepared DAC@SC biosorbent was characterized using Brunauer, Emmett and Teller (BET) and N2 adsorption isotherm, point of zero charge (pHPZC), elemental analysis (C:H:N), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The DAC@SC biosorbent was applied for the removal of the hexavalent chromium (Cr(VI)) ions and the alizarin red S (ARS) anionic dye (individually and in mixture). Experimental variables such as temperature, pH, and concentrations were optimized in detail. The monolayer adsorption capacities from the Langmuir isotherm model were 97.4 m/gand 18.84 for Cr(VI) and ARS, respectively. The adsorption kinetics of DAC@SC indicated that the adsorption process fit PSO kinetic model. The obtained negative values of ΔG and ΔH indicated that the adsorption of Cr(VI) and ARS onto DAC@SC is a spontaneous and exothermic process. The DAC@SC biocomposite was successfully applied for the removal of Cr(VI) and ARS from synthetic effluents and real wastewater samples with a recovery (R, %) more than 90%. The prepared DAC@SC was regenerated using 0.1 M K2CO3 eluent. The plausible adsorption mechanism of Cr(VI) and ARS onto the surface of DAC@SC biocomposite was elucidated.
IntroductionThe availability of accepted quality of water is one of the major problems faced in the twenty-first century1. The quality of water resources is declining daily due to various anthropogenic activities, unplanned urbanization, and increasing industrialization2.Recently, chromium pollution has drawn great attention ue to its harmful effectson the environment, human health and agriculture. There are two forms of chromium, trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). The hexavalent form is more toxic and carcinogenic than the trivalent. Chromium compounds especially Cr(VI) is dangerous to human health as it harms the digestive system, skin, and respiratory system. Cr(VI) enters various industrial fields like metal finishing, electroplating, atomic power plants, and metallurgy. The discharge limits of chromium have been developed by some industrial countries to reduce environmental pollution. WHO organization has instituted the total chromium maximum to be 0.05 mg/L3.Alizarin Red S (ARS) is an anionic, non-biodegradable and water-soluble sodium salt that belongs to anthraquinone dyes. The inappropriate discharge of ARS into water bodies might have a negative impact on marine life. The discharge of ARS to the environment is considered as a direct threat to the ecosystem4,5.Various ypes of dyes and metal ion are the major pollutants encountered in wastewater effluents, which disturb the aquatic environment6,7. So, the removal of water pollutants is an important issue.Many technologies have been emerging for treating and handling pollutant-laden wastewater. Some commonly used treatment technologies consist of biological treatments, membrane process, chemical, and electrochemical technology, reverse osmosis, ion exchange, electrodialysis, electrolysis, and adsorption techniques8.However, the limitations of most of these methods include the generation of toxic sludge, high operational and maintenance costs, and the intricate technique involved in the treatment9. Comparatively, the adsorption method is considered a better treatment process in wastewater treatment technologies due to ease of operation, convenience, and simplicity of design10,11. But it has a limitation of sludge generation (spent adsorbents after use) as other removal processes12.In recent years, man attempts have been made tofind inexpensive alternative materials as biosorbents that are both effective and acceptable for industrial use from both a technological (simplicity) and economic point of view13.A recent class of materials proposed for environmental applications such as the removal of pollutants from solutions is based on the use of plants such as hemp and flax.These two plants are annual, high-yielding crops grown for their fibers and seeds14,15,16. Hemp and flax are interesting raw, eco-friendly, lignocellulosic materials because of their ease of production (rapid growth, no pesticides), low cost, renewable character, particular chemical composition of their fibers (mainly cellulose, hemicelluloses and lignin), particular structure (multicellular fibers of fibrilar structure), physical and mechanical properties as well as their versatility. They are usable in the form of powder, fragments, fibers and oils since the entire plant (seeds and plant stem) is recoverable14. Lie other lignocellulosic fibes or plant fibers such as jute, ramie, sisal, kenaf and bamboo, hemp and flax contain a high content of cellulose and comprise three main constituents (cellulose, hemicelluloses, and lignin) and other minor components.As the main constituent of the flax fiber structure, cellulose builds the microfibrils in the cell wall structure, while hydroxyl groups on the C2, C3, and C6 positions in cellulose monomer units are responsible for the formation of a supermolecular structure with amorphous and crystalline regions by creating intramolecular and intermolecular hydrogen bonds between the cellulose chains17. Hemicelluloses, which contain hydrophilic hydroxyl groups, are connected to the cellulose by hydrogen bonds and are deposited in the interfibrillar spaces of the primary and secondary walls. Lignin is a complex three-dimensional polyphenolic polymer with a high molecular weight and low reactivity, deposited in the middle lamellae, and the secondary wall18. Asmentioned previously, these min structural components contain specific functional groups (hydroxyl, carbonyl, and methoxyl)19, which, combined with the specific structure of flax fibers, promote their characteristics, especially their sorption properties.One of the important features for the use of flax fiber-derived adsorbent for removal of dyes and metal ions is that it can be used on a large scale because of its huge availability. Also, biomass-derived adsorbents have high affinity/binding capacity for various types of contaminants, and also have good regeneration capacities. In addition, their good surface chemistry such as pore distribution, specific surface area, and functional groups help for the removal of dyes in the wastewater.Cellulose is a traditional low-cost efficient adsorbent which has high potential for heavy metal removal from wastewaters due to its abundance, chemical and mechanical stability, high adsorption capability and unique structural properties. Cellulose ha several advantages as it is ceap, renewable, available, regenerable, eco-friendly and biodegradable. Also, cellulose has a high uptake capacity and low density. Modifications of cellulose are performed to introduce functional groups. Cellulose is easily modified because of the presence of three hydroxyl groups in each cellulose unit. Cellulose is modified by several techniques like oxidation, esterification, etherification and halogenation20,21,22,23.Flax has been proposed for removal of Zn, Cu and, Pb24,25, Cadmium26,27, uranium19, and Cu(II)28. Pejić et al. recently reported the role of cellulosic and noncellulosic functional groups in the biosorption of Pb(II) ions by waste flax fibers29. Furthermore, flax fiber has been proposed for removal of basic yellow 37 dye30 and recently for the removal of methylene blue, crystal violet and brilliant green cationic dyes by Akl et al.31. Liu et al. utilized Nano-TiO2 self-assembled flax fiber for oil/ water separation32.In recent years, ionpair formation has been used toremove various organic and inorganic contaminants. The advantages of ion-pair formation include higher reactive surface area and faster and more complete reactions33. However, there are still some technical challenges associated with practical applications such as limitations imposed by the high reactivity and low stability. Inspired by these findings and taking into consideration the ion-pair formation, this study aimed at the synthesis of N-donor modified flax adsorbent for removal of Cr(VI) and ARS via ion pair formation between N-donor modified flax fiber and Cr(VI) or ARS. Flax fiber was oxidized with periodate preceding its condensation with semicarbazide hydrochloride for the synthesis of the cationic DAC@SC functionalized semicarbazide-modified flax fiber.To the best of our knowledge, no studies have been reported in the literature concerning the synthesis and use of DAC@SC biocomposite for the removal of ARS and Cr(VI).The present study was carred out with the following objectves:
i.
Design and characterization of cationic dialdehyde cellulose from flax fiber (DAC@SC) using various instrumental performances as elemental analysis, SEM, TEM, FTIR, 1HNMR, XRD and TGA.
ii.
Batch sorption experiments utilizing Cr(VI) and anionic dye (ARS) as pollutants.
iii.
Studying the optimum parameters like pH, the initial dye concentration, adsorbent dose, temperature, isotherms, thermodynamics and oscillation time.
iv.
Comparative evaluation of removal efficiency (R%) of Cr(VI) and ARS, feasibility, and reusability of DAC@SC with other adsorbents.
v.
Elucidation of the mechanisms involved in the process of adsorption of Cr(VI) and ARS onto DAC@SC biocomposite.
ExperimentalMaterialsSemicarbazide HCl (CH5N3O.HCl), potassium dichroate (K2Cr2O7), Alizarin red S (C14H7NaO7S), Fig. 1, tri-ethylamine (N(CH2CH3)3), hydroxyl amine hydrochloride (HONH2), absolute ethanol, sodium hydroxide (NaH) and hydrogen chloride (HCl), were purchased from Sigma Aldrich. All the purchased chemicals were used without any pre-treatment. Flax fibers were supplied by Tanta flax & Oil Company, Egypt. Before use, flax fibers were washed by dist.H2O and were dried in an oven at 50 °C. Potassium periodate (KIO4) 4% solution was prepared by dissolving 4 g of KIO4 in 100 ml dist.H2O. Semicarbazide hydrochloride 2% solution was prepared by adding 2 g of semicarbazide.HCl to 100 mL absolute ethanol. Then, the mixture was heated until the semicarbazide hydrochloride is dissolved in ethanol.Figure 1(a) Alizarin red S (ARS), (b) hexavalent chromium, Cr(VI).Full size imageInstrumentationThe specific surface area of the DAC@SC biocomposite was obtained using the Brunauer Emmet Teller (BET) analysis (Size Analyzer (QUANTACHROME–NOVA 2000 Series)The point of zero charge (pHPZC) is the pH value at which the biosorbent surface has a net zero charge. In this study, the pHPZC was determined using the soli addition method34. In a series of 100 mL jacketed glasses, 50 mL of KNO3 solutions of known concentration were transferred. The solutions of different initial pH (pHi) between 2 and 12 were prepared by adding either 0.1 M HCl or 0.1 M NaOH. One gram of biosorbent was then added to each solution with stirring for 48 h. The final pH (pHf) was measured and the difference between the initial and final pH values (ΔpH = pHi− pHf) was plotted against pHi. The pHpzc value is the point where the curve ΔpH vs pHi crosses the line ΔpH = 0.Estimation of the CNH composition for the DAC@SC biocomposite was achieved by a Costech (ECS-4010) elemental analyzer (Costech, Italy).The surface morphologies of native, oxidized and modified flax fiber (DAC@SC) biocomposite were inspected by a scanning electron microscope (A JSM-6510LV).The particle siz of DAC@SC was measured using Transmittance electron microscopy, (TEM Talos f200i thermo scientific).Fourier transform infrared (FTIR) spectra of the native flx fibers, DAC, DAC@SC biocomposite and the DAC@SC biocomposite having adsorbed the Cr(VI) and ARS were obtained by a Perkin–Elmer, Spectrum RX I using KBr pellets at wavenumber range from 4000 to 450 cm−1.1HNMR spectra of the prepared DAC and DAC@SC cellulosic materials were measured in DMSO and trifluroacetic acid (TFA) in the NM R Lap-National Research Center, Dokky, Egypt using a Joel 500 MHZ Japan.X-ray diffraction (XRD) patterns of the DAC@SC biocomposite were obtained by a PAN analytical X’Pert PRO diffractometer over the 2-theta (2θ) range from 10° to 40°.The thermal stability of oxidized flax fiber and DAC@SC biocompositewere examined by thermogravimetric analysis (Berkin Elmer TGA 4000) at a heating rate of 15 °C/min from 30 to 800 °C.A Shimadzu UV-2550 double-beam UV–Visible spectrophotometer with a 1 cm quartz cell wa used for measurements of Cr(VI) and ARS at λmax = 447 nm and 436 nm, respectively.A pH meter (Hi 931401, HANNA, Portugal) was used to measure the pH of sample olutions.PreparationsPreparation of dialdehyde cellulose (DAC)One gram of the native flax fiber was oxidized using 100 mL of 4% potassium periodate. The previous mixture was shaken for 1 h in complete darkness to form dialdehyde cellulose (DAC). The obtained DAC was washed several times with dist.H2O and was dried in an oven at 50 °C31.Determination of aldehyde content0.25 M hydroxylamine HCl (1 L) was prepared as following: 17.55 g of hydroxylamine (99%) and 3 mL of 0.1% methyl orange indicator were added to 150 mL of dist.H2O. Then, the solution was completed to 1000 mL and its pH was adjusted to 4.0 by using 0.1 M NaOH35. 0.1 g of DAC was added to 25 mL of 0.25 M hydroxylamine HCl in a100 mL aluminum covered conical flask, Fig. 2, and was stirred at 25 °C for 150 min. Then, DAC was filtered and dried in an oven for 60 min at100 °C. The filtrate was back titrated by using 0.1 M NaOH to pH 4 and the end point was achieved when the color is converted from red to yellow. The control expriment was performed by replacing the DAC with native flax fibers. The aldehyde content (A%) was calculated according to Eq. (1)36.$${ ext{AC}}\%=frac{ ext{NaOH Concentration }({ ext{V}}_{ ext{sample}}-{ ext{V}}_{ ext{control}})}{ ext{m}/ ext{Mwt}}X100$$
(1)
where AC% is the aldehyde content percentage, Vsample is the volume of NaOH in case of oxidized cellulose, Vcontrol is the volume of NaOH in case of native flax fiber, m, and Mwt are sample weight and cellulose molecular weight, respectively.Figure 2(a) Filtrate of 0.25 M hydroxylamine after stirring for 2.5 h with DAC; (b) after titration with 0.1 M NaOH.Full size imagePreparation of semicarbazide modified dialdehyde cellulose (DAC@SC) sorbentOne gram of oxidized flax fiber (DAC) was refluxed with 100 mL of 2% alcoholic semicarbazide.HCl and 0.5 mL ri-ethylamine for 4 h at 70 °C. Finally, the obtained modified DAC@SC biocomposite was washed several times with dist.H2O. The DAC@SC biocomposite was dried in the oven a 50 °C37. The synthesis of DAC@SC adsorbent is represented in Fig. 3.Figure 3Synthesis of DAC@SC biocomposite.Full size imageBiosorption and regenerationThe adsorption of Cr(VI) and ARS was carried out by batch experiments in triplicate samples in 125 mL stoppered bottles that contained 50 mL of adsorbate solutions and adsorbent dose. Then, the stoppered bottles were shaken at 150 rpm on the thermostated shaker at room temperature (25 °C). Sodium hydroxide and hydrochloric acid were used to adjust the pH of solution. The liquid supernatants that contain the remaining un-adsorbed Cr(VI) and ARS were measured. Various parameters were studied such as contact time ((15–140 min) for Cr(VI) and (30–180 min) for ARS), temperature (25–45 °C), adsorbent dose ((0.025–0.2 g) for Cr(VI) and (0.025–0.4 g) for ARS), pH (2–8), initil concentration of adsorbate ((50-350 mg/L) for Cr(VI) and (25-400 mg/L) for ARS) and ionic strength (0.0–0.2 mol/L) of sodium chloride.The removal efficiency (R, %) and te amount of the adsorbed adsorbate at equilibrium qe (mg/g) were determined using Eqs. (2) and (3), respectively.$${ ext{R}}\%=frac{{ ext{C}}_{ ext{i}}-{ ext{C}}_{ ext{f}}}{{ ext{C}}_{ ext{i}}} imes 100$$
(2)
$${ ext{q}}_{ ext{e}}=frac{left({ ext{C}}_{ ext{i}}-{ ext{C}}_{ ext{f}}
ight) imes ext{v}}{m}$$
(3)
where, Ci (mg/L) is the initial concentration of adsorbate, Cf (mg/L) is the equilibrium adsorbate concentration, m (wt, g) is the adsorbent dose, and V (L) is the adsorbate solution volume.Regeneration of DAC@SC biocomposite was carried out by adsorption–desorption experiments. Cr(VI) adsorption experiments were carried out by using 0.1 g of DAC@SC and 50 mL (200 mg/L) of Cr(VI) solution at pH 2 for 100 min. ARS adsorption experiments were achieved by using 0.15 g f DAC@SC and 50 mL (100 mg/L) of ARS solution at pH 2 for 120 min. For desorption studies, 50 ml of eluent 0.1 M k2CO3 and 0.1 g of DAC@SC-Cr(VI) or 0.15 g of DAC@SC-ARS were shaken for 1 . Finally, the regenerated adsorbents were used for another five repeated adsorption–desorption cycles.Preparation of real samplesWastewater sample preparationThe digestion of wastewater samples was elaborated by using 0.5 g of potassium per sulphate, K2S2O8, and 5 mL of 98% (w/w) H2SO4 were added to 1000 mL of water sample and heated for 2 h at 95 °C to digest all organic matter which may be present. After cooling to room temperature, 0.1 g of DAC@SC modified fiber was added to the sample and the pH value was adjusted to 2 with continuous stirring for 180 min and filtered. Another 0.1 g of DAC@SC modified flax fiber was added to the filtrate to ensure the complete separation of analytes. The remains of Cr(VI) or ARS were determined by using Unicam UV 2100 UV/Visible spectrometer at appropriate wavelngths.Results and discussionMaterials designSynthesis of dialdehyde cellulose (DAC)Potassium periodate is known as selective oxidizing agent which oxidizes two hydroxyl groups on two neighbring carbon atoms C2–C3 bond of the glucopyranoside ring that will be cleaved and converted into two dialdehyde groups. The oxidation degree which represents the percentage of monosaccharide units that reacted with periodate is calculated by aldehyde content determination38. The Aldehyde content of the prepared oxidized fiber is 35.71% as it is presented in Table 1.Table 1 Volumetric titration of dialdehyde-cellulose (DAC) for determination of average aldehyde content percentage AC%:Full size tablePhysicochemical properties of native flax fiber and DAC@SC biosorbentBrunauer–Emmett–Teller (BET) surface area analysis was applied to evaluate the specific surface properties of the samples. The calculations of BET specific surface area showed that native flax fibers have a higher surface area (44.2151 m2g) than that of the DAC@SC sorbent (10.3251 m2/g). The decrease of the specific surface area after chemical modification may be due to the covering of flax fiber pores by anchoring of semicabazide moieties which reduced the adsorption of N2 molecules used in the surface area measurement process. The relatively low surface area of the functionalized fibers indicated that the adsorption process Occurs mainly through the coordination of the semicarbazide groups with the Cr(VI) ions and ARS.The solubility of DAC@SC was investigated using different solvents such as ethanol 99.9%, HCl (0.1 M, 0.25 M, and 1 M) and NaOH (0.1 M, 0.25 M, and 1 M). It was evaluated that DAC@SC is not soluble in any used solvents.Optical imagesThe optical images of native flax fiber, oxidized flax fiber (DAC), modified flax fiber (DAC@SC), the metal-loaded DAC@SC-Cr(VI), the anionic dye-loaded DAC@SC-ARS and the regenerated DAC@SC are shown in Fig. 4a–f, respectively. The images showed obvious color changes for fax fiber before (pale yellow) and after modification with semicarbazide (golden yellow).Figure 4Optical images of (a) Native flax fibers, (b) oxidized flax fibers (DAC), (c) Semicarbazide modfied flax fibers (DAC@SC), (d) DAC@SC-ARS, (e) DAC@SC-Cr(VI), (f) regenerated DAC@SC.Full size imageCharacterizationElemental analysisThe obtained results of elemental analysis for both native flax and DAC@SC materials are present in Table 2. The increase in nitrogen percent from 0% in the case of native flax to 11.33% in the case of DAC@SC biosorbent is an indication of DAC@SC biosorbent formation. The inserted semicarbazide moieties were calculated to be approximately 1.41 mmol/g.Table 2 Elemental analysis of native flax fibers and DAC@SC biosorbent.Full size tableMorphologyThe surface morphology of native (Fig. 5a), oxidized (Fig. 5b) and DAC@SC modified flax (Fig. 5c) fibers has been detected by the scanning electron microscope. The presence of narrow strips on the oxidized fiber surface is deected as present in Fig. 5b and this may be returned to the periodate action during the oxidation process39. In Fig. 5c, the surface becomes rougher than the native and the oxidized which may e due to the chemical reaction between the semicarbazide.HCl and the oxidized flax fiber to form DAC@SC biocomposite.Figure 5SEM of (a) native flax fiber, (b) oxidized flax fiber, and (c) DAC@SC biocomposite.Full size imageTransmission electron microscopy (TEM)Transmission electron microscopy (TEM) was used for investigating the internal shape of DAC@SC biocomposite. Figure 6 shows the formation of particles of size ranging between 14.51 nm and 1.685 µm. in addition to nondisintegrated fibrils that were also observed.Figure 6Transmission electron micrograph (TEM) of a cross section of DAC@SC composite.Full size imageFTIR spectraFTIR analysis was used to reveal one of the distinguishing characteristics of DAC@SC biocomposite, which is knowing the type of active functional groups present on DAC@SC;thus estimating the ability of DAC@SC biocomposite to adsorb the anionic pollutants. The progressive steps for the synthesis of the DAC@SC as chelating fibers were recognized by utilizing FT-IRspectra and the obtained results are displayed in Fig. 7.Figure 7IR spectra of (a) native flax fiber, (b) oxidized flax fiber, (c) DAC@SC, (d.1) DAC@SC-Cr(VI), and (d.2) DAC@SC-ARS.Full size imageFigure 7a,b show the IR spectra of both native and oxidized strands flax fibers. The IR spectra of native strands flax fiber (Fig. 7a) gives fingerprint peak of C–O stretching vibrations at around 1070–1150 cm−1, peaks of O–H bending vibrations at around 1250–1420 cm−1 and peaks of O–H stretching vibrations at around 3500–3200 cm−1.The IR spectrum of oxidized flax fiber in Fig. 7b gives a new peak at around 1730 cm−1 which may be ascribed to aldehyde group stretching vibrations40.After the successive reaction with semicarbazide, the spectrum of the prepared DAC@SC (Fig. 7c) shows a new peak at nearly 160 cm−1 which can be ascribed to the azomethane group of the Schiff base which is formed between the dialdehyde groups of the oxidized flax fiber and the amino group of the semicarbazide and peakat nearly 3227 cm−1 which can be ascribed to the NH group of SC and broadening at 3404 cm−1 related to stretching vibration of the hydroxyl group and H bond of cellulose.Figure 7d shows the IR spectra of DAC@SC-Cr(VI) and DAC@SC-ARS after loading . Slight shifts related to stretching vibration of the hydroxyl group can be observed from 3404 to 3434 cm−1 for DAC@SC-Cr(VI) and 3439 cm−1 for DAC@SC-ARS and the peak became broader. Also, the peak of the azomethane is shifted for from 1682 to 1665 cm−1 for DAC@SC-Cr(VI) and 1667 cm−1 for DAC@SC-ARS36,39.
1H NMRThe most frequent analytical tools to study the structure of cellulose are solid and liquid phase nuclear magnetic resonance (NMR) while X-ray diffraction is appropriate for the characterization of the crystal forms41. Using solid phse 13C NMR also the different polymorphs of cellulose could be determined42, but it is less widely accessible and needs longer experiments than liquid phase NMR.The modified cellulose materials (DAC an DAC@SC) are insoluble in all molecular solvents42. Herein, we present the use of a DMSO/Trifluoroacetic acid mixture in the 1H NMR characterization of the DAC and DAC@SC biocomposite. 1H NMR confirmed the structure of the DAC and DAC@SC as present in Fig. 8. As an example, the 1H NMR of DAC present in Fig. 8a, showed a peak at 2.08 ppm is related to the proton that is present on C2 or C3. Broad peaks that appeared at 3.82 ppm and 4.98 ppm are related to 1H of C1 and OH, respectively. Figure 8b represents 1H NMR of DAC@SC biocomposite that showed new prominent peaks, broad signals around 2.91 ppm and 6.89 ppm that are attributed to NH and NH2 of semicarbazide, respectively.Figure 81H NMR of (a) DAC and (b) DAC@SC biocomposite.Full size imageX-ray diffractionXRD pattern of native, oxidize and modified flax fiber are shown in Fig. 9. The XRD patterns illustrate the main peak of crystalline flax at 22.835° which is related to the (200) reflection. Moreover, the less intense peaks arising t about 15.178°, 16.756°, and 34.475° are the characteristic of (11̅0), (110) and (004) reflections, respectively43,44,45. The peak around 2θ≈21 could be decrease in crystallinity due to amorphous part of the prepared modified flax fibre43. The decrease of crystallinity is due to the ring-opened formation of the glucopyranose units and destruction of their backbone. The crystallinity indices (CrI) of the samples were calculated according to the Segal method46.$${ ext{CrI}}\% =frac{{{{I}}_{200}} , – , {{{I}}_{ ext{am}}} , }{{{{I}}_{200}}} imes , 100$$
(4)
where I200 is the intensity of the crystal peak at the maximum 2θ = 22.835° and Iam is the intensity at the minimum at 2θ = 15.185°. The crystallinity indexes of native, oxidized and modified flax fibers are 73.19,71.77, and 71.24%, respectively. These results reveal that the ordered structure of crystalline flax fiber is not significantly altered after the modification process of flax fibers.Figure 9XRD patterns of flax,oxidized flax and DAC@SC samples.Full size imageThermogravimetric analysis (TGA)The TGA curves of oxidized cellulose and DAC@SC biocomposite samples were shown in Fig. 10. For oxidized flax fiber, Fig. 10a, the sample shows an initial weight loss ranging from 80 to 250 °C that would be related to the evaporation of the adsorbed water molecules. The second weight loss gradually starts at 250 °C which leads to a sharp fall at 330–400 °C. This would be corresponding to the degradation of the holocellulose content of flax fibers degradation and another degradation that appeared at 480 °C was observed. Oxidation of cellulose leads to a variation in the structure, crystallinity, and degree of polymerization, which in turn affect its physical and chemical properties47,48.Figure 10Theral analysis of (a) DAC and (b) DAC@SC composite.Full size imageWhile for DAC@SC, Fig. 10b, the first degradation step for DAC@SC biocomposite begins at 30 °C until 265 °C, which was due to the evaporation of the esidual water present in cellulose components49. The second degradation step occurred from 265 to 371 °C, DAC@SC biocomposite displayed gradual thermal transitions, basically related to the cellulosic chain degradation50. The major decomposition happened 272–372 °C range which indicates the pyrolysis of cellulose51. At 800 °C, the ash content of DAC powder is 4.1% increased to 18.3% in the case of DAC@SC biocomposite with the loading of semicarbazide, which proves increasing the thermal stability of the oxidized fibers with the loading of semicarbazide.Adsorption studiesPoint of zero charge (pHPZC)The point of zero charge of the biosorbent is one way to understand the biosorption mechanisms. The surface charge of DAC@SC biocomposite was evaluated by measuring the pH at the poit of zero charge (pHPZC). Generally, the adsorbent will exhibit better affinities for anions at pH < pHPZC and vice versa. The pHPZC value obtained for DAC@SC biocomposite was approximately 6.04. It was expecte that the adsorption of Cr(VI) and ARS could be enhanced at the experimental pH (pH 2) due to electrostatic interaction between the main species of Cr(VI), Cr2O72−, HCr2O7−, and SO3− of ARS and nitrogen-containing functional groups such as –NH3+ on the surface of DAC@SC52,53. Similar results were reported by Ma et al., in which their research observed that the electrostatic attraction between Cr(VI) and protonated amino groups increased the Cr(VI) removal efficiencies under acidic conditions54. In addition, the composition of flax fibers comprises abundant oxygen-containing functional groups such as –OH. Because of the protonation effect, the surface of adsorbents will have positive charges below pHPZC, thus improving the attraction for anions55.Effect of pHThe initial pH of he mixture solution plays an important role in biosorption of analytes due to its impact on the active binding sites of the biosorbent and species distribution of the metal ions and dyes56,57. The adsorption of Cr(I) and ARS are strongly pH dependent. So, the studying of pH parameter is very important. The pH parameter for Cr(VI) adsorption was studied by adding 0.1 g of DAC@SC to 50 mL of the 100 mg/L Cr(VI) aqueous solution at 25 °C for 2 h. ARS adsorption pH parameter was studied by adding 0.15 g of DAC@SC biocomposite to 50 mL of the 100 mg/L ARS aqueous solution at 25 °C for 2 h. In pH range (2–8), the Cr(VI) and ARS uptake were examined as a function of hydrogen ion concentration as present in Fig. 11a,b, respectively. It was observed that the maximum adsorption capacity was at pH 2. Experimental data confirms that the adsorption capacity for Cr(VI) and ARS are highly pH-dependent.Figure 11Effect of pH on adsorption of (a) Cr(VI) and (b) ARS (conditions: 0.1 g of DAC@SC in 50 mLof the 100 mg/L Cr(VI) solution. 0.15 g of DAC@SC in 50 mL of the 100 mg/L ARS aqueous solution at 25 °C for 2 h).Full size imageAs the initial pH increased from 2 to 4, the removal % of Cr(VI) ions and ARS dye decrased very sharply and after that it decreased gradually throughout the process at around 20.0% and 15% for Cr(VI) and ARS, respectively. A similar trend was also observed with the removal of hexavalent chromium using other biosorbents including activated carbon developed from date palm seed, invasive biomass Sargassum muticum, chufa corm peels, and walnut hull58,59.Hexavalent chromium ions exist in different forms in an aqueous solution such as HCrO4−, Cr2O72−, CrO42−and the stability of these forms depends mainly on the pH of the medium. It is well known that at very low pH values (pH < 4), the dominant anionic chromium species is the acid chromate ion (HCrO4−)60. In this pH range, the surface of biosorbent, which is highly positively charged due to protonation of functonal groups of adsorbent, attracts strongly HCrO4−. However, as the pH increased, the predominant form HCrO4− shifts to CrO42− and Cr2O72− ions and also the degree of protonation of the biosorbent surface reduces graually. So, the lower adsorption capacity observed from pH 4.0 may be explained by the competition of these anionic ions with OH− ions to be adsorbed on the surface of the adsorbent of which OH− predominates61.For the following adsorption experiments, pH 2.0 was selected as the optimum pH value for Cr(VI) solution. It was also observed that the decreasing of adsorption capacity with pH increasing from 2 to 8.Because of the strong protonation, the adsorbent surface becomes positively charged at low pH. The Cr(VI) adsorption was enhanced due to the electrostatic force between negatively-charged HCrO4− and Cr2O7–2 and SO3− of ARS and the positively charged adsorbent surface. Thus, this, in turn, enhances the affinity of DAC@SC biocomposite towards attracting positively chargedmetal ion and dye molecules depending on pH control, causing the improvement of Cr(VI) and ARS adsorption as shown in the equations below (5) and (6), respectively.$${ ext{DAC}}@{ ext{SC}}^{ + } + , left( {{ ext{RS}}}
ight) , – { ext{ SO}}_{{3}}^{ – } leftrightarrow { ext{DAC}}@{ ext{SC}}^{ + } ldots { ext{SO}}_{{3}}^{ – } left( {{ ext{ARS}}}
ight)$$
(5)
$${ ext{DAC}}@{ ext{SC}}^{ + } + , left( {{ ext{Cr}}left( {{ ext{VI}}}
ight)}
ight) – { ext{O}}^{ – } leftrightarrow { ext{DAC}}@{ ext{SC}}^{ + } ldots { ext{O}}^{ – } left( {{ ext{Cr}}left( {{ ext{VI}}}
ight)}
ight)$$
(6)
Effect of sorbent doseAdsorbent dose is very important parameter in adsorption capacity determination. It was investigated by adding various weights of DAC@SC adsorbent in 50 mL aqueous solution of 200 mg/L for Cr(VI) solution and 100 mg/L for ARS solution at 25 °C for 2 h at pH 2. It was observed that the removal efficiency and adsorption capaciy of Cr(VI) increased from 20 to 97.4%, and from 80 to 97.4 mg/g, respectively when the adsorbent dose from 0.025 to 0.1 g As the adsorbent dose was increased from 0.1 to 0.2 g, the removal efficiency showed few changes and adsorptioncapacity decreased from 97.4 to 48.925 mg/g as it is depicted in Fig. 12a. It is also observed that removal % of ARS increased from 10.9 to 94.13% and adsorption capacity increased from 13.08 to 18.83 mg/g with increasing the adsorbent dose from 0.025 to 0.15 g. With increasing the adsorbent dose from 0.15 to 0.4 g, the removal % showed slightly increasing and adsorption capacity decreased from 18.83 to 7.06 mg/g as it is depicted in Fig. 12b. This may be due to the increase in the specific surface area of the adsorbent and the presence of more available adsorption sites.Figure 12Effect of sorbent dose on adsorption of (a) Cr(VI) and (b) ARS(conditions: 50 mL aqueous solution of 200 mg/L for Cr(VI) solution and 100 mg/L for ARS solution at 25 °C for 2 h a pH 2).Full size imageEffect of initial concentration of Cr(VI) and ARSTo study the effect of initial concentration on Cr(VI) and ARS adsorption capacity, a 50 mL solution of Cr(VI) and ARS at a fixed-dose of DAC@SC adsorbent 0.1 g forCr(VI) and 0.15 g for ARS were taken at pH 2 for 2 h in range (50–350 ppm for Cr(VI) and 25–400 ppm for ARS). After that, initial concentrations were varied and the corresponding adsorption capacities and removal percentages were evaluated as shown in Fig. 13a,b. It was noticed that the adsorption capacity increased from 24.9 to 97.4 mg/g, and from 4.49 to 18.83 mg/g for Cr(VI) and ARS, respectively. With initial concentration increasing from 50 to 200 ppm for Cr(VI) and from 25 to 100 ppm for ARS. Moreover, with the increasing of initial concentration from 200 to 350 ppm for Cr(VI) and from 100 to 400 ppm for ARS, the adsorption capacities remained constant.Figure 13Effect of sorbent dose on adsorption of (a) Cr(VI) and (b) ARS (conditions: 0.1 g of DACSC for Cr(VI) and 0.15 g of DAC@SC for ARS were taken at pH 2 for 2 h in range 50–350 ppm for Cr(VI) and 25–400 ppm for ARS).Full size imageBiosorption isothermsThe adsorption isotherm of chromium (VI) ions and ARS onto DAC@SC biocomposte was studied by varying the initial concentration of metal from 30 to 300 mg/L, keeping other factors unchanged. The equilibrium biosorption was modeled using the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm equations. The coefficient of determination, R2, was employed to ascertain the fit of these isotherms with experimental data.The Langmuir isotherm is based on the assumption of monolayer coverage of adsorbate over a homogenous adsorbent surface with a finite number of adsorption sites.The model equation is represented by the following linearized equation:$$frac{{{ ext{C}}_{{ ext{e}}} }}{{{ ext{q}}_{{ ext{e}}} }} = frac{1}{{{ ext{k}}_{{ ext{L}}} { ext{q}}_{{ ext{m}}} }} + frac{{{ ext{C}}_{{ ext{e}}} }}{{{ ext{q}}_{{ ext{m}} }}$$
(7)
The Freundlich isotherm assumes a heterogeneous surface of the adsorbent and linearized form of the model is as follows:$$ ext{ln}{q}_{e}={ ext{ln}}{K}_{f}+frac{1}{n}{ ext{ln}}{C}_{e}$$
(8)
The D–R isotherm modl assumes that biosorption is related to surface porosity and pore volume, and examines biosorption energetically. The mean free energy of biosorption (EDR) obtained from the d–R model determines whether the adsorption structure is chemical or physical. 8< EDR < 16 kJ mol−1 indicates that the adsorption has a chemical character. If EDR < 8 kJ mol−1, it determines that the adsorption is physical13,62.The model equation is represented by the following linearized equation:$${ ext{lnq}}_{e}= ext{ ln}{ ext{q}}_{m} – ext{ k}{upvarepsilon }^{2}$$
(9)
where, Ce (ppm) is the initial concentration of the studied pollutant at equilibrium, qe (mg/g) is the capacity of the adsorbent for pollutant concentration at equilibrum, qm (mg/g) adsorption maximum amount, 1 , KL, KF, and K are heterogeneity factor, Langmuir coefficient (L/mg), Freundlich constant (mg g-1), and the Dubinin–Radushkevich constant, respectively. While ε is the adsorption potential and is given by Eq. (10).$$uvarepsilon = ext{RTln}left(1+frac{1}{{ ext{C}}_{ ext{e}}}
ight)$$
(10)
where R (8.314 J/mol K) is the gas constant, and T is the temperature in kelvin.The Langmuir, Freundlich and D-R isotherms determined for the biosorption of Cr(VI) and ARS to the DAC@SC biosorbent are shown in Fig. 14 and their derived parameters are given in Table 3. The Langmuir isotherm model (R2 = 0.999) seemed to describe better the adsorption process of Cr(VI) and ARS by the DAC@SC biocomposite than the Freundlich isotherm model (R2(Cr(VI) = 0.1272, R2(ARS) = 0.2027) This shows that the Cr(VI) and ARS molecules bind to the active sites on the biosorbent surface as a mono-layer. The maximum biosorbent capacity of Cr(VI) and ARS are 9.4mg/g, and 18.83 mg/g, respectively. The EDR of biosorption from the D-R model was calculated as 11.083 and 8.512 kJ mol−1 for Cr(VI) and ARS, respectively. These values suggest that the bio-sorption process of Cr(VI) and ARS onto the DAC@SC biocomposite may be carried ut by a mechanism being chemical in nature because the sorption energy lies within 8–16 kJ mol−1show that the Cr(VI) and ARS biosorption process on the biosorbent is chemisorption66.Figure 14Biosorption isotherms by DAC@SC: (a) Langmuir isotherm model for Cr(VI), (b) Langmuir isotherm model for ARS, (c) Freundlich isotherm model for Cr(VI), (d) Freundlich isotherm model for ARS, (e) DR isotherm model for Cr(VI), and (f) D-R isotherm model for ARS.Full size imageTable 3 Biosorption isotherm parameters of Cr(VI) and ARS by DAC@SC.Full size tableThe essential characteristics of the Langmuir isotherm parameters can be used to predict the affinity between the sorbate and sorbent using separation factor or dimensionless equiibrium parameter, “RL”, expressed as in the following equation63.$${R}_{l }= frac{1}{1+{K}_{l}{C}_{ ext{o}}}$$
(11)
In the present study, the RL values obtained for all initial concentrations of metal ions lie between 0 and 1 (Table 3), indicating that biosorptionof Cr(VI) ions and ARS by DAC@SC is a favorable process. This suggests the applicability of this biosorbent for Cr(VI) ion removal from aqueous solutions.Effect of oscillation time and adsorption kineticsOscillation time is an important parameter for the investigation of sorption efficiency. The contact time parameter for Cr(VI) adsorption was studied at different times from 30 to 140 min by using 0.1 g of (DAC@SC) material as an adsorbent dose that were respectively added to a series of bottles that contain 50 mL of 200 mg/L Cr(VI) solutions at 25 °C as shown in Fig. 15a. Contact time parameter for ARS adsorption was studied at different time from 15 to 180 min by adding 0.15 g of (DAC@SC) adsorbent to a seris of bottles that contain 50 mL of 100 mg/L of ARS solutions at 25 °C as shown in Fig. 15b. It is clear that the adsorption capacity of DAC@SC increased rapidly with the increase of contact time from 20 to 120 min and more than 90% of the equilibrium adsorption capacity for the tw analytes occurred within 100 min. At 120 min, the adsorption capacity became constant and the adsorption reached equilibrium. As shown, the adsorption process was divided into three stages: (1) an initial stage with adsorption occurring instantly; (2) subsequently slow adsorption and (3) a final stage with adsorption reaching equilibrium and remaining constant. The first stage can be attributed to the rapid attachment of the Cr(VI) and ARS to the surface of DAC@SC by surface mass transfer. At this stage, more than 80% of adsorption was found in the two cases. The second stage was slower, possibly because many of the available external sites were already occupied and because of the slow diffusion of analyte mlecules into the network of DAC@SC.Figure 15Effect of oscillation time on adsorption of (a) Cr(VI) (conditions: 0.1 g of DAC@SC, 50 mL of 200 mg/L Cr(VI), Temp.: 25 °C, time: 30–140 min). (b) ARS (conditions: 0.15 g DAC@SC, 50 mL of 100 mg/L of ARS, Temp.: 25 °C and time: 15–180 mi).Full size imageParameters obtained by adsorption kinetic studies provide information about the determination of the adsorption rate, modeling of the adsorption process, and metal interactions between the adsorbate and the adsorbent26. Pseudo-first-order kinetic (PFO) model, pseudo-second-order kinetic (PSO) model and intraparticle diffusion (IPD) models were applied to determine the adsorption kinetics of Cr(VI) and ARS on the DAC@SC biosorbent surface.The PFO model is used for reversible reactions in which an equilibrium is established between the liquid and solid phases. The PFO equation is shown in Eq. (12).$${1}/{ ext{q}}_{{ ext{t}}} left( {{ ext{ads}}}
ight) , = { ext{ k}}_{{1}} /{ ext{q}}_{{ ext{e}}({ ext{ads}})}} { ext{t }} + { 1}/{ ext{q}}_{{{ ext{e}}({ ext{ads}})}}$$
(12)
The PSO kinetic model is applied in chemical adsorption processes that generate covalent forces through the sharing or exchange of electrons between the biosorbent and the adsorbate. Th pseudo-second-order equation is shown in Eq. (13)$${ ext{t}}/{ ext{q}}_{{{ ext{t}}({ ext{ads}})}} = {1}/{ ext{k}}_{{2}} { ext{q}}_{{ ext{e(ads)}}}^{{2}} + , left( {{1}/{ ext{q}}_{{{ ext{e}}({ ext{ads}})}} }
ight){ ext{t}}$$
(13)
The intraparticle diffusion model (IPD) is shown in Eq. (14):$${q}_{t}={k}_{diff}{ imes t}^{0.5}+C$$
(14)
where qe(ads) (mg g-1) and qt(ads) (mg g-1), are the adsorption abilities at equilibrium and at time t (min), respectively. K2 is the pseudo-second-order adsorption rate constant, K1 is pseudo-first-order sorption rate constant, and Kdiff is IPD rate constant. C is the intercept and reflects the boundary layer effect. It was nticed that the contribution of the surface adsorption in the rate-limiting step increased with the intercept increasing.The fit of the experimental data to the PFO, PSO and IPD models is presented in Fig. 16 and the kinetic parameters derived from these models are presented in Table 4. It was observed that he adsorption of Cr(VI) and ARS reached equilibrium within 120 min (2 h) (Fig. 15). When the correlation coefficients (R2) of the PFO and PSO models were compared with each other, it was seen that the results fit the PSO kinetic model better. The appearance of two line components instead of a single line passing through the origin in the IPD model graph indicates that adsorption includes different diffusion stages that take place both on the surface and inside the surface. In this case, it was shown that it is not possible to explain the adsorption with a single kinetic model. Figure 16e,f of the IPD model for ARS and Cr(VI) adsorption reveal that the adsorption provides different dffusion stages that occurred on the DAC@SC surface and inside its surface. At first, the adsorption occurred fastly as many active sites are present. Then, with time passing the number of active sites on the DAC@SC biocomposite decreases and the diffusion of Cr(VI) and ARS into pores becomes more difficult s the adsorption becomes slower64,65.Figure 16Adsorption kinetics by DAC@SC: (a) Pseudo 1st order for Cr(VI), (b) Pseudo 1st order for ARS, (c) Pseudo 2nd order for Cr(VI), (d) Pseudo 2nd order for ARS, (e) IPD model for Cr(VI)and (f) IPD model for ARS.Full size imageTable 4 Kinetic parameters for the adsorption of Cr(VI) and ARS onto DAC@SC biosorbent.Full size tableThermodynamic studiesTo explore the adsorption process of Cr(VI) and ARS dye onto the DAC@SC biocomposite surface in terms of spontaneity and feasibility and to determine the degree of randomness at the solid/liquid interface, adsorption thermodynamic parameters were determined.The adsorption of Cr(VI) and ARS was studid at different temperatures from 25 to 45 °C at pH 2 for 2 h. Free energy parameter (ΔG°ads), adsorption entropy parameter (ΔS°ads), and heat of enthalpy parameter (ΔH°ads) of Cr(VI) metal ion, and ARS dye adsorption by DAC@SC adsorbent were calculated. ΔG°ads parameter was calculated from the following equatons Eqs. (15), (16) and (17).$${ ext{K}}_{{ ext{C}}} = { ext{C}}_{{{ ext{ad}}}} /{ ext{C}}_{{ ext{e}}}$$
(15)
$$Delta { ext{G}}^{ circ }_{{{ ext{ads}}}} { ext{n }} = , – { ext{RT ln K}}_{{ ext{C}}}$$
(16)
$$ ext{ln K}_ ext{C} = Delta ext{S}^{ circ}_ ext{adsn} /{ ext{R}} – Delta ext{H}^{circ}_ ext{adsn} / ext{RT}$$
(17)
where Kc is a thermodynamic equilibrium constant, Cad is the adsorbate (Cr(VI) or ARS) concentration taken by DAC@SC material at equilibrium (mg/g), Ce is the adsorbate (Cr(VI) or ARS) concentration at equilibrium (mg/L), and R is the universal gas constant.The rest of the parameters (ΔH°adsn and S°adsn) were calculated from the plot of ln Kc vs. 1/T as the slope of the plotting equals (− ΔH°adsn/R), and the intercept equals (ΔS°adsn/R), Fig. 17.Figure 17Plot of ln KC vs (1/T) absolute temperature for the adsorption of (a) Cr(VI); (b) ARS.Full size imageFrom the experimental data that present in Table 5, it was noticed that te negative ΔG°adsn value confirms that the adsorption of Cr(VI) and ARS by DAC@SC biocomposite is a spontaneous process. It was also observed that the negative ΔH°ads value confirms that the adsorption of Cr(VI) and ARS by DAC@SC material is exothermic. The negative ΔS°ads values showed that Cr(VI) metal ion, and ARS adsorption onto DAC@SC surface leads to lower disorder and higher arrangement66,67,68.Table 5 Thermodynamic parameters for the biosorption of Cr(VI) and ARS onto DAC@SC.Full size tableEffect of ionic strength on the adsorption capacityIonic strength parameter was studied by using Cl− inorganic electrolyte in the form KCl. It was investigated b the addition of 0.1 g of DAC@SC respectively to 50 mL aqueous solution of 200 mg/L Cr(VI), 100 mg/L ARS at 25 °C for 3 h and KCl concentration range between 0 and 0.2 mol/L. From experimental data shown in Fig. 18a,b, it can be noticed that with increasing inorganic electrolyte concentration, the adsorption capacity was decreased. A inding which indicated that the presence of inorganic electrolytes suppress the analyte’s adsorption3.Figure 18Effect of ionic strength on adsorption of: (a) Cr(VI); (b) ARS.Full size imageDesorption and reusability studiesDifferent eluents were tried for desorption of Cr(VI) and ARS from the DAC@SC as ethanol, HCl (0.2 M), NaOH (0.2 M), NaHCO3 (0.1 M) and K2CO3. It was found that K2CO3 was the most effective one among them. 0.1 M K2CO3 was successfully used for desorption of the target adsorbates from DAC@SC biocomposite at room temperature, Table 6.Table 6 Repeated adsorption–desorption cycles for DAC@SC regeneration by using K2C2O3.Full size tableThe r-usability of DAC@SC biocomposite was investigated for five cycles of sorption–desorption sequences under the optimum conditions. From the data presented in Table 6, it can be observed that DAC@SC has high sorption efficiency after five cycles (higher than 90%). So, it is predictable that DAC@SC could be a good sorbent for Cr(VI) and AS removal from aquatic solutions.Removal of Cr(VI) and ARS from multi-components’ solution using DAC@SC biosorbentAs actual wastewater contains different types of organic and inorganic contaminants together, it is important to examine the adsorption capability of synthesized DAC@SC in mixtures. For the adsorption experiment, 0.1 g of DAC@SC was added to 25 mL of each adsorbate solutions (100 ppm) at pH 2. Then the mixture was shaken at 120 rpm for 3 h. The equilibrium concentration of the adsorbates was calculated from UV–Vis data. The adsorption efficiency of anionic adsorbates is calculated using Eq. (2). The optical images of Cr(VI), ARS, Cr(VI) + ARSsolutions before and after adsorption in single and binary manner are shown in Fig. 19a–c. Obvious color changes can be noticed before and after adsorption of the single anion and mixed anion solutions. The absorption spectra of Cr(VI) and ARS solutions before adsorption and the absorption spectrum of the remain after adsorption are preented in Fig. 20a–c. For Cr(VI) the UV–Vis spectrum(Fig. 20a) shows two peaks at 395 and 447 nm while the UV–Vis spectrum of ARS(Fig. 20b) shows maximum peak at 436 nm. On the other hand, Fig. 20c shows that when the two anionic pollutants were mixed, overlapping of the peaks occurred and a new peak appeared at 470 nm. It was observed that at time 3 h, the new peak was completely disappeared. Additionally, the concentration of each of Cr(VI) and ARS in the remaining after adsorption of the mixture was determined. More than 95% of both Cr(VI) and ARS were simultaneously removed by the DAC@SC biocomposite.Figure 19Optical image of (a) Cr(VI) solution befoe and after adsorption, (b) ARS solution before and after adsorption, (c) mixture of ARS and Cr(VI) solution before and after adsorption.Full size imageFigure 20UV spectra of (a) of Cr (VI) before adsorption, (b) ARS before adsorption (c) UV spectra of mixture of Cr (VI) and ARS before and after adsorption by DAC@SC at different time intrvals.Full size imagePlausible mechanism of biosorption of Cr(VI) and ARS onto DAC@SC biosorbentTo investigate the possible mechanism of Cr(VI) adsorption on DAC@SC, morphology, surface charge and FTIR of the adsorbents were evaluated. The adsorption mechanism of the Cr(VI) and ARS anionic dye was designed in light of the effective groups available on DAC@SC surface as shown in Fig. 21. In fact, DAC@SC biocomposite is very abundant with active groups that can adsorb both anionic pollutants. These active groups come from the fact that the adsorbent is composed of dialdehyde cellulose and semicarbazide which in their origin are rich in active groups. Thu, the active groups are amino (–NH2), carbonyl, hydroxyl (-OH). In the acidic medium, the DAC@SC biocomposite acts on the adsorption of the Cr(VI) through the electrostatic interactions between the negatively charged oxygen on Cr(VI) and the positively charged groups (–NH3+, –OH+) of the DAC@SC biocomposite, Fig. 21a.Figure 21Plausible mehanism of biosorption of (a) Cr(VI) ions and (b) ARS onto DAC@SC.Full size imageOn the other hand, in the acidic medium, the DAC@SC biocomposite acts on the adsorption of the ARS dye through the electrostatic interactions between the sulfonate groups (–SO3−) of the ARS dye and the positively charged groups (–NH3+, –OH+) of the DAC@SC biocomposite, Fig. 21b. In addition, hydrogen interactions also play a vital role in the adsorption process for both species through the interaction between hydrogen on the surface of DAC@SC adsorbent and atoms including oxygen and nitrogen in the structure of the Cr(VI) and ARS, respectively69.Finally, n–π’s interactionscontribute to the adsorption process of ARS dye through the interaction between the electron-donating system represented by the nitrogen and oxygen groups in DAC@SC adsorbent and the electron-gaining system represented by the aromatic rings of ARS dye70, Fig. 21b.ApplicationsAnalysis of wastewater samplesAnalysis of wastewater samples was sed for offered method accuracy confirmation. From the experimental results present in Table 7, it was noted that a good covenant was achieved between the added adsorbate concentration and the obtained one by using the test procedure. The recoveries higher than 90% show that the anticipated procedure gives a suitable accuracy on real samples analysis.Table 7 Analysis of Cr(VI) and ARS in spiked wastewater samples by DAC@SC biosorbent (n = 3).Full size tableRemoval of Cr(VI) and ARS from simulated synthetic effluentsThe prepared DAC@SC biosrbent was tested for decontamination of synthetic effluents to check the usefulness of DAC@SC biosorbent in realapplications. Two simulated synthetic effluents were prepared as defined in Table 8. The synthetic effluents are consisting of various surfactants and salts. Each sample was spiked with different amounts of Cr(VI) and ARS and the process of SPE and determination of Cr(VI) and ARS was performed as previously mentioned. The results obtain areshown in Table 8. As it can be noticed, the DAC@SC was able to remove more than 95% of Cr(VI) and ARS from effluent A and B. Based on these results, we can conclude that the DAC@SC could be used successfully in the field of real wastewater treatment.Table 8 Determination of Cr(VI) and ARS in synthetic effluents by biosorption using 5 mg DAC@SC biocomposite at pH 2.0 (n = 5).Full size tablePerformance of the prepared DAC@SCIn order to enhance the value of our adsorbent, we carried out a comparative study of the maximum adsorption capacity obtained for the same pollutant to other adsorbents and activated carbon reported in the literature. Table 9 groued together the different values of qmax for the different adsorbents. We can see that the Cr(VI) and ARS adsorption observed in the present study is well positioned with respect to other researches with a maximum adsorption capacity qmax of 97.4 for Cr(VI) and 18.84 for ARS at 298 K, relatively, interesting compared to other adsorbents. Thedifferences of the Cr(VI) and ARS uptakes are due to the morphological properties of each adsorbent like the structure, the functional groups and the surface area. DAC@SC could be an attractive adsorbent for anionic species owing to its isoelectric point pHpzc. Desorption is an unavoidable process and is an intermediate stage toward the adsorbent regeneration. The latter is an essential point to estimate the reutilization of any adsorbent for industrial applications, owing to the ecological concerns and the needs for sustainable development. In the future, column scale and pilot plant experiments can be implemented to be applied in the wastewater teatment plant for cationic and anionic metal ions and textile dye removal from wastewater.Table 9 Comparison of equilibrium time of various adsorbents for Cr(VI) and ARS.Full size tableConclusionIn this work, flax fiber based semicarbazide biosorbent was prepared in two successive steps. In the first step, flax fibers were oxidized using potasium periodate (KIO4) to yield diadehyde cellulose (DAC). Dialdehyde cellulose was, then, refluxed with semicarbazide.HCl to produce the semicarbazide functionalized dialdehyde cellulose (DAC@SC). The prepared DAC@SC biocomposite was characterized by the BET, elemental analysis, FTIR, 1HNMR, SEM, TEM, TGA and XRD methods. The efficiency of the DAC@SC biocomposite was studied for the removal of Cr(VI) and ARS from aqueous solutions; the influence of the initial pH, Cr(VI) and ARS concentration, contact time, adsorbent dose and temperature on adsorption of Cr(VI) and ARS were investigated. When pH is 2, oscillation time is 120 min, and temperature i 25 °C, the maximum adsorption capacity was found to be 97.4 mg/g and 18.84 mg/g for Cr(VI) and ARS, respectively. The adsorption process here was well matched to PSO and Langmuir models. The 8 < EDR > 16 kJ/mol determined according to the D–R isotherm showed that the biosorption proceeded chemically. The negative free enthalpy ΔG° and ngative enthalpy ΔH° indicated that the adsorption of Cr(VI) and ARS onto DAC@SC is spontaneous and exothermic over the studied temperatures range. The prepared DAC@SC was regenerated using K2CO3 eluent. The plausible mechanism of adsorption of Cr(VI) and ARS dye on the surface of DAC@SC biocomposite is supposed to proceed through chemical interactions, the most prominent of which are electrostatic, H-bonding, and n–π interactions. This work points out that DAC@SC biocomposite could be used as a promising and effective adsorbent biosorbent for the removal of toxic anionic species from wastewater.The comparison of the maximum biosorption capacity o DAC@SC biosorbent with other sorbents used in Cr(VI) and ARS removal reported in the literature is given in Table 9. According to these results, it was determined that DAC@SC biosorbent is an effective biosorbent for Cr(VI) and ARS removal. In addition, due to the fact that flax is abundant, low cost and renewable due to being agricultural wase, DAC@SC biosorbent can be used as an alternative biosorbent in the removal of dyes and metal ions in wastewater.Finally, the process of synthesis of DAC@SC biosorbent, biosorption of analytes and the plausible mechanism of biosorption are represented in Fig. 22.Figure 22Synthesis of DAC@SC and its use for biosorption of Cr(VI) and ARS.Full size image
Data availability
All data generated or analysed during this study are included in this published article.
ReferencesZhou, Y., Lu, J., Zhou, Y. & Liu, Y. Recent advances for dyes removal using novel adsorbents: A review. Environ. Pollut. 252, 352–365. htts://doi.org/10.1016/j.envpol.2019.05.072 (2019).Article
CAS
PubMed
Google Scholar
Aragaw, T. A. & Bogale, F. M. Biomass-based adsorbents for removal of dyes from wastewater: A review. Front. Environ. Sci. 9, 558. https://doi.org/10.3389/fenvs (2021).Article
Google Scholar
Sureshkumar, V., Daniel, S. K., Ruckmani, K. & Sivakumar, . Fabrication of chitosan–magnetite nanocomposite strip for chromium removal. Appl. Nanosci. 6(2), 277–285. https://doi.org/10.1007/s13204-015-0429-3 (2016).Article
ADS
CAS
Google Scholar
Mukherjee, T., Das, P., Ghosh, S. K. & Rahaman, M. Removal of Alizarin Red S from Wastewater: Optimizing the Process Parameters for Electrocoagulation Using Taguchi Method (Springer, 2019).
Google Scholar
Gollakota, A. R. et al. Coal bottom ash derived zeolite (SSZ-13) for the sorption of synthetic anion Alizarin Red S (ARS) dye. J. Hazard. Mater. 416, 125925. https://doi.org/10.106/j.jhazmat.2021.125925 (2021).Article
CAS
PubMed
Google Scholar
Varghese, A. G., Paul, S. A. & Latha, M. S. Remediation of heavy metals and dyes from wastewater using cellulose-based adsorbents. Environ. Chem. Lett. 17, 867–877. https://doi.org/10.1007/s10311-018-00843-z (2019).Article
CAS
Google Scholar
Saravanan, A. et al. Adsorption characteristics of magneti nanoparticles coated mixed fungal biomass for toxic Cr (VI) ions in aquatic environment. Chemosphere 267, 129226. https://doi.org/10.1016/j.chemosphere.2020.129226 (2021).Article
ADS
CAS
PubMed
Google Scholar
Ahmad, A. et al. Recent advances in new generation dye removal technologies: Novel search for approaches to reprocess wastewater. RSC Adv. 5(39), 30801–30818. https://doi.org/10.1039/c4ra16959j (2015).Article
ADS
CAS
Google Scholar
Yahiaoui, C., Kameche, M., Innocent, C. & Khenifi, A. Conception of yeast microbial esalination cell: Applications to dye wastewater treatment and lead removal. Chem. Eng. Commun. 208(3), 364–375. https://doi.org/10.1080/00986445.2020.1721479 (2021).Article
CAS
Google Scholar
Aragaw, T. A. Recovery of iron hydroxides from electro-coagulated sludge for adsorption removals of dye wastewater: Adsorption capacity and adsorbent characteristics. Surf. Interfaces 18, 100439. https://doi.org/10.1016/j.surfn.2020.100439 (2020).Article
CAS
Google Scholar
Keskin, Z. S., Şenol, Z. M., Kaya, S. & Şimşek, S. Prunus mahaleb shell as a sustainable bioresource for carminic acid removal from aqueous solution: Experimental and theoretical studies. J. Mol. Struct. 1275, 134618. https://doi.org/10.1016/j.molstruc.2022.134618 (2023).Article
CAS
Google Scholar
Vakili, M. et al. Regeneration of chitosan-based adsorbents for eliminating dyes from aqueous solutions. Sep. Purif. Rev. 48(1), 1–13. https://doi.org/10.1080/1542119.2017.1406860 (2019).Article
CAS
Google Scholar
Mongioví, C. et al. Biosorbents from plant fibers of hemp and flax for metal removal: Comparison of their biosorption properties. Molecules 26(14), 4199. https://doi.org/10.3390/molecules26144199 (2021).Article
CAS
PubMed
PubMed Central
Google Scholar
Bouloc, P., Allegret, S. & Arnaud, L. Hemp: Industrial Production and Uses (CABI, 2013).Book
Google Scholar
Bono, P., Duc, A. L., Lozachmeur, M. & Day, A. Materials: New fields of research and development for the valorization of technical plant fibers (flax fiber and hemp). Oilseeds Fats Crops Lipids 22, 6 (2015).
Google Scholar
Fike, J. Industrial hemp: Renewed opportunities for an ancient crop. Crit. Rev. Plant Sci. 35(5–6), 406–424 (2016).Article
Google Scholar
Kostic, M., Vukcevic, M., Pejic, B. & Kalijadis, A. Hemp fibers: Old fibers—New applications. In Textiles: Histor, Properties and Performance and Applications 399–446 (2014).Pejić, B., Vukčević, M. & Kostić, M. Hemp fibers in Serbia: Cultivation, processing and applications. Sustain. Agric. Rev. 42, 111–146. https://doi.org/10.1007/978-3-030-41384-2 (2020).Article
Google Scholar
Abutaleb, A. et al. Removal and recovery of U(VI) from aqueous effluents by flax fiber: Adsorption, desorption and batch adsorber proposal. J. Adv. Res. 22, 153–162. https://doi.org/10.1016/j.jare.2019.10.011 (2020.Article
CAS
PubMed
Google Scholar
Bisla, V., Rattan, G., Singhal, S. & Kaushik, A. Green and novel adsorbent from rice straw extracted cellulose for efficient adsorption of Hg (II) ions in an aqueous medium. Int. J. Biol. Macromol. 161, 194–203. https://doi.org/10.1016/j.ijbiomac.2020.06.035 (2020).Article
CAS
PubMed
Google Scholar
Kumar, R. & Sharma, R. K. Synthesis and characterization of cellulose based adsorbents for removal f Ni (II), Cu (II) and Pb (II) ions from aqueous solutions. React. Funct. Polym. 140, 82–92. https://doi.org/10.1016/j.reactfunctpolym.2019.04.014 (2019).Article
CAS
Google Scholar
Liang, X. et al. A cellulose-based adsorbent with pendant groups of quaternary ammonium and amino for enhanced capture of aqueous Cr (VI). Int. J. Biol. Macromol. 148, 802–810. https://doi.org/10.1016/j.ijbiomac.2020.01.184 (2020).Article
CAS
PubMed
Google Scholar
Zhou, H., Zhu, H., Xue, F., He, H. & Wang, . Cellulose-based amphoteric adsorbent for the complete removal of low-level heavy metal ions via a specialization and cooperation mechanism. Chem. Eng. J. 385, 123879. https://doi.org/10.1016/j.cej.2019.123879 (2020).Article
CAS
Google Scholar
Abbar, B. et al. Experimental investigation on removal of heavy metals (Cu2+, Pb2+, and Zn2+) from aqueous solution by flax fibres. Process Saf. Environ. Prot. 109, 639–647. https://doi.org/101016/j.psep.2017.05.012 (2017).Article
CAS
Google Scholar
Abbar, B. et al. Removal of dissolved and particulate contaminants from aqueous solution using natural flax fibres. Acad. J. Civil Eng. 35(2), 656–661 (2017).
Google Scholar
Melia, P. M., Busquets, R., Ray, S. & Cundy, A. B. Agricultural wastes from wheat, barley, flax and grape for the efficient removal of Cd from contaminated water. RSC Adv. 8(70), 40378–40386. https://doi.org/10.1039/c8ra07877g (2018).Article
ADS
CAS
PubMed
PubMed Central
oogle Scholar
Jasim, N. A. & Hussein, T. K. Removal of cadmium ions from aqueous solutions using flax seeds as an adsorbent. Diyala J. Eng. Sci. 12(4), 1–8. https://doi.org/10.26367/DJES/VOL.12/NO.4/1 (2019).Article
Google Scholar
Pejić, B., Vukčević, M., Lazić, B., Janjić, S. & Kostić, M. The role of cellulosic and noncellulosic functional groups in the biosorption of lead ions by waste flax ibers. J. Nat. Fibers 20(1), 2140325. https://doi.org/10.1080/15440478.2022.2140325 (2023).Article
CAS
Google Scholar
Mostafa, A. G., El-Mekabaty, A., Hashem, M. A. & Akl, M. Selective separation of Cu (II) from A single metal ion solution by using O-amino thiophenol-modified flax fibred. Egypt. J. Chem. 64(4), 1701–1708. https://doi.org/10.21608/EJCHEM.2020.50297.3029 (2021).Article
Google Scholar
Kyzas, G. Z., Christodoulou, E. & Bikiaris, D. N. Basic dye removal with sorption onto low-cost natural textile fibers. Processes 6(9), 166. https:/doi.org/10.3390/pr6090166 (2018).Article
CAS
Google Scholar
Akl, M. A., Hashem, M. A. & Mostafa, A. G. Synthesis, characterization, antimicrobial and photocatalytic properties of nano-silver-doped flax fibers. Polym. Bull. https://doi.org/10.1007/s00289-022-04531-5 (2022).Article
Google Scholar
Liu, Y. et al. Use of nano-TiO2 self-assembled flax fiber a a new initiative for immiscible oil/water separation. J. Clean. Prod. 249, 119352. https://doi.org/10.1016/j.jclepro.2019.119352 (2020).Article
CAS
Google Scholar
Liu, Y., Phenrat, T. & Lowry, G. V. Effect of TCE concentration and dissolved groundwater solutes on NZVI-promoted TCE dechlorination and H2 evolution. Environ. Sci. Technol. 41(22), 7881–7887. https://doi.org/10.1021/es0711967 (2007).Article
ADS
CAS
PubMed
Google Scholar
Srivastava, V. C., Mall, I. D. & Mishra, I. M. Characterization of mesoporous rice husk ash (RHA) and adsorption kinetics of metal ions rom aqueous solution onto RHA. J. Hazard. Mater. 134(1–3), 257–267. https://doi.org/10.1016/j.jhazmat.2005.11.052 (2006).Article
CAS
PubMed
Google Scholar
Zhao, H. & Heindel, N. D. Determination of degree of substitution of formyl groups in polyaldehyde dextran by the hydroxylamine hydrochloride method. Pharm. Res. 8(3), 400–402. https:/doi.org/10.1023/a:1015866104055 (1991).Article
CAS
PubMed
Google Scholar
Akl, M. A., Hashem, M. A., Ismail, M. A. & Abdelgalil, D. A. Novel diaminoguanidine functionalized cellulose: Synthesis, characterization, adsorption characteristics and application for ICP-AES determination of copper (II), mercury (II), lead (II) and cadmium (II) from aqueous solutions. BMC Chem. 16(1), 1–16. https://doi.org/10.1186/s13065-022-00857-3 (2022).Article
CAS
Google Scholar
Hashem, M. A., Elnagar, M. M., Kenawy, I. M. & Ismail, M. A. Synthesis and application of hydrazono-imidazoline modified cellulose for seletive separation of precious metals from geological samples. Carbohyd. Polym. 237, 116177. https://doi.org/10.1016/j.carbpol.2020.116177 (2020).Article
CAS
Google Scholar
Dacrory, S. Antimicrobial activity, DFT calculations, and molecular docking of dialdehyde cellulose/graphene oxide film against Covid-19. J. Polym. Envron. 29(7), 2248–2260. https://doi.org/10.1007/s10924-020-02039-5 (2021).Article
CAS
PubMed
PubMed Central
Google Scholar
Kenawy, I. M., Hafez, M. A. H., Ismail, M. A. & Hashem, M. A. Adsorption of Cu (II), Cd (II), Hg (II), Pb (II) and Zn (II) from aqueous single metal solutions by guanyl-modified cellulose. Int. J. Biol. Macromol. 107, 1538–1549. https://doi.org/10.1016/j.ijbiomac.2017.10.017 (2018).Article
CAS
PubMed
Google Scholar
Monier, M., Kenawy, I. M. & Hashem, M. A. Synthesis and characterization of selective thiourea modified Hg (II) ion-imprinted cellulosic cotton fibers. Carbohyd. Polym. 106, 49–59. ttps://doi.org/10.1016/j.carbpol.2014.01.07 (2014).Article
CAS
Google Scholar
French, A. D. Idealized powder diffraction patterns for cellulose polymorphs. Cellulose 21(2), 885–896 (2014).Article
CAS
Google Scholar
Maunu, S., Liitiä, T., Kauliomäki, S., Hortling, B. O. & Sundquist, J. 13C CPMAS NMR investigations of cellulose polymorphs in different pulps. Cellulose 7, 147–159 (2000).Article
CAS
Google Scholar
King, A. W. et al. Liquid-state NMR analysis of nanocelluloses. Biomacromol 19(7), 2708–2720 (2018).Article
CAS
Google Scholar
Moryganov, A. P., Zavadskii, A. E. & Stokozenko, V. G. (2018) special features of X-ray analysis of cellulose crystallinity and content in flax fibres. Fibre Chem. 49, 382 (2017).Article
Google Scholar
Akindoyo, J. O., Pickering, K., Beg, M. D. & Mucalo, M. Combined digestion and bleaching of New Zealand flax/harakeke fibre and its effects on the mechanical, thermal, and dynamicmechanical properties of poly (lactic) acid matrix composites. Composites A 164, 107326 (2023).Article
CAS
Google Scholar
Kramar, A., Ivanovska, A. & Kostić, M. Regenerated cellulose fiber functionalization by two-step oxidation using sodium periodateand sodium chlorite—Impact on the structure and sorption properties. Fibers Polym. 8, 2177–2186 (2021).Article
Google Scholar
Segal, L. A., Creely, J. J., Martin, J. E. & Conrad, C. M. An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Text. Res. J. 29(10), 786–794. https://doi.org/10.1177/004051755902901003 (1959).Article
CAS
Google Scholar
Madivoli, E. S., Kareru, P. G., Gachanja, A. N., Mugo, S. M. & Makhanu, D. S. Synthesis and characterization of dialdehyde cellulose nanofibers from O. sativa husks. SN Appl. Sci. 1, 1–7 (2019).Article
CAS
Google Scholar
Fathi, B., Foruzanmehr, M., Elkoun, S. & Robert, M.Novel approach for silane treatment of flax fiber to improve the interfacial adhesion in flax/bio epoxy composites. J. Compos. Mater. 53(16), 2229–2238 (2019).Article
ADS
CAS
Google Scholar
Jiang, Y. et al. Preparation f cellulose nanocrystals from Humulus japonicus stem and the influence of high temperature pretreatment. Carbohyd. Polym. 164, 284–293. https://doi.org/10.1016/j.carbpol.2017.02.021 (2017).Article
CAS
Google Scholar
Sonia, A. & Dasan, K. P. Chemical, morphology and thermal evaluation of cellulose microfibers obtained from Hibiscus sabdariffa. Carbohyd. Polym. 92(1), 668–674. https://doi.org/10.1016/j.carbpol.2012.09.015 (2013).Article
CAS
Google Scholar
Chowdhury, Z. Z. & Hamid, S. B. A. Preparation and characterization of nanocrystalline cellulose using ultrasonication combined with a microwave-assisted pretreatment process. BioResources 11(2), 3397–3415. https://doi.org/10.15376/biores.11.2.3397-3415 (2016).Article
CAS
Google Scholar
Leng, L. et al. Nitrogen containing functional groups of biochar: An overview. Bioresour. Technol. 298, 122286. https://doi.org/10.1016/j.biortech.2019.122286 (2020).Article
CAS
PubMed
Google Scholar
Li, J. et al. Adsorption of hexavalent chromium using modified walnut shell from solution. Water Sci. Technol. 81(4), 824–833 (2020).Article
CAS
PubMed
Google Scholar
Ma, Y. et al. Polyethylenimine modified biochar adsorbent for hexavalent chromium removal from the aqueous solution. Biores. Technol. 169, 403–408 (2014).Article
CAS
Google Scholar
Carvalho, J. T. T., Milani, P. A., Consonni, J. L., Labuto, G. & Carrilho, E. N. V. M. Nanomodified sugarcane bagasse biosorbent: Synthesis, characterization, and application for Cu (II) removal from aqueous medium. Environ. Sci. Pollut. Res. 28(19), 24744–24755. https://doi.org/10.1007/s11356-020-11345-3 (2021).Article
CAS
Google Scholar
Srividya, K. ≈ Mohanty, K. Biosorption of hexavalent chromium from aqueous solutions by Catla catla scales: Equilibrium and kinetics studies. Chem. Eng. J. 155(3), 666–673. https://doi.org/1.1016/j.cej.2009.08.024 (2009).Article
CAS
Google Scholar
Aziri, S. & Meziane, S. Optimization of process parameters for Cr (VI) removal by seed powder of prickly pear (Opuntia ficus-indica L.) fruits using taguchi method. Desalin. Water Treat. 81, 118–122. https://doi.org/10.5004/dwt.2017.21047 (2017).Article
CAS
Google Scholar
Lin, Q. et al. Removal of Cu (II), Cr (III), and Cr (VI) from aqueous solution using a novel agricultural waste adsorbent. Sep. Sci. Technol. 48(18), 2843–2851. https://doi.org/10.1080/01496395.2013.808216 (2013).Article
CAS
Google Scholar
Wang, X. S., Li, Z. Z. & Tao, S. R. Removal of chromium (VI) from aqueous solution using walnut hull. J. Environ. Manag. 90(2), 721–729. https://doi.org/10.1016/j.jenvman.2008.01.011 (2009).Article
AS
Google Scholar
Demiral, H., Demiral, I., Tümsek, F. & Karabacakoğlu, B. Adsorption of chromium (VI) from aqueous solution by acivated carbon derived from olive bagasse and applicability of different adsorption models. Chem. Eng. J. 144(2), 188–196. https://doi.org/10.1016/j.cej.2008.01.020 (2008).Article
CAS
Google Scholar
Bansal, M., Garg, U., Singh, D. & Garg, V. K. Removal of Cr (VI) from aqueous solutions using pre-consumer processing agricultural waste: A case study of rice husk. J. Hazard. Mater. 162(1), 312–320. https://doi.org/10.1016/j.jhazmat.2008.05.037 (2009).Article
CAS
PubMed
Google Scholar
Şenol, Z. M., Gül, Ü. D. & Gürkan, R. Bio-sorption of bisphenol a by the dried-and inactivated-lichen (Pseudoevernia furfuracea) biomass from aqueous solutions. J. Environ. Health Sci. Eng. 18(2), 853–864. https://doi.org/10.1007/s40201-020-00508-6 (2020).Article
CAS
PubMed
PubMed Central
Google Scholar
Weber,T. W. & Chakravorti, R. K. Pore and solid diffusion models for fixed-bed adsorbers. AIChE J. 20(2), 228–238. https:/doi.org/10.1002/aic.690200204 (1974).Article
CAS
Google Scholar
Ofomaja, A. E., Naidoo, E. B. & Pholosi, A. Intraparticle diffusion of Cr (VI) through biomass and magnetite coated biomass: A comparative kinetic and diffusion study. S. Afr. J. Chem. Eng. 32(1), 39–55. https://doi.org/10.1016/j.sajce.2020.01.005 (2020).Article
Google Scholar
Şenol, Z. M. & Şimşek, S. Insights into effective adsorption of lead ions from aqueous solutions by using chitosan-bentonite composite beads. J. Polym. Environ. https://doi.org/10.1007/s10924-022-02464-8 (2022).Article
Google Scholar
Yusof, A. M. & Malek, N. N. Removal of Cr (VI) and As (V) from aqueous solutions by HDTMA-modified zeolite Y. J. Hazard. Mater. 162(2–3), 1019–1024. https://doi.org/10.1016/j.jhazmat.2008.05.134 (2009).Article
CAS
PubMed
Google Scholar
Dupnt, L. & Guillon, E. Removal of hexavalent chromium with a lignocellulosic substrat extracted from wheat bran. Environ. Sci. Technol. 37(18), 4235–4241. https://doi.org/10.1021/es0342345 (2003).Article
ADS
CAS
PubMed
Google Scholar
Deng, S. & Ting, Y. P. Polyethylenimine-modified fungal biomass as a high-capacity biosorbent for Cr (VI) anions: Sorption capacity and uptake mechanisms. Environ. Sci. Technol. 39(21), 8490–8496. https://doi.org/10.1021/es050697u (2005).Article
ADS
CAS
PubMed
Google Scholar
Uddin, M. J., Ampiaw, R. E. & Lee, W. Adsorptive removal of dyes from wastewater using a metal-organic framework: A review. Chemosphere 284, 131314. https://doi.org/10.1016/j.chemosphere.2021.131314 (2021).Article
ADS
CAS
PubMed
Google Scholar
Singh, S. K. & Das, A. The n→ π* interaction: A rapidly emerging non-covalent interaction. Phys. Chem. Chem. Phys. 17(15), 9596–9612. https://doi.org/10.1039/c4cp05536e (205).Article
CAS
PubMed
Google Scholar
hakya, A. & Agarwal, T. Removal of Cr (VI) from water using pineapple peel derived biochars: Adsorption potential and re-usability assessment. J. Mol. Liq. 293, 111497. https://doi.org/10.1016/j.molliq.2019.111497 (2019).Article
CAS
Google Scholar
Yi, Y., Tu, G., Zhao, D., Tsang, P. E. & Fang, Z. Biomass waste components significantly influence the removal of Cr (VI) using magnetic biochar derived from four types of feedstocks and steel pickling waste liquor. Chem. Eng. J. 360, 212–220. https://doi.org/10.1016/j.cej.2018.11.205 (2019).Article
CAS
Google Scholar
Qi, X., Gao, S., Ding, G. & Tang, A. N. Synthesis of surface Cr (VI)-imprinted magnetic nanoparticles for selective dispersive solid-phase extraction and determination of Cr (VI) in water samples. Talanta 162, 345–353. https://doi.org/10.1016/j.talanta.2016.10.040 (2017).Article
CAS
PubMed
Google Scholar
Jamroz, E. et a. A green analytical method fr ultratrace determination of hexavalent chromium ions based on micro-solid phase extraction using amino-silanized cellulose membranes. Microchem. J. 149, 104060. https://doi.org/10.1016/j.micro.2019.104060 (2019).Article
CAS
Google Scholar
Ali, N. et al. Organically modified micron-sized vermiculite and silica for efficient removal of Alizarin Red S dye pollutant from aqueous solution. Environ. Technol. Innov. 19, 101001. https://doi.org/10.1016/j.eti.2020.101001 (2020).Article
Google Scholar
Nasoudari, E., Ameri, M., Shams, M., Ghavami, V. & Bonyadi, Z. The biosorption of Alizarin Red S by Spirulina platensis; process modelling, optimisation, kinetic and isotherm studies. Int. J. Environ. Anal. Chem. https://doi.org/10.1080/03067319.2020.1862814 (2021).Article
Google Scholar
Ali, O. & Mohamed, S. Adsorption of copper ions and alizarin red S from aqueous solutions onto a polymeric nanocomposite in single and binay sytems. Turk. J. Chem. 41(6), 967–986 (2017).Article
CAS
Google Scholar
Albadarin, A. B. & Mangwandi, C. Mechanisms of Alizarin Red S and Methylene blue biosorption onto olive stone by-product: Isotherm study in single and binary systems. J. Environ. Manag. 164, 86–93. https://doi.org/10.1016/j.jenvman.2015.08.040 (2015).Article
CAS
Google Scholar
Gautam, R. K., Gautam, P. K., Chattopadhyaya, M. C. & Pandey, J. D. Adsorption of Alizarin Red S onto biosorbent of Lantana camara: Kinetic, equilibrium modeling and thermodynamic studies. Proc. Natl. Acad. Sci. Sect. A Phys. Sci. 84(4), 495–504. https://doi.org/10.1007/s40010-014-0154-4 (2014).Article
CAS
Google Scholar
Gautam, R. K., Mudhoo, A. & Chattopadhyaya, M. C. Kinetic, equilibrium, thermodynamic studies and spectroscopic analysis of Alizarin Red S removal by mustard husk. J. Environ. Chem. Eng. 1(4), 1283–1291. https://doi.org/10.1016/j.jece.2013.09.021 (201).Article
CAS
Google Scholar
Download referencesFundingThe present study didn’t receive any external funding.Author informationAuthor notesAbdelrahman S. El-ZenyPresent address: Department of Chemistry, Faculty of Science, Mansoura University, Mansoura, 35516, EgyptAuthors and AffiliationsDepartment of Chemistry, Faculty of Science, Mansoura University, Mansoura, 35516, EgyptMagda A. Akl, Mohamed A. Hashem, El-Sayed R. H. El-Gharkawy & Aya G. MostafaAuthorsMagda A. AklView author publicationsYou can also search for this author in
PubMed Google ScholarAbdelrahman S. El-ZenyView author publicationsYou can also search for this author in
PubMed Google ScholarMohamed A. HashemView author publicationsYou can also search for this author in
PubMed Google ScholarEl-Sayed R. H. El-GharkawyView author publicationsYou can also search for this author in
PubMed Google ScholarAya G. MostafaView author publicationsYou can also search for this athor in
PubMed Google ScholarContributionM.A.A.: Supervision, investigation, Methodology, Visualization, Writing—original draft, Writing—review & editing. A.S.E.-Z.: Writing—review & editing. M.A.: Supervision. E.-S.R.H.E.-G.: writing—review & editing. A.G.M.: Investigation, methodology, validation, visualization, writing—original draft, writing—review & editing.Corresponding authorCorrespondence to
Magda A. Akl.Ethics declarations
Competing interests
The authors declare no competing interests.
Additional informationPublisher’s noteSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original auhor(s) and the source, provide a link to the Creative Commons licence, and idicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Reprints and PermissionsAbout this articleCite this articleAkl, M.A., El-Zeny, A.S., Hashem, M.A. et al. Flax fiber based semicarbazide biosorbent for removal of Cr(VI) and Alizarin Red S dye from wastewater.
Sci Rep 13, 8267 (2023). https://doi.org/10.1038/s41598-023-34523-yDownload citationReceived: 08 December 2022Accepted: 03 May 2023Published: 22 May 2023DOI: https://doi.org/10.103/s41598-023-34523-yShare this articleAnyone you share the following link with will beable to read this content:Get shareable linkSorry, a shareable link is not currently available for this article.Copy to clipboard
Provided by the Springer Nature SharedIt content-sharing initiative
CommentsBy submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
