Activated carbon filters are widely used to remove gaseous pollutants in order to guarantee a healthy living environment. The standard method for evaluating the adsorption performance of filters is conducted at ~100 ppm. Although this accelerates the test and avoids the high requirements of the test device, it is still far from the contaminant concentration in the indoor environment, and adsorbents in practical application may show different capabilities. Therefore, this study compared several methods for predicting the adsorption performance of activated carbon and recommended a procedure based on the Wheeler–Jonas model to estimate the breakthrough curve at low concentrations using experimental data at high concentrations. The results showed that the Langmuir model and Wood–Lodewyckx correlation were the most suitable for obtaining the equilibrium adsorption capacity and mass transfer coefficient, which are critical parameters in the Wheeler–Jonas model. The predicted service life was derived from the breakthrough curve. A modification method based on a relationship with inlet gas concentration was proposed to reduce the prediction deviation of the service life. After modification, the maximum deviation was within two hours and the relative deviation was no more than 7%.
People spend most of their time indoors. The volatile organic compounds (VOCs) in indoor air represented by toluene inevitably affect people's health. Activated carbon can effectively reduce indoor VOCs pollution. The experiments in the previous studies were carried out at the concentration of tens or hundreds of ppm, which could not reflect the actual adsorption performance of activated carbon in the actual conditions. In this study, a method was proposed to predict breakthrough curve of toluene at ~1 ppm. The method was based on Wheeler-Jonas model, the equilibrium adsorption capacity was predicted by the Freundlich equation, and the adsorption rate constant was obtained by Yoon-Nelson equation. The predicted breakthrough curves were in good agreement with the experimental data in the range of 0.5~4.0 ppm. The adsorption rate constant was predicted using the relationship with inlet concentration of toluene. When the breakout fraction was 20-85%, the relative deviation was 5.54% and 4.08% at 0.5 and 1.0 ppm. This method can predict the adsorption performance and service life of activated carbon for toluene at ppb~ppm level.
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