Photocatalytic oxidation of azo dye solutions by impregnation of ZnO on fungi

Abstract

In this study, the semiconductor photocatalyst zinc oxide (ZnO) was used to impregnate on Aspergillus carbonarius (AC) and Penicilliwn glabrum (PG) fungi for photocatalytic oxidation of azo dye solutions. The photo catalytic decolorization of two textile dyes, Basic Red 18 (BR18) and Reactive Red 180 (RR180), was investigated and the impact of catalyst loading as well as initial dye concentration was systematically examined. Complete decolorization of BR18 was obtained by ZnO impregnated Aspergillus carbonarius (ZnO/AC) and Penicillium glabrum (ZnO/PG). The results also showed that the highest RR180 decolorization levels were 76.2% and 73.7% for ZnO/AC and ZnO/PG, respectively. The optimum catalyst loading was found to be 2 g/L. Catalyst reusability was also tested during five cycles and the bio-sorbent matrix (dead fungus) showed good stability after five reuse cycles. Photocatalytic decolorization of BR18 dye was much faster than RR180 dye, which we attributed to the electrostatic charge interaction between catalyst surface and dye molecules.