Application of indigenous inorganic sorbents in combination with membrane technology for treatment of radioactive liquid waste from decontamination processes

Abstract

Zeolites / Decontamination / Radioactive waste microfiltration / UltrafiltrationSummary. The purpose of the work was to improve the process for treatment of liquid radioactive waste containing complexing agents, which are generated during the decontamination operations.We performed some experiments using simulated waste solutions like secondary waste from the modified CANDEREM process (Canadian Decontamination and Remediation Process) and secondary waste from the modified CANDECON process (Canadian Decontamination Process).To improve efficiency and economics of the process it was proposed to treat the waste by combining the sorption of radionuclides on natural inorganic sorbents (zeolites) with membrane filtration.Standard procedures are applied to compare the sorption of radionuclides on different sorbent forms-determination of the ion exchange capacity, construction of sorption isotherms, determination of the distribution coefficients, and kinetics experiments.To check the influence of converting the sorbents to various cationic forms on their sorption properties, distribution coefficients of 137 Cs and 57 Co on natural zeolites from local deposits converted to NH 4 + , Na + or H + forms were determined. The results obtained show that the distribution coefficients of 137 Cs on the materials converted to Na + form are higher than for the remaining forms studied [1].The parameters of Langmuir, Freundlich and DubininRadushkevich adsorption isotherms have been determined using sorption data. The Dubinin-Radushkevich model shows better correlation between the theoretical and experimental data for 137 Cs sorption on natural zeolites from local deposits converted to NH 4 + and H + forms than Langmuir and Freundlich equations.Kinetic studies were carried out with various zeolite forms. The sorbents studied are natural zeolites from local deposits (Marsid-Romania).The batch sorption kinetics has been tested for pseudosecond order reaction. The pseudo-second order model fits the experimental data well for all of the systems studied.

Removal of heavy metals and pollutants by membrane adsorption techniques

“…The decontamination efficiency achieves 99.94% and the volume concentration ratio achieves 12.5 at pH 10 for solution fed into the membrane separation system. Dulama et al (2010) proposed to treat the waste by combining the sorption of radionuclides on natural inorganic sorbents (zeolites) with membrane filtration. Zhu et al (2014a, b) prepared PVA/chitosan magnetic composite beads and used for Co 2+ removed from radioactive waste.…”

Liquid Radioactive Wastes Treatment: A Review

“…The performance of different sorbents was compared by determining the ion exchange capacity, distribution coefficients, and evaluating the sorption characteristics. The obtained results showed that the distribution coefficients of Cs on the Na-form converted materials are higher than for that of NH 4 -and H-forms [41,42]. The biosorption of U by seaweed Sargassum filipendula was investigated under dynamic conditions at various bed heights [43].…”

Magnetic nanocomposites based on Zn,Al-LDH intercalated with citric and EDTA groups for the removal of U(vi) from environmental and wastewater: synergistic effect and adsorption mechanism study

“…4 Numerous studies have shown 6 that U(VI) is present in environmental water and wastewater mainly in the soluble anionic carbonate forms such as UO 2 (CO 3 ) 2 2− and UO 2 (CO 3 ) 3 4− which are not sufficiently eliminated by mineral suspensions and clay components of soils. Numerous methods have been proposed to remove U(VI) from waste and contaminated environmental water 7 such as solvent extraction, 8 distillation, 9 coagulation, 10 reverse osmosis, 11 precipitation, 12 adsorption/ion exchange, 13 membrane ltration and biological technologies. 14 Each of these methods has its advantages and disadvantages.…”

“…Numerous methods have been proposed to remove U( vi ) from waste and contaminated environmental water 7 such as solvent extraction, 8 distillation, 9 coagulation, 10 reverse osmosis, 11 precipitation, 12 adsorption/ion exchange, 13 membrane filtration and biological technologies. 14 Each of these methods has its advantages and disadvantages.…”