Cesium and strontium exchange by the framework potassium titanium silicateK3HTi4O4(SiO4)(3)center dot 4H(2)O

Potassium titanium silicate with a semicrystalline framework of the formula K3HTi4O3(SiO4)(3). 4H(2)O has been prepared under mild hydrothermal condit ions and its protonic form, H4Ti4O4(SiO4)(3). 8H(2)O, was obtained by acid treatment of the potassium compound. A comparative ion exchange testing of the H4Ti4O4(SiO4)(3). 8H(2)O towards alkali and alkaline earth metals in a broad pH and concentration range was carried out. It was found that potassi um titanium silicate is a moderately weak cation exchanger, possessing high ion exchange capacity (up to 4-5 meq/g) and showing preference for heavy a lkali and alkaline earth metals uptake. The selectivity of K3HTi4O4(SiO4)(3 ). 4H(2)O towards Cs+ and Sr2+ ions in alkaline and acid media in the prese nce of competitive inorganic ions and certain organic compounds was also st udied. The data obtained suggest that despite the existence of well defined tunnel structure with parameters fitting for cesium ion in the K3HTi4O4(Si O4)(3). 4H(2)O, potassium titanium silicate could remove cesium (and stront ium) efficiently only under some specific conditions, namely, at pH close t o neutral and in the absence of competitive ions and especially of organic complexing agents.