Impact of CeO2 nanoparticles on the aggregation kinetics and stability of polystyrene nanoplastics: Importance of surface functionalization and solution chemistry

Xing Li, Erkai He, Bing Xia, Cornelis A.M. Van Gestel, Willie J.G.M. Peijnenburg, Xinde Cao, Hao Qiu*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

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Abstract

The increasing application of plastics is accompanied by increasing concern over the stability and potential risk of nanoplastics. Heteroaggregation with metal-based nanoparticles (e.g., CeO2-NPs) is critical to the environmental mobility of nanoplastics, as they are likely to be jointly emitted to the aquatic environment. Here, time-resolved dynamic light scattering was employed to evaluate the influence of CeO2-NPs on the aggregation kinetics of differentially surface functionalized polystyrene nanoplastics (PS-NPs) in various water types. Natural organic matters and ionic strength were dominating factors influencing the heteroaggregation of PS-NPs and CeO2-NPs in surface waters. The critical coagulation concentrations of PS-NPs were dependent on their surface coatings, which decreased in the presence of CeO2-NPs due to electrostatic attraction and/or specific adsorption. Incubation of PS-NPs and CeO2-NPs under different pH confirmed the importance of electrostatic force in the aggregation of PS NPs. A relatively low humic acid (HA) concentration promoted the heteroaggregation of NH2-coated PS-NPs and CeO2-NPs because the introduction of a HA surface coating decreased the electrostatic hindrance. At high HA concentrations, the aggregation was inhibited by steric repulsion. The combined effects of high efficiency of double layer compression, bridging and complexation contributed to the high capacity of Ca2+ in destabilizing the particles. These findings demonstrate that the environmental behavior of nanoplastics is influenced by the presence of other non-plastic particles and improve our understanding of the interactions between PS-NPs and CeO2-NPs in complex and realistic aqueous environments.

Original languageEnglish
Article number116324
Pages (from-to)1-12
Number of pages12
JournalWater Research
Volume186
Early online date20 Aug 2020
DOIs
Publication statusPublished - 1 Nov 2020

Keywords

  • Engineered nanoparticles
  • Hydrochemical condition
  • Stability
  • Surface functional groups

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