Crystalline silicotitanate

Another application for adsorption of metal impurities is in the nuclear power industry. Radioactive cesium is one of the compounds that is difficult to remove from radioactive waste. This is because ordinary resins and zeolites do not effectively adsorb radioactive cesium. In 1997, lONSlV lE-911 crystalline silicotitan-ate (CST) ion exchangers were developed and effectively used to clean up radioactive wastes in the Melton Valley tanks at Oak Ridge [268, 269], CST was discovered [270] by researchers at Sandia National Laboratories and Texas A M University, with commercial manufacture carried out by UOP. 

The lonsiv ion exchange resins are extraction technologies used to separate radionuclides from alkaline wastewater in the presence of competing cations. These resins include lonsiv IE-910 and lonsiv IE-911, which are manufactured using a new class of crystalline silicotitanates (CSTs) invented by researchers from Sandia National Laboratory (SNL) and Texas A M University. CSTs demonstrate high distribution coefficients in acidic, neutral, and alkaline solutions with high concentrations of competitive ions such as sodium and potassium. The affinity of CSTs for strontium in neutral or alkaline wastes is also high. 

Radiocesium is a significant issue as a part of the DOE clean-up effort Selective sequestration of cesium has been addressed by polymer-bound crown ethers e.g. the SuperLig 644) and the crystalline silicotitanates. While both of these methods are effective, they each have their drawbacks. By lining the pores of SAMMS with ferrocyanide complexes, it is possible to remove all the cesium from waste simulant solutions in a matter of minutes [12]. This sorbent is not... 

Synthesis efforts in this project to date focused on producing a sorbent with increased 90Sr and actinide removal performance. Specific types of sorbents produced and evaluated for removal performance include sodium nonatitanate, metal-substituted sodium nonatitanates, crystalline silicotitanates, titanosilicates having a pharmacosiderite structure and heteropolyniobates. Table 2 provides a list of sorbent materials tested. Performance testing featured a simulated waste solution comprised of the major anionic components of SRS waste solutions as the respective sodium salts and specific amounts of strontium and actinide elements. 

Sodium Nonatitanate (SnT) Niobium-Substituted SnT (Nb-SnT) Crystalline Silicotitanate (CST) Niobium-Substituted CST (Nb-CST) Titanosilicate Pharmacosiderite (TSP) Heteropolyniobates (IPX)... 

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