Biogenic Synthesis of ZnO Nanoparticles Using Enterobacter cloacae for Efficient Photocatalytic Degradation of Reactive Red 120
摘要
Biogenic redox mediators derived from diverse biological sources have emerged as sustainable tools in nanoparticle synthesis, offering a green alternative to conventional toxic chemical reducers. The current investigation explores the fabrication of Zinc oxide nanoparticles (ZnO NPs) via biogenic approach using bacterial strain Enterobacter cloacae VITPBS14 obtained from textile industry effluent and exploring their photocatalytic application for the environmental remediation of azo dye Reactive Red 120 (RR120). The prepared ZnO NPs were characterized by UV–Vis spectroscopy, which showed a distinct absorption peak at 380 nm with a band gap of 2.95 eV, and photoluminescence (PL) spectroscopy, which exhibited a broad emission band around 420 nm. XRD analysis confirmed a hexagonal wurtzite crystalline structure with an average crystallite size of 29.25 nm, while Raman spectroscopy displayed a strong E₂ (high) mode at 433 cm⁻1, characteristic of ZnO’s wurtzite phase. SEM revealed a rod-shaped morphology, and EDX confirmed high elemental purity. AFM analysis provided surface roughness parameters, and FTIR spectra exhibited a Zn–O stretching vibration at ~ 495 cm⁻1. Dynamic light scattering (DLS) indicated an average hydrodynamic diameter of 30.2 nm, and the zeta potential (–40 mV) suggested high colloidal stability. A photocatalytic study was conducted using the synthesized ZnO nano-catalyst for the degradation of the azo dye Reactive Red 120 under ambient natural sunlight condition. Maximum decolorization of 81% was achieved within 150 min under optimized conditions of pH 7, dye concentration 10 ppm, and catalyst loading 0.5 mg/mL. Statistical optimization using a central composite design model further validated these conditions. In addition, photo-toxicity assays confirmed the non-toxic nature of the degradation products. These findings indicates that the synthesized ZnO NPs hold a significant potential as a promising alternative for the photocatalytic breakdown of dye compounds.