Removal of radioactive iodide from simulated liquid waste in an integrated precipitation reactor and membrane separator (PR-MS) system

• A novel integrated PR-MS system was developed to remove I− efficiently at lab-scale.
• Possible reactions were presented and I− was transferred to CuI(s) in the PR.
• The addition of Na2SO3 played an important role in the protection of Cu+.
• Solid-liquid separation and copper removal were simultaneously attained in the MS.

A novel integrated precipitation reactor (PR) and membrane separator (MS) system was developed for the removal of radioactive I− from simulated liquid waste. The PR-MS system was evaluated at the lab-scale, the I− removal efficiency reached approximately 97.0% and the concentration factor (CF) value was 1050 when the concentration of added Na2SO3 was 40 mg/L and the CuCl dosage was 260 mg/L. The addition of Na2SO3 played an important role in the removal of dissolved oxygen (DO) and the formation of CuI. These reactions, including the oxidation of SO32−, the dissociation of CuCl, the disproportionation of Cu+, and the formation of CuI and Cu2O, occurred in the PR. Furthermore, the influence of the concentration of added CO32− on copper removal was investigated, and solid-liquid separation and copper removal were simultaneously attained in the MS. The I− removal efficiency gradually decreased from 97.0% to 58.5% and the Cu2+ concentration in the effluent decreased from 18.71 mg/L to 0.719 mg/L with the addition of CO32− at a concentration that ranged from 0 to 80 mg/L. Experimental results show the PR-MS system is of great potential for industrial application on treatment of liquid waste contaminated with radioactive I−.