Photocatalytic degradation of anthracene using titanium dioxide

T human population is suffering increased exposure to existing and new chemicals and environmental toxins. Among the various environmental toxins, PAHs are an important class of environmental contaminants, and many PAHs are known or suspected carcinogens. PAHs are produced in the environment through the incomplete burning of organic fuels and cover wide classes of compounds. Exposure to some of these compounds is well-known to cause cancer in mice and they are suspected to be carcinogenic compounds for humans. The photocatalytic degradation of anthracene in aqueous solutions in the presence of TiO2 suspension has been investigated with the use of UV-irradiation. This study includes comparison between two types of titanium dioxide (P25 and UV100), also includes effect of different parameters on photocatalytic oxidation of anthracene by titanium dioxide were studied, such as: anthracene concentration, pH of aqueous solution, light intensity, addition of H2O2 and temperature on photocatalytic oxidation. The results showed that titanium dioxide, P25 type is better than UV100 type. The results also showed the optimum conditions for degradation process by photocatalytic oxidation are; perfect concentration of anthracene is 25 ppm, 6.8 of pH is the best value for anthracne, 2.5 mW. Cm-2 of light intensity, degradation rate of anthracene without addition of hydrogen peroxide is fastest and 308.15K is the appropriate degree of temperature. The results indicated that the photocatalytic degradation of anthracene was well described by pseudo first order kinetics according to the LangmuirHinshelwood model. The effect of temperature on the efficiency of photodegradation of anthracene was also studied in the range 278.15-308.15 K. The activation energy was calculated according to Arrhenius plot, and was found equal to 12.76 kJ.mol-1 for TiO2 (Degussa P25). The main product of anthracene after degradation was 9, 10-anthraquinone which was identified by GC-MS.The intermediate compound that produced of degradation of anthracene was 9,10-anthraquinone. This product characterises by FTIR and GC-MS, the complete degradation for 9-10 anthraquinone was achieved.