Surface-Modified TiO 2 Nanotube Anodes for Sustainable Electrochemical Treatment of Real Electroplating Industry Wastewater

Real electroplating industry wastewater (REIWW), containing high concentrations of toxic heavy metal ions (HMIs), was collected for treatment, as effective removal prior to discharge is essential to prevent environmental and ecological risks. This study investigated REIWW treatment using electro-oxidation (EO) with a Ti/TiO 2 /GO-SnO 2 anode. In batch mode, the effects of pH (1–9), current density (14–60 mA cm −2 ), and treatment time (30–210 min) were optimized using response surface methodology based on the Box–Behnken design. Under optimal conditions, removal efficiencies of 94.42% for Ni (W 1 ), 97.21% for Zn (W 2 ), 93.12% for Cu (W 3 ), and 92.0% for COD (W 4 ) were achieved, with an energy consumption (W 5 ) of 9.32 kWh m −3 . A once-through continuous mode was optimized using central composite design by varying flow rate (2–10 ml min −1 ) and treatment time (30–240 min). At optimized parameters, removal efficiencies for W 1 –W 4 ranged between 91.0% and 94.11%, with W 5 of 13.5 kWh m −3 . The stability of the Ti/TiO 2 /GO-SnO 2 anode was confirmed after 60 operational cycles, with SEM analysis demonstrating negligible surface deterioration. The improved BOD 5 /COD ratio and toxicity results indicated enhanced biodegradability and safe discharge potential. Overall, the EO process employing the Ti/TiO 2 /GO-SnO 2 anode demonstrates high efficiency and strong potential for the treatment of REIWW.