Impact of carbon nanotubes on the mobility of sulfonamide antibiotics in sediments in the Xiangjiang River

Abstract

Manufactured in numerous factories, and contained in various consumer products, carbon nanotubes (CNTs) and sulfonamide antibiotics (SAs) may be released into the environment by many pathways. The sorption behavior of CNTs on SAs may increase the environmental and health risks when exposed to SAs–CNTs composites. In this study, we investigated the mobility of SAs in sediment columns in the presence/absence of CNTs. Three kinds of SAs (sulfamethoxazole, sulfapyridine, and sulfadiazine) and two kinds of CNTs (multi-walled carbon nanotubes, MWCNTs and single-walled carbon nanotubes, SWCNTs) in sediments from the Xiangjiang River were investigated in this study. The results showed that the SAs were of high mobility in sediment columns. However, CNTs with a concentration of 4.8 mg g⁻¹ in the sediment could dramatically retain SAs, which might be due to the limited transport of CNTs and their high adsorption capacities of SAs. The percentage of SAs retention in sediment became higher when CNTs existed in the inflow, suggesting that a strong CNTs-associated SAs reaction might occur in the sediment. The findings in this study indicated that CNTs in the sediment environment or river system can reduce the mobility of SAs, which should be taken into account when evaluating the potential environmental risks of SAs and CNTs.