Studies On Catalytic Degradation Of Organic Contaminants By Pulsed High-Voltage Discharge Plasma Process

Pulsed high-voltage discharge plasma (PDP) is a novel alternative to Advanced Oxidation technologies (AOTs). However, there are many drawbacks, e,g. long treatment time, low utilization rate of active species and low energy efficiency. Based on such problems, effectively utilizing the physicochemical effects of electrohydraulic discharge is to enhance the removal rate and power energy efficiency. In the paper, to get such aims, many different catalysts were introduced into the PDP processes.To efficiently utilize light energy induced from the process of electrohydraulic discharge, nanosized TiO₂ catalyst were introduced into the system. The parameters of the process were optimized. The mechanism of enhancing effect was proposed that the process existed the ultraviolet light emitted and positive electric field could initiate the electron/holes pair separation on the surface of TiO₂, resulting into more amounts of hydroxyl radicals, oxygen and super-oxide radicals. Moreover more amounts of hydrogen peroxide were produced, so the degradation and mineralization rate were accelerated. Based on above system, the introduction of iron ion was to develop a new Fenton-like PDP (or PDPT) catalytic system. The mechanism of the successive development of Fenton-like reactions was proposed. In the PDP/Fe²⁺ (or Fe²⁺) process, the regeneration of Fe²⁺ from Fe²⁺ predominately results from the photocatalytic reduction of UV light and the reductive effect of quinone intermediates (1,4-hydroquinone and 1,4-benzoquinone). However, in the PDPT/ Fe²⁺ (or Fe³⁺) process it primarily resulted from the photocatalytic reduction of UV light and the photo-reduction of photo-generated electrons on the surface of TiO2 by UV light illumination from pulsed discharge plasma. Such reactions made electrohydraulic discharge plasma successfully initiate Fenton-like reactions in highly-oxidative PDP or PDPT system, resulting into the enhanced degradation of organic compound 4-CP and power energy efficiency.