Three-dimension titanium phosphate aerogel for selective removal of radioactive strontium(II) from contaminated waters

The effective removal of radioactive strontium (especially 90Sr) from nuclear wastewater is crucial to environ-mental safety. Nevertheless, materials with excellent selectivity in Sr removal remain a challenge since the similarity with alkaline earth metal ions in the liquid phase. In this work, a novel titanium phosphate (TiP) aerogel was investigated for Sr(II) removal from the radioactive wastewater based on the sol-gel method and supercritical drying technique. The TiP aerogel has amorphous, three-dimensional and mesoporous structures with abundant phosphate groups, which was confirmed by X-ray diffraction (XRD), energy dispersive spec-troscopy (EDS), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FT-IR). The adsorbent exhibited high efficiency and selectivity for the removal of Sr(II) with an extensive distribution co-efficient up to 4740.03 mL/g. The adsorption equilibrium reached within 10 min and the maximum adsorption capacity was 373.6 mg/g at pH 5. And the kinetics and thermodynamics data fitted well with the pseudo-second -order model and Langmuir model respectively. It can be attributed to the rapid trapping and slow intraparticle diffusion of Sr(II) inside the mesoporous channels of the TiP aerogel. Furthermore, TiP aerogel exhibited over 80% removal for 50 mg/L Sr2+ in real water systems (seawater, lake water and tap water). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy revealed that strong ionic bonding formed during Sr(II) adsorption with the phosphate group on TiP aerogel. These results indicated that TiP aerogel is a promising high-capacity adsorbent for the effective and selective capture of Sr(II) from radioactive wastewater.

Automated summary

In this study, a novel TiP aerogel was developed for the selective removal of Sr(II) from radioactive wastewater. The TiP aerogel demonstrated high efficiency and selectivity, with a distribution coefficient of up to 4740.03 mL/g. It exhibited rapid adsorption kinetics and a maximum adsorption capacity of 373.6 mg/g at pH 5. The TiP aerogel also showed over 80% removal for 50 mg/L Sr2+ in real water systems. The results indicate that TiP aerogel is a promising adsorbent for the effective and selective capture of Sr(II) from radioactive wastewater.