Synthesis, performance, and nonlinear modeling of modified nano-sized magnetite for removal of Cr(VI) from aqueous solutions

Contamination of water bodies with toxic and non-biodegradable heavy metals is a serious environmental problem. Chromium is a very important contaminant in soil, industrial waste, groundwater, and surface water sources. This study was conducted to assess hexavalent chromium (Cr(VI)) adsorption onto modified magnetite nanoparticles from aqueous solution. The effects of adsorbent dose, pH, contact time, initial Cr(VI) concentrations, adsorption capacity, and modeling of kinetic and isotherm adsorption of Cr(VI) were investigated. Modified magnetite nanoparticles were synthesized by using a co-precipitation method, and its structural and textural properties were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The maximum removal of Cr(VI) was achieved at pH 4.0. A contact time of 60 min was required to reach the equilibrium. Experimental data were fitted with different nonlinear isotherm and kinetic models. The results showed that the adsorption data were fitted well by the Redlich and Peterson and Freundlich isotherm models. The kinetic data were best fitted to pseudo-second-order kinetic model. The results indicate that modified nano-sized magnetite could be employed as adsorbent for the removal of Cr(VI) in aqueous environments effectively.