The kinetic activity value of adsorbent is the main basis for the design of adsorption system.
The adsorption rateThe adsorption process often takes a long time to reach equilibrium, and the contact time is limited in the actual production process.Therefore, the amount of adsorption depends on the adsorption rate, and the adsorption rate is related to the adsorption process, the adsorption process can be divided intoThe adsorption process often takes a long time to reach equilibrium, and the contact time is limited in the actual production process.Therefore, the amount of adsorption depends on the adsorption rate, and the adsorption rate is related to the adsorption process, which can be divided into the following steps:
(1) External diffusion, the adsorbate from the main air flow through the air film around the particles to the outer surface of the adsorbent; (2) Internal diffusion, the adsorbate from the outer surface through micropores to the surface of the adsorbent micropores
(3) adsorption, the adsorbent reached the microporous surface of the adsorbent is adsorbed
(4) The desorbed adsorbate diffuses to the main body of the gas phase through internal and external diffusionPhysical adsorption process is generally controlled by internal and external diffusion, chemical adsorption is controlled by both surface dynamics and internal and external diffusion.Because of the complexity of the adsorption process and many influencing factors, it is difficult to derive the rate theoretically, so it is generally determined by experience or model experiment.In the case of multi-component adsorption, due to the competition and interference between each component, the component with strong adsorption ability can replace the other component that has been absorbed, so that the penetration curve of each component has obvious changes.
The penetration point of the components with relatively weak adsorption capacity was significantly advanced, while the penetration time of the components with strong adsorption capacity was delayed.
In this paper, E-L equation and IAST theory are used for theoretical prediction and analysis of multi-component adsorption equilibrium, and compared with experimental results.
The results show that although the prediction of total adsorption amount by E-L equation is in good agreement with the experimental results, the prediction of each component adsorption amount by E-L equation often produces positive and negative deviation, and the average error is usually more than 20%.wood based activated carbon manufacturer
However, IAST can eliminate the positive and negative deviation well, and the average error is less than 10%, which is more consistent with the experimental results.
The operating parameters showed that the adsorption capacity of activated carbon would decrease with the increase of temperature, gas velocity or humidity.
The appropriate operating range is: temperature within 40℃, gas speed between 0.1~0.5 m/s, humidity is best not more than 40%.
In this range, the relationship between pressure drop and gas velocity basically conforms to Ergun equation.
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