Chitosan@MnO2-perlite composite for the adsorptive removal of Cr(VI) from water

Herein, hexavalent chromium (Cr(VI)) adsorption was explored on strategically designed Cs@MnO₂-perlite composite. Characterization confirmed composite's robust structure and high specific surface area, contributing to its superior adsorption performance. Comprehensive kinetic, isothermal, and thermodynamic modelling studies were regulated to understand the adsorption behavior and efficiency. Adsorption kinetics followed a pseudo-first-order model, indicating that the rate of adsorption was proportional to the number of active sites available on the composite. Isothermal analysis showed that the adsorption data was fitted to Langmuir model (R² = 0.99), suggesting monolayer Cr(VI) adsorption with a maximum monolayer adsorption capacity of 281.7 mg/g at 60 °C. Thermodynamic parameters revealed that the adsorption process was entropy-driven, spontaneous, and endothermic, indicating increased randomness at the solid-solution interface and the necessity of heat input for adsorption. Regeneration studies demonstrated the composite's reusability and long-term stability, showing a minimal 5 % reduction in Cr(VI) removal efficiency even after five consecutive cycles, highlighting its potential for cost-effective and sustainable environmental applications. The removal efficiency of Cr(VI) on Cs@MnO₂-perlite was also investigated through DFT calculations and Monte Carlo simulations. Results showed strong interactions between all components of the Cs@MnO₂-perlite and Cr(VI) ions. These findings highlight the potential of Cs@MnO₂-perlite composite as an effective adsorbent for Cr(VI) removal from aqueous solutions, with significant implications for environmental remediation efforts.