Removal of Cr(VI) using iron nanoparticles supported on porous cation-exchange resin

In this study, the iron nanoparticles were synthesized by ferrous sulfate method using LiBH4 as a reducing agent. The reduction of Cr(VI) to Cr(III) by iron nanoparticles supported on a porous cation-exchange resin and the retention of Cr(III) and Fe(III) as products on the resin were achieved in a single step. The size and surface area of iron nanoparticles were determined by transmission electron microscopy and BET surface area analysis. The loading of the iron nanoparticles on porous cationic resin support was confirmed by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy as well as chemical analysis. Porous cationic support material composed of sulphonated styrene–divinylbenzene copolymer of three different diameter sizes i.e., 1.2–45, 45–150 and 150–270μm was synthesized by suspension polymerization. The cationic support was characterized by FTIR spectroscopy, mercury porosimetry, particle size analysis, and sulphonic acid content estimations. The iron nanoparticles were dispersed into porous cationic support material and then the composite was applied for reduction of Cr(VI). The reduction capacity of Cr(VI) was higher in smaller size diameter of support material (1.2 to 45μm) as compared to the larger diameter. Fe(III) and Cr(III) produced from the reaction of Fe0 and Cr(VI) were adsorbed onto the porous cationic support material. The reduction capacity of Cr(VI) and adsorption capacities of Fe(III) and Cr(III) were evaluated at different temperatures, concentrations of iron nanoparticles loaded on porous cationic exchange resin and pH.