Study On The Photodegradation Of Ciprofloxacin In Water

As a fluoroquinolone antibiotic, ciprofloxacin which is widely applied in medical, animal husbandry, agriculture and aquaculture can enter the aquatic environment through variety of ways. Ciprofloxacin which exit in the environment would damage the health of human body and ecological ,because it not only can be toxic to the central nervous system, liver , kidney, and hematologic system of human body, but also have bacterial resistance. So its environmental behavior already arouse people's more and more attention. In surface waters, photochemical degradation is the main factor in determining the fate of organic matter. This present study the effect of photodegradation of ciprofloxacin when add the different compounds which simulate the environment.After established the analysis method of ciprofloxacin in water, we studied the infection in the dark or under 500W Xenon light. The research results show that: no photodegradation occurred in the dark and the photolysis of ciprofloxacin followed first-order kinetics under the light. With increase of initial concentration of ciprofloxacin, the photo-degradation rate of ciprofloxacin decreased gradually.We also studied the different influences on photo-degradation of ciprofloxacin in different dissolved oxygen levels, the different concentrations of nitrate, nitrite, ammonium ions, and different pE values when these three forms of N elements coexisted. The result showed that nitrate promoted the degradation of ciprofloxacin, nitrite inhibited it and ammonium had little effect. the influence of the dissolved oxygen levels to the photo-degradation of ciprofloxacin is the same with that of nitrate. The photodegradation rate of ciprofloxacin decreased and then increased follow with the increase of pE value. When nitrate coexisted with ammonium, they wouldn't affect each other. When nitrite coexisted with nitrate, the degradation rate was less than theoretical value. It indicated that nitrite inhibited the photo-degradation of ciprofloxacin by nitrate.At the same time, we study the affect of photodegradation by the factor which we simulated the nature water , such as pH, humic acid, Cl^- and so on. The result showed that with increase of pH among the 5-8, the photodegradation rate of ciprofloxacin decreased gradually. Cl- promoted the degradation of ciprofloxacin, Zn²⁺, Cu²⁺ and HA inhibited it and both CTAB and Tween-80 had little effect. Fe³⁺ and SDBS promoted the degradation in low concentrations, and in high concentrations inhibited it.