Preparation and adsorption properties of zinc-doped titanium-based cesium ion sieves
Titanium-based ion sieve adsorbents have good application prospects in the extraction of cesium from salt lake brine and the treatment of radioactive nuclear wastewater.In this paper,based on the improved sol-gel technology,trace Zn2+was doped into the Ti—O lattice of Cs2Ti6O13 to improve the cell structure,and the zinc doped titanate precursor material(CZnTO)was prepared.The precursor was subjected to acid treatment to form a zinc-doped protonated titanate(HZnTO).The prepared HZnTO was characterized by XRD,SEM,EDS,FTIR,Raman spectroscopy and XPS,which showed that the incorporation of trace amounts of Zn2+did not destroy the original layered structure.Through adsorption experiments,the effects of aqueous pH,initial cesium ion concentration,adsorption time and temperature on the adsorption behavior of HZnTO were investigated.The studies found that at 288K,pH=1 1 and an initial Cs+concentration of 3000mg/L,the adsorption of HZnTO for about 2h could achieve a saturated adsorption capacity of 323mg/g.In a low concentration solution with an initial Cs+concentration of 30mg/L,HZnTO could still maintain an adsorption and removal rate of over 80%.The adsorption of Cs+on HZnTO conformed to the quasi second order kinetic equation and Langmuir adsorption isotherm,indicating that the adsorption of Cs+on HZnTO was chemical adsorption mainly by single molecular layer adsorption.Selective adsorption experiments and cyclic adsorption-desorption experiments showed that the selectivity of HZnTO for Cs+was much higher than that of other ions.After 7 cycles of cyclic adsorption,the adsorption capacity of HZnTO could still reach 87.6%of that of the initial cycle,demonstrating a good stability.
cesium ion sievedopingadsorptionkineticsthermodynamics