Adsorption of water vapor onto and its electrothermal desorption from activated carbons with different electric conductivities

This work is mainly involved with study of adsorption and electrothermal desorption of water vapor on the activated carbons (ACs) with different electric conductivities. The ACs were modified by using microwave irradiation in a nitrogen atmosphere, and then the surface oxygen content and the electric conductivity performances of the modified samples were respectively characterized using X-ray photoelectron spectrometer and electric heating experiments. The isotherms of the water vapor on the modified ACs were measured by means of batch adsorption experiments. The results show that the microwave-assisted modification make the surface oxygen contents of the ACs decrease so that the electric conductivities of the ACs are greatly improved, which would enhance the electric heating desorption efficiency of water from the modified ACs. The electrothermal desorption rate of water increases with an increase in the electric conductivities of the ACs and in the voltage exerted on the bed. The better electric conductivity performances of the ACs could make the water adsorbed on the ACs be desorbed more quickly. For example, for the AC900, it only took 100 s to desorb 80% of the amounts adsorbed of water on the AC900.

► Microwave irradiation in nitrogen made the oxygen content of the ACs decreased. ► Electric conductivities of the ACs were greatly improved by microwave irradiation. ► Electrothermal desorption was firstly applied to desorption of water from the ACs. ► Electrothermal desorption rate of water on ACs increased with electric conductivity.