Study On Degradation Of Typical Anticancer Drug5-fluorouracil By Fenton And Photo-fenton Processes

It is urgent and necessary to develop effective methods to remove the residualpharmaceuticals in aquatic environment, due to their potential ecological risk. The degradation ofa typical anti-cancer drug5-fluorouracil (5-FU) in simulated wastewater by Fenton,oxalic-Fenton and photo-Fenton processes were investigated in this paper. The effect of Fentonreagent dosage, initial pH, reaction time, organic matters and light conditions were evaluated, theoptimum condition and reaction kinetics were determined via factor experiments. The mainresearch results are as follows:(1) Under the optimal conditions of initial pH of3, Fe2+dosage of5mg·L-1, H2O2/Fe2+molar ratio of2:1,87%5-FU (1mg·L-1) degradation can be achieved after30min by Fentonprocess. The degradation of5-FU by Fenton process showed an initial rapid phase (0-2min) andsubsequent retard phase, and the degradation kinetic fitted the combined first-order kineticmodel.(2) Results showed that the degradation rate of5-FU (1mg·L-1) reached more than90%caused by oxalic-Fenton process, on the optimal conditions of initial pH of2~5, Fe2+dosage of5mg·L-1, H2O2/Fe2+molar ratio of2:1, oxalic dosage of5mg·L-1and reaction time of30min.The degradation of5-FU by oxalic-Fenton process also showed an initial rapid phase (0-2min)and subsequent retard phase, and the degradation kinetic fitted the combined first-order kineticmodel. The removal rate of5-FU by oxalic-Fenton process is higher than Fenton process. Inoxalic-Fenton process, applicable pH range (2-6) was obviously broader than that for Fentonprocess (2-4). Because in oxalic-Fenton system, the addition of oxalate improved the solubility，reactivity and catalytic efficiency of Fe2+, as a result improved5-FU removal efficiency, andexpanded the demanded pH range in the reaction.(3) The degradation of5-FU by photo-Fenton process based on the preliminary experimentsof H2O2、UV、UV/H2O2process. Different treatments employed on5-FU degradation werecompared, H2O2alone or UV alone can hardly caused5-FU degradation. The results showed thatthe degradation rate of5-FU (1mg·L-1) reached96.53%caused by oxalic-Fenton process, on theoptimal conditions of initial pH of4, H2O2dosage of50mmol·L-1, and reaction time of120minby illuminating of a500W mercury lamp. The increase of lamp power contributed to improveddegradation effect of5-FU through light-Fenton process to some extent, the degradationefficiency order of different light sources was: Visible Light <sunlight <UV. The degradationrate of5-FU (1mg·L-1) reached100%caused by UV-Fenton process, on the optimal conditions ofinitial pH of3, Fe2+dosage of3.75mg·L-1, H2O2/Fe2+molar ratio of2:1, and reaction time of30min by illuminating of a500W mercury lamp, and the degradation kinetic of5-FU by UV/H2O2and light-Fenton processes both follows first order kinetic model. The degradation efficiency of5-FU wastewater improves obviously by UV-Fenton process than by ordinary Fenton, and UV-Fenton process economize more dosages of H2O2and Fe2+by full utilization of H2O2。...