Steady-state and transient photolysis of p-nitroaniline in acetonitrile

Both transient photolysis and steady-state photo-degradation experiments were performed to gain insight into the kinetics and mechanisms of degradation of p-nitroaniline (p-NA) in acetonitrile (MeCN) solutions. Complete degradation of p-NA was observed at diverse irradiation conditions under 254 nm UV light. Once H2O2 was added into the experimental system, degradation of p-NA was enhanced remarkably. The removal rate increased rapidly with increment of the irradiation time and reached 90% at 30 min. p-NA could be totally removed after 90 min in UV/H2O2 process. In the presence of O2 and H2O2, removal rate increased linearly with increment of the irradiation time and reached 90% at 10 min. p-NA could be totally removed after 20 min in UV/(O2 + H2O2) process. For transient photolysis, excited states of p-NA were observed after 355 and 266 nm laser flash photolysis (LFP). The transient absorption spectra were recorded and bimolecular rate constant of 6.89 × 109 M−1 s−1 was calculated for the self-quenching of 3p-NA*. Production of 3p-NA* in MeCN and H2O mixed solution was also studied. LFP of p-NA with addition of H2O2 was investigated for the first time.