Solid phase extraction, separation and preconcentration of rare elements thorium(IV), uranium(VI), zirconium(IV), cerium(IV) and chromium(III) amid several other foreign ions with eriochrome black T anchored to 3-D networking silica gel

Abstract

The present work reports the systematic studies on extraction, separation and preconcentration of Th(IV), U(VI), Zr(IV), Ce(IV) and Cr(III) amid several other foreign ions using EBT anchored {SiO2}n3-D microarray. The effect of various sorption parameters, such as pH, concentration, temperature, sample volume, flow-rate and co-existing foreign ions were investigated. Quantitative sorption was ensured at solution pH: 6.0–6.5 for Th(IV), Ce(IV), Cr(III) and pH: 2.75–3.0 for Zr(IV), U(VI) couple. Analysis on extracted species and extraction sites reveals that [Th4(μ2-OH)8(H2O)4]8+, [Ce6(μ2-OH)12(H2O)5]12+, [Cr3(μ2-OH)4(H2O)]5+, [(UO2)3(μ2-OH)5(H2O)3]+ and [Zr4(μ2-OH)8(H2O)0.5]8+ for the respective metal ions gets extracted at HOMO of the extractor. HOMO-{metal ion species} was found to be 1:1 complexation. Sorption was endothermic, entropy-gaining, instantaneous and spontaneous in nature. A density functional theory (DFT) calculation has been performed to analyze the 3-D structure and electronic distribution of the synthesized extractor.