Equilibrium, kinetic, and thermodynamic studies on the sorption of some heavy metal ions by the phosphorus-containing polymer sorbent

Abstract

The sorption of Cu+², Ni+², Co+², and Zn+² ions onto the phosphorus-containing sorbent were studied as a function of the contact time, temperature, and concentration of the initial metal ions. The equilibrium studies are presented by the Langmuir, Freundlich, and Temkin isotherm models. The sorption data are well described by the Langmuir isotherm model, and they also can be simulated by the Freundlich isotherm model. The pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were applied to test the experimental data of the kinetic studies. The pseudo-second-order kinetic model provided the best correlation of the experimental data compared to the other kinetic models. The sorption capacity of the metal ions increased with temperature increasing. The positive value of enthalpy (ΔH°) and the negative value of Gibbs free energy (ΔG°) indicated that the sorption process was endothermic and spontaneous.