A Qualitative Analysis of the Effects of Water Vapor on Multi-Component Vapor-Phase Carbon Adsorption

Abstract

The effects of water vapor on binary vapor adsorption of toluene and methylene chloride by activated carbon were investigated on a bench-scale experimental system. Three levels of relative humidity (15,65 and 90 percent) in conjunction with different concentrations of individual adsorbates (from 400 to 1200 ppmv) were tested by tracing the breakthrough curves of each adsorbate eluted from a fixed-bed adsorber. The adsorption capacities of the activated carbon tested for each adsorbate under the various conditions were obtained from calculations based on area integration of the breakthrough curves. It was found that with increasing relative humidity, the shape of breakthrough curves was asymmetrically distorted and the width of the breakthrough curves was broadened for toluene and steepened for methylene chloride. The adsorption capacities for both toluene and methylene chloride were decreased with the increase of relative humidity. The magnitude of the effect of water vapor is greater at the lower toluene concentration and at the higher concentration of methylene chloride. The mechanisms of water vapor influence on the process of multicomponent vapor adsorption are discussed.

Influence of pore structure and pretreatments of activated carbons and water effects on breakthrough dynamics of tert-butylbenzene

“…The influence of the texture of carbon granules (size and volume of pores, specific surface area, granule size d, and carbon bed depth L), the gas stream humidity and velocity, and the amounts of pre-adsorbed water are investigated on absorption of organics in different media [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. However, these investigations were carried out without calculation of the corresponding distribution functions related to both breakthrough and structural characteristics.…”

“…Absorption of harmful organic compounds by activated carbons from gas and liquid media is of interest and of importance for human and environmental protection purposes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The influence of the texture of carbon granules (size and volume of pores, specific surface area, granule size d, and carbon bed depth L), the gas stream humidity and velocity, and the amounts of pre-adsorbed water are investigated on absorption of organics in different media [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

Evaluation of Gas‐Phase Filter Performance for a Gas Mixture

“…In many cases the activated carbon that has adsorbed moisture, loses this moisture by displacement in its preference for organic vapors. Although activated carbon is hydrophobic and has negligible affinity for water vapor, earlier researches have shown that high relative humidity (RH) can negatively influence the performance of activated carbon [4,[9][10][11][12][13][14][15]. Table 1 summarizes the research on VOC adsorption on activated carbon.…”

Evaluation of a Combined Ultraviolet Photocatalytic Oxidation(UVPCO)/Chemisorbent Air Cleaner for Indoor Air Applications

“…Systems with small amounts of carbon are effective for only short periods (Muller, 1993). VOC removal efficiency and capacity decrease with increased humidity and air temperature (e.g., Gong and Keener, 1993). When the inlet air contains multiple VOCs (which is always the case in buildings) and a significant fraction of carbon becomes saturated with VOCs, higher molecular weight VOCs can drive previously sorbed lower molecular weight VOCs back into the air stream (Liu, 1993).…”