Journal of Hazardous Materials 148 (2007) 1–5 Review Complete electrochemical dechlorination of chlorobenzenes in the presence of naphthalene mediator Aishah A. Jalil a,∗ , N. Fatimah A. Panjang a , Suffiyana Akhbar a , Murni Sundang a , Norhuda Tajuddin a , Sugeng Triwahyono b a Faculty of Chemical and Natural Resources Engineering, Malaysia b Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia Received 23 February 2007; received in revised form 4 May 2007; accepted 7 June 2007 Available online 12 June 2007 Abstract Electrochemical dechlorination of chlorobenzene in organic solutions was studied. Electrolysis of chlorobenzene in acetonitrile solution in a one-compartment cell fitted with a platinum cathode and a zinc anode at 60 mA/cm 2 and 0 ◦ C was found to be the optimum conditions, which gave complete dechlorination of chlorobenzene. However, similar result could not be achieved when applying these conditions to 1,3-dichlorobenzene and 1,2,4-trichlorobenzene. We found that the use of naphthalene which reacted as a mediator in the appropriate system could accelerate the reduction and gave complete dechlorination of those chlorobenzenes. Moreover, in the presence of naphthalene the reaction time could be shortened by half compared to dechlorination in the absence of naphthalene. © 2007 Elsevier B.V. All rights reserved. Keywords: Electrolysis; Dechlorination; Chlorobenzenes; Naphthalene; Mediator Contents 1. Introduction ............................................................................................................... 1 2. Materials and methods ..................................................................................................... 2 2.1. Reagents, materials and solutions ..................................................................................... 2 2.2. Apparatus and procedures ............................................................................................ 2 3. Results and discussion ..................................................................................................... 2 3.1. Dechlorination in the absence of naphthalene .......................................................................... 2 3.2. Dechlorination in the presence of naphthalene .......................................................................... 3 4. Conclusion ............................................................................................................... 4 Acknowledgement ......................................................................................................... 4 References ................................................................................................................ 4 1. Introduction Polychlorinated aromatic compounds are environmentally persistent chemicals, recalcitrant toward degradation, which bioaccumulate in fatty tissue and show carcinogenic and muta- ∗ Corresponding author. Tel.: +60 7 5535523; fax: +60 7 5581463. E-mail addresses: aishah@fkkksa.utm.my, aishah aj@yahoo.com (A.A. Jalil), sugeng@ibnusina.utm.my (S. Triwahyono). genic activity, so they are a class of pollutants of special environmental concern [1]. Various degradation techniques have been studied in order to destroy these toxic chemicals such as by incineration [2–5], various reducing reagents, namely hydro- gen together with catalysts in both heterogeneous [6–10] and homogeneous systems [8,11,12], Raney Nickel alloy [13–15], metals [16–18] and metal hydrides [19–21]. However, these methods required high temperature, expensive and may also pro- duce more hazardous byproducts such as dioxins and furans due to the incomplete combustion. In addition, detoxifying of those 0304-3894/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2007.06.024