Manganese oxides are minerals widely distributed in the environment due to the several microorganisms that can synthesize them. These minerals are between the most powerful natural oxidants, which achieve the oxidation of organic matter and humic acids. Even different researches have shown that chemical degradation of organic pollutants is possible by oxidation using manganese dioxides. The presence of organic pollutants in environment due to its indiscriminate use represent a serious problem worldwide because their accumulation in soil and water implies a potential risk to human health and wildlife. Among these organic pollutants, broad-spectrum and non-selective systemic herbicides, such as picloram [4-Amino-3,5,6-trichloro-2-pyridinecarboxylic acid] and 2,4-D [2,4-Dichlorophenoxyacetic acid], are some of the most used pesticides in Mexico to prevent the growth of undesirable weed on the cultures. That is why these compounds are the pollutants most found in waters environment and even in urban environments along nationwide. Previous studies demonstrated that manganese oxides can promote the oxidation of 2,4-D and two degradation products were identified, 2,4-dichlorophenol and CO2. On the other hand, degradation of picloram by another oxides, such as TiO2, has been reported but there is not a clear identification neither of by-products formed as a result of this interaction or oxidation through manganese oxides. The main goals of the current study are to evaluate the oxidation performance of 2,4-D and picloram by manganese dioxide and to identify formally the nature of the by-products formed during the degradation of these herbicides. To achieve that, interaction experiments were carried out both in methanol and in aqueous media. After that, degradation ratio is determined by HPLC-UV analyze and soluble manganese is obtained by ICP-OES. Moreover, structural techniques are being carried out to suggest a possible oxidation mechanism.

Assessment of the interactions of herbicides with manganese dioxide to evaluate its availability as a possible remediation process

253rd National Meeting (2017)

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