ASSESSING THE FATE OF ORGANIC CONTAMINANTS IN AQUATIC ENVIRONMENTS - MECHANISM AND KINETICS OF HYDROLYSIS OF A CARBOXYLIC ESTER

The processes that govern the distribution and fate of organic compoun ds in aquatic environments include transport phenomena as well as biol ogical and abiotic transformations. To assess the behavior afa chemica l under certain environmental conditions, it is necessary to collect b oth compound-specific (e.g., pK(a)) and system-specific (e.g., pH) pro perties. The data required today by many authorities for the approval of new compounds include information about the persistence of these ch emicals in aquatic environments. One of the important transformation p rocesses to be considered is hydrolysis-that is, the reaction of the c ompound with water Hydrolysis and the kinetics of transformations of o rganic compounds have been dealt with in only a small number of recent papers in this Journal (1-4), and their focus has been very different . In this paper, we propose an integrated experiment that was develope d for an upper-level undergraduate environmental chemistry laboratory It has been carried out successfully during several one-week laborator y courses in aquatic chemistry given for students of environmental sci ences and engineering in their second or third year at university. Req uiring relatively simple equipment and using an environmentally signif icant reaction as an example, the experiment serves mainly 3 purposes: (i) to introduce and apply the basic concepts of chemical kinetics an d mechanisms of hydrolysis, (ii) to illustrate what it means to genera te reliable kinetic reaction parameters, and (iii) to acquaint student s with the practical aspects of some important analytical methods (liq uid chromatography, UV-vis spectroscopy, pH measurement). If HPLC equi pment is not available, the lab course could still be offered (followi ng the original method [5] using a UV-vis photometer only).