Influence of Changes in OM Content and Form on the Adsorption of Two Typical Antibiotics to SPM

Abstract

Abstract Antibiotics are commonly detected in natural waters. Suspended particulate matter (SPM) in surface water has a good adsorption capacity for antibiotics, and the organic matter (OM) in SPM is the key factor for this adsorption. We investigated the contribution of OM content and form to the adsorption of tetracycline (TC) and norfloxacin (NOR) in the SPM of Taihu Lake. To change the content and form of OM in SPM, we burned it at 505 ℃ and oxidised it with H2O2, respectively. The OM in the sample that was combusted (expressed as SPM-505 ℃) was almost entirely eliminated, and the adsorption amount of TC decreased by 14.8% when compared to the original sample, while the adsorption amount of NOR decreased by 64.8%, indicating that OM content contributes to the adsorption of antibiotics. Although the OM content in the oxidised sample (expressed as SPM-H2O2) decreased, the adsorption amounts of TC and NOR increased by 31.7% and 2.8%, respectively, compared with the original sample. The infrared spectrum and elemental analysis results showed that the morphology of the OM changed, suggesting that the structure of the OM contributes substantially to the adsorption of antibiotics. The contribution of OM to NOR adsorption was greater than that of TC. In conclusion, the results verify the importance of OM in adsorbing antibiotics onto SPM, which may provide basic data for antibiotic migration in surface water.