Stability, aggregation, and sedimentation behaviors of typical nano metal oxide particles in aqueous environment

Hongliang Dai; Ting Han; Junting Cui; Xiang Li; Haq Nawaz Abbasi; Xingang Wang; Zechong Guo; Yong Chen

doi:10.1016/j.jenvman.2022.115217

Stability, aggregation, and sedimentation behaviors of typical nano metal oxide particles in aqueous environment

J Environ Manage. 2022 Aug 15:316:115217. doi: 10.1016/j.jenvman.2022.115217. Epub 2022 May 10.

Authors

Hongliang Dai¹, Ting Han², Junting Cui³, Xiang Li⁴, Haq Nawaz Abbasi⁵, Xingang Wang⁶, Zechong Guo⁷, Yong Chen⁸

Affiliations

¹ School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, China; School of Environmental and Engineering, Huazhong University of Science and Technology, Wuhan, China. Electronic address: daihongliang@just.edu.cn.
² School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, China. Electronic address: hanting970424@163.com.
³ School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, China. Electronic address: cuijt416@163.com.
⁴ School Energy & Environment, Southeast University, 2 Sipailou Road, Nanjing, China. Electronic address: lixiangseu@seu.edu.cn.
⁵ Department of Environmental Science, Federal Urdu University of Arts, Science and Technology, Karachi, Pakistan. Electronic address: hn.abbasi@fuuast.edu.pk.
⁶ School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, China. Electronic address: hofs@just.edu.cn.
⁷ School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, China; School of Environmental and Engineering, Huazhong University of Science and Technology, Wuhan, China. Electronic address: guozechong@just.edu.cn.
⁸ School of Environmental and Engineering, Huazhong University of Science and Technology, Wuhan, China. Electronic address: ychen@hust.edu.cn.

PMID: 35561494
DOI: 10.1016/j.jenvman.2022.115217

Abstract

The wide use of nano metal oxide particles (NMOPs) brings about their inevitable release into the water environment, affecting the environment and human health. Therefore, the stability, aggregation, and sedimentation process of four typical NMOPs (ZnO NPs, CeO₂ NPs, TiO₂ NPs, and CuO NPs) were investigated in artificial water and real municipal sewage to reveal their complicated behavior. Results showed that NMOPs aggregated at the pH of zero-charge point, and their hydrodynamic diameters and aggregation rates could reach the maximum values. The hydrodynamic diameters and aggregation rates of ZnO NPs, CeO₂ NPs, TiO₂ NPs, and CuO NPs at the zero-charge point were 617, 1760, 870, 1502 nm, and 31.7, 1158.1, 48.3, 115.7 nm/min, respectively. In addition, the dissolution of NMOPs led to the sedimentation rates under acidic conditions being much lower than those under neutral and alkaline conditions. The aggregation and sedimentation performance of NMOPs were affected by not only pH but also ionic strength (IS) and species. The aggregation rates of NMOPs increased with the increase of IS (0-10 mM), and the maximum aggregation rate of CeO₂ NPs was 470.1 nm/min (pH = 7 and CaCl₂ = 10 mM). According to Coulomb's law, divalent cations (Mg²⁺, Ca²⁺) were more competitively adsorbed on the surface of NMOPs than monovalent cations (K⁺, Na⁺), which increased the zeta potential and aggregation rate of NMOPs. Furthermore, the NMOPs were easier to aggregate in municipal sewage because of the homogeneous aggregation between nanoparticles and heterogeneous aggregation with natural colloids. The total interaction energy between NMOPs was calculated by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical formula, which was consistent with the experimental results.

Keywords: Aggregation and sedimentation; Cation valence; Derjaguin-landau-verwey-overbeek (DLVO); Municipal sewage; Nano metal oxide particles (NMOPs).

MeSH terms

Humans
Nanoparticles*
Oxides
Sewage
Water
Zinc Oxide*

Substances

Oxides
Sewage
Water
Zinc Oxide