Synthetic solutions of phenol, o-, m-and p-cresol were oxidised by using Fenton's reagent. The application of substoichiometric dosage of H 2 O 2 led to the formation of intermediate compounds, continuing later the oxidation to complete oxidation. An important objective was to analyze the effect of hydrogen peroxide dosage applied and the reaction pH together with the iron oxidation state on the degradation level. A kinetic model was derived from a reaction mechanism postulated which was used to analyze the results of the experiments. Another aim was to analyze the hydrogen peroxide consumption. Noteworthy results include an increase in oxidant consumption to intensify phenol removal. Furthermore, oxidant consumption was analyzed through the ratio H 2 O 2 to phenol removed and the average specific rate of removal (ASRR). By analyzing these two parameters it has been possible to ascertain the most favorable strategy for an efficient application of H 2 O 2 .

The characterization of radical oxidation was studied in phenolic compounds degradation by a H

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This study investigates the environmental quality of water treatments by evaluating the effectiveness of advanced oxidation technologies, such as H2O2/Fe(II) and H2O2/UV, in treating phenol-contaminated effluents. Toxicity measurements complement the chemical analyses used to evaluate the environmental quality of a treated effluent and are an additional method for interpreting the effects of chemicals not directly measured. This study proposes an estimation model for toxicity based on the Microtox test that is adaptable to the contaminant concentration of each case. The model allows for analysis of the contribution of the different components of the treated effluent: hydrogen peroxide, phenolics, colored compounds, and others. In the second part of this work, a study was conducted of the toxicity of samples treated with the aforementioned oxidative systems. In the Fenton system, the sample after oxidation was analyzed, and it was observed that the toxicity was due to intermediate oxidation compounds, such as carboxylic acids, which rejects the influence of compounds of color and other phenolics. The H2O2/UV system tracks the progress of toxicity. This parameter quickly reaches minimum values (within about 15 min) from the start of the reaction and is a representation of the final values of primary degradation. Therefore, it is not recommended to extend the oxidation beyond this point to minimize the toxicity.

Synthetic dyes are extensively used in textile dyeing, paper printing, colour photography, pharmaceuticals, food, cosmetics and other industries. In spite of their diversity there are a certain number of properties common to many dye compounds, such as aromatic constitution, chromophore groups and others. Similarly to other dyes and due to the formation of colour intermediates, in the case of Rhodamine 6G colour capacity is maintained in the initial steps of dye degradation. For this reason in the degradation of a dye it is necessary to distinguish between two processes that take place simultaneously: dye removal and decolourization. This study was conducted by using a water solution of 50 mg/L of Rhodamine 6G (Rh-6G), as a model of a dye wastewater, in the hydrogen peroxide/UV system. The kinetic model proposed in this paper for the removing of Rh- 6G is a sequential first-order reaction. This model describes acceptably the changes in two kinds of compound for a wide interval of H