Removal of nickel from the actual electrolytic wastewater by bentonite supported nanoscale zero valent iron

A large number of wastewater is produced in the process of electroplating industry, and pose serious threats to humanity. Nanoscale zero valent iron (nZVI) has a desirable reductive adsorption capacity for treatment of the electroplating wastewater, but limited by its agglomeration and oxidation. In this study, the composite material nZVI@B was prepared using the emulsion of nZVI and sodium bentonite, and characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The aggregation and oxidation phenomena of nZVI particles were decreased with the successfully supported on bentonite. The decontamination abilities of nZVI@B were tested by removal of nickel (Ni) from the electroplating wastewater. The results showed that the nZVI@B has a 99.96% removal efficiency at 120 min, which is greatly better than those of nZVI and bentonite. The reactivity of the nZVI can be effectively improved by dispersed in the interlayer of Bentonite and reduced to contact with water. The lower solution pH value, initial concentration, and higher dosage had positive effects on Ni removal. But the effect of temperature on final removal efficiency was not remarkable. Furthermore, the tailings obtained though the batch experiments were detected by energy-dispersive X-ray spectroscopy, the content of Ni is in the range from 25% to 40%, which can reduce the total amount of tailing slag treatment and the difficulty of recycling.