TiO2 광촉매 공정을 이용한 Enrofloxacin의 분해 특성

Abstract

Photocatalytic degradation characteristics of enrofloxacin, which is one offluoroquinolones widely used in humans and veterinary medicines, using UVreactor with installed TiO2-coated screw type sheet, were investigated. TheUV reactor was also equipped with 4 ozone UV lamps (UV254+185 nm), takingthe light intensity of 63 ㎼/㎠ for each lamp, In addition, effects ofindependent variables affecting photocatalytic degradation of enrofloxacin andoptimal conditions for its removal were also studied, using response surfacemethodology (RSM).Removal efficiencies of enrofloxacin were increased with the increase oflight intensity in the range of 63 ～ 252 ㎼/㎠, and were similar in theconcentrations of 1 ～ 10 mg/L, but decreased greatly at 20 mg/L in theeffect of initial enrofloxacin concentrations. They decreased in the order of pH7 > pH 5 > pH 9 in the effect of pH, decreased with increasing NaClconcentrations in the range of 10 ～ 30 ‰ in the effect of NaClconcentrations, and increased with increasing up to 25 mM, but decreased at50 mM in the effect of H2O2 concentrations.The RSM-central composite design was applied as the method of statisticalanalysis through experiments, and the major independent variables applied fortreated concentration and removal efficiency of enrofloxacin, were UVintensity (㎼/㎠), initial concentration (mg/L), H2O2 concentration added(mg/L), and reaction time (min). With the results of multiple regressionanalysis, the difference in confidence intervals in which each independentvariable depends on the experimental value and predicted value for treatedconcentration and removal efficiency of enrofloxacin, with high correlation ofdetermination coefficient 96.2% and 89.7%, respectively, indicating thatphotocatalytic reaction used in this study directly affected its removalefficiency and independent variable was affected each other.When drwing a contour plot between variables and response, UV lightintensity of 126 ㎼/㎠, initial enrofloxacin concentration of 10 mg/L, reactiontime of 120 min and concentration of H2O2 concentration of 25 mM were setto a fixed value and the remaining variables were analyzed. The removalefficiencies of 99% were obtained under the conditions of UV light intensityof above 200 ㎼/㎠, lower enrofloxacin concentration, reaction time of above120 min, and H2O2 concentration of 25 mM, through the interaction ofindependent variable with all fixed values. For H2O2 concentration added, itsremoval efficiency was increased up to 25 mM, but decreased above 25 mM.Finally, a satisfactory operating parameters were derived from photocatalyticdecomposition process used in this study using response optimization in RSM.From this results, optimal removal efficiency of above 94% could be obtainedunder the conditions of UV light intensity of above 200 ㎼/㎠, reaction timeof 165 min, H2O2 concentration of 10 mM, when operating at initialconcentration of 10 mg/L.