Systematic Assessment of the Influence of Hydrogen Peroxide Dosage on Caffeine Degradation by the Photo-Fenton Process

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 con...

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