OXIDATION OF SULFUR-CONTAINING S-TRIAZINES DURING GROUNDWATER HYPOCHLORINATION

With the aim to identify the reaction by-products, the oxidation of fo ur sulfur-containing s-trazines (prometryne, terbutryne, ametryne and desmetryne) by sodium hypochlorite (NaClO) has been investigated using oxidant and herbicides initial concentrations respectively of 11 ppm and 3 ppm. Furthermore, to study the effect of reagent concentration o n the oxidation rate, only for prometryne, the reaction has been carri ed out at two more oxidant and herbicide initial concentrations (ppm): 3 and 0.003, 0.011 and 0.003. Oxidation reactions were monitored by h igh performance liquid chromatography (HPLC), while the identification of by-products was at first carried out by HPLC-mass spectrometry (HP LC-MS) and then confirmed by accurate mass measurements. The results i ndicate that all the investigated triazines react in the same way. In the experimental conditions (T = 20-degrees-C, pH = 8, reaction time = 48 h) the reaction gives rise to three identified oxidation by-produc ts: the sulfoxide, the sulfone and the sulfone's hydrolysis product. A s expected, the lower the reagent's concentration the slower the oxida tion rate. Based on the obtained results, a general pathway for the ox idation of sulfur-containing s-triazines is proposed.