Decolorization of Azodyes by Chemically and Biosynthesized ZnO Nanoparticles

Abstract

Dye contaminants in industrial effluents contribute significantly to environmental pollution. Conventional waste water treatment methods are expensive and energy consuming. These limitations could be overcome by the use of nanobioremediation processes. The present work was an effort to study decolorization of azodyes by ZnO nanoparticles (NPs). Rubine GDB (R-GDB) and Congo Red (CR) were the azodyes selected for the study. The ZnO NPs were successfully synthesized by chemical and biological methods. Chemical synthesis of ZnO NPs was carried out by co-precipitation method; biological synthesis was done using bacteria Bacillus subtilis. The synthesized nanoparticles were characterized by UV-Vis Spectroscopy, SEM and XRD. The UV spectrophotometer showed peaks in the range of 300-400 nm. SEM pictures indicated the presence of NPs in the size of 100nm-200nm. XRD results were analyzed on the basis of the peaks that were seen. EDX analysis showed the presence of Zn particles and oxygen particles majorly. Decolorization efficiency was evualated by calculating % decolorization by Meyer’s method. Chemically synthesized NPs showed maximum % decolorization of the R-GDB (89.058 %) and CR (88.888%). The biosynthesized NPs showed the least decolorization (R- GDB -18 % and CR 20.357 %). However, moderate percentages of decolorization of both the azodyes were observed when a combination of the NPs was used (R-GDB -36.072 % and CR- 39.824 %). Nanoparticles showed good potential for the decolorization of the azo dyes. With further optimization of the parameters the present findings show that dye decolorization by chemically synthesized ZnO NPs could be used as a probable nanobioremediation approach to treat wastewaters.