Effect of [Fe2+/total metal] on treatment of heavy metals from laboratory wasteliquid by ferrite process

In this study, the X-ray absorption near-edge structure shows that poisonous Cr6+ in the laboratory wasteliquid were reduced to Cr3+ by adding Fe2+ at [Fe2+/total metal, mole ratio higher than 4:1. The X-ray diffraction analysis shows that greater the [Fe2+/total metal] mole ratios used (such as 6:1, 10:1, 20:1 and 30:1), the more spinel-structured ferrites were formed (0.26, 0.30, 0.48 and 0.59). When [Fe2+/total metal] mole ratio was larger than 20:1, the saturation magnetization and coercive field were about 5.21 emu/g and 6.2 kOe, respectively. The ferrite precipitates could be recovered as magnitude materials. However, the TCLP test result was beyond the standard of EPA when the [Fe2+/total metal] mole ratio was 30:1. The optimum operation for the laboratory wasteliquid by ferrite process in the [Fe2+/total metal] mole ratio was 20:1.