~ APPL I ED CATALYS I S A: GENERAL ELSEVIER Applied Catalysis A: General 143 (1996) 185-202 Electrochemical oxidation of aqueous phenol at a carbon black slurry electrode J.L. Boudenne a O. Cerclier a,, j. Gal~a a E. Van der Vlist b a Laboratoire de Chirnie- Environnement (JE n°458), case 29, Universit~ de Provence, 3, place Victor Hugo, 13331 Marseille cedex 3, France b Soci~t~ AQEL, Avenue Beaunier, 42160 Andrezieux-Boutheon Cedex, France Received 7 December 1994; revised 18 June 1995; accepted 26 December 1995 Abstract The electrochemical oxidation of an aqueous phenol solution was studied via a novel process. Experiments were conducted by recirculating a slurry electrode made of the product to be treated (phenol) and a catalyst (carbon black) through a flow-by electrolyser with a vertical stack of perforated Ti/Pt electrodes. Both the capacity of high adsorption of organic compounds and gases and the conductivity properties of Carbon Black allowed the acceleration of the degradation. High pressure liquid chromatography (HPLC) analysis was used to follow phenol loss and the formation of by-products. Gas chromatography (GC) analysis revealed the presence of two gases: oxygen -electrogenerated by the oxidation of water- and carbon dioxide produced by both phenol and CB oxidation. Other experiments under nitrogen and oxygen flow were performed in a closed reactor cell and proved that oxygen generated by Ti/Pt electrodes is sufficient to obtain the full degradation of phenol. The effects of CB concentration (ranging from 0 to 4 g 1-1), of the nature of CB and of the applied current (from 0 to 20 A) were investigated. An increase of CB concentration and applied current was found to shift product distribution to favour the formation of carbon dioxide. A removal efficiency of 100% was obtained in a reaction time of 15 min under the following conditions: an initial phenol concentration of 1 mmol 1- ~, 4 g 1- ~ of CB, an applied current of 10 A, a flow rate of 10 ml s 1 and a temperature of 30°C. Keywords: Slurry electrode; Carbon black; Phenol; Electrochemical oxidation * Corresponding author. Tel. ( + 33)91106325; Fax. ( + 33)91106377. 0926-860X/96/$15.00 Copyright © 1996 PH S0926- 860X(96)00027-0