Synthesis of titanosilicate crystal analogous to Ivanyukite as a highly effective Cs+ and Sr2+ adsorbent

Abstract

Invayukite analogous of Titanium Silicate, stands for ITS, was synthesized with alkali ions, silica, and titanium precursor using hydrothermal methods. The adsorbent is similar to ETS or Ivanyukite mineral in structures, but the synthesized composite show different XRD patterns and single crystal (15nm) confirmed by TEM and SEM. The ITS consists of octahedral and tetrahedral units composed of 8-membered ring pores which make a 3-dimensional framework containing exchangeable ions. The possible ion exchange mechanism for ITS was described by XRD, and Electron diffraction patterns. The ITS which has the best performance (ITS-1) is synthesized at 180 ℃ for 4 days with pH 13.8. The maximum adsorption capacity for ITS-1 is 503.71 mg g$^{-1}$ for Cs+ and 259.75 mg g$^{-1}$ for Sr2+, respectively. Moreover, the adsorption kinetics of ITS-1 for both Cs$^+$ and Sr2$^+$ shows outstanding performance with the equilibrium of 99 % removal efficiency within 10 min. In the presence of excess competitive ions in solution, the ITS-1 represents the better performance than the other ITS, which suggests that mixture of Na$^+$ and K$^+$ ions in the adsorbent structure gives greater affinity for Cs$^+$ and Sr2$^+$ ions, especially Na$^+$ ion solutions. Thus, ITS-1 can be a good adsorbent for treating radio-contaminated water with enhenced capacity and selectivity, by removing Cs$^+$ and Sr2$^+$ ions simultaneously.