One-pot synthesis of silicon-based zirconium phosphate for the enhanced adsorption of Sr (II) from the contaminated wastewater

The composite of zirconium phosphate (ZrP) loaded on mesoporous silica pellet (MSP) was typically prepared by one-pot liquid phase grafting method to develop an effective inorganic adsorbent for strontium (Sr) ion removal from the contaminated water. The as-synthesized product was well characterized by energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), N2 adsorption–desorption isotherms and FT–IR. The adsorption of Sr2+ on ZrP/MSP composite was systematically investigated as the functions of pH, contact time, ionic strength, and various ions interference. It showed that Sr adsorption on ZrP/MSP was highly dependent on pH and the concentration of metal ion, achieving larger adsorption capacity, faster adsorption equilibrium, and higher ion selectivity than those of bare ZrP under batch reaction conditions. The Langmuir model and the pseudo-second-order model separately fitted the adsorption isotherm and kinetic data better than the Freundlich and pseudo-first-order ones. These results suggested that our present methodology may provide a general synthesis of silica supported zirconium phosphate with mesoporous structure in large surface areas which could be used as inorganic composite adsorbent for effective removal of strontium ions from the contaminated solutions.