Photolysis of Fe(III) complex with ethylenediamine-N,N′-disuccinic acid and its efficiency in generation of •OH radical

The mechanism of photolysis of the Fe(III) complex with ethylenediamine-N,N '-disuccinic acid ([FeEDDS](-)) was revealed using a combination of time resolved and stationary photochemical methods. Using laser flash photolysis (lambda(ex) = 355 nm), the formation of the primary intermediate, the radical complex of Fe(II) with quantum yield (m0 = 0.21) was detected for the first time. The lifetime (1.8 ms) and the spectral characteristics (lambda(max) = 520 nm, epsilon(520 nm) = 160 M-1 cm(-1)) of this intermediate were also determined. The dependence of the quantum yield of photolysis of the [FeEDDS](-) complex (phi(FeEDDS)) and the hydroxyl radical quantum yield (mOH) on the excitation wavelength, pH, and concentrations of the ligand and iron ions were obtained for the first time. It has been established that under optimal conditions at neutral pH, the value of phi(FeEDDS) is about 0.8, and mOH is about 0.15. It was found that phi(FeEDDS) does not depend on the initial concentrations of Fe(III), EDDS, but depends on pH, the excitation wavelength and the presence of oxygen. phi(OH) does not depend on the initial concentrations of Fe (III), EDDS, but depends on pH and the excitation wavelength. The high phi(OH) values make the [FeEDDS](-) complex a suitable system for the generation of center dot OH radical at neutral pH under UV radiation.