Synthetic dyes, especially azo dyes, are extensively used in textile industries and these are also perceived as the major challenge to remove the toxicity caused by them in an aqueous system. There are many technologies like membrane filtration, photocatalysis, adsorption, flocculation, ozonation, reverse osmosis, chemical oxidation, and coagulation. Among several technologies, Adsorption is the most promising method for treating wastewater. In the present study, Coconut husk (CH) was selected as a biomass which was converted into carbonaceous biochar. CH was doped with transition metal-cobalt in a ratio of (10:1) and pyrolyzed at 600 degrees C. The Cobalt @ coconut husk biochar (Co@CHBc) was analyzed by FTIR, FESEM, and XRD spectroscopy. The maximum removal of methyl orange (MO) dye was 99% which was observed at pH = 4.0, contact time of 30 min, adsorbent dosage of 1 g, and initial dye concentration of 20 mg L-1 at room temperature. The removal of MO dye was achieved in a shorter time as compared to the previous studies mentioned in the literature. Thermodynamic studies suggest that the adsorption is endothermic for MO dye removal. The pseudo-second-order model was observed to be the most suitable for the adsorption data having regression coefficients (R2) 0.996, and the Langmuir isotherm was the finest fit for the equilibrium data with R2 0.9958. The Co@CHBc demonstrated a remarkable regeneration capacity up to 5 cycles, after being subjected to 0.1 M NaOH. A real dye sample experiment was conducted to validate the applicability of the Co@CHBc. A proposed reaction mechanism was designed on model analysis based. Using the GCMS technique, it was proved that the MO dye was broken down into non-hazardous components like carbon dioxide, water, and sulfate after adsorption. The Co@CHBc provides an innovative and environmentally friendly method for removing dyes from wastewater, within the circular economy framework. Thus, the newly synthesized Co@CHBc may be an excellent choice for treating wastewater containing dyestuffs.
