Study of the aromatic by-products formed from ozonation of anilines in aqueous solution.
Aqueous solutions of aniline and p-chloroaniline were treated with ozone in order to study the reaction and oxidation by-products. Aniline solutions were ozonated at low and high pH, so as to compare both molecular and hydroxyl free radical mechanisms, respectively. The main identified aromatic by-products were nitrobenzene and azobenzene when the experiment was carried out at acid pH. Formation of nitrobenzene, azobenzene, azoxybenzene and 2-pyridine-carboxylic was observed when the ozonation was carried out at basic pH. p-Chloroaniline was treated with ozone only at high pH and the identified by-products were in accordance with those obtained in the ozonation of aniline: p-chloronitrobenzene, 4,4'-dichloroazobenzene and 4-chloro-2-pyridine-carboxylic acid. All the aromatic by-products found were less toxic than the raw materials. The pseudo-first-order constants in aniline concentration were calculated, whilst kinetic in p-chloroaniline concentration could not be adjusted to a first-order reaction.
Sarasa
Judith
J
Department of Chemical Engineering and Environmental Technology, University of Zaragoza, Spain. jsarasa@posta.unizar.es
Cortés
Susana
S
Ormad
Peñia
P
Gracia
Raquel
R
Ovelleiro
José Luis
JL
D000814:Aniline Compounds / Q000737:chemistry*; D002849:Chromatography, Gas; D006841:Hydrocarbons, Aromatic / Q000138:chemical synthesis*; D006863:Hydrogen-Ion Concentration; D010126:Ozone / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D014867:Water / Q000737:chemistry*
D000814:Aniline Compounds; D006841:Hydrocarbons, Aromatic; D012996:Solutions; D014867:Water; D010126:Ozone; C023650:aniline; C004658:4-chloroaniline