In light of the escalating environmental concerns surrounding heavy metal pollution, particularly the widespread presence of lead, Pb(II) contaminants, there is a pressing need to advance our methods for efficient remediation. This urgency underscores the significance of developing innovative adsorbents, such as biochar functionalized with layered double hydroxide (LDH), as a promising solution to enhance the removal of Pb(II) pollutants from various environmental matrices. This study used co-precipitation to synthesize coconut fiber biochar/zinc-aluminium layered double hydroxide (CFBC-Zn/Al LDH). The CFBC-Zn/Al LDH serves as an adsorbent for removing Pb(II) in a series of batch adsorption tests. Three samples pyrolyzed at 500 degrees C, 600 degrees C, and 700 degrees C immobilized Zn-Al LDH. The chemical structure, surface area, and morphology analysis for the CFBC-Zn/Al LDH were investigated by analyzing X-ray Diffraction (XRD), Fourier-transform Infrared Spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and Brunauer-Emmett-Teller (BET). The SEM-EDX analysis revealed the presence of finely crystalline LDH within the textured surfaces of the original CFBC samples. Additionally, confirmation of the successful creation of Zn/Al LDH composites with CFBC was established through the appearance of corresponding peaks in both XRD and FTIR analyses. The removal of Pb(II) by the CFBC-Zn/Al LDH was studied by varying the pH of the solution, the initial concentration of Pb(II), and the contact time. A batch adsorption experiment demonstrated that the 700 degrees C pyrolyzed CFBC had great adsorption performance towards Pb(II). The maximum adsorption capacity for CFBC-Zn/Al LDH-700 Pb(II) samples was 163.89 mg/g at pH 6 for 200 mg/L. The Pb(II) removal for CFBC-Zn/Al LDH is greater than pristine CFBC samples. The adsorption was found to follow Langmuir and pseudo-second-order, respectively, according to both adsorption and kinetic isotherms models. Hence, the incorporation of Zn/Al LDH onto cost-effective coconut fiber biochar demonstrated superior adsorption efficiency for Pb(II) when compared to the unmodified coconut fiber biochar.
