Complexation of iron by salicylic acid and its effect on atrazine photodegradation in aqueous solution

The photodegradation of atrazine and the photochemical formation of Fe(II) and H2O2 in aqueous solutions containing salicylic acid and Fe(III) were studied under simulated sunlight irradiation. Atrazine photolysis followed first-order reaction kinetics, and the rate constant (k) corresponding to the solution of Fe(III)-salicylic acid complex (Fe(III)-SA) was only 0.0153 h(-1), roughly one eighth of the k observed in the Fe(III) alone solution (0.115 h(-1)). Compared with Fe(III) solution, the presence of salicylic acid significantly enhanced the formation of Fe(II) but greatly decreased H2O2 generation, and their subsequent product, hydroxyl radical (E (TM) OH), was much less, accounting for the low rate of atrazine photodegradation in Fe(III)-SA solution. The interaction of Fe(III) with salicylic acid was analyzed using Fourier-transform infrared (FTIR) spectroscopy and UV-visible absorption, indicating that Fe(III)-salicylic acid complex could be formed by ligand exchange between the hydrogen ions in salicylic acid and Fe(III) ions.