Cesium absorption and selectivity studies on titanosilicate sorbents

This thesis describes the production of a directly synthesized titanosilicate and a coated titanosilicate sorbent that demonstrate high affinity and selectivity for the cesium cation. Initial studies showed that these mesoporous titanosilicates bound >90% of cesium from a 1.0 X 10^-3 M (168.4 ppm) CsCl solution. The directly synthesized titanosilicate was studied further to determine the factors that may effect the affinity that the gels have for cesium. The pH of the gel and the CsCl solution was altered in order to find the optimum pH for cesium binding. Other factors that were studied were the influence that competitor ions had, the amount of time that the gel and the CsCl solution needed to be in contact, and the maximum concentration at which the gel could bind >70% of the cesium from solution. Once this was determined, the capacity of the gel was calculated (0.500 mmol Cs^+/g gel).

Different instrumental techniques were performed in order to effectively characterize the titanosilicate gels. Brunauer Emmitt Teller (BET) measurements were done in order to determine the surface area and porosity of each gel. X-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, and solid state nuclear magnetic resonance (SSNMR) were three characterization techniques that aided in identifying mixed metal oxide linkages (Si-O-Ti) within the titanosilicates Atomic emission (AE) spectroscopy was another tool that was used in this research. This method was used to determine how much cesium was left in solution after the solution had been in contact with the titanosilicate gel. Consequently, the fractional absorption and the affinity constant (Kj) could be calculated for each gel.