Spectroscopic evidence for organic diacid complexation with dissolved silica in aqueous systems—I. Oxalic acid

Increased solubility of quartz and mobilization in contaminated groundwater due to the complexation with dissolved organic acids has been recently proposed [Bennett and Siegel, Nature 326 , 684–686 (1987)]. Using laser Raman and Fourier transform infrared spectroscopies, we have examined mixed solutions of oxalic and silicic acids at near neutral pH in the tenth molar concentration ranges in an attempt to directly observe the proposed organo-silicate complexes. In both laser Raman and infrared spectra, product bands were observed that indicate an oxalate/silicic acid ester is being formed in the reaction. These data support the observation that organic diacids can lead to enhanced solubility of quartz in hydrogeological systems.