Sophia, S.Shetty K, V.2026-02-042024Journal of Environmental Chemical Engineering, 2024, 12, 3, pp. -22132929https://doi.org/10.1016/j.jece.2024.112966https://idr.nitk.ac.in/handle/123456789/21083Industrial effluents containing hazardous phenolic compounds such as 4-nitrophenol (4-NP) can threaten aquatic ecosystems and the environment. To address the environmental issues due to nitrophenol-contaminated industrial effluents and rapidly generating electronic waste (e-waste), catalytic nanoparticles are biosynthesized utilizing the waste printed circuit boards (WPCBs) and the cell-free supernatant (CFS) of the bacteria Alcaligenes aquatilis for the catalytic reduction of 4-NP with sodium borohydride (NaBH<inf>4</inf>). The optimum synthesis parameters to maximize 4-NP reduction were an initial pH of 12.4 and a volume ratio of metal leachate to CFS of 1:3. These nanoparticles were found to be heteroatom-doped CuO/Cu<inf>2</inf>O (Bio-CuO/Cu<inf>2</inf>O-PCB) with spherical shape, average crystallite size of 19 nm and average particle size of 19.2 nm. The biosynthesized nanoparticles exhibited excellent catalytic activity in the reduction of 4-NP with a pseudo-first-order rate constant (k<inf>app</inf>) of 0.526 min-1, induction period of 2 min, and 90% reduction of 4-NP in 6 min. This work demonstrates the recovery of metal resources from waste as nanoparticles with excellent catalytic activity using a green, eco-friendly synthesis method under ambient conditions. Bio-CuO/Cu<inf>2</inf>O-PCB showed better activity than commercial CuO, biosynthesized and chemically synthesized CuO using precursor salt. The developed synthesis method is eco-friendly and could yield a recyclable catalyst for reducing harmful aromatic pollutants such as 4-NP present in wastewater to 4-aminophenol, a pharmaceutical intermediate. © 2024 Elsevier LtdCatalyst activityCopper oxidesEffluentsElectronic WasteMetal nanoparticlesParticle sizePhenolsRate constantsSewageSodium BorohydrideWater pollution% reductions4-NitrophenolCopper oxide nanoparticlesE-wastesElectronics wastesHeteroatomsIndustrial effluentMicrobial synthesisNitrophenol reductionNitrophenolsSynthesis (chemical)