A. Lopez et al., Formation of volatile halogenated by-products during chlorination of isoproturon aqueous solutions, CHEMOSPHERE, 45(3), 2001, pp. 269-274
The present paper deals with the formation of volatile halogenated by-produ
cts (POX) during the chlorination (160 mg/l) of aqueous solutions of the he
rbicide isoproturon (40 mg/l). Chlorination reactions have been carried out
over 48 h, at ambient temperature, at two pHs (6 and 9) and in the presenc
e or not of bromide ions (80 mg/l). The main results obtained have been as
follows: (1) in the presence of bromide, isoproturon degradation is rather
fast and it results affected by pH, complete isoproturon degradation is ach
ieved within 1 and 15 min at pH 6 and 9, respectively; (2) in the absence o
f bromide herbicide degradation is slow (complete degradation is achieved w
ithin 180 min) and it is not affected by pH; (3) at pH 6, regardless of the
presence of bromide, the maximum amount of POX formed is low (similar to 1
5 mu mol X-/l) and remains constant during the reaction; (4) at pH 9 the am
ount of POX formed is far greater and continuously increases during the rea
ction, reaching a value of about 110 mu mol X-/l after 48 h; (5) two differ
ent groups of by-products have been identified by solid phase micro extract
ion (SPME)-gas chromatography (GC)-mass spectrometry (MS) for the reactions
carried out with or without bromide; among them, aliphatic as well as arom
atic byproducts containing chlorine, bromine or both halogens are present e
ven though the most abundant are halogenated-methane derivatives (haloforms
); pH value affects the amount of these by-products but does not modify the
ir chemical nature. (C) 2001 Elsevier Science Ltd. All rights reserved.