Development of a modified bio-sorbent for efficient Cd (II) adsorption: characterisation and process optimization

This research outlines the comprehensive manufacture and characterisation of a novel phosphate-modified cellulose-based adsorbent (CDOP), designed to effectively remove cadmium ions (Cd2+) from wastewater. The research team employed various characterisation techniques, including FTIR, NMR, SEM, TGA, and elemental analysis, to confirm successful modification and enhanced surface properties. The adsorption behaviour was systematically examined under different operational parameters, including contact time, pH, initial Cd concentration, adsorbent dosage, and temperature. Maximum adsorption efficiency was achieved at a pH of 6, with a capacity of 311.7 mg/g. The adsorption kinetics followed the pseudo-second-order model, indicative of chemisorption. Equilibrium data were fitted to the Langmuir isotherm, indicating monolayer adsorption on a uniform surface. Thermodynamic evaluations confirmed that the adsorption process is both spontaneous and endothermic. Additionally, the adsorbent exhibited a strong preference for Cd2+ ions, maintaining its effectiveness even in the presence of other metal ions in the solution. Elution and reuse tests demonstrated its reusability over eight cycles with minimal efficiency loss, and its successful application to real wastewater samples highlighted its potential to impact cadmium decontamination significantly.