Enrichment of indium from aqueous solution using functionalized sorbent

Abstract

The present method utilizes styrene-divinylbenzene-based polymeric material containing phthalic acid as chelating agent to concentrate ultra trace amounts of indium ions in aqueous

solutions. Sorption behaviour of In(III) ions under static and dynamic conditions onto the new synthetic resin is reported here. Maximum sorption has been achieved from solution with 8 min of agitation time in the <i>p</i>H<i> </i>range 5-8. The lowest concentration for quantitative recovery is 5 ppb with the preconcentration factor 666. The kinetics and thermodynamics of sorption have been studied in detail. The kinetics follows the first order rate equation with the rate constant <i>k, </i>equal to 0.645 ± 0.05 min^{- l}. The variation of equilibrium constant <i>k</i>_cwith temperature between 10°C to 50°C yields values of Δ<i>H </i>33.7±1.96 kJmol^-1, Δ<i>S</i> 136.9±6.4 Jmol^-1K^-1 and Δ<i>G</i>_303K -7690 ± 200 Jmol^-1K^-1. The sorption data in the concentration range 5.26×10^-6 to 2.19×10^-4 <i>M </i>L^-1 In(III) ions follow Langmuir, Freundlich, and Dubinin-Radushkevich isotherms at all the temperatures investigated. The sorption of In(III) ions onto the synthesized resin in the presence of common anions and cations has also been measured.