Optimization of factors affecting hexavalent chromium removal from simulated electroplating wastewater by synthesized magnetite nanoparticles

Hexavalent chromium is a mutagen and carcinogen that is of significant concern in water and waste-water. In the present study, magnetite nanoparticles (n-Mag) were investigated as a potential remediation technology for the decontamination of Cr (VI)-contaminated wastewater. Synthesized n-Mag was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET-N-2 technology. To screen and optimize the factors affecting Cr (VI) removal efficiency by synthesized nanoparticles, Plackett-Burman (PB) and Taguchi experimental designs were used respectively. The crystalline produced n-Mag was in the size range of 60-70 nm and had a specific surface area (SSA) of 31.55 m(2) g(-1). Results of PB design showed that the most significant factors affecting Cr (VI) removal efficiency were initial Cr (VI) concentration, pH, n-Mag dosage, and temperature. In a pH of 2, 20 mg L-1 of Cr (VI) concentration, 4 g L-1 of n-Mag, temperature of 40 degrees C, 220 rpm of shaking speed, and 60 min of contact time, the complete removal efficiency of Cr (VI) was achieved. Batch experiments revealed that the removal of Cr (VI) by n-Mag was consistent with pseudo-second order reaction kinetics. The competition from common coexisting ions such as NO3- -, SO42-, and Cl- were not considerable, unless in the higher concentration of SO42-. These results indicated that the readily synthesized magnetite nanoparticles have promising applications for the removal of Cr (VI) from aqueous solution.