[Photodegradation of paracetamol in nitrate solution].

The photodegradation of paracetamol in nitrate solutions in the range of environmental concentration was studied using mercury lamp with middle pressure as simulated solar source. Experiments were carried out to study the influences of pH value, nitrate concentration and the substances such as humic substance, bicarbonate, which are popular in natural water, on the photodegradation of paracetamol in nitrate solutions. The results demonstrate that the photodegradation of paracetamol follows a pseudo-first-order kinetics and the photodegradation rate increases rapidly with increasing initial concentration of nitrate. The first order constant increases with the increase of pH and the concentration of bicarbonate. When SRFA concentration is more than 10 mg/L, the presence of SRFA stimulates the photodegradation of paracetamol. The addition of NOHA decreases the photodegradation rate of paracetamol. Hydroxyl radical is found in the reaction solutions using methanol and isopropanol as its molecular probes. We identified the photodegradation products of paracetamol in the presence of nitrate with GC/MS methods. The photodegradation pathways of paracetamol are also discussed.