Preliminary Study On Water Environmental Behavior Of Two Quinolone Antibiotics

Quinolone antibiotics are widely used in animal husbandry and aquaculture,and their residual problems in the environment have attracted great attention.Therefore,studying the adsorption,migration and transformation characteristics of antibiotics in the water environment that is great significance for understanding the environmental behavior of antibiotics and effectively removing the pollution risk of antibiotics.In this paper,the adsorption kinetics of two kinds of quinolone antibiotics of Ciprofloxacin?CIP?and Enrofloxacin?ENR?were studied by laboratory simulation experiments.Different temperatures,pH values and soil were analyzed.The difference in adsorption under initial concentration conditions;reveals the effects of different light conditions on the degradation of two antibiotics in lake water and ultrapure water;four typical submerged macrophytes?Ceratophyllum demersum,Hydrilla verticillata,foxtail?Absorption of antibiotics by Myriophyllum verticillatum and Vallisneria natans).Through the research of this paper,the following important conclusions are drawn:?1?The adsorption kinetics study showed that the pseudo-second-kinetic equation can better fit the adsorption process of the two quinolone antibiotics?R²>0.99?,and the adsorption of the two antibiotics by the sediment is mainly chemical adsorption.Under the conditions of 298 k,303 k and 308 k,the Langmuir model can better describe the isothermal adsorption behavior of the two antibiotics.The maximum adsorption capacity Qm of the sediment for CIP and ENR is 16.5933 mg/g,respectively.303 k)and 9.2583mg/g?308 k?,at the same temperature,the sediment adsorption capacity of CIP is greater than ENR.?2?Desorption experiments show that although the sediment shows a stronger adsorption capacity for CIP,CIP is more easily desorbed by Ca²⁺in the water environment.The presence of Ca²⁺in the water environment has a significant effect on the adsorption-desorption behavior of the two quinolone antibiotics in the sediment.In the range of pH 3⁹,the sediment has a good adsorption rate?about 80%?for both antibiotics,and the adsorption rates of CIP and ENR are above 90%at pH=5,The three cations Ca²⁺,Mg²⁺and K⁺inhibited the adsorption of CIP on the sediment;Ca²⁺and Mg²⁺had a certain inhibitory effect on the adsorption of ENR on the sediment,while K⁺showed a weak promotion effect on the adsorption of ENR on the sediment.This study shows that the two quinolone antibiotics have good adsorption in the sediment of Poyang Lake,but considering the presence of Ca²⁺-based constant cations in the water environment of Poyang Lake Basin,the net adsorption of the two antibiotics by sediment.The rate is about40%to 50%.?3?Under the same illumination conditions,the lake water has a certain inhibitory effect on the photodegradation of two quinolone antibiotics.In the ultrapure water-2000 Lx system,the photolysis of the two antibiotics is better,which is 62.41%?CIP?,55.22%?ENR?,the first-order kinetic equation can better fit the photodegradation process of CIP?R²>0.9?,and the K-light of the quasi-kinetic equation is lower than the pseudo-second-order kinetic equation of adsorption experiment.The adsorption rate constant,therefore,in the short-term,in the presence of sediment and light in the environment,the sediment adsorption is dominant.?4?Goldfish,Hydrilla verticillata,Myriophyllum spicatum and Vallisneria have certain removal effects on two kinds of quinolone antibiotics.Among the four submerged plants,the removal rate of CIP was the highest,which was 38.04%.The removal rate of CIP was the lowest,being 24.11%;the removal rate of ENR was 62.31%?Myriophyllum sp.?,40.15%?T.algae?,30.48%?Bitter grass?,and 22.94%?Black algae?.In the water environment where sediment,plants and light are present,CIP and ENR are mainly adsorbed by sediment in the short term.Submerged plants and light have certain removal effects on both quinolones,but the removal rate is relative to Slow adsorption,initial concentration of antibiotics,temperature,intensity of care,type and concentration of cations in water have a certain impact on the fate of the two quinolone antibiotics.