Insights into breakthrough properties of gaseous benzene under varying adsorptive conditions

Abstract

Adsorption is considered a well-established technique for the removal/recovery of target compounds from ambient air. As the application range of adsorption has been increased, the usefulness of the adsorbent becomes clearer and comprehensive knowledge of sorbent use was required. The performance evaluation of the adsorbent determines its availability in real-world applications and suggests the direction to effectively remove/recover air pollutants. As the adsorption performance of the adsorbent can be affected by various parameters present in the actual environment, a basic knowledge of the Influence factors in real world is essential. However, in previous studies, the evaluation of adsorption performance was performed under unrealistic conditions such as high pressure and low velocity. Therefore, this study investigated the breakthrough characteristics of gaseous benzene on Tenax TA and granular activated carbon (GAC), which are most commonly used for the collection and removal of volatile organic compounds (VOCs). For this, the adsorption performances of benzene on Tenax TA and granular activated carbon were evaluated using breakthrough volume, sorption capacity, and partition co-efficient under ambient conditions. To this end, the behaviors of benzene on each sorbent were explored across varying multiple parameters (i.e., inlet pressure, sorbent mass, and flow rate). In chapter 1, the adsorption properties of Tenax TA were evaluated using benzene as model compound through a series of adsorption experiments with the aid of air server/thermal desorber-gas chromatography/mass spectrometry (AS/TD-GC/MS) system. Their sorption behavior was evaluated across varying inlet partial pressures of benzene (0.005, 0.01, 0.05, and 0.1 Pa at 1 atm) at each of three different sorbent masses (30, 50 and 100 mg). The sorption capacity was then assessed using the linearized isotherm data sets. The replicated results were found in the best fit with Freundlich isotherm model. Therefore, the adsorption of benzene molecule took place on a heterogeneous surface by attributing to the active sites on the Tenax TA. It indicates that the physisorption was dominant on the overall adsorption performance between gaseous benzene and Tenax TA. In chapter 2, the sorption behavior of benzene on GAC was investigated by simulating the honeycomb structure which is most used in the real air purification process. More specifically, their adsorption performance was evaluated at various flow rates of 0.1 to 3 L min-1 to determine the effect of flow rate on benzene removal against GAC. In addition, the effect of the extended concentration of the benzene has also been evaluated in order to investigate the change on adsorption performance by measuring the breakthrough behavior across varying concentration levels (0.1, 1, and 10 Pa at 1 atm). Overall, in this study, optimal adsorption conditions were determined by taking into account various parameters affecting benzene adsorption on Tenax TA and granular activated carbon.