Cation-π mechanism promotes the adsorption of humic acid on polystyrene nanoplastics to differently affect their aggregation: Evidence from experimental characterization and DFT calculation

被引：16

作者：

Kong, Yu ^{[1
]}

Li, Xiaona ^{[1
]}

Tao, Mengna ^{[1
]}

Cao, Xuesong ^{[1
]}

Wang, Zhenyu ^{[1
,2
]}

Xing, Baoshan ^{[3
]}

机构：

[1] Jiangnan Univ, Inst Environm Proc & Pollut Control, Sch Environm & Civil Engn, Wuxi 214122, Peoples R China

[2] Suzhou Univ Sci & Technol, Jiangsu Collaborat Innovat Ctr Technol & Mat Water, Suzhou 215009, Peoples R China

[3] Univ Massachusetts, Stockbridge Sch Agr, Amherst, MA 01003 USA

来源：

JOURNAL OF HAZARDOUS MATERIALS | 2023年 / 459卷

基金：

中国国家自然科学基金;

关键词：

Multiple water-chemistry factors; Aggregation; Humic acid; Cation type; DFT calculation; DISSOLVED ORGANIC-CARBON; MICROPLASTICS; SORPTION; IONS;

D O I：

10.1016/j.jhazmat.2023.132071

中图分类号：

X [环境科学、安全科学];

学科分类号：

08 ; 0830 ;

摘要：

Multiple water-chemistry factors determine nanoplastics aggregation and thus change their bioavailability and ecological risks in natural aquatic environments. However, the dominant factors and their interactive mechanisms remain elusive. In this study, polystyrene nanoplastics (PSNPs) showed greater colloidal stability in Li Lake water compared to ultrapure water. The RDA and PARAFAC results suggested that dissolved organic carbon, humic acid (HA) in particular, Ca2+, and pH are critical factors influencing PSNPs aggregation. Batch experiments showed that the critical coagulation concentration (CCC) of PSNPs was increased with pH increase; HA increased the CCC of PSNPs in NaCl by 2.6-fold but decreased that in CaCl2 by 1.8-fold. Moreover, cations increased the adsorption of HA on PSNPs. The DFT results suggested that HA-cations complexes (EAE =-1.10 eV and-0.51 eV for HA-Ca2+ and HA-Na+, respectively) but not HA alone (EAE =-0.33 eV) are the main scenarios for their adsorption on PSNPs, and a cation-& pi; mechanism between PSNPs and HA-cations complexes dominates PSNPs aggregation in this scenario. The findings are significant for better understanding the environmental process and fate of nanoplastics in aquatic environments.Environmental implication: Nanoplastics are kinds of emerging contaminants. Nanoplastic aggregation determines their bioavailability and toxic risks to ecological health. Herein, the hydrodynamic sizes of PSNPs in local Li Lake water was tested and a redundancy analysis was performed to examine the key water-chemistry factors driving PSNPs aggregation. Moreover, the mechanisms in PSNPs aggregation driven by multiple dominant water chemistry factors including cations, pH, and DOC were firstly unveiled by combining experimental characterization and theoretical computations. This work improves our understanding of the environmental fate of nanoplastics and provides a theoretical basis for the risk assessment and control of nanoplastics in real aquatic environments.

引用

页数：10