Cotransport of micro- and nano-plastics with chlortetracycline hydrochloride in saturated porous media: Effects of physicochemical heterogeneities and ionic strength

Lilin Xu; Yan Liang; Changjun Liao; Tian Xie; Hanbin Zhang; Xingyu Liu; Zhiwei Lu; Dengjun Wang

doi:10.1016/j.watres.2021.117886

Cotransport of micro- and nano-plastics with chlortetracycline hydrochloride in saturated porous media: Effects of physicochemical heterogeneities and ionic strength

Water Res. 2022 Feb 1:209:117886. doi: 10.1016/j.watres.2021.117886. Epub 2021 Nov 21.

Authors

Lilin Xu¹, Yan Liang², Changjun Liao³, Tian Xie³, Hanbin Zhang¹, Xingyu Liu¹, Zhiwei Lu¹, Dengjun Wang⁴

Affiliations

¹ School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China.
² School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; Guangxi Bossco Environmental Protection Technology Co., Ltd, Nanning 530007, China. Electronic address: liangyan@gxu.edu.cn.
³ Guangxi Bossco Environmental Protection Technology Co., Ltd, Nanning 530007, China.
⁴ School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, United States.

PMID: 34861437
DOI: 10.1016/j.watres.2021.117886

Abstract

Global production and use of plastics have resulted in the wide dissemination of micro- and nano-plastics (MNPs) to the natural environment. Potentially acting as a vector, the role of MNPs on the fate and transport of environmental pollutants (e.g., antibiotics such as chlortetracycline hydrochloride; CTC) has garnered global concern recently. Herein, the cotransport of MNPs and CTC in columns packed with uncoated sand or soil colloid-coated sand (SCCS) under different degrees of physicochemical heterogeneity and ionic strength was systematically explored. Our results show that MNPs and CTC inhibit the transport of each other when they coexist. The adsorption of CTC onto sand grains, soil colloids, and MNPs, as well as the aggregation of MNPs in the presence of CTC could be the major contributors to the enhanced retention of CTC and MNPs. In SCCS with different degrees of soil colloid coating, the adsorption of CTC on soil colloids is critical to influence the transport of CTC, and the nonlinear retention of MNPs to soil colloids is mainly attributed to the alteration of collector surface roughness by soil colloids. High ionic strength slightly facilitates CTC transport due to the competition for adsorption sites and the formation of CTC macromolecules, but significantly inhibits MNPs transport by suppressing the electrostatic double layers based on colloid stability theory. Consequently, the cotransport of MNPs and CTC is governed by the coupled interplay of collector surface roughness and chemical heterogeneity, due to the soil colloid coatings and the adsorbed CTC on the surfaces associated with solution chemistries such as ionic strength. Increased cotransport of MNPs and CTC occurred under a higher concentration of MNPs due to a larger number of adsorption sites for CTC. Our findings advance the current understanding of the complex cotransport of MNPs and antibiotics in the environment. This information is valuable for understanding contaminant fate and formulating strategies for environmental remediation due to the contamination of MNPs and co-occurring contaminants.

Keywords: Chlortetracycline hydrochloride; Micro and nano-plastics; Natural soil colloid; Porous media; Transport.