Investigation of solution chemistry effects on sorption behavior of Sr(II) on sepiolite fibers

Abstract

In this work, sepiolite fibers were prepared by acid purification, high-speed stirring and ultrasonic dispersion treatment of natural sepiolite and characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and zeta potential techniques. The effects of contact time, solid content, pH, ionic strength, coexistent electrolyte ions and humic substances (HSs) on Sr(II) sorption to sepiolite fibers were investigated by batch method. The results indicated that the sorption of Sr(II) on sepiolite fibers increased with the increase of pH and decreased with the increase of ionic strength, suggesting that ion exchange and surface complexation were the main sorption mechanisms in the sorption process. The Langmuir and Freundlich models were applied to simulate the sorption isotherms and the results showed that the Langmuir model fitted the experimental data better than the Freundlich model. The sorption of Sr(II) by sepiolite fibers was affected evidently by the presence of HSs. This work highlighted the interactions between HSs and Sr(II) and contributed to determining the mutual effects of organic and inorganic matters on the sorption of metal ions in environmental pollution cleanup.