Reactions of NSAIDs (Mefenamic Acid and Diclofenac) by O3/GAC Processes---Intermediates, Pathway and Kinetic Models

Mefenamic acid and diclofenac are the common non-steroidal anti-inflamamatory drugs (NSAIDs), within the pollutant class known as pharmaceuticals and personal care products (PPCPs). The globally consumed volume of diclofenac is estimated to be 940 tons per year, 877 tons of diclofenac was sold in 2007 in 76 major countries with IMS Health data, including Taiwan. Diclofenac is a diphenylamine derivative and therefore structurally related to mefenamic acid. In the aquatic environment, i.e., river and surface waters, diclofenac is one of the most frequently detected pharmaceuticals. Microorganisms that usually comprise the biofilms which were inhibited by diclofenac at the concentration levels of 100 μg L-1. In livers, kidneys, and gills of rainbow trout, cytopathology occurs at 1 μg L-1. Recently, several investigations on the removal of diclofenac or mefenamic acid from contaminated water by means of advanced oxidation processes were revealed. Ozonation was very effective in eliminating polar compounds, however, potentially toxic species may be generated due to the incomplete degradation of organic pollutants in the course of oxidation process. In the literatures, there was limited information to discuss the removal of oxidizing-intermediate of NSAIDs. Therefore, the objective of the research work will utilize the ozone/GAC processes to NSIDs (Mefenamic acid and Diclofenac) contaminants oxidize/decompose, and adsorb. Moreover, the determination of the ozonation intermediates of Mefenamic acid and Diclofenac compounds, pathway and kinetic models are the key task forces to develop the best available treatment processes (BAT), i.e., O3 /GAC process.