Adsorption-desorption of oxytetracycline on marine sediments: Kinetics and influencing factors

Abstract

h i g h l i g h t sOTC sorption on marine sediments were investigated using batch and stirred flow chamber (SFC) experiments. Second order kinetic model successfully described OTC adsorption/desorption kinetics. Adsorption/desorption rate is controlled by diffusive mass transfer process. Solution pH and salinity have large impact on the extent of OTC sorption. A weak hysteresis was observed in OTC adsorption-desorption process. a r t i c l e i n f o b s t r a c tTo reveal the kinetics and mechanisms of antibiotic adsorption/desorption processes, batch and stirred flow chamber (SFC) experiments were carried out with oxytetracycline (OTC) on two marine sediments. The OTC adsorption capacities of the marine sediments were relatively weak and related to their organic carbon (OC) and contents of fine particles. Sorption isotherms of OTC on marine sediment can be well described by both the Langmuir and Freundlich models. Langmuir adsorption maxima (q max ) and Freundlich distribution coefficients (K f ) increased with the decrease of salinity and pH, which indicated the importance of variable charged sites on sediment surfaces. A second order kinetic model successfully described adsorption and desorption kinetics of OTC and well reproduced the concentration change during stop-flow. The adsorption kinetic rates (k a ) for OTC under different experimental conditions ranged from 2.00 Â 10 À4 to 1.97 Â 10 À3 L (mg min) À1 . Results of SFC experiments indicated that diffusive mass transfer was the dominant mechanism of the time-dependent adsorption of OTC and its release from marine sediment was mildly hysteretic. The high desorption percentage (43e75% for LZB and 58 e75% for BHB) implied that binding strength of OTC on two marine sediments was weak. In conclusion, marine sediment characteristics and environmental factors such as salinity, pH, and flow rate are critical factors determine extent of OTC sorption on marine sediment and need to be incorporated in modeling fate and transport of OTC in marine environment.

Bioprocessing for elimination antibiotics and hormones from swine wastewater

“…Additionally, the adsorption of TCs by active sludge could be well explained by Langmuir isotherm model (Li & Zhang, 2016;Mihciokur & Oguz, 2016;Prado et al, 2009a). Li and Zhang (2016) indicated that a pseudo-second-order model could successfully describe adsorption and desorption kinetics of TC and OTC on activated sludge.…”

Kinetic study on the sorption and degradation of antibiotics in the estuarine water: an evaluation based on single and multiple reactions

“…In this case, the cations of CIP enhanced its sorption capacity on the negatively charged sediment particles through electrostatic attraction. The sorption amounts of all the antibiotics on sediment H were slightly (ANOVA; p > 0.05) greater than those on sediment L. This was because sediment with a high organic matter and/or ironaluminum oxides has a stronger sorption capacity for antibiotics (Cao et al 2015;Li and Zhang 2016;Riaz et al 2018).…”

Phosphate affects adsorption and desorption of oxytetracycline in the seawater-sediment systems

“…The sediment samples were placed into a freeze dryer (Songyuan, China) for 4 days to remove all the water. The detail information of marine sediment samples was described previously (Li and Zhang 2016). Briefly, the point of zero charge (PZC) was 9.2 for sediment BHB, and 9.4 for sediment LZB, suggesting a small amount of net positive charge during adsorption/ desorption experiments (pH = 7.7~8.0); the total organic carbon contents in sediment BHB and LZB were 0.48% and 0.15%, respectively; the clay fraction (< 4 μm) in sediment BHB and LZB were 30.7% and 8.5%, respectively.…”