Kinetic study of the complexation of gallic acid with Fe(II)

Kinetic study on the complexation of gallic acid with ferrous sulfate was performed using UV–Vis absorption spectroscopy. Under the experimental conditions, the stoichiometric composition of the formed complex is 1:1. The complexation reaction was found to be a second-order one. The influences of temperature, ionic strength and solvents on the complexation reaction were investigated. According to the Arrhenius equation, the apparent activation energy of the complexation reaction was evaluated to be 71.64 kJ × mol−1. A three-step reaction mechanism was proposed, which can well explain the kinetic results obtained.