Dynamic And Static Quenching Of Ofloxacin By Dissolved Organic Matter

The environmental behavior and risk assessment of antibiotics processes have received widespread attention, a new type of organic pollutants in the environment. Environmental behavior of antibiotics and their potential risks depend on different processes by which the antibiotics enter the environment. Different processes depend on varied media. Dissolved Organic Matter (DOM) is a kind of macromolecular organic matter that could be dissolved in water. DOM serves as a special carrier of environmental pollutants due to its mobility. To provide reliable theoretical support for the environmental behavior and risk assessment of antibiotics, we focus on the interaction of antibiotics-DOM. Thus, common used antibiotics-Ofloxacin (OFL) and DOM from sediment of Dianchi Lake were selected to examine their interaction through fluorescence property and fluorescence quenching approach. At the same time, the method could be supplement for fluorescence quenching method. We finished kinetic experiment of OFL-DOM at different temperatures, isotherm of OFL-DOM with dialysis membrane equilibrium system, relative characterization and complementary experiments successfully distinguished. Dynamic and static quenching at different temperature were.Experimental results indicated that:1. It is feasible that the kinetic study of the fluorescence quenching method can helpful to understand the OFL-DOM interaction. For the fluorescence quenching method, the inner filter effect (IFE) has become the focus of discussion because it is a key factor in quantifying the interaction. We discussed the IFE factor from potassium bromide (KBr) and phenanthrene(PHE) quenching system and found that the factor by calculation and experiment could prove the reliability of IFE correction very well.2. Pseudo first order two-compartment kinetic model (PFOM-2) could well fit kinetic curve of OFL-DOM at different temperature. We selected different models:Pseudo first-order one-compartment kinetic model (PFOM-1), PFOM-2, Pseudo second-order one-compartment kinetic model (PSOM-1), Pseudo second-order two-compartment kinetic model (PSOM-2). Error distribution of mentioned models indicated PFOM-2was the best model and this fitting could provide for kinetic study of OFL-DOM.3. We discussed parameters of PFOM-2—q1=qo+q1*(1-e-k1-1)+q2*(1-e-k2-t) in our experiment. The parameters varied with temperature, and according to theory of fluorescence quenching, could be used to identify dynamic and static quenching quantities. Fluorescence quenching was proved to be feasible in our study verified by traditional method—dialysis membrane equilibrium system. Both methods produced concordant results indicating reliability of the fluorescence quenching.4. Method static and dynamic quenching were compared based on associated method parameters. Relative contribution of dynamic quenching was in the range of30%～90% under experiment condition.5. For static quenching, we observed two different processes, one was fast and the other was slow. Thus, we supposed that fast process may caused by surface function groups of OFL and DOM. The slower may be affected by hydrophobic area of DOM.6. FTIR spectra of DOM, OFL and DOM-OFL proved the interaction between OFL and surface function groups of DOM. Spectroscopy equipment can be helpful with qualitative and visual analysis when studying interaction between pollutants and DOM to facilitate the understanding of mechanism itself and the studying of DOM conformation.7.The interaction between DOM and pyrene, phenanthrene by fluorescence quenching equilibrium experiment, indicated that organic content could be an important factor of their interaction mechanism.