abstract: Radioactive cesium (137Cs), released from nuclear power plants and nuclear accidental releases, is a problem due to difficulties regarding its removal. Efforts have been focused on removing cesium and the remediation of the contaminated environment. Traditional treatment techniques include Prussian blue and nano zero-valent ion (nZVI) and nano-Fe/Cu particles to remove Cs from water; however, they are not efficient at removing Cs when present at low concentrations of about 10 parts-per-billion (ppb), typical of concentrations found in the radioactive contaminated sites. The objective of this study was to develop an innovative and simple method to remove Cs+ present at low concentrations by engineering a proteoliposome transporter composed of an uptake protein reconstituted into a liposome vesicle. To achieve this, the uptake protein, Kup, from E. coli, was isolated through protein extraction and purification procedures. The new and simple extraction methodology developed in this study was highly efficient and resulted in purified Kup at ~1 mg/mL. A new method was also developed to insert purified Kup protein into the bilayers of liposome vesicles. Finally, removal of CsCl (10 and 100 ppb) was demonstrated by spiking the constructed proteoliposome in lab-fortified water, followed by incubation and ultracentrifugation, and measuring Cs+ with inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS results from testing water contaminated with 100 ppb CsCl, revealed that adding 0.1 – 8 mL of Kup proteoliposome resulted in 0.29 – 12.7% Cs removal. Addition of 0.1 – 2 mL of proteoliposome to water contaminated with 10 ppb CsCl resulted in 0.65 – 3.43% Cs removal. These removal efficiencies were greater than the control, liposome with no protein. A linear relationship was observed between the amount of proteoliposome added to the contaminated water and removal percentage. Consequently, by adding more volumes of proteoliposome, removal can be simply improved. This suggests that with ~ 60-70 mL of proteoliposome, removal of about 90% can be achieved. The novel technique developed herein is a contribution to emerging technologies in the water and wastewater treatment industry. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2018

ABSTRACT EXCHANGES OF STRONTIUM ON CLINOPTILOLITE ZEOLITE G&Uuml / L, &Ouml / zkan MS, Department of Chemical Engineering Supervisor: Prof. Dr. Hayrettin Y&uuml / cel November 2003, 110 Pages Sr-90 and Cs-137, nuclear fission products, are the major sources of medium-level radioactive waste which must be decontaminated. Inorganic ion exchangers are the preferred materials to eliminate radioisotopes from aqueous nuclear waste because of their high selectivity, radiation and thermal stability, low cost and likely compatibility with cement containment. Clinoptilolite and other zeolites are widely used in nuclear industry for the removal of radioisotopes from aqueous nuclear waste. In this study, the performance of local clinoptilolite zeolite from G&ouml / rdes region has been investigated so as to determine the conditions under which it can be used effectively in the column for strontium and cesium removal. It was found that under different loading conditions, breakthrough capacity varied from 0 to 0.4078 meq/g for strontium removal, breakthrough capacity varied from 0.1178 to 0.7800 meq/g for cesium removal. It was also determined that the increase of the flow rate reduced the exchange capacity of the bed. Effect of cationic form of the zeolite (Na-CLI: Sodium form of clinoptilolite and Original-CLI: Original form of clinoptilolite) on the breakthrough capacity was also searched. It was observed that Na-CLI performed much better for the removal of strontium and cesium with respect to its original form. In addition, effect of presence of calcium in the feed solution on the breakthrough capacity was investigated and it was found that presence of calcium in the feed solution makes strontium removal essentially impossible, in the case of cesium, presence of calcium in the feed solution decreases breakthrough capacity significantly.

Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethoxysilane with PTA in acidic media. The obtained material had high BET surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its XRD patterns were absent. This proved the embedding of PTA on a sub-molecular level. The material demonstrated high adsorption capacity of Cs. Unexpectedly, porosity of the adsorbent increased after substitution of most protons by cesium cations. Cation exchange also favored agglomeration of the material particles. Kinetic studies showed that the adsorption data correlates strongly with the pseudo-second order model. The adsorbent had two types of adsorption sites: heteropolyacid anions and silanol groups. However, adsorption on silanol groups was very sensitive to the temperature. At the increased temperature, the nature of adsorption fit the Langmuir model extremely well. The obtained results can be used in the development of an effective adsorbent for clean-up of water contaminated by radioactive cesium-137.

Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethyl orthosilicate with PTA in acidic media. The obtained material had high Brunauer-Emmett-Teller Theory (BET) surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its X-ray diffraction patterns were absent. This proved the embedding of PTA on a sub-molecular level and not as a second phase. Acidic sites were determined by neutralization with base in aprotic solvent, followed by titration of the remaining base with an acid. The material demonstrated high adsorption capacity of Cs. Kinetic studies showed that the adsorption data correlates strongly with the pseudo-second order model. At higher temperatures, the nature of adsorption fit the Langmuir model extremely well. The obtained results can be used in the development of an effective adsorbent for clean-up of water contaminated by radioactive 137Cs.

The purpose of the work described in this thesis was to explore the use of fractional crystallization as a technology that can be used to separate medium-curie waste from the Hanford Site tank farms into a high-curie waste stream, which can be sent to a Waste Treatment and Immobilization Plant (WTP), and a low-curie waste stream, which can be sent to Bulk Vitrification. The successful semi-batch crystallization of sodium salts from two single shell tank simulant solutions (SST Early Feed, SST Late Feed) demonstrated that the recovered crystalline product met the purity requirement for exclusion of cesium, sodium recovery in the crystalline product and the requirement on the sulfate-to-sodium molar ratio in the stream to be diverted to the WTP. The experimental apparatus, procedures and results obtained in this thesis on scaled-down experiments of SST Early and Late Feed simulated solutions were adapted and reproduced under hot-cell with actual wastes by our partners at Hanford. To prepare the application of the pretreatment process to pilot scale process, several varation to the feed solutions were investigated including the presence of carboxylates and amines organics compounds and solids particles. Results of the study showed that 4 organics species presented complications to the process (NTA, HEDTA, EDTA and sodium citrate) while the other species (Formate, acetate, glycolate and IDA) and solids particles did not in the conditions of the stored wastes. In this thesis, the kinetics of the crystalline species formed at the condition of the early feed certification run (66 °C and 25 g/h evaporation) were determined along with the effect of the operating temperature and evaporation rate on these kinetics. On one hand, the study of evaporation rate values ranging from 25g/h to 75g/h showed that an increase in evaporation rate increased the specific nucleation while decreasing the specific growth rate. On the other hand, experiments on operating temperature ranging from 35 °C to 75 °C displayed that the nucleation rate of all species increased with temperature at the exception of sodium carbonate monohydrate and burkeite crystals, and that the growth rate of all species increased with temperature at the exception of sodium nitrate. Furthermore, sulfate based crystals such as trisodium fluoride sulfate were only roduced at 45 °C and 75 °C. A simple steady state MSMPR population balance model was developed expressing the total population density function as the sum of the specific population density functions. The specific semi-batch crystallization kinetics were implemented in this model.

The purpose of the work described in this thesis was to explore the use of fractional crystallization as a technology that can be used to separate medium-curie waste from the Hanford Site tank farms into a high-curie waste stream, which can be sent to a Waste Treatment and Immobilization Plant (WTP), and a low-curie waste stream, which can be sent to Bulk Vitrification. The successful semi-batch crystallization of sodium salts from two single shell tank simulant solutions (SST Early Feed, SST Late Feed) demonstrated that the recovered crystalline product met the purity requirement for exclusion of cesium, sodium recovery in the crystalline product and the requirement on the sulfate-to-sodium molar ratio in the stream to be diverted to the WTP. In this thesis, experimental apparatus, procedures and results are given on scaled-down experiments of SST Early Feed for hot-cell adaptation along with operating parameters and crystallization mechanism studies on early feed multi-solute crystallization. Moreover, guidance is given regarding future steps towards adapting the technology to multi-salt crystallization kinetic parameter estimates and modeling. Crystallization, Evaporative Fractional Crystallization, Nuclear Waste Pretreatment, Cesium Removal, Hanford, SST Early and Late feed, Multi-solute, Multi-salts, Simulant Testing