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

Abstract

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 (^·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.

Keywords

salicylic acid / iron / atrazine / photodegradation