Use of zeolite in reducing environmental risk of polonium: kinetic models

A study was conducted to understand the mechanism of adsorption kinetic that is effective in removal of ²⁰⁹Po by clinoptilolite, a natural zeolite, from aquatic environments. Studies of the adsorption kinetics of ²⁰⁹Po were carried out by interacting zeolite with ²⁰⁹Po at different time intervals. Experimental polonium adsorption data obtained in our previous article were applied to some known kinetic models such as pseudo-first order, pseudo-second order, Elowich, Bangham, Homogeneous particle diffusion and Shell step models. The data obtained from the models revealed that the rate-limiting step is more compatible with the pseudo-second order model, which is based on the assumption that chemical sorption. According to the results obtained, the calculated the amount of ²⁰⁹Po adsorbed at equilibrium (q_e) and the equilibrium rate constant of pseudo-second-order sorption (k₂) were found to be 0.3302 ng g⁻¹, − 4.4 × 10^–5 ng g⁻¹ min⁻¹, respectively.