Modeling Ion-Exchange for Cesium Removal from Alkaline Radioactive Waste Solutions

Application of response surface method in the separation of radioactive material: a review

Response Surface Method (RSM) is one of the most popular and powerful tools for experimental design and optimization. This paper first reviewed the research progress of RSM in the separation and recovery of various radioactive materials, and verified the application of RSM in adsorption isotherm analysis and thermodynamic calculation. The main advantage of RSM in radioactive material separation is the reduction in the number of experiments required, resulting in considerably less radioactive material consumption, secondary waste generation, workload and radiation dose, which is valuable for the research of radioactive material separation.

Hydrothermal oxidation of pre-dissolved resorcinol-formaldehyde resins as a new approach to safe processing of spent cesium-selective organic ion-exchangers

Here we report a new approach to predisposal processing of spent resorcinol-formaldehyde resins (RFR) selective to cesium radionuclides via dissolution and hydrothermal oxidation (HTO) with the mineralization efficiency above 85%. Using a combination of potentiometric and colloid titration, we have shown that dissolution of RFR by consecutive treatment with nitric acid and sodium hydroxide solutions at optimal concentrations of 3-5 mol/L and 1 mol/L, respectively, yields colloid solutions of partially depolymerized and oxidized RFR. The efficiency of HTO of resorcinol and RFR solutions with hydrogen peroxide was investigated in a flow-type stainless steel reactor in the temperature range 165-250 °С and at linear flow rates of 1-3 cm/min. It was demonstrated that HTO allowed efficient resorcinol mineralization using hydrogen peroxide at H₂O₂: resorcinol molar ratios above 10 at 195 °С and a linear flow rate of 2 cm/min. Due to the colloidal nature of organics in RFR solution, its efficient decomposition occurred at higher temperature or molar excess of the oxidizer as compared to resorcinol, but in both cases HTO was the most efficient in acidic media yielding acetic acid as the main oxidation resistant product.