Effects of Molecular Properties on Adsorption of Six-Carbon VOCs by Activated Carbon in a Fixed Adsorber

Abstract

Gravimetric adsorption equipment with a microbalance was used to measure the adsorption of volatile organic compounds (VOCs) by activated carbon from 288 to 313 K. VOCs [n-hexane, cyclohexane, 1-hexene, 2-methylpentane, 3methylpentane, 2,2-dimethylbutane, acetone, butanone, and 2pentanone (Pentan-2-one)] were used as adsorbates in the adsorption system. Considering the geometric barrier, the critical diameter, and the boiling point, the adsorption capacities for sixcarbon (C 6 ) alkane isomers decrease in the order of n-hexane, 3methylpentane, and 2-methylpentane. The adsorbates, including nonpolar or weakly polar substances, and substances with smaller geometric obstacles and smaller molecular weights, were more easily adsorbed by the activated carbon. However, the dipole−dipole interactive force at higher pressures resulted in a higher adsorption capacity for 1-hexene than for n-hexane. Both polarity and molecular size should be considered in the analysis of the adsorption of ketones by activated carbon. The adsorption equilibrium constants decreased with increases in temperature because a higher temperature was unfavorable for adsorption. The results for the Toth adsorption isotherm model fitted by the adsorption data showed that the experimental data and the Toth adsorption isotherm model were consistent with each other, as evidenced by the low deviation between the experimental data and those from the fitted model.

A karst-inspired hierarchical Mg/Al layered double hydroxide with a high entropy-driven process for interception and storage

“…62 If the Z value obviously deviates from 1, it shows that the adsorption system has stronger heterogeneity. 63 At different temperatures, the Z value of Karst-LDH deviates from 1 at most, which indicates that Karst-LDH has strong reactivity and an obvious heterogeneous reaction tendency.…”

Evaluation of HKUST-1 as Volatile Organic Compound Adsorbents for Respiratory Filters

“…The non-polarity of cyclohexane causes weak adsorption, being one of the few VOC molecules with zero dipole moment . In addition, from the registered adsorption experiments, it can be inferred that the diffusion rate controls the adsorption mechanism through the pores of the carbon. , Most importantly, humid streams result, for all known adsorbents, in a major reduction of the adsorption capacity and lead to breakthrough time reductions. For activated carbons, the negative impact of humid streams is generally observed for RH > 50%, which corresponds to air purification applications in almost all relevant conditions of use.…”

Modelling of adsorption technologies for controlling indoor air quality

“…The type and quality of pollutants, their concentration and emission rate are extremely diverse and depends on many factors [3]. In households, the most common pollutants with health risks are volatile organic compounds [4], formaldehyde [5][6][7] and in some cases, ozone, radon, carbon monoxide and tobacco smoke [8]. Radon is the first cause of lung cancer among non-smokers [9].…”