Plasma modification of a natural zeolite to improve its adsorption capacity of strontium ions from water samples

In this paper, surface modification of a natural zeolite by dielectric barrier discharge (DBD) plasma has been studied. The natural zeolite was modified by DBD plasma to enhance its adsorption capacity to strontium ions. Various conditions including the treatment time, the voltage and the effective length of plasma were optimized to achieve the best adsorption capacity of Sr2+ ions from water solution. The optimized modification parameters were obtained as; the plasma region length equal to 8 cm; a 9 kV voltage difference and the plasma treatment time of 20 min. After the plasma modification, the adsorption capacity of Sr2+ ions toward the natural zeolite increased more than 56%. The surface properties of the zeolite, before and after plasma treatment, were investigated using FT-IR, TGA, XRD and BET adsorption methods. A 35% increasing in the microporosity and several new functional groups were observed for the plasma-treated zeolite. Langmuir, Freundlich, Temkin and Sips isotherm models were applied to analyze the experimental data and Langmuir linear method showed the best fit for the strontium ions (R-2 = 0.997%).