The present investigation explores the antibacterial potential of novel ZnO-NPs synthesized from Acacia nilotica pods extract and immobilized onto sodium alginate beads to control bacterial pollution in wastewater. Phenolics and flavonoids were major phytoconstituents acting as capping, reducing, and stabilizing agents. UV–Vis analysis showed strong absorption band at 340 nm. XRD and TEM revealed hexagonal crystalline structure for zincite of average particles diameter 33.87 and 32.74 nm, respectively. FTIR demonstrated several bands with functional groups (O–H, C-H, C = O, C = C, and C–O–C) involved in ZnO-NPs synthesis. SEM images showed NPs surface completely colonized by E.coli, while EDX spectrum showed signals for zinc (52.94%) and oxygen (26.58%) confirming NPs purity. Adhesion capacity studies revealed ZnO-NPs potential (0.5 g) to remove E.coli after 120 min. Kinetic and isotherm studies indicated that pseudo-second-order model and Freundlich isotherm were best fit describing adhesion mechanism. Electrostatic attraction between negatively charged E.coli and positively charged ZnO-NPs was followed by generation of H₂O₂ leading to cell apoptosis. Adhesion optimization using Box–Behnken design under response surface methodology was 99.8% at disinfectant dose 30 g/L, contact time 6 h, and E.coli concentration 150 × 10⁷ cfu/mL. For application, real wastewater was treated with removal 98.2%, 97.2%, and 96.5% for total coliform, fecal coliform, and E.coli, respectively, after 6 h. ZnO-NPs showed sustainable efficiency during four consecutive cycles of treatment. The study concluded the efficiency, eco-friendly and cost-effectiveness of phytofabricated ZnO-NPs as disinfectants for wastewater and recommended future studies on large scale for possible wastewater reuse in safe unrestricted irrigation.

本研究探讨了由金合欢荚提取物合成的新型 ZnO-NP 的抗菌潜力，并将其固定在海藻酸钠珠上以控制废水中的细菌污染。酚类和类黄酮是主要的植物成分，充当封端剂、还原剂和稳定剂。紫外可见分光光度计在 340 nm 处显示出强吸收带。XRD和TEM揭示了平均粒径分别为33.87和32.74 nm的红锌矿的六方晶体结构。FTIR 显示了几个带参与 ZnO-NP 合成的官能团（O–H、CH、C = O、C = C 和 C–O–C）。SEM 图像显示 NP 表面完全被大肠杆菌定植，而 EDX 光谱显示锌 (52.94%) 和氧 (26.58%) 信号，证实了 NP 纯度。粘附能力研究表明 ZnO-NPs（0.5 g）有可能在 120 分钟后去除大肠杆菌。动力学和等温线研究表明伪二阶模型和Freundlich等温线最适合描述粘附机制。带负电的大肠杆菌和带正电的ZnO-NPs之间的静电吸引随后产生H ₂ O ₂，​​导致细胞凋亡。在消毒剂剂量 30 g/L、接触时间 6 小时和大肠杆菌浓度 150 × 10 ⁷  cfu/mL下，使用 Box–Behnken 设计在响应面法下的粘附优化为 99.8% 。在实际应用中，实际废水处理 6 小时后，总大肠菌群、粪大肠菌群和大肠杆菌的去除率分别为 98.2%、97.2% 和 96.5%。ZnO-NPs 在四个连续的处理周期中表现出可持续的效率。该研究总结了植物制造的 ZnO-NPs 作为废水消毒剂的效率、环境友好性和成本效益，并建议未来进行大规模研究，以实现安全无限​​制灌溉中可能的废水再利用。