Biogenic Synthesis of Copper Oxide Nanoparticles Using E. coli for Photocatalytic Degradation of Synthetic Textile Dyes

Abstract

The uncontrolled discharge of synthetic dyes from the textile industries poses a major threat to freshwater ecosystems, human health and the environment. Conventional dye removal methods often fall short due to inefficiency, high cost, or environmental toxicity. The present study explores an eco-friendly approach to dye degradation through the green synthesis of copper oxide (CuO) nanoparticles using Escherichia coli. The biosynthesized CuO nanoparticles were characterized using UV-Vis spectroscopy, SEM, and FTIR, confirming their nanoscale size, spherical morphology, and functional surface chemistry with Cu–O bonding. Their photocatalytic performance was evaluated against two model textile dyes: Reactive Red and Methylene Blue, representing anionic and cationic dye classes, respectively. Results revealed dose- and time-dependent degradation, with the first 7 hours under sunlight and the remaining period in an incubator at 37 °C. For Reactive Red, 5 ml of CuO NPs achieved 22.33% degradation after 7 hours of sunlight exposure and 25.05% by the end of 24 hours. For Methylene Blue, 5 ml of CuO NPs achieved 10.85% degradation after 7 hours in sunlight and 14.32% after 24 hours. Reactive Red dye was consistently degraded more efficiently than Methylene Blue, likely due to its azo structure interacting more effectively with CuO catalytic sites. The study demonstrates that biologically synthesized CuO nanoparticles offer a cost-effective, sustainable, and efficient solution for dye-laden wastewater remediation. These findings highlight the potential of microbially mediated nanotechnology for real-world environmental applications and contribute to the growing shift toward green chemistry in pollutant treatment systems.