Degradation Efficiency of EDTMPS by BDD Anode Electrochemical Advanced Oxidation System
Ethylene diamine tetra (methylene phosphonic acid) sodium (EDTMPS), an organic phosphonate scale and corrosion inhibitor, is widely used in industrial recirculating cooling water systems. Its efficient degradation in blowdown water is critical for water reuse. This study employed a plate-frame electrochemical advanced oxidation (EAOP) system with a boron-doped diamond (BDD) anode to degrade EDTMPS. The effects of operating conditions (temperature, voltage, liquid flow rate) and water quality parameters (pH, electrolyte concentration, chloride ion concentration) were systematically investigated. Optimal degradation efficiency of 99.48% was achieved at 50 °C, 300 mL·min−1, 7.0 V, pH 10, and 0.05 mol·L−1 Na2SO4. Electron paramagnetic resonance (EPR) characterization of chloride-containing systems indicated that reactive species included hydroxyl radicals, sulfate radicals, and possibly chlorine radicals. In a coexisting system with benzotriazole (BTA), EAOPs degraded EDTMPS and BTA with comparable efficiencies. The results demonstrate that BDD-based EAOPs is effective for removing organic phosphonates from low-chloride, low-hardness cooling water, offering a promising approach for blowdown water treatment and reuse.