A Model To Predict the Adsorber Thermal Behavior during Treatment of Volatile Organic Compounds onto Wet Activated Carbon

Abstract

A model for adsorption of volatile organic compounds (VOCs) onto a wet activated carbon bed was proposed in this study. This model accounts for temperature changes induced by the reversed and coupled mass-transfer processes of both organic species adsorption and water desorption. Indeed, it was experimentally pointed out that temperature rises, which result from the exothermal nature of the energetic interactions between the organic molecule and the activated carbon surface, are notably reduced when the adsorbent contains an initial moisture of approximately 10% in weight. Moreover, it was shown that water rate desorption was enhanced in the presence of organic vapor. This phenomenon may be explained by the displacement of sorbed water bythe organic molecules, owing to more intensive interactions with the activated carbon surface. The model proposed was elaborated from a previous comprehensive analysis of the diffusion mechanisms governing VOC adsorption at high concentrations onto a dry activated carbon bed. In a similar way, a theoretical approach was developed to model water desorption during drying of a wet activated carbon bed under pure flowing air. At last, a theoretical depiction of both competitive and reverse processes was outlined. The final model fits reasonably with experimental data relative to both breakthrough curves and thermal wave shape along the bed, even if local temperature change calculation may require some further improvement.

Visualization of the exothermal VOC adsorption in a fixed-bed activated carbon adsorber

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Visualization of the exothermal VOC adsorption in a fixed-bed activated carbon adsorber

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Modeling breakthrough curves of volatile organic compounds on activated carbon fibers

“…The dynamics of a fixed bed involve transport by axial dispersion in the mobile phase, convective transport in the mobile phase, accumulation in the bed void and accumulation in the adsorbent (Markovska et al 2001;Chuang et al 2003;Pré et al 2002). Equilibrium between the two phases is assumed at the fluid-solid interface.…”

Plasma-Assisted Regeneration of Activated Carbon: Current Status and Prospects

“…However, the adsorption capacity of AC is inherently limited. Once AC reaches its adsorption saturation, it loses its adsorption capacity, becoming solid waste and contributing to secondary pollution [4].…”

Visualization of the exothermal VOC adsorption in a fixed-bed activated carbon adsorber

“……”

Modeling breakthrough curves of volatile organic compounds on activated carbon fibers

“…The dynamics of a fixed bed involve transport by axial dispersion in the mobile phase, convective transport in the mobile phase, accumulation in the bed void and accumulation in the adsorbent (Markovska et al 2001;Chuang et al 2003;Pré et al 2002). Equilibrium between the two phases is assumed at the fluid-solid interface.…”

Plasma-Assisted Regeneration of Activated Carbon: Current Status and Prospects

“…However, the adsorption capacity of AC is inherently limited. Once AC reaches its adsorption saturation, it loses its adsorption capacity, becoming solid waste and contributing to secondary pollution [4].…”

Visualization of the exothermal VOC adsorption in a fixed-bed activated carbon adsorber

“……”

Modeling breakthrough curves of volatile organic compounds on activated carbon fibers

“…The dynamics of a fixed bed involve transport by axial dispersion in the mobile phase, convective transport in the mobile phase, accumulation in the bed void and accumulation in the adsorbent (Markovska et al 2001;Chuang et al 2003;Pré et al 2002). Equilibrium between the two phases is assumed at the fluid-solid interface.…”

Plasma-Assisted Regeneration of Activated Carbon: Current Status and Prospects

“…However, the adsorption capacity of AC is inherently limited. Once AC reaches its adsorption saturation, it loses its adsorption capacity, becoming solid waste and contributing to secondary pollution [4].…”