Adsorption of silver ions from aqueous solutions using copolymer containing sodium methacrylate functional groups

The negative effects of silver, which is one of the heavy metals, on the environment are known. Hence, to remove this dangerous heavy metal from the environment, poly(methacrylic acid), whose adsorption capability has been tested in previous studies, was used. But unfortunately, it performed poorly for silver ions. Therefore, this polymer was modified as poly(sodium methacrylate) using NaOH catalyst and used in the adsorption experiment process to obtain more efficient results. Some important functional groups in the modified copolymer were analyzed by FTIR measurement and the thermal stability of the copolymer by TGA measurement. To better interpret the adsorption process, some isotherms such as Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) isotherms were examined. Using the (D-R) isotherm, the reaction energy was found to be 8.98 kJ/mol, which indicates that the adsorption process is of a chemical ion exchange type. The data from the experimental processes were also evaluated with some kinetic models such as the Elovich, the modified Freundlich, the pseudo-first-order, and the pseudo-second-order kinetic models. Among these models, the pseudo-second-order kinetic models of the adsorption of Ag(I) on poly(sodium methacrylate) showed the best agreement with the experimental data.