A novel electrochemical advanced oxidation technology using a low-cost graphite plate anode for batik-printing wastewater treatment

Batik-printing industries in Pekalongan, Indonesia, are major water pollution sources, releasing wastewater containing complex dyes and persistent organic pollutants that degrade water quality and disrupt aquatic ecosystems. Electrochemical advanced oxidation processes (EAOP) offer a cost-effective and versatile alternative for treating such pollutants. This study developed a low-cost EAOP treatment technology using carbon electrodes, employing a graphite anode and a stainless steel plate cathode. Key variables, including anode material, retention time, NaCl concentration, pH, and voltage, were investigated to optimize treatment performance. Fe(II) was used as a catalyst to support the electro-Fenton method, with color and Chemical Oxygen Demand (COD) as pollutant removal efficiency indicators. A graphite plate was successfully fabricated, exhibiting high crystallinity, with nearly 100 % carbon and electroactivity. It outperformed Ti/RuIrO2, Ti/RuO2, and Ti/PtIr anodes in COD and color removal from batik-printing wastewater. Color removal rate followed a second-order kinetic model with a constant of 0.00009 (mg/L)−1.min−1; COD removal rate followed a first-order kinetic model with a constant of 0.0011 min−1. The electrode achieved 98.0 ± 0.2 % color and 98.9 ± 0.3 % COD removal under optimal conditions (4 g/L NaCl, 6 V, pH 4, 0.06 g/L FeSO4, 45-min retention time). Estimated production cost is 3.65 USD, substantially lower than Ti/RuO2 (25 USD), Ti/RuIrO2 (30 USD), and Ti/PtIr (40 USD). We found that EAOP with a fabricated graphite anode under optimized operational conditions is effective for batik-printing wastewater treatment.