Highly efficient removal of strontium from contaminated wastewater by a porous zirconium phosphate material

Effective and efficient disposal of radioactive pollution has been crucial for responding to unexpected nuclear accidents and guaranteeing the sustainable development of nuclear energy. In this study, a kind of porous zirconium phosphate was synthesized with a sol-gel process followed by a post-synthesis modification to remove the radioactive Sr²⁺ from wastewater. The prepared materials were characterized by different technologies including FT-IR, SEM-EDS, XRD and XPS, and then the adsorption performance was evaluated in batch and column modes. Experimental results suggested that the porous zirconium phosphate adsorbent was successfully prepared with Na⁺ dispersed in the channels for exchange. It inherited the excellent properties of zirconium dioxide aerogel and exhibited mesoporous structure and large specific surface area. Compared with traditional zirconium phosphate, the adsorption kinetics and the adsorption capacity were improved simultaneously. Especially, it showed excellent selectivity towards Sr²⁺ among different cations, and even could remove the low-level Sr²⁺ from natural seawater efficiently, which powerfully demonstrated that the prepared material could be applied in the treatment of practical wastewater. Spectra studies uncovered that the adsorption activities were dominated by the ion exchange mechanism between external Sr²⁺ and interlaminar Na⁺ or H⁺. In conclusion, this paper not only reports a novel synthesis strategy for the acquisition of porous zirconium phosphate, but also presents a promising adsorbent for the Sr²⁺ removal.