Nonylphenol polyethoxylate degradation by means of electrocoagulation and electrochemical Fenton

This study investigated the degradation of nonylphenol polyethoxylate (9 ethylene oxide unities, NP9EO) in aqueous solution and textile wastewater by electrocoagulation (iron and aluminum electrodes) and electrochemical Fenton. The studied processes had as parameters NP9EO concentration (measured by HPLC), chemical oxygen demand (COD), integrated absorbance (200-800 nm) and hydrogen peroxide concentration (H2O2). First, it was determined the NP9EO concentration in textile wastewater by means of a modified procedure based on the extraction of surfactants. A factorial design 2(4) was employed to optimize the experimental conditions for NP9EO degradation in aqueous solution by electrocoagulation, through the following variables: NP9EO concentration, applied current, temperature and electrode material. The use of aluminum electrodes brought the most significant effects. The best performance was achieved by experiments using 20 mg L-1 aqueous NP9EO, 1.5 A and aluminum electrodes (around 95% removal in 30 min). The best experimental conditions achieved using factorial design were applied to textile wastewater treatment. The electrocoagulation using Al-electrodes allowed the NP9EO degradation and COD reduction of 95 and 50%, respectively, in only 15 min treatment. In order to enhance the aqueous NP9EO degradation obtained by electrocoagulation with iron electrodes, electrochemical Fenton was also performed and 95% NP9EO removal was achieved in 5 min (aqueous solution) and 10 min (wastewater) treatment, respectively. Besides the organic load removal (COD reduction) having not surpassed 55% in both processes, the total NP9EO removal of the textile wastewater was equally efficient by both aqueous solution and textile wastewater treatment (causing almost total degradation). (C) 2005 Elsevier B.V. All rights reserved.