Application of Liquid Phase Plasma in Photocatalytic Hydrogen Production from Wastewaters Containing Organic Pollutants

The hazardous wastes and toxic water pollutants have brought out serious environmental problems associated with attracted much attention. In the various physical, chemical and biological techniques for treatment of wastewaters, heterogeneous photocatalysis has been considered as an effective alternative for water remediation. Photocatalytic water splitting is effective for converting water to hydrogen as a clean and renewable energy. It has been also applied on deconposition of organic materias in wastewater. The development of high photosensitive catalysts has been studied under UV and visible light illumination. Although a range of light sources have been employed in photocatalysis, few studies have examined photocatalysis for hydrogen generation using liquid phase plasma by irradiation into water directly.

Photocatalytic decomposion using liquid phase plasma was assesd to produce hydrogen and to remove polluant from wastewater containing organic materials. Characteristics of liquid phase plasma irradiation were examined in the photocatalytic water splitting for hydrogen evolution on modified TiO₂ photocatalysts. Optical emission spectra were characterized with variation of plasma discharging parameters of the liquid phase plasma. Pathway of photocatalytic reaction for hydrogen evolution was also evaluated with degradation of organic pollutants.

The hydrogen was generated in the photodecomposition of water through the liquid phase plasma irradiation without photocatalysts. The active species generated by the liquid phase plasma irradiation brought out the hydrogen evolution regardless of the photocatalysts. The rate of hydrogen evolution depended on the parameters of liquid phase plasma discharging. The hydrogen evolution was significantly enhanced by irradiation of liquid phase plasma from the wastewater. The organic pollutant assisted to improve the hydrogen production with adding of hydrogen by its decomposition.