Kinetics of Cu2+ binding to the poly(acrylic acid) hydrogel

Isothermal kinetics of copper (ion) binding to poly(acrylic acid) (PAA) hydrogel at 20, 25, 35 and 45 C was investigated. Isothermal conversions and kinetic curves of Cu2+ binding to the PAA hydrogel were determined. It was found that the well-known kinetic models of Peppas cannot be applied to describing the entire process of Cu2+ binding. The new method for the determination of the kinetic model of the Cu2+ binding process, as well as the activation energy density distribution functions of PAA hydrogel interaction with Cu2+, were established. It was found that Cu2+ diffusion to the active centers (with E-a = 9 kJ/mol) has a dominant influence on the kinetics of the process at temperatures T >= 30 degrees C, but at T >= 30 degrees C and for the degree of bound Cu2+ alpha >= 0.2, the interaction of Cu2+ from the adsorption center with E-a = 26 kJ/mol is dominant.