Characterization of the microplastic photoaging under the action of typical salt ions of biological nitrogen removal processes

Muchuan Qin; Yun-Yan Wang; Mingfei Xu; Jia Tang; Xi Tang; Qaisar Mahmood; Chong-Jian Tang

doi:10.1016/j.scitotenv.2023.169596

Characterization of the microplastic photoaging under the action of typical salt ions of biological nitrogen removal processes

Sci Total Environ. 2024 Feb 20:912:169596. doi: 10.1016/j.scitotenv.2023.169596. Epub 2023 Dec 24.

Authors

Muchuan Qin¹, Yun-Yan Wang², Mingfei Xu³, Jia Tang⁴, Xi Tang⁵, Qaisar Mahmood⁶, Chong-Jian Tang⁷

Affiliations

¹ Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, Changsha 410083, China. Electronic address: 203512176@csu.edu.cn.
² Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, Changsha 410083, China. Electronic address: wyy@csu.edu.cn.
³ Dagang Oilfield Production Technology Research Institute, Binhai New Area, Tianjin 300280, China. Electronic address: xumfei@petrochina.com.cn.
⁴ Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, Changsha 410083, China.
⁵ Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, Changsha 410083, China. Electronic address: tangxi@csu.edu.cn.
⁶ Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad Campus, Pakistan. Electronic address: drqaisar@cuiatd.edu.pk.
⁷ Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, Changsha 410083, China. Electronic address: chjtang@csu.edu.cn.

PMID: 38147940
DOI: 10.1016/j.scitotenv.2023.169596

Abstract

Microplastics (MPs) are one of the most prevalent and diverse contaminants, and wastewater treatment plants are significant MP aggregators. Controlling the pollution caused by microplastics requires an understanding of how they age. The properties of the MPs photoaging process under the influence of salt ions typical of biological nitrogen elimination processes were disclosed in this work. The aging process of polyvinyl chloride microplastics (PVC-MPs) was greatly slowed down by greater HCO₃^- and NO₂^- concentrations, according to a comparison of the carbonyl index changes that occurred during photoaging. The carbonyl index had a negative correlation with the thermal stability of the photo-aged PVC-MPs, and aging accelerated the elimination of chlorine from the water. The samples were aged by UV radiation after 36 h at 40 °C, and the amount of chlorine eliminated was 10.13 times greater than that of the original MPs samples. It was discovered that the leachate concentration of aged MPs dramatically increased with decreasing particle size and was positively connected with the level of aging by comparing the concentration of leachate for two particle sizes (1 mm and 100 m). Photoaging caused MPs to become rougher, which in turn improved the NO₃^--N, NH₄⁺-N, and NO₂^--N adsorption by PVC-MPs.

Keywords: Inorganic salts; Microplastics; Photooxidation; Polyvinyl chloride; Substance release; Wastewater treatment system.

MeSH terms

Chlorides
Chlorine
Denitrification
Microplastics
Nitrogen
Nitrogen Dioxide
Plastics
Polyvinyl Chloride
Skin Aging*
Sodium Chloride
Water Pollutants, Chemical*

Substances

Plastics
Microplastics
Chlorine
Nitrogen Dioxide
Sodium Chloride
Chlorides
Nitrogen
Polyvinyl Chloride
Water Pollutants, Chemical