Response surface methodology for the modelling of 85Sr adsorption on zeolite 3A and pumice

The adsorption of 85Sr from aqueous solutions on to zeolite 3A and three types of pumice materials (i.e. Kayseri, Isparta and Nevsehir) was investigated in this study. Experiments with radioactive 85Sr were performed to test the sorption ability of the sorbents to remove this radioisotope from liquid radioactive wastes. The influence of sorbent dosage and initial activity of feed solution on the decontamination factor were analysed and optimized by means of response surface methodology. The parameters of the experiments, namely temperature, pH, time, stirring efficiency, were selected in preliminary tests. The experimental results showed that the most efficient pumice sorbent for 85Sr is Isparta, for which a maximal decontamination factor of 76.92 was obtained by using the sorbent dosage of 0.5% w/v. However, the commercial zeolite 3A was 2.71-fold more efficient than Isparta pumice for decontamination of strontium radioactive solutions. Isparta pumice is a low-cost natural sorbent, and its ability to effectively bind strontium radioisotope from water solutions suggests that this material has further applications for radioactive waste treatment.