SDS capped and PVA capped ZnO nanostructures with high photocatalytic performance toward photodegradation of reactive red (RR141) azo dye

Abstract

Two types of ZnO nanostructures have been synthesized successfully in high yield by using either sodium dodecylsulfate (SDS) or polyvinyl alcohol (PVA) as a capping agent via a facile and low temperture chemical precipitation method. The synthesized ZnO samples show well crystallized wurtzite hexagonal phase. The SDS surfactant played a crucial effect on morphology, specific surface area and photocatalytic performance of the ZnO photocatalyst. SDS capped ZnO with high specific surface area of 14.8m2g−1 shows much higher photocatalytic performance in comparision to that of PVA capped ZnO. Nearly 95% and 88% of reactive red (RR141) azo dye decomposed after irradiation for 240min under UV light and 80min under solar light, respectively. The photodegradation reaction follows the pseudo first-order kinetics with the high rate constant (k) of 0.04min−1. The SDS capped ZnO photocatalyst retains its original efficiency of about 87% even after the third cycles of reuse indicating the advantages of stability and reusability. Hole and hydroxyl radical are the two major reactive species involving in photodegradation of azo dye. ZnO nanostructures with SDS as a capping agent will be suitable for photodegradation of organic pollutants in the environmental protection. The method and ideas presented herein will potentially provide cheaper and cleaner means for treatment of a large volume of organic dyes. The photodegradation process can be performed very easily even under solar light irradiation. This offers some insight into the progress of technological applications related to the degradation of industrial dyes.