Effect of Moisture on the Adsorption of Volatile Organic Compounds by Zeolite $13\times$

The adsorption of volatile methanol, acetone, and benzene onto zeolite $13\times$ was studied in the presence of water vapor. Breakthrough curves for these volatile organic compounds (VOCs) were measured by using a gas-phase Fourier transformation infrared (FT-IR) spectrometer instead of a gas chromatograph (GC) because a gas-phase FT-IR spectrometer provides a more rapid response to the change of gas concentration than that of GC. To observe the influences of humidity (i.e., water vapor) on the performance of zeolite $13\times$ during the VOC adsorption, the adsorption experiments were carried out at three different initial concentrations and two humidity conditions for each VOC. The results showed a significant influence of increased humidity on the breakthrough time, the shapes of breakthrough curves, and the uptake of VOCs. For the case of the benzene and water vapor coadsorption system, the presence of the moisture caused a greater decrease in the VOC uptake as well as the breakthrough time than for the other VOC–water coadsorption systems. A modified Freundlich-type isotherm was introduced in this study to describe the decrease in the uptake of VOCs in the presence of the moisture. This modified empirical equation provided a good fit to experimental results, with an average error of 8%.