Electrochemical system for simultaneous treatment of textile dyeing effluents and hydrogen recovery

The textile industry is a major contributor to global water pollution, generating complex wastewater that conventional treatments struggle to remediate. Electrochemical processes are effective alternatives, degrading persistent organic pollutants while simultaneously producing hydrogen as a valuable byproduct. However, current electrochemical systems often disregard hydrogen recovery and face challenges such as low wastewater conductivity, high energy consumption, and gas contamination. This study presents a novel bicompartmental electrochemical reactor designed for simultaneous textile dye wastewater treatment and hydrogen recovery. The system incorporates an anion-exchange membrane (AEM) to fully separate the anolyte and catholyte, preventing gas cross-contamination and improving energy efficiency. Key parameters, including current density, electrode materials, and dyeing auxiliaries are systematically evaluated in this study. This electrochemical system effectively decolorizes real textile wastewater, being the dye (Procion Blue H-EXL) degraded following a pseudo-first-order kinetics. Optimal conditions for industrial application are identified using a multicriteria approach, selecting Ir-Ru/MMO as the anode and Ni as the cathode at 150 mA/cm² for treating dye textile effluents that use NaCl as a salt. For dye wastewaters containing Na₂SO₄ instead of NaCl, a BDD anode is chosen to generate hydroxyl radical for effective treatment and Ni is also selected as the cathode. The applied charge required for 95 % dye degradation ranges from 1.7 to 12.3 Ah/g dye depending on the salt and alkali used in the dye process, with the kinetics with NaOH being from two to five times faster than with Na₂CO₃. Additionally, the system achieves stable hydrogen production with high Faradaic efficiency (94.3-96.9 %) and purity (98.7 %), with an energy recovery potential of 23-33 % relative to the treatment energy consumption. This scalable and efficient electrochemical system offers a promising solution for industrial textile wastewater treatment while enabling sustainable hydrogen production.