Flash fixation of heavy metals from two industrial wastes into ferrite by microwave hydrothermal co-treatment

Flash fixation of heavy metals from electroplating wastewater (EPW) and pickling waste liquor (PWL) into ferrite lattice can be investigated by microwave hydrothermal process. The toxicity of wastewater may be reduced by the redox reaction between Cr(VI) in electroplating wastewater and Fe(II) in pickling waste liquor. Box-Behnken design (BBD) experiment gives optimal process condition of ferrite formation as follows: wastewater volume ratio (V(PWL):V(EPW) = 0.20), pH value 11 and retention time 15 min, on which formed ferrite has a soft magnetic property with high saturation magnetization (M(s)) 47.4 emu/g. The rapid ferrite process has lower activation energy 7.01 kJ/mol according to grain growth kinetics. Concerning the environmental and economy, we introduced a new and interesting method for water remediation simultaneously synthesizing ferrite by using microwave mediated hydrothermal processes.