Treatment of simulated low level radioactive wastewater by supported liquid membranes: uphill transport of Ce(III) using CMPO as carrier

Abstract

Abstract In order to examine the feasibility of treating low level radioactive wastewater by supported liquid membranes (SLMs), experiments were performed using a stirred permeation cell. Aqueous solutions of nitric acid and/or sodium nitrate containing about 550 ppm Ce(III), 490 ppm Fe(III), 320 ppm Cr(III) and 330 ppm Ca(II) were used as a simulated low level radioactive wastewater. The liquid membrane consisted of octyl(phenyl)- N , N -diisobutylcarbamoylmethylphsophine oxide as a carrier of cerium, tributylphosphate as a modifier and dodecane as a solvent. The strip solutions were water and aqueous sodium citrate solutions. The effects of various experimental conditions such as concentrations of cerium, HNO 3 and NaNO 3 in the feed solution, liquid membrane composition and temperature were investigated. Rapid transport and enrichment of cerium were realized by adding sodium citrate to the strip solution as the masking agent of cerium and also using a feed solution of low nitric acid concentration and high sodium nitrate concentration. Increasing the temperature from 298 to 318 K was very effective in enhancing the permeation rate of cerium. The membrane area required for removing 99.9% of cerium from the feed solution containing about 550 ppm Ce was estimated as 3.3 m 2 at 1 m 3 day −1 of the treatment rate.