Poly (Acrylic Acid-Acrylamide) Hydrogel for Ni(II) and Cr(III) Adsorption: Isotherm, Kinetics and Thermodynamic Studies

Abstract

The use of a hydrogel composed of poly acrylic acid acrylamide (AA-AAm) as an adsorbent for removing nickel and chromium ions from synthetic wastewater was investigated. The effects of various factors such as pH, retention time, hydrogel dosage, and initial metal concentration on the adsorption of Ni(II) and Cr(III) were examined. Adsorption performance was evaluated using isotherms, kinetics, and thermodynamics. The results showed that the adsorption process for both metals followed a pseudo-second-order model with good correlation coefficients. The Freundlich isotherm model was found to be a better fit for the adsorption process, suggesting that both physical and chemical processes were involved in the adsorption of Ni and Cr. Thermodynamic analysis demonstrated that the adsorption process is spontaneous (negative ΔG) but endothermic (positive ΔH), indicating that heat energy is required for the adsorption process. Overall, the findings suggest that the poly AA-AAm hydrogel has excellent potential as an adsorbent for removing heavy metals from wastewater. The presence of heavy metals in wastewater is a significant environmental and health concern.