Department of Environmental Engineering, Faculty of Engineering and Research Center for Environmental and Hazardous Substance Management, Khon Kaen University, Khon Kaen, Thailand.
Department of Environmental Engineering, King Mongkut's University of Technology Thonburi, Tungkru, Bangkok, Thailand.
Water Environ Res. 2024 Aug;96(8):e11102. doi: 10.1002/wer.11102.
Magnetite nanoparticles (nano-FeO) and nano-FeO immobilized with bacterial extracellular polymeric substances (EPSs) extracted from Lysinibacillus sp. WH (FeO/bact) were comparatively studied for the removal of Cr (VI) ions from aqueous solution in batch study. The objectives were to explore the removal of Cr (VI) efficiency by nano-FeO and FeO/bact under varying bacterial concentrations at a range of acidic pH. Results indicated that 150 ppm Cr (VI) could be effectively removed by 5 g/L of nano-FeO at pH 4, with the efficiency of 89.2 ± 12%. The equilibrium time, determined by a pseudo-second-order model (R = 0.9983), was after 5 h, indicating chemical adsorption. The Cr (VI) removal by the nano-FeO immobilized with bacterial EPS was effective and steady under a wide range of acidic conditions although bacterial EPS has an alkaline nature. Here, we are the first to demonstrate that Cr (VI) removal efficiency by different concentrations of EPS was not significantly different, suggesting EPS concentration is possibly not the most crucial factor to be optimized for Cr (VI) removal in the future. This study shows the potential application of nano-FeO immobilized with bacterial EPS for wastewater treatment. PRACTITIONER POINTS: The equilibrium time for magnetite nanoparticles to remove Cr (VI) is 5 h, suggesting chemical adsorption. The Cr (VI) removal efficiency of either magnetite nanoparticles or bacterial EPS is stable under a wide range of acidic conditions. Magnetite nanoparticles immobilized with bacterial EPS extracted from Lysinibacillus sp. WH has a potential application for Cr (VI) removal in wastewater.
磁性纳米颗粒（纳米-FeO）和纳米-FeO 固定在从 Lysinibacillus sp. WH 中提取的细菌胞外聚合物物质（EPS）上（FeO/bact），在批处理研究中比较了它们从水溶液中去除 Cr（VI）离子的效果。目的是在不同的酸性 pH 值下，研究不同细菌浓度下纳米-FeO 和 FeO/bact 对 Cr（VI）的去除效率。结果表明，在 pH 4 下，5 g/L 的纳米-FeO 可以有效地去除 150 ppm 的 Cr（VI），去除效率为 89.2±12%。通过拟二级模型（R=0.9983）确定的平衡时间为 5 小时后，表明是化学吸附。尽管细菌 EPS 呈碱性，但在广泛的酸性条件下，细菌 EPS 固定的纳米-FeO 对 Cr（VI）的去除效果稳定。在这里，我们首次证明，不同浓度的 EPS 对 Cr（VI）的去除效率没有显著差异，这表明 EPS 浓度可能不是未来优化 Cr（VI）去除的最关键因素。这项研究表明，细菌 EPS 固定的纳米-FeO 在废水处理方面具有潜在的应用。
