Desorption and regeneration of activated carbon

The physical adsorption of activated carbon is a reversible process. However, this reversible process is a microscopic phenomenon, that is, at all times, activated carbon is both adsorbing and desorbing substances. When the adsorption rate is higher than the desorption rate, it shows macro adsorption; When the two are equal, the activated carbon is saturated; The desorption rate is higher than that of adsorption, and it is desorption in macro view.

For this physical adsorption, the increase of temperature will move the equilibrium point of adsorption saturation forward, that is, the adsorption capacity will decrease. Therefore, the higher the room temperature, the shorter the replacement cycle of the activated carbon filter element.

Activated carbon regeneration refers to the process of using physical or chemical methods to remove the adsorbate adsorbed on the micropores of activated carbon and restore its adsorption performance without destroying its original structure. In the process of activated carbon adsorption, it can adsorb both adsorbate and solvent. Due to different affinity, after a certain period of adsorption, it is necessary to take measures to destroy this equilibrium relationship for activated carbon regeneration, which is mainly based on the following aspects:

① Change the chemical properties of the adsorbate ② extract with a solvent with strong affinity for the adsorbate ③ replace the adsorbate with a substance with greater affinity for the activated carbon than the adsorbate, and then desorb the replaced substance, so that the activated carbon can be regenerated ④ change the equilibrium conditions by external heating and increasing the temperature ⑤ regenerate by reducing the concentration (or pressure) of the solute in the solvent ⑥ decompose or oxidize the adsorbate (organic matter) to remove it

The main function of carbon in the use process can also adsorb some toxic substances, heavy metals and other harmful substances to human body. In addition, the carbon regeneration process requires industrial strong acid cleaning, so the use of regenerated carbon without knowledge will have a great risk to drinking water. The low-cost activated carbon filter element may also use regenerated carbon as raw material.