Synthesis and application of chloroacetamides in pyridinium based ionic liquid for high temperature extraction of uranyl ion: A novel and 'green' approach for extractive mass transfer at elevated temperature

Two different chloroacetamides viz 2-chloro-N-methyl-N-phenylacetamide (MACA) and 2-chloro-N-(3-methylpyridin-2-yl)acetamide (AMPCA) have been synthesized and applied for the extraction of uranyl ions from acidic feed. 1-Ethyl-2-methylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid (IL) has been used at elevated temperature for liquid-liquid biphasic mass transfer. An effort has also been made to study the mechanism of extraction, kinetics, thermodynamics, speciation, radiolytic stability and elution behavior of UO22+. The investigation revealed the predominance of 'cation exchange' mechanism. The D values in 2-chloro-N-methyl-N-phenylacetamide (MACA) were found to be more than that of 2-chloro-N-(3-methylpyridin-2-yl)acetamide (AMPCA). The species were found to be[(UO2(NO3) (MACA)(2)](+) and [(UO2(NO3)(AMPCA)(2)](+). Back extraction studies using aqueous solution of oxalic acid and sodium carbonate revealed that, the stripping of uranyl ion from AMPCA in ionic liquid was better than that of MACA. However, MACA exhibited better radiolytic stability as compared to AMPCA in ionic liquid. To understand the complexation of UO22+ with MACA and AMPCA, theoretical calculations were carried out. (C) 2022 Elsevier B.V. All rights reserved.