Submerged Arc Breakdown of Methylene Blue in Aqueous Solutions R.L. Boxman, N. Parkansky, A. Vegerhof, B. Alterkop, Electrical Discharge and Plasma Laboratory, Tel Aviv University, Tel Aviv 69978, Israel O. Berkh School of Electrical Engineering, Tel Aviv University, POB 39040, Tel Aviv 69978, Israel Abstract: Low voltage, low energy submerged pulsed arcs between a pair of carbon or iron electrodes with a pulse repetition rate of 100 Hz, energies of 2.6-192 mJ and durations of 20, 50 and 100 s were used to remove methylene blue (MB) contamination from 30 ml aqueous solutions. The MB concentration decreased exponentially with rates of 0.0006-0.0143 s -1 during processing with the carbon electrode pair. With the iron electrodes, the MB concentration initially decreased faster than with the carbon electrodes, but later saturated. The effects of the treatment on the pH of the solution and on the Zeta–potential of the particles formed as a result of electrode erosion were studied in the presence and in the absence of MB. . Keywords: Submerged pulsed arc, water treatment, plasma, decontamination. 1. Introduction It has been shown that plasma technologies have the capability to treat water using several mechanisms such as radical reactions, shock waves, ultra-violet radiation, ionic reactions, electron processes and thermal dissociation [1-4]. It is suspected that these factors, singularly or synergistically, may be responsible for concurrently oxidizing trace contaminates and disinfecting microorganisms in water. In particular, the submerged pulsed high- current and high voltage electrical discharge, i.e. a discharge between two electrodes in a liquid, sometimes referred to as an electro-hydraulic discharge [1], has been shown to oxidize many organic compounds [5-8]. The use of electro- hydraulic discharge systems use in water treatment applications is rather recent and remains to be optimized for various types of contaminants and microorganisms. A low voltage arc applied between two submerged carbon electrodes was used to breakdown sulfadimethoxine and to decontaminate aqueous solutions from other biological and chemical agents [2,9]. However low voltage submerged arc removal of MB or other dyes from aqueous solutions has not been reported previously. The objectives of this research were to: (1) remove MB from aqueous solutions using low voltage, low energy submerged pulsed arcs, (2) determine the removal efficiency with iron and carbon electrode pairs, and (3) determine the influence of the discharge on the solution pH, mobility and Zeta–potential of particles produced from electrode erosion.