A New Concept to Recover Heavy Metals from Industrial Wastewater

Herein, we present a new, economic, energy-saving and environment-friendly technique to treat industrial wastewater. With our concept we succeeded (1) to purify metal (A, B) loaded wastewater, (2) to prevent production of highly voluminous hydroxide sludge and (3) to recover metals as a secondary resource, as (doped) ferrites (A 2+ Fe 3+ 2-x B 3+ x O 4 ), delafossite (A 1+ Fe 3+ 1-x B 3+ x O 2 ), binary oxides and/or zero-valent metals directly from aqueous solutions at low temperatures between 40 °C and 90 °C. The procedure includes a facile precipitation reaction and ageing of the residues in some cases. The wastewater purification rates achieved by this treatment technique are 99.98 % – 100 % for Cu, Zn, Ni, Ag, Fe, Pd, Cr, Pb and Mn at optimal conditions. Using this method no highly voluminous hydroxide sludge is produced. The recovery of the heavy metals is economically feasible due to high ratios of the specific element (A, B) in the residue. In some cases the precipitated synthesis product itself, e.g. nano crystalline delafossite can be directly used for industrial applications. Therefore, this concept can effectively prevent pollution, provide a source for usable heavy metals and avoid dissipation of metals into the Environment.