Adsorption of Strontium from an Aqueous Solution by TiO2-Pillared Zeolite

Abstract

Strontium is a heavy metal that is commonly found in many groundwater systems because of migration from historic nuclear waste storage sites. Its radiation effect can cause bone cancer, tumors, and leukemia. An economical and the most effective method to remove heavy metals from aqueous solutions is adsorption. In this study, we synthesized a TiO2-pillared zeolite to improve the adsorption efficiency of the zeolite. The TiO2-pillared zeolite was synthesized via the pillarization process. Adsorbent characterization was done using X-ray powder diffraction, which showed that TiO2 was successfully pillared. Fourier-transform infrared spectroscopy showed a shift in the peak at a wavenumber of 3425.70 cm?1, which can be attributed to the addition of TiO2. A parameter study conducted using a batch experiment showed that optimal strontium adsorption took place at pH 5 and contact time of 80 min. The Freundlich adsorption isotherm fitted the experimental data well, illustrating the adsorption of strontium as being non-ideal, reversible, and multilayer adsorption that occurs on the heterogeneous surface of the TiO2-pillared zeolite. A thermodynamic study indicated that strontium adsorption on the TiO2-pillared zeolite was an endothermic process, takes place spontaneously, and is quite stable.

Keywords

• adsorption
• strontium
• titanium dioxide
• zeolite