Ion exchange in concentrated solutions utilizing hydrous crystalline silicotitanates /
During the past half century, nuclear defense activities have
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=743267731&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | During the past half century, nuclear defense activities have produced a large volume of radioactive waste. Currently, the Hanford Reservation in Washington stores more than 65 million gallons of radioactive waste in 177 tanks. These wastes are complex solutions containing radioactive cesium which needs to be removed. However, due to the high concentrations of sodium in the wastes and the presence of other Group I cations such as potassium and rabidium, the process for removal of cesium has to be highly selective for cesium. Hydrous crystalline silicotitanates, labeled TAM5, invented by Anthony et al. at Texas A&M University and Sandia National Laboratories show high selectivity for cesium in acidic, neutral and basic solutions. This material is stable in a radioactive environment which is important for removing radioactive cesium. Designingwaste treatment facilities and determining the optimum operating conditions for using TAM5 to remove radioactive cesium from aqueous waste requires knowledge of the distribution coefficient of cesium, which is a fimction of waste composition and usually needs to be determined experimentally. Because a wide range of compositions will be encountered in waste treabnent, an extensive amount of experiments will be required. Therefore, a method that predicts the equilibrium performance will significantly reduce the time and effort required for such an experimental program. In this work, binary and multicomponent ion exchange experiments were conducted to determine the ion exchange performance of TAM5. Step changes were observed on the binary ion exchange isotherms, and solid phase is ideal along the isotherms prior to the step changes. The apparent ion exchange capacity of cesium prior to the step changes is 0.58 mmol/g. ne apparent capacities prior to the step changes of mbidium, potassium and strontium are double the cesium apparent capacity. By representing the ion exchange unit of TAM5 as N@)XNa, the solid phase can be considered as completely ideal. An equilibrium model was developed which includes ion exchange between cesium, mbidium, potassium, sodium, proton and strontium. The model was used to predict ion exchange in complex simulants. The predictions match the experimental data very well. |
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| Item Description: | Vita. "Major Subject: Chemical Engineering". |
| Physical Description: | xiv, 151 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |