Synergistic Effect On Degradation Of The Herbicide Diuron By Low Temperature Plasma And Activated Carbon Fiber

Diuron is a commonly used phenylurea herbicide,which have stable chemical property and is difficult to deal with.Pulluented by diuron,the farmland drainage and manufacturers drain easily polluted rivers and lakes or even the source of water,and cause human body,animals health hazard and environmental pollution.The processing method for water diuron mainly include:adsorption,microbiological method and advanced oxidation technology.And in the advanced research oxidation technology,the electrochemical and photocatalytic method is the most studied.Treatment of low temperature plasma discharge diuron solution alone,by changing the reaction parameters to find the optimum reaction conditions,the output power is bigger,plasma electrode is thicker;the air velocity is greater;diuron removal effect is better;and the diuron degradation of quartz glass is higher than ordinary glass;the adding of Fe2+ can improve the removal rate of diuron;when pH=6 the treatment has the best effect;the determination of time of about 24h can ensure the stability and accuracy of determination results,conforms to the first-order reaction kinetic equation.In the reaction process,the pH value is gradually reduced;the degradation rate of TOC increased gradually,but lower than the rate of diuron degradation,that is only a part of the removal of diuron mineralized.The final selection of the optimum reaction conditions were:the diuron solution is 200mL,output power is 60W,the quartz glass,the discharge space is 2.5mm,air flow rate is set to 0.15m3/h,activated carbon fiber dosage is 0.3g.The experiments on adsorption of diuron by activated carbon fiber separate found that:the activated carbon fiber dosage is bigger,the air velocity is larger,the better the effect of removal of diuron;the micro activated carbon fiber has good structure,through SEM and TEM photos;and in the replicated adsorption experiment of activated carbon fiber,can found that with increasing repeat times,adsorption decreased gradually,and in fifth repeated times,adsorbent extent is only 52.2%.Low temperature plasma and activated carbon fiber combined treatment showed good synergistic effect,and the reaction of 5min diuron degradation rate reached 90%.The degradation effect is better than that of activated carbon fiber adsorption of diuron alone,more than that of diuron treated by low temperature plasma discharge.When PH=6,the degradation is the best;the emoval rate of TOC is 75%;characteristics of degradation of diuron conforms to apparent first-order reaction kinetics.Though the physical characterization and chemical characterization of activated carbon fiber,can find the mechanism of synergistic effect existed:after the synergistic reaction,there are more specific surface area,more microporous in the characterization of activated carbon fibers,and the number of surface acidic functional groups also increased to make it have the better adsorption and catalytic properties.In the synergistic reaction,the surface of active carbon fiber for diuron degradation center,here can produce a large number of active substances,to react directly with diuron,in situ regeneration,and the internal and external of activated carbon fiber as high concentration organic solution transport to the surface vacancy,moving in circles.