Influence of water chemistry on the environmental behaviors of commercial ZnO nanoparticles in various water and wastewater samples

• Published in: Journal of hazardous materials Vol. 322; no. Pt B; pp. 348 - 356
• Main Authors: Peng, Yu-Huei, Tsai, Yi-Chun, Hsiung, Chia-En, Lin, Yi-Hsuan, Shih, Yang-hsin
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2017
• Subjects: Aggregation; Dissolution; Nanoparticles; Sedimentation; Stability; Waste water; Wastewater; Water chemistry; Zinc oxide; Zinc oxide nanoparticle; USA, Florida, Suwannee R; Aggregation; Zinc oxide nanoparticle; Wastewater; Sedimentation; Dissolution
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2016.10.003

[Display omitted] •High dosage of SO42− (>10meq/L) stabilized ZnO NPs by inverting surface potential.•The electrolyte-driven aggregation of ZnO NPs was inhibited by 10mg/L SRHA.•ZnO NPs kept stable in a wastewater with high TOC and even high ionic strength.•High TOC and low pH compromised high ionic strength on the dissolution of ZnO NPs. Zinc oxide nanoparticles (ZnO NPs) are widely used nanomaterials and their environmental impacts have received increasing attention. The fate and toxicity of ZnO NPs in the environment are determined by their stability and dissolution. In this study, the influence of water chemistry on aggregation, sedimentation, and dissolution of ZnO NPs was investigated. The stabilized ZnO NPs aggregated and precipitated when the aqueous pH closed to their zero point of charge (pHzpc). Counter-ions neutralized the surface charge of NPs and promoted their destabilization. However, a high concentration of counter-ion (SO42−, >10meq/L) made the NPs more stable because of the inverted surface potential. The stability of ZnO NPs was maintained by high concentration of Suwannee River humic acid (SRHA, 10mg/L) even the concentration of electrolytes was high. The influence of water chemistry on the stability and dissolution of ZnO NPs was further demonstrated in different wastewaters. In one wastewater sample, ZnO NPs was unexpectedly stable and with a high dissolution, which was due to the effects of pH value, organic matter concentration, as well as the concentration of counter ions. Our findings facilitate the predictions of the fate of stabilized ZnO NPs in the environment.