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

► Valuable ferrite materials can be prepared by co-treating pickling waste liquor and electroplating wastewater. ► Toxic Cr(VI) in electroplating wastewater can be reduced to Cr(III) by utilizing the reducibility of Fe(II) in pickling waste liquor. ► Fast-heating provided by microwave hydrothermal process can be a cost-effective way compared with those high energy consumed methods. ► Heavy metals Zn and Cr in the ferrite lattice are chemically stable.