Current study of separation mechanism in chromatography heavily relies on the measurement of macroscopic properties, such as retention time and peak width. This dissertation describes the vibrational spectroscopy characterization of separation processes.Raman Spectroscopic characterization of a silica-based, strong anion exchange stationary phase in concentrated aqueous solutions is presented. Spectral response of stationary phase quaternary amine is closely related to changes in interaction between counter anions and the amine functional groups as the result of anion hydration. The molecular-level information obtained will provide useful guidance for control of stationary phase selectivity.To study the effects of stationary phase pore size on separations processes, monodisperse silica particles in the sub-100 nm range are prepared and self-assembled to well-ordered, three-dimensional colloidal arrays. A modified LaMer model is proposed and demonstrated for optimization of reaction conditions that lead to uniform and spherical silica particles. This approach greatly reduces the number of training experiments required for optimization. Fast Fourier transformation of colloidal array scanning electron microscopy images indicates closely-packed hexagonal packing patterns.Using these arrays, a novel system for the measurement of molecular diffusion coefficients in nanopores is reported. This system consists of an ordered colloidal array with well-defined pore structure deposited onto an internal reflection element for in-sit collection of kinetic information by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). A mathematical model is established to extract diffusion coefficients from these data. A decrease of approximately eight orders of magnitude in molecular diffusion coefficients is observed for molecular transport in nanopores.Finally, by using this colloidal array-ATR-FTIR system and the corresponding mathematical models that describe absorption in the colloidal array, the distribution in the nanopores of the acetonitrile organic modifier in an aqueous mobile phase solvent system is determined. Based on the results of 50 nm colloidal arrays, pore surface properties have a strong effect on the distribution of organic molecules from bulk solution to the pores.

Commercial production and use of carbon-based nanomaterials will inevitably lead to the release of nanoscale compounds into to the environment. While fullerene nanoparticles, such as nC60 and multi-wall nanotubes (MWNTs), exhibit toxicity to certain microbes and human cell lines, their transport and deposition in subsurface environments are largely unknown. In this study, nanoparticle transport experiments were conducted in one-dimensional columns packed with water-saturated glass beads, quartz sands, or natural soil. Results demonstrated that nC60 transport was strongly influenced by electrolyte species and concentration, as well as mean grain size and flow rate. The attachment of nC60 was largely irreversible, with introduction of pH 12 water required to detach substantial quantities of retained nC60. Measured nC60 breakthrough curves and retention profiles in quartz sands suggest that the retention of nC60 was primarily due to attachment in a first energy minimum and that clean-bed filtration theory alone was not sufficient to describe the experimental data. In the presence of stabilizing agents, including surfactant, fulvic and humic acids, significant enhancement of nC60 transport in quartz sands was observed. In two natural soils, Appling and Webster soil, complete retention of nC60 was observed, even after introducing up to 65 pore volumes of nC60 suspension. However, nC60 readily transported through Appling soil in the presence of surfactant. For MWNTs with a manufacture-reported (MR) length of 50 μm readily transported through sand columns and the retention of MWNTs at higher input concentrations increased with the MR length. The data also suggested MWNTs exhibited higher mobility in quartz sands than nC60 or single-wall nanotubes under similar chemical conditions. These findings advance our current understanding of fundamental processes governing nanoparticle transport and retention in porous media and provide reliable experimental data for the development of nanoparticle transport models.