Enhanced physicochemical properties of Himalayan Weeping Bamboo-biochar for rapid multicomponent textile dyes uptake under classical and ultrasound irradiation: A comparative study

This study focused on synthesizing a low-cost adsorbent via a unique two-step solvothermal slow pyrolysis of Drepanostachyum falcatum plant biomass. It evaluated its adsorption capabilities for removing various textile dyes, including methylene blue (MB), basic fuchsin (BF), and methyl orange (MO), from aqueous solutions. Under conventional and ultrasound-assisted conditions, the adsorption performance was assessed for single, binary, and ternary dye systems. Comprehensive investigations examined the effects of environmental factors such as temperature, pH, humic acid, and interfering ions on adsorption. The findings revealed that ultrasonication significantly accelerated the adsorption process, making it up to six times faster than classical adsorption methods, and equilibrium was reached in one-tenth the time required without ultrasound. The experimental data best fit the pseudo-second-order kinetics model, indicating that chemisorption was the dominant adsorption mechanism. Additionally, the Freundlich isotherm suggested multilayer sorption on the biochar surface. Maximum adsorption capacities under ultrasound were found to be 139.34 mg/g for MB, 75.09 mg/g for MO, and 98.13 mg/g for BF dyes, with a higher affinity observed for cationic dyes compared to anionic dyes. The study provides insights into an efficient, novel synthesis method for converting waste biomass into a valuable adsorbent for dye removal. It also highlights the role of ultrasound in enhancing physicochemical properties, facilitating improved mass transfer, and promoting better interaction between the dyes and the adsorbent.