Adsorption of Substituted Benzene Derivatives on Silica: Effects of Electron Withdrawing and Donating Groups

Abstract

A fundamental understanding of the forces that drive uptake and binding of aromatic molecules on well-characterized surfaces such as silica is important for predicting the fate of toxic industrial compounds in the environment. Therefore, the adsorption of simple substituted benzene derivatives has been investigated on a hydroxyl-functionalized surface to probe the effects of electron withdrawing and donating functional groups on gas–surface binding. Specifically, this work probes how methyl and halide functional groups affect the properties of the OH---π hydrogen bond and other surface–adsorbate interactions that play an important role in the uptake of aromatic molecules. Our approach utilizes infrared spectroscopy to study hydrogen-bond formation and temperature-programmed desorption to measure activation energies of desorption. Results from this work indicate that substituted benzene derivatives adsorb to silica via a cooperative effect involving the SiOH---π hydrogen bond and additional substituent–sur...