A. Lopez et al., DEGRADATION OF HERBICIDES (AMETRYN AND ISOPROTURON) DURING WATER DISINFECTION BY MEANS OF 2 OXIDANTS (HYPOCHLORITE AND CHLORINE DIOXIDE), Water science and technology, 35(4), 1997, pp. 129-136
Citations number
18
Categorie Soggetti
Water Resources","Environmental Sciences","Engineering, Civil
The paper reports the results of an investigation aimed to find out th
e number and the chemical structures of byproducts which form during t
he reactions occurring in aqueous solution between two very common dis
infectants, sodium hypochlorite (NaClO) and chlorine dioxide (ClO2), a
nd two herbicides widely used in agriculture and frequently found in g
roundwaters: ametryn and isoproturon. Under controlled experimental co
nditions [T=20 degrees C, pH=7, reaction-time = 48h, herbicide/disinfe
ctant molar ratios: 0.05 and 0.05x10(-2)], ametryn reactions with chlo
rine dioxide much slower than with sodium hypochlorite, whereas the op
posite trend has been observed for isoproturon. In any case, however,
the higher the reagents concentration the faster the reactions. As for
reaction byproducts, they have been detected by HPLC and identified b
y HPLC-MS. In particular, ametryn (R-S-CH3) reaction with NaClO gives
rise to the consecutive formation of four derivatives: the sulphoxide
(R-SO-CH3), the sulphone (R-SO2-CH3), the sulphonate ester (R-O-SO2-CH
3) and its hydrolysis product (R-OH). Within the fixed reaction time (
48h), ametryn reaction with ClO2 forms only the sulphoxide derivative
(R-SO-CH3). As for isoproturon, it reacts with both oxidants forming a
romatic-ring substituted derivatives. In particular, during the reacti
ons with NaClO and ClO2, four and two (chlorinated and/or hydroxylated
) derivatives are respectively formed. (C) 1997 IAWQ. Published by Els
evier Science Ltd.