Studies on the separation and in-situ sintering solidification of strontium by a highly-efficient titanate-based adsorbent

Nuclear accident and daily nuclear plants are the main strontium (Sr2+) releasing source and the removal of strontium from aqueous solution has aroused great attention. Among the different remediation ways, adsorption with the properties of low cost, high-removal efficiency, and excellent operational simplicity is intensively adopted in the removal of hazard ions in aqueous solution. However, adsorbent could be accumulated and might cause secondary solid wastes after the treatment of hazard ions, which increases troubles and challenges in the disposal process. In this work, a sodium titanate powder (Na2TinO2n+1) was prepared by an improved sol-gel method. The X-ray diffraction (XRD) demonstrates that Na2TinO2n+1 is transformed into anatase structure after calcining at 400 °C for 10 h. The specific surface area (BET) of the synthesized adsorbent is 65.01 m2/g. The results of batch adsorption experiments reveal that Na2TinO2n+1 is a promising adsorbent for removing Sr2+, which the maximum adsorption capacity could achieve to 49.6 mg/g. The adsorbent also shows high selectivity towards Sr2+ in the co-existence ions of Ba2+, Ca2+, Mg2+, Cs+, K+, and the affinity order is Sr2+ > Ba2+ > Ca2+ > Mg2+>Cs+>K+. In the solidification stage, Sr–Na2TinO2n+1 adsorbent is cold pressed at 40Mp and then calcined into titanate ceramics (Na–Sr-TinO2n+1) at 1100 °C. The leaching experiment of titanate ceramics on various medium exhibits excellent solidification capability towards adsorbed Sr2+. [Display omitted] •Layer titante of Na2TinO2n+1 is synthesized by a simple sol-gel reaction.•Na2TinO2n+1 exhibits high efficiency in the capture of strontium.•SrTinO2n+1 is calcined to format titanate ceramic for in-situ solidification of strontium.•Strontium titanate ceramic materials exhibit excellent leaching resistance properties.