hexavalent chromium’s (chromium vi) removal from the simulated electroplating industry wastewater by maghemite nanoparticles

background: removing heavy metals from industrial wastewaters by iron nanoparticles has been much noticed in the recent years. chromium is considered as one of the emphasis environmental pollutants. there are high concentrations of chromium in the wastewater of electroplating industries. magnetic iron nanoparticles are used to control and eliminate the heavy metals from industrial effluents through the mechanisms of adsorption, ion exchange and electro-static forces. the aim of this study was to evaluate the efficiency of magnetic nanoparticles for hexavalent chromium’s (vi) removal from the simulated electroplating wastewater and the parameters that influence its removal. methods: the maghemite nanoparticles were prepared by sol-gel method and addition of two and trivalent iron chloride in the water environment under alkaline conditions. then the factors influencing this process, including nano-particle concentration, initial concentration of chromium, ph, mixing rate, and retention time were studied. findings: the findings of this study showed that in the conditions of ph 2, initial chromium concentration of 10 mg/l, synthesized magnetite nanoparticles with a dose of 1 g/ l, retention time of 5 minutes, and mixing rate of 250 rpm, about 86% of chromium (vi) is removed. in addition, characteristics of nanoparticles including, particles structure, composition, size and zeta potential was determined using analytical devices such as xrd, xrf, zeta potential and particle seizer.   conclusion: it is concluded that magnetite nanoparticles have high performance for removal of chromium (vi) from the simulated electroplating wastewater, and removal efficiency is reversely related with ph.