Sorption of oxytetracycline to microsized colloids under concentrated salt solution: A perspective on terrestrial-to-ocean transfer of antibiotics

• Published in: The Science of the total environment Vol. 905; p. 167005
• Main Authors: Nguyen, Anh Q., Nguyen, Anh T.Q., Nguyen, Ngoc T.M., Nguyen, Anh D., Bui, Hoi V., Nguyen-Thanh, Lan, Nguyen, Minh N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.12.2023
• Subjects: Colloidal properties; Estuary; Oxytetracycline; Soil clay; Surface charge; Oxytetracycline; Surface charge; Estuary; Colloidal properties; Soil clay
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.167005

The sorption of antibiotics on soil minerals and their cotransport have been widely studied for the past few years; however, these processes in concentrated salt solutions (estuary-like conditions) are not fully understood. This study aims to determine the possible sorption of oxytetracycline (OTC) on various natural and synthesized microsized minerals (including haematite, goethite, kaolinite, bentonite, lateritic, kaolinitic and illitic soil clays) under conditions mimicking pure, fresh, brackish and sea waters. The sorption of OTC was found to decrease in surface charge (herein zeta potential), hence altering the colloidal properties of the materials used. The sorption capacities of soil clays for OTC follow the inequality illitic soil clay > kaolinitic soil clay > lateritic soil clay, and the sorption capacities were found to decrease at higher salt concentrations. Seawater can intensify the release of the sorbed OTC from soil clay surfaces while favouring the coaggregation of the remaining OTC with soil clays. This implies that the long-range transport of OTC or other similar antibiotics can be governed by the mineralogical composition/properties of the suspended particles. More importantly, increasing salt concentrations in estuaries may form a chemical barrier at which limited amounts of OTC/antibiotics can pass through, while the remaining OTC/antibiotics can be favoured to aggregate simultaneously with suspended mineral particles. [Display omitted] •Sorption of OTC on soil clays follows the inequality: illitic > kaolinitic > lateritic.•The sorption capacities were found to decrease in the higher salt concentrations.•Sea water can intensify the release of the sorbed OTC from soil clay's surfaces.•Suspended minerals can govern the long-range transport of antibiotics.