The interaction "light, Fe(III)" as a tool for pollutant removal in aqueous solution: degradation of alcohol ethoxylates

The photoinduced degradation of an alcohol ethoxylate (AE) (Brij 30) by Fe(III) in aqueous solution has been investigated. The study was carried out with the major fraction of ethoxymers having an alkyl chain length of 12 carbon atoms and n ethoxy units E (C12En) The Fe(III) sensitised degradation of this fraction occurs efficiently at 365 nm. The rate of degradation depends on the concentration of Fe(OH)(2+), the most photoreactive species in terms of (OH)-O-. radical formation. Formate ethoxylates were identified as photoproducts and shortening of the ethoxylated chain all along the degradation process was observed. The mechanism of Brij 30 degradation implies a major (OH)-O-. radicals attack on the polyethoxylated chain. For prolonged irradiations, the total degradation of Brij 30 and of the photoproducts is obtained. Consequently, the degradation photoinduced by iron (III) could be an efficient method of AEs removal in water. (C) 1999 Elsevier Science Ltd. All rights reserved.