Caffeine degradation performance via photo-Fenton treatment was investigated under different dosage conditions. Experiments were planned according to a design of experiments to characterize hydrogen peroxide dosage protocols. Fenton reagent loads were first determined after a preliminary study. The addition of a fixed hydrogen peroxide load was controlled by an initial load fraction and the span of the continuous flow producing the total load. The experiments were carried out using 12 L solution samples of commercial coffee (300 mg L −1 , approximately 17 mg L −1 of caffeine). Hence, HPLC data revealed that all treatments completely removed caffeine from samples, while TOC monitoring revealed reductions of up to 70%. Using reaction conversion as a performance index, the methodological approach presented enabled a comparison of dosage protocols and determination of those producing enhanced results. For the particular case addressed, the operation scheme that most increased treatment performance produced a conversion which was 25% higher than that obtained without dosage.

No abstract

An experimental study of the homogeneous Fenton and photo-Fenton degradation of 4-amidophenol

No abstract

Despite being acknowledged as an emerging contaminant, sulphamethazine (SMT) degradation has received scarce attention in the advanced oxidation processes field. Thus, this work addresses the degradation of SMT in water solutions (12 L of 25mgL-1 samples) by means of a photo-Fenton process and a systematic H202 dosage protocol that enhances its performance. A conventional photo-Fenton process led to 86% mineralization after 120 min treatment when adding the Fenton reactants at once (initial concentrations were 10mgL-1 Fe(II) and 200mgL-1 H2O2). Conversely, the process achieved the total mineralization of the samples in less than 75 min when the same amount of H202 was continuously dosed according to a conveniently tuned dosage protocol. In both cases, total SMT degradation was achieved within 10 min. Hence, this work's aim is to determine the efficient dosage conditions of H2O2. The results show that a significant improvement of the photo-Fenton mineralization of SMT solutions is possible by adjusting the dosage of H2O2.