Adsorption kinetics and mechanisms of nano chitosan coated cotton fiber for the removal of heavy metals from industrial effluents

The present study successfully removed heavy metals from industrial effluent using nanochitosan-coated cotton fiber (NCCF) crosslinked with citric acid, demonstrating the potential of advanced technologies in removing heavy metals from large amounts of wastewater caused by the world's unchecked population growth and widespread industrialization that has caused pollution. Structural, morphological, and thermal properties of NCCF were determined. Results revealed that the nanochitosan component improves the adsorption capacity of cotton fiber (CF) through the increased surface area and porosity of NCCF. Sorption studies were conducted based on pH, kinetics, isotherms, and desorption results. The Langmuir and Freundlich adsorption isotherms were utilized to examine the CF and NCCF adsorption mechanisms. NCCF exhibited maximum Langmuir adsorption capacities of 4.76 mmol/g for Cd²⁺, 6.40 mmol/g for Pb²⁺, and 12.50 mmol/g for Cr⁶⁺. Kinetic studies revealed that the pseudo-first-order kinetics model best describes the adsorption process. The results of the adsorption kinetics study showed that NCCF has a shorter half-time of adsorption than CF does during the adsorption process. This suggests that NCCF has a greater initial adsorption rate and adsorption capacity than CF. These findings are expected to lead to industrial applications in wastewater treatment as sustainable and highly effective materials.