Effect of carboxyl and hydroxyl groups attached to the benzene ring on the photodegradation of polycyclic aromatic hydrocarbons in ice

The effect of carboxyl and hydroxyl groups attached to the benzene ring on the photodegradation of anthracene (Ant) and pyrene (Pyr) in ice was investigated. The present study aims to explore the inhibition mechanism of five dissolved organic matter (DOM) model compounds' materials such as benzoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, and 3-phenyl propionic acid on the degradation of Ant and Pyr in ice. The photodegradation rate of Ant and Pyr were 50.33 and 37.44% in ice, with the photodegradation rate of Ant being greater than that of Pyr. The five DOM model compounds inhibited the photolysis of Ant and Pyr, and the influence mechanism on the photodegradation of Ant and Pyr depended upon the types and positions of functional groups on the benzene. Among them, the structure in which the carboxyl group was directly connected to the benzene ring and carboxyl was located at the ortho position of a hydroxy group had a strong inhibitory effect on the photodegradation of Ant and Pyr. Light-screening effects and quenching effects were the main inhibiting mechanism, and the binding ability of DOM model compounds material and PAHs is dominantly correlated with its inhibiting effect.