Sun Leiye, Wu Jiayan, Chen Meiqing, Wang Tianming, Shang Zhongbo, Liu Jieyu, Huang Minye, Wu Pingxiao
School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, PR China.
School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, PR China; Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, PR China; Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou 510006, PR China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, Guangzhou 510006, PR China.
Sci Total Environ. 2023 Nov 25;901:165928. doi: 10.1016/j.scitotenv.2023.165928. Epub 2023 Jul 30.
Nanoplastics (NPs) usually coexist with impurity-bearing ferrihydrite (ImFh), and their interaction is related to their environmental fate. In this study, the aggregation between ImFh (impurities: Al, Mn and Si) and polystyrene nanoplastics (PSNPs), as well as the sedimentation of ImFh-PSNP complex particles in the aqueous phase were investigated systematically with particle concentrations of 100 mg/L ImFh and 10 mg/L PSNPs. Our results revealed that the PSNP suspension was dispersive and stable under various pH values and low ion strength. After coexisting with ImFh, PSNPs aggregated with the positively charged ImFh to form ImFh-PSNP complex particles, which destroyed the stability of PSNPs. The increase in pH and Na concentration could inhibit their aggregation, but high Na concentration (>20 mM) caused the homoaggregation of PSNPs. The aggregation capacity of PSNPs with ImFh was in the order of Al-bearing Fh > Fh > Mn-bearing Fh > Si-bearing Fh. Zeta potential and Derjaguin-Landau-Verwey-Overbeek (DLVO) calculations indicated that Al-bearing Fh showed higher positive potential than pure Fh, which caused stronger electrostatic interactions with PSNPs. However, Mn and Si in ImFh decreased the positive potential and inhibited the electrostatic interaction with PSNPs, and the effect of Si was greater than that of Mn. The aggregation between ImFh and PSNPs inhibited the sedimentation of their complex particles, and the higher aggregation capacity appeared to have a greater inhibition degree. Due to the "electrostatic patches" effect of PSNPs, the energy barrier of the ImFh-PSNPs particles was higher than that of the ImFh particles. Our findings clarified the influence of impurities on the interaction between ImFh and PSNPs and provided insight regarding their fate in the environment.
纳米塑料（NPs）通常与含杂质的水铁矿（ImFh）共存，它们之间的相互作用与其环境归宿有关。在本研究中，以100 mg/L的ImFh和10 mg/L的聚苯乙烯纳米塑料（PSNPs）的颗粒浓度，系统研究了ImFh（杂质：Al、Mn和Si）与聚苯乙烯纳米塑料（PSNPs）之间的聚集以及ImFh-PSNP复合颗粒在水相中的沉降。我们的结果表明，PSNP悬浮液在各种pH值和低离子强度下是分散且稳定的。与ImFh共存后，PSNPs与带正电的ImFh聚集形成ImFh-PSNP复合颗粒，这破坏了PSNPs的稳定性。pH值和Na浓度的增加可抑制它们的聚集，但高Na浓度（>20 mM）会导致PSNPs的同聚。PSNPs与ImFh的聚集能力顺序为：含Al水铁矿>Fh>含Mn水铁矿>含Si水铁矿。zeta电位和Derjaguin-Landau-Verwey-Overbeek（DLVO）计算表明，含Al水铁矿比纯Fh具有更高的正电位，这导致与PSNPs的静电相互作用更强。然而，ImFh中的Mn和Si降低了正电位并抑制了与PSNPs的静电相互作用，且Si的影响大于Mn。ImFh与PSNPs之间的聚集抑制了它们复合颗粒的沉降，较高的聚集能力似乎具有更大的抑制程度。由于PSNPs的“静电补丁”效应，ImFh-PSNPs颗粒的能垒高于ImFh颗粒。我们的研究结果阐明了杂质对ImFh与PSNPs之间相互作用的影响，并为它们在环境中的归宿提供了见解。
