Photocatalytic Degradation of Benzene for Polishing of Refinery Wastewater

Abstract

Aromatic organic compounds such as benzene, toluene, ethyl-benzene, and xylene (BTEX) are essential ingredient of refinery wastewater. Their presence in wastewater is a major environmental concern because these compounds are flammable, toxic, carcinogenic, and mutagenic. In this study, benzene was selected as a representative pollutant due to its intensive health impacts and more solubility in water among other BTEX compounds, for investigation of a sequential process, whereby, post-GAC adsorption effluent is exposed to photocatalysis, using titania, for polishing. The concentration of benzene was reduced from 1000 ppm to below 0.140 ppm, which is the permissible limit for wastewater. Photocatalytic degradation of benzene may follow a close chain (phenolic) or open chain (muconaldehyde) pathway which has been under debatable for over three decades. In order to clarify this confusion, the photocatalytic degradation pathway of benzene has been carefully investigated. Based on the results of High Performance Liquid Chromatography (HPLC), it is confirmed that benzene follows both closed chain (phenolic) and open chain routes (muconaldehyde).