Adsorption occurs at the interface between two different phases. The adsorption process is the diffusion process on the interface. It is adsorption that occurs on the solid surface, which is caused by the residual attraction on the solid surface.
Adsorption can be divided into physical adsorption and chemical adsorption; physical adsorption is also called van der Waals adsorption, which is caused by the electrostatic force or van der Waals attraction between the adsorbent and the adsorbate molecules. When the molecular attraction between the solid and the gas is greater than the attraction between the gas molecules, the gas molecules will condense on the solid surface even if the gas pressure is lower than the saturated vapor pressure corresponding to the operating temperature. Physical adsorption is an endothermic process.
Chemical adsorption, also known as active adsorption, is caused by the chemical reaction force between the adsorbent surface and the adsorbate molecules. It involves the destruction and recombination of chemical bonds in molecules. Therefore, the adsorption heat of the chemical adsorption process is greater than that of the physical adsorption process.
In the adsorption process, there is no strict boundary between physical adsorption and chemical adsorption. The same substance is often chemically adsorbed at a lower temperature. The adsorption of activated carbon fiber is mainly physical adsorption, but due to the presence of surfactants, there is also a certain chemical adsorption effect.
b. Characteristics of activated carbon adsorption of waste gas:
(1) The adsorption of aromatic compounds is better than that of non-aromatic compounds.
(2) The physical adsorption of hydrocarbons with branched bonds is better than that of straight-chain hydrocarbons.
(3) The adsorption of organic matter containing inorganic groups is always lower than that of organic matter without inorganic groups.
(4) The adsorption of compounds with large molecular weight and high boiling point is always higher than that of compounds with small molecular weight and low boiling point.
(5) The higher the adsorbate concentration, the higher the adsorption capacity.
(6) The larger the internal surface area of ??the adsorbent, the higher the adsorption capacity.
Activated Carbon Fiber
The adsorption method using a new adsorption material, activated carbon fiber (ACF), as an adsorbent is a new method for recovering organic waste gas developed in recent years. It is considered to be an effective new method for recovering and purifying organic waste gas. In recent years, it has attracted great attention from researchers and related companies. Compared with traditional activated carbon, activated carbon fiber has the following excellent properties:
1) Large specific surface area and high effective adsorption capacity;
2) Fast adsorption and desorption, low energy consumption, and easy regeneration;
3) High strength and long service life;
4) Various shapes, convenient for engineering applications;
5) Can adsorb low concentration gases;
6) Strong adsorption selectivity.