Study of a novel high voltage pulsed discharge reactor with porous titanium electrodes

Abstract

A study was conducted regarding the degradation of methyl orange (MO) in solution using a novel pulsed discharge reactor. The effects of the electrode gap, oxygen flow rate, electrode connection method, input voltage and pulse frequency and initial solution concentration on MO removal performance (characterized by MO removal efficiency or TOC mineralization rate) were investigated. The experimental results indicated that GH of 3mm and LH of 5mm were beneficial to MO removal efficiency; a moderate oxygen flow rate of 0.16 or 0.12m3/h was favorable for MO removal efficiency or TOC mineralization rate, respectively; the positive–negative (+−) connection, i.e. the bottom titanium electrode was connected to the HV power supply and the top electrode was connected to the ground, was better than the negative–positive (−+) connection; discharge voltage of 30kV and pulse frequency of 100Hz was the reasonable choice, regarding the MO removal efficiency and TOC mineralization rate as well as the energy yield and the stable discharge status. MO in a lower initial concentration of solution was more easily to be degraded. Ozone generated during pulse discharge was likely to be one of the main active species for MO degradation, meanwhile, intermediates recalcitrant to ozone, including small molecular acids and inorganic ions, were proved to be generated. Although a higher initial MO solution concentration negatively affected the MO removal performance, it could positively influence the energy yield. A layer of titanium dioxide film was presumed to form on the surface of a titanium plate electrode.