Process Comparison for Caffeine Degradation: Fenton, Photo-Fenton, UV/H2O2 and UV/Fe3+

The fenton, photo-fenton, UV/H2O2 and UV/Fe3+ processes were applied as advanced oxidative treatments in the degradation of caffeine. Parameters such as pH, initial reagent concentration and artificial and natural radiation were evaluated. The tests carried out indicated that the photo-fenton process studied here had its best performance at pH ~ 4.4; however, at pH without adjustment and near to neutral (~ 6.1), the result was also satisfactory at the end of the reaction (~ 51%). The degradation of caffeine, under the conditions studied with artificial radiation, was superior to natural radiation. In addition, it was found that H2O2 was the reagent that most influenced the experimental results obtained, and when studied separately, it was noted that natural pH conditions present excellent results of caffeine degradation. Comparing the artificial radiation used (125 and 250 W), there was no significant influence on the degradation of caffeine. Other parameters analyzed for both the photo-fenton reaction and the UV/H2O2 reaction were the aquatic matrix and, for comparison, the degradation of another emerging pollutant, ibuprofen. In general, the results obtained showed that the UV/H2O2 reaction is promising in the degradation of pollutants such as caffeine.