Chiang Mai Journal of Science

 Initial experiments were performed to screen a suitable catalyst for catalytic ozonation of sulfamethoxazole (SMX). Among catalysts investigated such as CeO₂, MnO₂, CeO₂/MnO₂, and GAC. The GAC catalyst was found appropriate for further study because it adsorbed more SMX from solution and gave higher mineralization of water matrix comparatively. Furtherexperiments were conducted to study the effect of initial concentration of SMX/COD, pH of solution, and water matrix types for removal of SMX in O3/GAC combination. Results described that degree of mineralization was higher in dilute solution of SMX (150 mg/L of initial COD value) compared to higher concentrations (250 mg/L, 340 Mg/L of initial COD). The rate of COD removal increased as a function of initial pH of solution but the effect of pH of solution was mineral for pH values > 7. The effect of water matrix types was minimal on removal of SMX. However, rates of removal of COD were slightly higher in case of deionized water compared to lake water and synthetic water matrix. With addition of tert-butyl alcohol in selected runs showed that O3/SMX reactions contributed much more than OH/SMX reactions indecreasing concentration of SMX in solution. The consumption of ozone was increased considerably at high pH values.