Mn (III) as a new environmentally friendly oxidizing reagent for chemical oxygen determination.

DAFINKA YURCHIEVA ; ANDREA MÜLLER; LORENA VIDAL ; CLAUDIA E. DOMINI ; ANTONIO CANALS

Badajoz

Congreso; 9th Meeting of the European Society of Sonochemistry (ESS); 2004

Chemical oxygen demand (COD) is an important parameter in water-pollution control analysissince it is closely related to the organic contamination level of a water or wastewater sample. Bydefinition, COD is ?a measure of the oxygen equivalent to the organic matter content of a samplethat is susceptible to oxidation by a strong chemical oxidant? (1).The conventional method for COD determination is based on oxidation of the samples with a toxicreagent such as potassium permanganate or potassium dichromate. This standard method is timeconsuming and its accuracy depends on operator skill (2).A newly COD test using Mn (III) to oxidize organic compounds in water without the disposalproblems associated with the other method has been developed. The chemistry behind the Mn (III)is unique and not widely known. However, this method shows some advantages versus the previousmethods (is not photosensitive; is stable at room temperature, and the reagent is an environmentallyfriendly alternative).The objective of this work was to optimise a rapid procedure in order to determine the COD valuein water and wastewater by oxidizing organic compounds with Mn (III) assisted by both microwaveradiation and ultrasound energy (3,4). Hence, the results obtained in this comparative study of threedifferent processes used for sample heating: (i) conventional conductive-convective; (ii) microwaveradiation and; (iii) ultrasound energy will be present. From this study it could be concluded thatmicrowave radiation and ultrasound energy reduce significantly the reaction time (i.e., a fewminutes) and the sample and reagents consumption (more ecological).Keywords: chemical oxygen demand, microwave radiation, ultrasound energy, Mn (III)References1- Cuesta, A., Canals, A. and Todolí, J.L., ?Main parameters and assays involved with the organicpollution of water?, in ?Handbook of water analysis?, Nollet, L.M.L. (ed.), Marcel Dekker Inc.,2000.2- Korenaga, T., Zhou, X., Okada, K. and Moriwake, T., Anal. Chimica Acta, 272, 237-244 (1993).3- Cuesta, A., Todolí, J.L. and Canals, A., Spectrochim. Acta, 51, 1791-1800 (1996).