Removal Of Ce³⁺ And Sr²⁺ From Low Level Simulated Radioactive Solutions Via Polymer-enhanced Ultrafiltration

According to Long-term National Development Plan of Nuclear Power, Chinawill build and running a40million kilowatts nuclear power plant. In addition, theconstruction of inland nuclear power plants have been incorporated into the country’snuclear power development plan. Low level radioactive waste will produced duringthe nuclear research process, In low level of radioactive wastewater the content of Ceand Sr is more than other nuclides in the solution, and fission products90Sr and144Ceare recognized as an effective dose equivalent to human contribution to the largerradionuclides.90Sr is highly toxic radionuclides, mainly gathered in the bones and isdifficult to discharge; Half-life of144Ce is5×1015years, and they will pollute thewater, plants, animals and soil. Eventually they will enter the body through the foodchain, and cause harm to humans, So it’s necessary to adopt appropriate way toremove Ce and Sr.Traditional low-level radioactive liquid waste treatment methods includechemical precipitation, evaporation and concentration, adsorption and ion exchange,they have their own features and range of applications. The membrane technologywas favored as an emerging technology with low power consumption, no chemicalreaction to complete the separation process, the separation efficiency advantages.Polymer-Enhanced Ultrafiltration having an excellent performance and broadapplication in the removal of radionuclides.In this paper, water-soluble compounds containing amino polyethyleneimine(PEI) was used to assisted polyether sulfone (PES) ultrafiltration membrane toremove low-level radioactive wastewater simulation cerium and strontium. Theresults show that: When using PEI assisted ultrafiltration to remove Ce3+, the bestexperimental conditions are P/M=15, pH=5, and three MWCO ultrafiltrationmembrane retention rate were88.23%,(5kDa),87.01%(10kDa) and89.78%(30kDa),respectively. The abnormal rejection of30kDa ultrafiltration membrane may be due toCe-PEI complex dimensions nearly to30kDa membrane pore size; When Na+andCa2+added to the solution, the rejection of Cerium will be decreased. Investigate theeffect of pH on the rejection of Sr2+at best complex P/M=15, When using PEIassisted ultrafiltration to remove Sr2+; there have a double pH peak, i.e., pH=6and8,a double peak may be due to the presence of-NH,-NH2in PEI, and their complexing ability at different pH values is different; When added the same amount of Na+andCa2+to the solution, the rejection of Cerium will be decreased more when added Ca2+to the solution.In the experiment, The membrane permeate flux is linear increase with theincrease of transmembrane pressure; Three kinds of membrane permeate flux have atendency to decrease with the increase of operation time, and the rank of threemembranes permeate flux decrease rate is:30kDa＞10kDa＞5kDa. In this paperusing acid and alkaline to clean the contaminated membrane, but may be due to thecomplexity composition of the contaminated layer of membrane resulting that themembrane flux have decreased.