Kinetic and analytical study of the photo-induced degradation of monuron by nitrates and nitrites under irradiation or in the dark.
The photo-induced transformation of monuron (3-(4-chlorophenyl)-1,1 dimethylurea) was investigated in an aqueous solution containing nitrates and nitrites at 310 nm and 365 nm, respectively. In both NO(3)(-) and NO(2)(-) conditions, the degradation of monuron followed pseudo-first order kinetics. The intermediate products were identified by GC-MS, and the nitration, hydroxylation and coupling reactions were determined. In addition, the oxidation of the N-terminus group, the substitution of chlorine by ˙OH and the nitration by ˙NO(2) radical onto the phenyl ring were observed. The photo-induced transformation of monuron was studied under variable conditions of pH, inducer concentration, substrate concentration, humic acids, oxygen content and salts used as hydroxyl radical scavengers. The photodegradation rates were strongly influenced by all the above parameters. The degradation of monuron was also studied in the dark and in the presence of NO(2)(-) as well as in an aqueous solution with the addition of hydrogen peroxide.
Laboratory of Sciences and Technology of the Environment, University Mentouri, 25000 Constantine, Algeria. boucheloukhh@yahoo.fr
Hadjira
H
Boucheloukh
Tahar
T
Sehili
Nadia
N
Kouachi
Kamel
K
Djebbar
D003624:Darkness; D016166:Free Radical Scavengers / Q000737:chemistry; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008782:Methylurea Compounds / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D009573:Nitrites / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010782:Photolysis
D016166:Free Radical Scavengers; D006812:Humic Substances; D008782:Methylurea Compounds; D009566:Nitrates; D009573:Nitrites; D017665:Hydroxyl Radical; C100088:monuron; D010100:Oxygen