Effects of activated carbon surface properties on the adsorption of volatile organic compounds

Abstract

Physical and chemical properties of activated carbon (AC) were analyzed to investigate the effects of adsorbate properties on AC adsorption performance. Fixed-bed adsorption experiments were conducted with toluene, acetone, and xylene as adsorbates. From the results, the adsorption capacities of the three adsorbates had the following order: xylene > toluene > acetone. The correlation between experimental data and adsorbate properties was also analyzed. The results showed that different functional groups corresponding to the properties of adsorbates influenced the adsorptive properties of AC differently. The adsorption capacity of AC increased linearly as the molecular weight, dynamic diameter, boiling point, and density of the adsorbate increased. However, adsorption capacity decreased as the polarity index and vapor pressure of the adsorbate increased. For adsorption onto three types of AC, the adsorption energies of the three adsorbates had the following order: xylene > toluene > acetone.Implications: This paper focused on the research on adsorption behavior of activated carbon based on adsorbate properties. Adsorption experiments were conducted under the same condition while the adsorbates were toluene, acetone, and xylene, respectively. Correlation analysis between experimental data and adsorbate properties was conducted. The different groups have different influence on the adsorptive properties of ACs. The adsorption capacity of activated carbon increases with the increase of adsorbate molecular weight, dynamic diameter, boiling point, and density, and that this relationship is linear. The relationship between adsorption capacity and the polarity index and vapor pressure of adsorbate shows an opposite trend, and the adsorption capacities and adsorption energies of three kinds of activated carbon for these three adsorbates had the following order: xylene > toluene > acetone.

A needle trap device packed with MIL‐100(Fe) metal organic frameworks for efficient headspace sampling and analysis of urinary BTEXs

“…As observed, the peak area responses of BTEXs were increased with increasing desorption temperature from 225 to 250°C. The BTEX compounds have various boiling points (in the range 80.1–144.4°C at atmospheric pressure), dynamic diameters, vapor pressures and carbon atoms (from six to eight carbon atoms) in their molecular structures (Li, Sun, Li, & Keener, ). Therefore, the desorption temperature has a key role in the desorption efficiency of BTEXs from MIL‐100(Fe)@Fe 3 O 4 @SiO 2 sorbent packed inside NTD, so that the greatest peak area responses of the analytes were observed at 1 min desorption time.…”

Abatement of VOCs with Alternate Adsorption and Plasma-Assisted Regeneration: A Review

“…Adsorption of VOCs on MIL-101 also showed shape selectivity towards VOCs molecules: The adsorption capacity of p-xylene was higher than that of m-xylene and o-xylene even though they have almost equal molecule cross-sectional areas ( Figure 5). It has also been observed that the VOC concentration can have a positive influence on the adsorption capacity of a material [22,72] and that other chemical properties of VOCs such as oxidation state can also influence adsorption.…”

“…Polar compounds have higher boiling points or lower vapor pressures than non-polar compounds. VOCs, which have a high molecular weight and high boiling point can be effectively adsorbed on AC [72]. At higher boiling points, liquefaction and condensation occur more readily leading to increased adsorption capacity [67,68].…”

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“…• Molecular structure Adsorption capability of organic vapors to the activated carbon increased for the higher molecular weight of the adsorbate [50].…”