Microporous titanosilicate ETS-10 for the removal of divalent heavy metals

Abstract

In this work, synthesis of pure ETS-10 is described. The effects of titanium sources, fluoride ion, pH of synthesis gels, Na + and K + ions, and SiO 2/TiO 2 molar ratios in synthesis gels, and synthesis time and temperature on the crystallization of ETS-10 are discussed. The experimental results showed that nano-sized Degussa TiO 2 (commercially known as P25) is the best titanium source, with which highly pure ETS-10, as identified by XRD, SEM, and NMR, can be synthesized from an optimized synthesis system of 3.4Na 2O-1.5K 2O-TiO 2xSiO 2-yH 2O (x = 4.5-5.5 and y = 150-180) without using any seeds or organic template. The adsorption data of divalent heavy metal ions demonstrated that, in addition to an extremely fast adsorption kinetics, the adsorptive capacities of Pb 2+, Cu 2+ and Cd 2+ on ETS-10 can attain up to 1.3, 0.92 and 0.87 mmol g -1, respectively, which are the highest adsorptive capacities of the heavy metal ions on zeolite materials reported so far, indicating that ETS-10 is a very promising adsorbent for divalent heavy metals. © 2005 Elsevier B.V. All rights reserved.