DOPING SILVER TO ACTIVATED ZNO TO PROMOTE THE PHOTOCATALYTIC EFFICIENCY FOR AZO DYE DEGRADATION
Katya Milenova, Alexander Eliyas, Vladimir Blaskov, Irina Stambolova, Slavcho Rakovsky
Pages: 259-264 Published: 2 Jun 2014
Views: 2,194 Downloads: 1,067
Abstract: Various silver doped ZnO activated powders were prepared through an original method of activation. The samples were characterized using XRD analysis, single point BET method, scanning electron microscopy (SEM). The photocatalytic properties of the samples were tested in the reaction of Reactive Black 5 azo dye (model waste water contaminant) oxidative discoloration in a semi-batch reactor. The silver doped samples have higher degree of cristallinity in comparison to the undoped sample and superior photocatalytic performance under UV-A light illumination. Another factor promoting the photocatalytic properties is the increase of the dopant content decreasing the ZnO particle mean size and increasing the specific surface area of the doped samples. The role of silver nanoparticles is to serve as traps for the photoexcited electrons thus preventing recombination and increasing the lifetime of the positively charged holes, acting as oxidation active sites.