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 Cu²⁺-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.