Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
Water Res. 2022 Jan 1;208:117884. doi: 10.1016/j.watres.2021.117884. Epub 2021 Nov 21.
Nanoplastics (NPs) pollution of aquatic systems is becoming an emerging environmental issue due to their stable structure, high mobility, and easy interactions with ambient contaminants. Effective removal technologies are urgently needed to mitigate their toxic effects. In this study, we systematically investigated the removal effectiveness and mechanisms of a commonly detected nanoplastics, carboxyl-modified polystyrene (PS-COOH) via coagulation and sedimentation processes using aluminum chloride (AlCl) as a coagulant. PS-COOH appeared as clearly defined and discrete spherical nanoparticles in water with a hydrodynamic diameter of 50 nm. The addition of 10 mg/L AlCl compressed and even destroyed the negatively charged PS-COOH surface layer, decreased the energy barrier, and efficiently removed 96.6% of 50 mg/L PS-COOH. The dominant removal mechanisms included electrostatic adsorption and intermolecular interactions. Increasing the pH from 3.5 to 8.5 sharply enhanced the PS-COOH removal, whereas significant loss was observed at pH 10.0. High temperature (23 °C) favored the removal of PS-COOH compared to lower temperature (4 °C). High PS-COOH removal efficiency was observed over the salinity range of 0 - 35‰. The presence of positively charged AlO did not affect the PS-COOH removal, while negatively charged SiO reduced the PS-COOH removal from 96.6% to 93.2%. Moreover, the coagulation and sedimentation process efficiently removed 90.2% of 50 mg/L PS-COOH in real surface water even though it was rich in inorganic ions and total organic carbon. The fast and efficient capture of PS-COOH by AlCl via a simple coagulation and sedimentation process provides a new insight for the treatment of NPs from aqueous environment.
纳米塑料（NPs）由于其稳定的结构、高迁移性和容易与环境污染物相互作用，对水生系统的污染正成为一个新出现的环境问题。迫切需要有效的去除技术来减轻其毒性影响。在这项研究中，我们系统地研究了一种常见纳米塑料羧基化聚苯乙烯（PS-COOH）通过氯化铝（AlCl）作为混凝剂的混凝和沉淀过程的去除效果和机制。PS-COOH 在水中呈现出清晰定义的离散球形纳米颗粒，水动力直径为 50nm。添加 10mg/L AlCl 压缩甚至破坏了带负电荷的 PS-COOH 表面层，降低了能垒，并有效地去除了 50mg/L PS-COOH 的 96.6%。主要的去除机制包括静电吸附和分子间相互作用。将 pH 值从 3.5 增加到 8.5 会急剧提高 PS-COOH 的去除率，而在 pH 值为 10.0 时会观察到明显的损失。与低温（4°C）相比，高温（23°C）有利于 PS-COOH 的去除。在 0-35‰的盐度范围内，PS-COOH 的去除效率很高。带正电荷的 AlO 对 PS-COOH 的去除没有影响，而带负电荷的 SiO 则将 PS-COOH 的去除率从 96.6%降低到 93.2%。此外，即使富含无机离子和总有机碳，混凝和沉淀过程也能有效地去除实际地表水 50mg/L PS-COOH 的 90.2%。AlCl 通过简单的混凝和沉淀过程快速有效地捕获 PS-COOH，为处理水环境中的 NPs 提供了新的思路。
