Removal of radionuclides, macrocomponent metal ions, and organic compounds from solutions by nanofiltration

Abstract

Removal of Mg²⁺, Сa²⁺, Cu²⁺, Ni²⁺, Zn²⁺, Fe³⁺, and Pr³⁺ ions, tracer amounts of ¹³⁷Cs, ⁸⁵Sr, and ⁶⁰Co radionuclides, and oxalate and ethylenediaminetetraacetate ions from solutions using a polymeric nanofiltration (NF) membrane produced by RM Nanotekh (Russia) was studied. The selectivity (S) of the NF membrane to multicharged metal cations is considerably higher than to single-charged cations. The NF membrane exhibits the highest selectivity (S = 94–97%) to triple-charged Fe³⁺ and Pr³⁺ ions and double-charged Cu²⁺ ions. The selectivity to double-charged Mg²⁺ and Zn²⁺ ions is somewhat lower (90–94% on the average). Among doublecharged cations, the NF membrane exhibits the lowest selectivity (80–88%) to Ni²⁺ and Cа²⁺ ions. The NF membrane shows high performance in retention of tracer amounts of Sr (S = 95%) and Co (S > 99%) radionuclides, and also of oxalate (S = 94.5%) and ethylenediaminetetraacetate (S = 97.5%) ions. Examples of using the nanofiltration method for removing ⁶⁰Co from a model solution simulating NPP bottom residue and for removing transition metal impurities from a LiCl solution are presented.