Enhancing the adsorption of chromium(VI) from the acidic chloride media using solvent impregnated resin (SIR)

Abstract

In this study, the solvent impregnated resin (SIR) based on impregnation of Cynaex 923 in Amberlite XAD-7HP resin was used to remove hazardous chromium(VI) from the acidic chloride media. The results showed that SIR adsorbed chro-mium effectively when the solution pH was low (acidity of solution; 0.3– 2.0 M). The adsorption mechanism of the SIR for chromium(VI) could be explained taking into account the interaction between the protonated oxygen atoms of polyacrylate (ester group) in the resin and the solvation of Cyanex 923 with trioxochloromate (CrO3Cl–) complexes. The involvement of both the polymeric support and extract-ant for chromium adsorption enhanced uptake capacity of SIR to 28.2 mg Cr/g SIR (1.0 g SIR contained 0.375 g the extractant) compared to that of 16.9 mg Cr/g resin. Freu-ndlich isotherm was more suitable than Langmuir isotherm and Thomas model described well the adsorption behavior of chromium in column. Chromium was eluted effectively from chromium-loaded SIR by 0.1 M sodium hydroxide solution, and elution efficiency reached 92% in the first stage. The regenerated SIR when reused for adsorption of chromium showed almost the same level of efficiency at least in three cycles.