Xie Ruiyin, Xing Xiaohui, Nie Xin, Ma Xunsong, Wan Quan, Chen Qingsong, Li Zixiong, Wang Jingxin
Guangdong Provincial Engineering Research Center of Public Health Detection and Assessment, School of Public Health, Guangdong Pharmaceutical University, Guangzhou 510310, China; State Key Laboratory of Ore Deposit Geochemistry, Research Center of Ecological Environment and Resource Utilization, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
Guangdong Provincial Engineering Research Center of Public Health Detection and Assessment, School of Public Health, Guangdong Pharmaceutical University, Guangzhou 510310, China.
Sci Total Environ. 2023 Dec 15;904:166783. doi: 10.1016/j.scitotenv.2023.166783. Epub 2023 Sep 2.
The ubiquitous nanoplastics (NPs) in the environment are emerging contaminants due to their risks to human health and ecosystems. The interaction between NPs and minerals determines the environmental and ecological risks of NPs. In this study, the deposition behaviors of carboxyl modified polystyrene nanoplastics (COOH-PSNPs) with goethite (α-FeOOH) were systematically investigated under various solution chemistry and organic macromolecules (OMs) conditions (i.e., pH, ionic type, humic acid (HA), sodium alginate (SA), and bovine serum albumin (BSA)). The study found that electrostatic interactions dominated the interaction between COOH-PSNPs and goethite. The deposition rates of COOH-PSNPs decreased with an increase in solution pH, due to the enhanced electrostatic repulsion by higher pH. Introducing cations or anions could compress the electrostatic double layers and compete for interaction sites on COOH-PSNPs and goethite, thereby reducing the deposition rates of COOH-PSNPs. The stabilization effects, which were positive with ions valence, followed the orders of NaCl ≈ KCl < CaCl, NaNO ≈ NaCl < NaSO < NaPO. Specific adsorption of SO or HPO caused a potential reversal of goethite from positive to negative, leading to the electrostatic forces between COOH-PSNPs and goethite changed from attraction to repulsion, and thus significantly decreasing deposition of COOH-PSNPs. Organic macromolecules could markedly inhibit the deposition of COOH-PSNPs with goethite because of enhanced electrostatic repulsion, steric hindrance, and competition of surface binding sites. The ability for inhibiting the deposition of COOH-PSNPs followed the sequence of SA > HA > BSA, which was related to their structure (SA: linear, semi-flexible, HA: globular, semi-rigid, BSA: globular, with protein tertiary structure) and surface charge density (SA > HA > BSA). The results of this study highlight the complexity of the interactions between NPs and minerals under different environments and provide valuable insights in understanding transport mechanisms and environmental fate of nanoplastics in aquatic environments.
环境中普遍存在的纳米塑料（NPs）因其对人类健康和生态系统构成风险，正成为新兴污染物。纳米塑料与矿物质之间的相互作用决定了纳米塑料的环境和生态风险。在本研究中，系统研究了羧基修饰的聚苯乙烯纳米塑料（COOH-PSNPs）与针铁矿（α-FeOOH）在各种溶液化学和有机大分子（OMs）条件下（即pH值、离子类型、腐殖酸（HA）、海藻酸钠（SA）和牛血清白蛋白（BSA））的沉积行为。研究发现，静电相互作用主导了COOH-PSNPs与针铁矿之间的相互作用。由于较高pH值增强了静电排斥作用，COOH-PSNPs的沉积速率随溶液pH值的升高而降低。引入阳离子或阴离子会压缩静电双层，并竞争COOH-PSNPs和针铁矿上的相互作用位点，从而降低COOH-PSNPs的沉积速率。稳定作用与离子价态呈正相关，顺序为NaCl ≈ KCl < CaCl，NaNO ≈ NaCl < NaSO < NaPO。SO或HPO的特异性吸附导致针铁矿的表面电位从正变为负，使得COOH-PSNPs与针铁矿之间的静电力从吸引变为排斥，从而显著降低了COOH-PSNPs的沉积。有机大分子由于增强的静电排斥、空间位阻和表面结合位点的竞争，能够显著抑制COOH-PSNPs与针铁矿的沉积。抑制COOH-PSNPs沉积的能力顺序为SA > HA > BSA，这与其结构（SA：线性、半柔性，HA：球状、半刚性，BSA：球状，具有蛋白质三级结构）和表面电荷密度（SA > HA > BSA）有关。本研究结果突出了不同环境下纳米塑料与矿物质之间相互作用的复杂性，并为理解纳米塑料在水生环境中的迁移机制和环境归宿提供了有价值的见解。
