Impact Of Carbon Nanotubes On The Mobility Of Sulfonamide Antibiotics In Sediment

In recent years, with the large-scale industrialization of nanotechnology, carbon nanotubes(CNTs) are considered as one of the most promising materials, with the applications in many fields, including electronics, pharmaceuticals and environmental science due to its large specific surface area and high surface energy. However, the release of CNTs into the atmosphere, water and soil environment is inevitable through manufacture, application, and disposal process. It may be a potential threat to the ecology system. Sulfonamide antibiotics(SAs) are a kind of drug which have a broad range of antimicrobial effect. The pathways of SAs entering environmental system include pharmaceutical manufacturing, livestock treatment and medical waste disposal. However, SAs are not removable through the typical sewage treatment plants and can bioaccumulate up the food chains. These facts lead to the detection of SAs in environments around the world, including soil, surface water, sediment, and groundwater system. The sorption behavior of CNTs on SAs may increase the environmental and health risks when exposure to SAs-CNTs composite.The main objectives of this study were to understand the sorption beha vior of SAs to CNTs and sediments, to investigate the impact of CNTs on the mobility of SAs in sediment, and to assess the effect of transportation of SAs associated with CNTs on sediment system. 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 Xiangjiang River were investigated in this study. Results showed that the SAs were of high mobility in sediment columns. However, CNTs with a concentration of 4.8 mg/g in sediment could dramatically retain SAs, which might due to the limited transport of CNTs and their high adsorption capacities of SAs. The percentage of SAs retention in sediment got higher when CNTs existing in inflow, suggesting that a strong CNTs-associated SAs reaction might occur in 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.