Experimental and Modeled Results Describing the Low-Concentration Acetone Adsorption onto Coconut Shell Activated Carbon

Abstract

Polar VOCs represented by ketones deteriorate indoor air quality and affect human health. Adsorption by activated carbons can effectively remove harmful gases, but relatively little is known about the adsorption capacity of polar VOCs at a low concentration level. So, this paper adopted acetone as the typical polar VOC to test its adsorption on the coconut shell activated carbon and developed a prediction model to estimate the breakthrough time. The results will help users master the acetone adsorption behavior under realistic conditions and thus estimate the service life of the filters. The adsorption test of acetone with concentrations of 0.5, 1.0, 2.0, 3.0, and 4.0 ppm was carried out. Four adsorption isotherms, namely, Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin, were used to fit the data. The Freundlich model fitted best when was used to determine the equilibrium capacity of acetone. An approach based on the Thomas model was proposed to predict the acetone breakthrough curve. The mass transfer coefficient of acetone adsorption with a relatively high concentration (1.0–4.0 ppm) was calculated based on the Thomas model, and the relationship between the mass transfer coefficient and acetone inlet concentration was established to obtain the mass transfer coefficient of acetone at the predicted concentration. The equilibrium capacity and mass transfer coefficient were substituted into the Thomas model to predict the breakthrough curve of acetone at a lower concentration. The results showed that the shape of the predicted curve was much closer to the measured data of acetone adsorption. The relative deviation between the predicted service life and measured data was 10%, indicating that the Thomas model was suitable for predicting acetone adsorption at low concentrations.