臭氧及臭氧/紫外光對Mefenamic acid去除影響之研究

Abstract

Mefenamic acid (MEF) is a widely used anti-inflammatory drug. MEF is a diphenylamine derivative pollutant (DPA) which is the third compound in the European Union list of priority pollutants, because of its harmful properties with numeral toxic derivatives being observed in the aquatic environment. Many investigations have revealed that MEF can not be completely removed by conventional sewage treatment plants (STP) and was detected in STP effluents at trace levels. Therefore, the presence of MEF in the aquatic environment should be assessed critically. The objective of this study was to evaluate the removal of MEF using ozonation and O3/UV processes. The effect of various operating parameters including ozone dose, pH, light intensity (UV), alkalinity, and humic acid on the removal of MEF in ozonation and O3/UV processes was investigated. In addition, the formation of ozonation by-products was also studied. Meanwhile, a simplified model based on MEF decomposition was developed to determine the reaction rate constants of MEF and to interpret the degradation of MEF. Finally, a response surface method was used to evaluate the effect of operation parameters on the degradation efficiency of MEF by ozonation and O3/UV processes. The results show that ozonation and O3/UV processes were efficient in degrading MEF. In both processes, increase of ozone dosage and decrease of pH enhanced MEF removal. The presence of humic acid can reduce MEF removal also. The MEF degradation model can predict the MEF degradation well. The reaction rate constants of MEF can be determined in a second order reaction. In addition, the aldehyde concentration increased with increasing pH in the ozonation process, which indicated the involvement of hydroxyl radical in aldehyde formation. By using the response surface method, it was found that MEF degradation was sensitive to factors such as ozone concentration, pH, reaction time, and humic acid concentration.