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Roles of pH, cation valence, and ionic strength in the stability and aggregation behavior of zinc oxide nanoparticles.
J Environ Manage. 2020 Aug 01; 267:110656.JE

Abstract

The effects of pH, cation valence, and ionic strength (IS) on the stability and aggregation behavior of zinc oxide nanoparticles (ZnO NPs) were investigated in this study. Results showed that ZnO NPs were most prone to aggregation at the isoelectric point (pH = 8.7), with an aggregation rate (ΔD/Δt) of 30.1. ZnO NPs showed a greater propensity for dissolution at lower pH (pH < 7), and Zn2+ was more rapidly released into the aqueous phase in acidic solutions than neutral or alkaline conditions. The C/C0 of ZnO NPs was about 21.56% and remained stable in acidic solution of pH 4.0. Additionally, slow sedimentation with a C/C0 ratio of 95.0% was observed due to an increase in repulsive interactions between nanoparticles under pH = 10. The effect of cations on the ΔD/Δt of ZnO NPs decreased in strength as follows: Ca2+ > Mg2+ > K+ > Na+. High-valence metal cations (Ca2+, Mg2+) were more competitively adsorbed onto the surface of ZnO NPs with a hydrogen atom due to Coulomb's law, increasing the zeta potential and stabilizing the suspension of ZnO NPs at IS < 10 mM. Furthermore, compression of the electric double layer (EDL) became stronger than electrostatic adsorption with increasing IS, reaching a maximum ΔD/Δt of 23.3 (Ca2+, pH = 7, IS = 1 M). The C/C0 ratio of ZnO NPs decreased from 100% to 56.5% (Na+), 52.2% (K+), 45.2% (Mg2+), and 40.1% (Ca2+) at pH = 7 and an IS of 0.5 M. In addition to the cation valence, the hydration forces and ionic radii of the metal cations might be other factors that affected the interactions of metal cations with ZnO NPs. Finally, the total interaction energy between ZnO NPs was calculated using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical formula, and the calculated results were in agreement with the experimental outcomes under various aquatic environmental conditions.

Authors+Show Affiliations

School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212018, China; Marine Equipment and Technology Institute, Jiangsu University of Science and Technology, Zhenjiang, 212003, China. Electronic address: hofs@just.edu.cn.School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212018, China; Marine Equipment and Technology Institute, Jiangsu University of Science and Technology, Zhenjiang, 212003, China. Electronic address: 18252588460@163.com.School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212018, China; Marine Equipment and Technology Institute, Jiangsu University of Science and Technology, Zhenjiang, 212003, China. Electronic address: 18252588451@163.com.School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212018, China; Marine Equipment and Technology Institute, Jiangsu University of Science and Technology, Zhenjiang, 212003, China. Electronic address: hanting970424@163.com.School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin, 300387, China. Electronic address: wangjiemailbox@163.com.School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212018, China; Jindalai Environmental Protection Co., Ltd, Jiangxi, 330100, China; Marine Equipment and Technology Institute, Jiangsu University of Science and Technology, Zhenjiang, 212003, China. Electronic address: daihongliang@just.edu.cn.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

32349960

Citation

Wang, Xingang, et al. "Roles of pH, Cation Valence, and Ionic Strength in the Stability and Aggregation Behavior of Zinc Oxide Nanoparticles." Journal of Environmental Management, vol. 267, 2020, p. 110656.
Wang X, Sun T, Zhu H, et al. Roles of pH, cation valence, and ionic strength in the stability and aggregation behavior of zinc oxide nanoparticles. J Environ Manage. 2020;267:110656.
Wang, X., Sun, T., Zhu, H., Han, T., Wang, J., & Dai, H. (2020). Roles of pH, cation valence, and ionic strength in the stability and aggregation behavior of zinc oxide nanoparticles. Journal of Environmental Management, 267, 110656. https://doi.org/10.1016/j.jenvman.2020.110656
Wang X, et al. Roles of pH, Cation Valence, and Ionic Strength in the Stability and Aggregation Behavior of Zinc Oxide Nanoparticles. J Environ Manage. 2020 Aug 1;267:110656. PubMed PMID: 32349960.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Roles of pH, cation valence, and ionic strength in the stability and aggregation behavior of zinc oxide nanoparticles. AU - Wang,Xingang, AU - Sun,Tongshuai, AU - Zhu,Hui, AU - Han,Ting, AU - Wang,Jie, AU - Dai,Hongliang, Y1 - 2020/04/28/ PY - 2019/12/23/received PY - 2020/03/26/revised PY - 2020/04/24/accepted PY - 2020/5/1/pubmed PY - 2020/5/21/medline PY - 2020/5/1/entrez KW - Aggregation and sedimentation KW - Cation valence KW - Derjaguin-landau-verwey-overbeek (DLVO) KW - Ionic strength KW - Zinc oxide nanoparticles SP - 110656 EP - 110656 JF - Journal of environmental management JO - J. Environ. Manage. VL - 267 N2 - The effects of pH, cation valence, and ionic strength (IS) on the stability and aggregation behavior of zinc oxide nanoparticles (ZnO NPs) were investigated in this study. Results showed that ZnO NPs were most prone to aggregation at the isoelectric point (pH = 8.7), with an aggregation rate (ΔD/Δt) of 30.1. ZnO NPs showed a greater propensity for dissolution at lower pH (pH < 7), and Zn2+ was more rapidly released into the aqueous phase in acidic solutions than neutral or alkaline conditions. The C/C0 of ZnO NPs was about 21.56% and remained stable in acidic solution of pH 4.0. Additionally, slow sedimentation with a C/C0 ratio of 95.0% was observed due to an increase in repulsive interactions between nanoparticles under pH = 10. The effect of cations on the ΔD/Δt of ZnO NPs decreased in strength as follows: Ca2+ > Mg2+ > K+ > Na+. High-valence metal cations (Ca2+, Mg2+) were more competitively adsorbed onto the surface of ZnO NPs with a hydrogen atom due to Coulomb's law, increasing the zeta potential and stabilizing the suspension of ZnO NPs at IS < 10 mM. Furthermore, compression of the electric double layer (EDL) became stronger than electrostatic adsorption with increasing IS, reaching a maximum ΔD/Δt of 23.3 (Ca2+, pH = 7, IS = 1 M). The C/C0 ratio of ZnO NPs decreased from 100% to 56.5% (Na+), 52.2% (K+), 45.2% (Mg2+), and 40.1% (Ca2+) at pH = 7 and an IS of 0.5 M. In addition to the cation valence, the hydration forces and ionic radii of the metal cations might be other factors that affected the interactions of metal cations with ZnO NPs. Finally, the total interaction energy between ZnO NPs was calculated using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical formula, and the calculated results were in agreement with the experimental outcomes under various aquatic environmental conditions. SN - 1095-8630 UR - https://www.unboundmedicine.com/medline/citation/32349960/Roles_of_pH,_cation_valence,_and_ionic_strength_in_the_stability_and_aggregation_behavior_of_zinc_oxide_nanoparticles L2 - https://linkinghub.elsevier.com/retrieve/pii/S0301-4797(20)30588-0 DB - PRIME DP - Unbound Medicine ER -