Effective photocatalytic degradation and kinetic modelling of azo dyes by zinc oxide nanoparticles from Brevibacterium casei

The present investigation emphasizes the synthesis of Zinc Oxide Nanoparticles (ZnO NPs) through Brevibacterium casei isolated from the dye-contaminated soil. Microbial synthesis approaches are more efficient than plant sources or cell cultures because of their efficiency, scalability, the rapid life cycle of the organisms and to develop of an eco-friendly dye degradation method. The characterization of the synthesized ZnO NPs was done using UV Visible spectroscopy, XRD, FT-IR Spectroscopy, FE-SEM, EDAX, DLS, ZETA Potential, HR-TEM, SAED, and AFM Analysis. Microbially synthesized NPs act as efficient photocatalysts for the elimination of azo dyes, Methyl orange (MO) and Rhodamine B (RhB), in an aqueous solution under visible light. The impact of operational factors such as the quantity of ZnO NPs, pH, and concentration of both dyes (MO and RhB) on dye degradation were investigated. Both dyes (MO and RhB) are broken down photocatalytically by applying the pseudo-first-order kinetic mechanism. Using ZnO NPs at the optimum load of 100 mg/L, solution pH 8 (MO), and pH 9 (RhB), and the degradation of 10 mg/L MO and RhB was evaluated as 92% and 90.5% after 8 hours of exposure, respectively. Given its affordable cost and high photocatalytic efficacy, nanosized ZnO might be used on a broad scale to cleanse wastewater contaminated with azo dyes such as Methyl Orange and Rhodamine B. • The Biosynthesis of ZnO NPs using Brevibacterium casei is more advantageous than the chemical method. • ZnO NPs were utilized as a photocatalyst in the dye degradation process. • Pseudo-first-order kinetics was applied for harmful azo dye degradation studies. • Under the optimum operational parameters, 92% and 90.5% of MO and RhB removal were achieved in 8 h respectively.