Photocatalytic Degradation of Phenol by Immobilized Nano ZnO on Concrete Surface

Phenol is a toxic and refractory water pollutant that cannot be completely degraded through common wastewater treatment methods. Methods such as active carbon adsorption, oxidation or biological digestion are not satisfying enough and only convert the pollutant from one phase to another, or may produce much more other toxic substances. The photocatalysis process is a new promising methodology among highly efficient methods for elimination of relatively recalcitrant organic compounds. Furthermore, application of nano materials as catalyst has successfully improved the efficiency of this method. In this report, the aqueous oxidation of phenol over ZnO is investigated as a potential method for abatement of this pollutant. Concrete has been used as the immobilized surface and activation energy was provided with 8W UV-A lamps. Results of the SEM test also confirm an appropriate cover of ZnO on the concrete surface. The effects of operating parameters such as the initial phenol concentration, the light intensity, the dosage of ZnO particles, and pH were studied. The photocatalytic system afforded the highest degradation efficiency at C0= 50 mg / L, ZnO=80 g / m2, pH=11, light intensity= 32 W and over 90% of the initial phenol was degraded after 5 hours.