Electrochemical Treatment of Industrial Wastewater Degrading Tetrabutylammonium Bromide Using a Quasidivided Cell Design

A robust, simple, and safe anodic treatment of an industrial wastewater is developed containing tetrabutylammonium (TBA) salts. The use of a quasidivided electrolysis cell set-up proves to be the key to success. Quasidivision enables the generation of oxidizing mediators without the necessity of an expensive and/or fragile membrane as separator. Screening experiments with significantly different current densities between anode and cathode reveal a higher efficiency compared to similar current densities at both electrodes. Furthermore, acidification of the wastewater prior to electrolysis improves the degradation efficiency by prevention of sulfurous electrode coatings (electrofouling). Under optimized conditions, the concentration of TBA cations is diminished to levels (<1 ppm) far below those required by environmental guidelines. 99% of the TBA species are depleted in total with a degradation rate around 1 mmol TBA bromide/100 min with an energy consumption of 2.5 kWh L^-1. The developed process is applicable to wastewater with a varying composition.