In situ ATR-FTIR spectroscopy for functional groups of humic substances complexing with metal ions

Tanaka, Tadao ; Sakamoto, Yoshiaki ; Ogawa, Hiromichi

To obtain structural information on functional groups of humic substances complexing with metal ions, infrared (IR) spectral analysis of the humic substances dissolving in aqueous solutions has been studied by ATR (Attenuated Total Reflection) method. By using the ATR method, IR spectral shifts of humic substance due to complexation with metal ions were observed. The observation provided with information on complexation kinetics, and on characteristics of functional groups depending on solvent properties, such as pH and solute concentrations. These information was difficult to be obtained by conventional FTIR spectroscopy using powdered humic substances. The obtained results show that IR spectral shifts on the functional groups of the humic substances complexed with metal ions could be possibly characterized by using the ATR-FTIR spectroscopy.