Phenol Photocatalytic Degradation by Advanced Oxidation Process under Ultraviolet Radiation Using Titanium Dioxide

Background. The main objective of this study was to examine the photocatalytic degradation of phenol from laboratory samples and petrochemical industries wastewater under UV radiation by using nanoparticles of titanium dioxide coated on the inner and outer quartz glass tubes. Method. The first stage of this study was conducted to stabilize the titanium dioxide nanoparticles in anatase crystal phase, using dip-coating sol-gel method on the inner and outer surfaces of quartz glass tubes. The effect of important parameters including initial phenol concentration, TiO2 catalyst dose, duration of UV radiation, pH of solution, and contact time was investigated. Results. In the dip-coat lining stage, the produced nanoparticles with anatase crystalline structure have the average particle size of 30？nm and are uniformly distributed over the tube surface. The removal efficiency of phenol was increased with the descending of the solution pH and initial phenol concentration and rising of the contact time. Conclusion. Results showed that the light easily passes through four layers of coating (about 105？nm). The highest removal efficiency of phenol with photocatalytic UV/TiO2 process was 50% at initial phenol concentration of 30？mg/L, solution pH of 3, and 300？min contact time. The comparison of synthetic solution and petrochemical wastewater showed that at same conditions the phenol removal efficiency was equal. 1. Introduction The most important problem that can threaten the water ecology and public health is the toxic and resistant compounds that can release to the environment through industrial wastewater [1]. Among the chemical compounds that are present in industrial wastewaters, the phenol and its derivatives are prevalent in industrial effluent; in addition, they can be released to water resources through natural ways (degradation of algae or of organic vegetation). Also, due to the physical structure, phenol was found in chemical solutions and even in the municipal wastewater. Due to relatively stability in environment, solubility in water, high toxicity, and associated health problems, phenol removal from industrial wastewater is important [2]. The phenol compounds can be released to environment through some industrial wastewater including coal industry, resin industries, paint industries, pesticides, medicine and cosmetic products, oil refinery, petrochemical, coal mines, aluminum and steel industries, compost, car production, and chemical industry, which can lead to water resources contamination. Phenol is also found in cleaning materials and