Enhanced photo-Fenton process for tetracycline degradation using efficient hydrogen peroxide dosage

• Tetracycline in water solutions is shown to be totally degraded via photo-Fenton treatment.
• Subject to dosage, a H2O2 load can mineralize a tetracycline solution to different extents.
• H2O2 dosage is modeled via two parameters, upon which a design of experiments is proposed.
• Design of experiments dosage conditions yield mineralization rates ranging from 77% to almost 100%.
• If conveniently dosed, stoichiometric H2O2 loads can achieve total mineralization.

The remediation of water solutions containing tetracycline antibiotic (TC) using photo-Fenton treatments has received scarce attention in the literature. However TC deserves attention due to its condition of emerging contaminant. In this work, TC oxidation in water solutions (12 L, 40 mg L−1) by means of photo-Fenton reaction under variable hydrogen peroxide dosage is investigated. This shows a more efficient use of the hydroxyl radicals produced in the reaction medium and enhances treatment performance. First, a suitable range of Fenton reagent loads is determined in a preliminary study. The hydrogen peroxide dosage is parameterized through two variables: the initial release of the total load, y0 (kick-off), and the time tini at which the continuous dosage of the rest of the load starts. Hence, a design of experiments (22) can be used to characterize the performance of the process under different hydrogen peroxide dosage protocols. The results obtained this way show that total TC remediation is attained in all the cases studied, but alike amounts of hydrogen peroxide lead to total mineralization only when the dosage scheme is conveniently tuned. Therefore, the photo-Fenton treatment has proved to be effective in removing TC from water solutions, and the opportunity for an efficient dosage to reduce the requirements of hydrogen peroxide has also been confirmed.

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