Abstract

POZNYAK, Tatyana; TAPIA, Rocío; VIVERO, Juan  and  CHAIREZ, Isaac. Effect of pH to the Decomposition of Aqueous Phenols Mixture by Ozone. J. Mex. Chem. Soc [online]. 2006, vol.50, n.1, pp.28-35. ISSN 1870-249X.

The degradation of the mixture of phenol and its chlorinated derivatives with ozone is studied. The studied compounds are phenol (Ph), 4 - chlorophenol (4-CPh) and 2,4 - dichlorophenol (2,4-DCPh). The kinetic performances of each phenolic compound in the model mixture are examined. The pH influence to the decomposition dynamics for different phenolic compounds in the range 2 - 12 is investigated. The increase of the decomposition rate under the pH increasing was observed. In the studied pH range, phenol and chlorophenols ozonation proceeds rapidly. The UV absorvency is used for the preliminary control of the phenols decomposition degree. The HPLC analysis was used to identify intermediates and final products formed during ozonation of the phenols mixture. It is shown that the basic intermediates are muconic and fumaric acids, malonic and maleic acids, catechol and hydroquinone. The final products are oxalic acid and formic acid. In the case of alkaline media, the principal final product is oxalic acid. Furthermore, intermediates and final decomposition products obtained at the different pH are compared. According to the obtained results, the possible mechanism of ozonation by the reaction of hydroxylation and dechloration in the early stage is proposed. The BOD₅/COD ratio is used as a biodegradability measure for the comparison of biodegradability of initial compounds and final products composition.

Keywords : ozonation; water; phenols; decomposition; pH.

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