Degradation of chlortoluron in water disinfection processes: a kinetic study.
The kinetics of the reaction between chlortoluron, a phenylurea herbicide [N'-(2-hydroxy-4-methyl-5-chlorophenyl)-N,N-dimethylurea], and hypochlorite, the active species in water disinfection processes involving chlorine, were investigated by HPLC-UV and HPLC-electrospray ionisation mass spectrometry (HPLC-ESI-MS). In particular, the concentrations of the main chlortoluron by-products were monitored as a function of time by HPLC-ESI-MS and a kinetic model was developed to fit the relevant curves. The results showed that chlortoluron degradation starts with two parallel pathways, namely, chlorination and hydroxylation of the aromatic ring, which are then followed by consecutive chlorination reactions, and after almost 2 weeks by ring opening and partial mineralisation, as confirmed by head-space solid-phase microextraction gas chromatography-MS (SPME-GC-MS) and total organic carbon (TOC) measurements. Kinetic constants for the first reactions of the overall process, under pseudo-first-order conditions (hypochlorite excess), were estimated by a fitting procedure.
Losito
I
I
Dipartimento di Chimica, Università degli Studi di Bari, Via Orabona 4, 70126 Bari, Italy.
Zambonin
C G
CG
Palmisano
F
F
D002851:Chromatography, High Pressure Liquid; D004202:Disinfectants / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006540:Herbicides / Q000737:chemistry*; D006997:Hypochlorous Acid / Q000737:chemistry*; D007700:Kinetics; D009930:Organic Chemicals; D010671:Phenylurea Compounds / Q000737:chemistry*; D014876:Water Pollution / Q000517:prevention & control; D014881:Water Supply
D004202:Disinfectants; D006540:Herbicides; D009930:Organic Chemicals; D010671:Phenylurea Compounds; D006997:Hypochlorous Acid; C007033:chlortoluron