Removal of Cr(VI) from aqueous solution by polysulfone microcapsules containing Cyanex 923 as extraction reagent

This paper describes the removal of Cr(VI) from aqueous solution in batch sorption technique by using polysulfone microcapsules containing Cyanex 923 as extraction reagent. The microcapsules containing Cyanex 923 (MCs-Cyanex 923) were prepared by solvent evaporation method and characterized by using optical microscope, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Thermal Gravimetric Analysis (TGA). The results showed that maximum removal of Cr(VI) was obtained when ratio of Cyanex 923 to polysulfone was 1.0. The complex formation between Cr(VI) and Cyanex 923 favoured at initial pH of 1.0. The equilibrium time was 30 min and it obeyed the pseudo second-order kinetic model. The Redlich Peterson and Langmuir isotherm models better represented the sorption data in comparison to Freundlich isotherm. The Langmuir sorption capacity of MCs-Cyanex 923 for Cr(VI) was 0.430 mmol g−1. The MCs-Cyanex 923 preferably sorbed Cr(VI) against various metal ions, including Cr(III), Ni(II), Pb(II), Cu(II), Zn(II), Cd(II), Co(II). The regeneration studies also showed that MCs-Cyanex 923 could be re-used for the adsorption of Cr(VI) from aqueous solutions over 3 cycles.