Adsorption of Cr(VI) ions from wastewater using water-based polyacrylic resin

Hexavalent chromium (Cr(VI)) contamination in water poses severe environmental and health risks, necessitating efficient and sustainable removal technologies. A water-based polyacrylic resin was synthesized via inverse emulsion polymerization using methyl methacrylate, acrylic acid, and maleic anhydride, thereby avoiding the use of organic solvents. Under optimal conditions (0.8 g dosage, pH 2, 318 K, 12 h), the resin achieves 98.73% Cr(VI) removal from 1 mg/L wastewater, following the pseudo-second-order kinetic model (R² = 0.9927). Furthermore, the adsorption is well-fitted to the Langmuir model (R² = 0.9911), yielding a calculated maximum adsorption capacity of 142.86 mg/g. FTIR analysis confirms chemisorption via Cr-O bond formation as the key mechanism. Thermodynamic analysis supports this chemisorption dominance, revealing an exothermic process (ΔH = 138.47 kJ/mol) with high spontaneity (ΔG < 0). Characterization via SEM/XRD shows the resin's 3D porous structure maintains integrity post-adsorption. Significantly, acid-base elution enables high regeneration efficiency (> 93%) over 5 cycles without secondary pollution. These findings highlight the promising potential of the water-based polyacrylic resin as a macromolecular adsorbent for the efficient removal of Cr(VI) ions from wastewater, offering a viable solution for wastewater treatment.