Electrochemical Degradation of Nonylphenol Ethoxylate-7 (NP₇EO) Using a DiaClean® Cell Equipped with Boron-Doped Diamond Electrodes (BDD)

Nowadays, the increasing pollution of natural water effluents with surfactant, wetting, dispersing, and emulsifying agents which contain nonylphenol ethoxylate (NP₇EO) is an emerging problem that has not received the enough attention. Currently, it is known that degrading this type of highly stable compounds is possible through advanced electrochemical oxidation (AEO), but the degradation of NP₇EO has not been tested yet. Thus, this work carries out a study of the degradation of the NP₇EO (500 mg L⁻¹) through advanced electrochemical oxidation, using a DiaClean® cell, equipped with boron-doped diamond electrodes (BDD, 70 cm²). The cell operated in a recirculation system with a peristaltic pump, which allowed to control the electrolyte flow. The buffer media for degradation was NH₄OH 0.1 M/HCl 0.05 M (pH 9.25). The effect of the current density (j = 20, 30, 40 mA cm⁻²) was studied, and the cell efficiency for each condition was evaluated. The degradation was followed by total organic carbon (TOC), chemical oxygen demand (COD), and absorbance. The cell potential was monitored to determine the operating costs. The best conditions for the mineralization of NP₇EO (initial concentration = 500 mg L⁻¹) were applying 40 mA cm⁻² and at a flow rate of 12.6 L min⁻¹ during 8 h of electrolysis, achieving a 90% of TOC removal. Therefore, this technology appears as a promising alternative for degrading surfactants like NP₇EO in aqueous media.