Liu Beibei, Guo Kangying, Yue Qinyan, Gao Yue, Gao Baoyu
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China.
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China.
Water Res. 2024 Nov 15;266:122440. doi: 10.1016/j.watres.2024.122440. Epub 2024 Sep 12.
Hydrolyzed AlTi species are essential metal-based coagulants in a coagulation process to remove nanoplastics (NPs). Understanding the molecular interactions between hydrolyzed AlTi species and NPs is key to promoting coagulation efficiency. In this study, the coagulation performance and intrinsic mechanism of different AlTi species (including monomeric AlTi and polymeric AlTi species-AlTi) for NPs removal were systematically investigated. We found that the polymeric AlTi species exhibited higher turbidity removal (95.0 %) and lower residual Al content (20.67 μg/L) at a low dosage over monomeric AlTi species. Al and AlTi formed by in situ hydrolysis were the dominant species to destabilize and aggregate NPs at pH 6. Main coagulation mechanisms were dominated by charge neutralization, complexation between the aliphatic CH of NPs and Al/Ti-OH, and cation-π interaction between polycations and the aromatic structure of NPs. The preformed AlTi showed multiple positive charge binding sites assisting its easy adsorption on NPs by electrostatic attraction, and then formed microscale aggregates through charge neutralization or intermolecular interaction. The preformed AlTi demonstrated a high stability and coagulation performance with respect to pH changes in raw water, whereas the promotion of μ-OH bridges dissociation by OH and the presence of electrostatic repulsion significantly decreased the NPs removal by monomeric AlTi at high pH. This study provides valuable theoretical insights into the interaction between NPs and various hydrolyzed AlTi species.
水解的铝钛物种是混凝过程中去除纳米塑料（NPs）的重要金属基混凝剂。了解水解铝钛物种与纳米塑料之间的分子相互作用是提高混凝效率的关键。在本研究中，系统研究了不同铝钛物种（包括单体铝钛和聚合铝钛物种-AlTi）去除纳米塑料的混凝性能和内在机制。我们发现，在低剂量下，聚合铝钛物种比单体铝钛物种表现出更高的浊度去除率（95.0%）和更低的残余铝含量（20.67μg/L）。在pH值为6时，原位水解形成的铝和铝钛是使纳米塑料失稳并聚集的主要物种。主要混凝机制包括电荷中和、纳米塑料的脂肪族CH与Al/Ti-OH之间的络合以及聚阳离子与纳米塑料芳香结构之间的阳离子-π相互作用。预制的铝钛具有多个正电荷结合位点，可以通过静电吸引轻松吸附在纳米塑料上，然后通过电荷中和或分子间相互作用形成微观聚集体。预制的铝钛对原水pH变化具有较高的稳定性和混凝性能，而在高pH值下，OH促进μ-OH桥解离以及静电排斥的存在显著降低了单体铝钛对纳米塑料的去除率。本研究为纳米塑料与各种水解铝钛物种之间的相互作用提供了有价值的理论见解。
