Purification of heavy metal loaded wastewater from electroplating industry under synthesis of delafossite (ABO2) by "Lt-delafossite process".

In this study we present a new, environmental friendly and economic method, called Lt-delafossite process to treat industrial wastewater (initial Cu(2+)-concentrations of 1-15.6 g/l) by subsequent synthesis of nano-crystalline (doped) delafossite (CuFeO2) solely by precipitation and ageing at temperatures between 50 °C and 90 °C. The reached water purification rates are exclusively ≥99.99% for both wastewater models and wastewaters from electroplating industry. We succeeded to synthesize a mixture of 3R and 2H delafossite at 50 °C after 90 h and ≥70 °C after 16 h of ageing directly from industrial wastewater without any additional phases. In all cases green rust (GR), a Fe(II-III) layered double hydroxysulphate, Cu2O (cuprite) and Fe10O14(OH)2 (ferrihydrite) precipitates first. During ageing of the residues the metastable phases transform to delafossite. The residues are characterized by XRD, FTIR, SEM, TEM, VFTB and Mößbauer measurements.