Activated carbon desorption method
Activated carbon A black porous solid carbonaceous material. In the early stage, wood, hard husk or animal bones were carbonized and activated, and then converted to coal by pulverization, molding or carbonization and activation with uniform coal particles. The main component is carbon, and contains a small amount of oxygen, hydrogen, sulfur, nitrogen, chlorine and other elements. Ordinary activated carbon has a specific surface area of ​​between 500 and 1700 m 2 /g. It has strong adsorption performance and is an industrial adsorbent with a wide range of uses.
(1) Activated carbon temperature desorption. The amount of adsorption of the substance decreases as the temperature increases, and the temperature of the adsorbent rises to desorb the adsorbed component. This method is also called temperature-dependent desorption, and the temperature during the whole process. It is cyclical. Microwave desorption is a technology improved by temperature desorption. Microwave desorption technology has been applied to gas separation, drying and air purification and wastewater treatment. In practice, this method is also the most commonly used method of desorption.
(2) Activated carbon decompression decompression. The amount of adsorption of the substance increases as the pressure increases. Adsorption at a higher pressure, lowering the pressure or vacuuming can regenerate the adsorbent. This method is also called pressure swing adsorption. This method is often used for gas desorption.
(3) Activated carbon washing and desorption. The adsorbent is washed with a gas (liquid) that is not adsorbed, and the adsorbed component is desorbed. The use of this method inevitably causes the problem of mixing the rinsing agent with the adsorbed component, and it is necessary to separate them by other methods, so that this method has the inconvenience of multiple separations.
(4) Activated carbon displacement desorption. Displacement desorption works by replacing the absorbed component with a substance that is more viscous than the adsorbed component. The consequence is that the displaced material is adsorbed on the adsorbent and must be separated by other means. For example, activated carbon has a certain adsorption capacity for Ca2+ and C1-, and these ions occupy the active center of adsorption, which can adversely affect the adsorption of inorganic elemental or organic substances on activated carbon. Therefore, after the activated carbon is used to adsorb the substance in the solution to be separated, CaCl2 is used as the desorbing agent to reduce the adsorption stability of the activated carbon on the adsorbate, thereby achieving the purpose of reducing the desorption activation energy.
(5) Activated carbon magnetization desorption. Since the properties of the single molecule water are much more active than the water molecules in the cluster, its dipole characteristics can be sufficiently exhibited, thereby increasing the polarity of the water. The pre-magnetic treatment can increase the polarity of the water, which fully explains the decrease in the adsorption capacity of the activated carbon after the pre-magnetic treatment. When the strength of the magnetic field increases, the more individual water molecules are separated, the greater the hindrance effect, and the more the adsorption capacity is reduced. The activated carbon itself is a non-polar substance. The surface of the activated carbon has an oxidizing substance due to activation, and the adsorbent is activated under humid air conditions, which makes the surface oxidizing substance of the activated carbon dominate with an acidic oxide, so that the activated carbon has Polarity, capable of adsorbing substances with higher polarity. Since these polar groups tend to adsorb polar water, the adsorbent adsorbs non-polar substances in the aqueous solution. This method is commonly used for the desorption of adsorbates in solution.
(6) Ultrasonic desorption of activated carbon. Ultrasonic (field) changes the equilibrium relationship of the adsorption phase by generating a synergistic effect. After the third component is added to the adsorption system under the action of ultrasonic (field), the phase equilibrium relationship of the system moves to a greater extent than the solid phase adsorption amount decreases. Adsorption system under normal conditions. According to the principle of action of ultrasonic waves, it may be because the third component changes the polarity of the fluid phase, increases the surface tension of the cavitation nucleus, and causes the tiny gas nucleus to be compressed to shorten the collapse and closure cycle, resulting in a stronger Ultrasonic cavitation. Therefore, after adsorbing the substance in the solution to be separated by the activated carbon, the synergistic effect of the ultrasonic wave (field) can be used to change the equilibrium relationship of the adsorption phase, and the adsorption stability of the activated carbon on the adsorbate can be reduced, thereby achieving the purpose of reducing the desorption energy.
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