Optimization of a novel waste-based hydrogel and its application in heavy metal removal

Abstract

This research investigates the adsorption of pollutants using the Chitosan-Sodium triphosphate-SiO₂ nanocomposite (CS-TPP-NSi). The study employs characterization techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), mapping, Fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis, to examine the structural properties of the nanocomposite. Kinetic, isothermal, and capacity assessments are conducted to understand how lead and zinc contaminants are adsorbed. The isotherm models, including Langmuir, Freundlich, and Temkin, reveal that monolayer adsorption is the primary mechanism. The Langmuir model shows a maximum adsorption capacity of 112.35 mg/g for lead and 60.97 mg/g for zinc, with high correlation coefficients of 0.994 and 0.998, respectively. Kinetic tests demonstrate that the nanocomposite has fast adsorption kinetics and high capacity. Additionally, the study examines how initial pollutant concentrations affect adsorption efficiency, with Freundlich constants (K_F) of 24.32 for lead and 21.84 for zinc. The findings enhance our understanding of adsorption mechanisms and highlight the potential of CS-TPP-NSi for environmental remediation.