Activated carbon adsorption is a common method for treating waste gas. The adsorption method uses porous activated carbon, silicate, anthracite, etc. to adsorb organic gas molecules onto their surface for purification. Advantages: high purification rate (activated carbon adsorption can reach more than 99%), practical and widespread, simple operation, and low investment. Disadvantages: large system wind pressure loss, resulting in high energy consumption, difficult to control the saturation point of the adsorbent, limited adsorbent capacity, and high operating dosage.

Activated carbon is a very good adsorbent. It uses charcoal, various fruit shells and high-quality coal as raw materials, and is processed and manufactured through a series of processes such as crushing, screening, catalyst activation, rinsing, drying and screening by physical and chemical methods. Activated carbon has the dual characteristics of physical adsorption and chemical adsorption, and can selectively adsorb various substances in the gas phase and liquid phase to achieve the purpose of decolorization, disinfection, deodorization and purification. The activated carbon adsorption method uses activated carbon as a physical adsorbent to concentrate the harmful substances produced during electrostatic spraying on the solid surface, so that the waste gas can be purified and treated. This adsorption process is a physical process that occurs at the interface between the solid phase and the gas phase.

Activated carbon is divided into two categories: granular and fibrous. In comparison, granular activated carbon has uniform pores. In addition to small pores, there are also large pores of 0.55 nanometers. The specific surface area is generally 600-1600 square meters per gram. The treated gas diffuses from the outside to the inside over a long distance, so the adsorption and desorption are slow. The adsorption capacity of granular activated carbon that has been oxidized is stronger. Fibrous activated carbon has smaller pores and a larger specific surface area. It relies on the mutual attraction between molecules for adsorption, and does not react chemically with each other. It is a physical adsorption process.

The activated carbon adsorption device is a device that absorbs hydrocarbons when the waste gas generated during electrostatic spraying passes through the activated carbon layer, and discharges the purified gas into the atmosphere. Small adsorption devices generally use vertical adsorption tanks; large adsorption devices generally use horizontal adsorption tanks.

Let's take a look at the size and structure of the activated carbon adsorption device commonly used in the paint spraying room. For the cylindrical adsorption device, its diameter is 1 to 2 meters. For the vertical adsorption device, its height is roughly equal to the diameter, and its activated carbon layer height is 1.5 to 1.8 meters.

For horizontal adsorption devices, the height of the activated carbon layer is 0.3-0.8m, which can be single-layer or multi-layer, and the gas passing speed is 0.3-0.6m/s; if the layer height is increased, the adsorption capacity and power cost will increase accordingly. With the adsorption process of activated carbon, the equipment resistance increases slowly. When the activated carbon adsorption is saturated, the equipment resistance reaches a maximum value, and the purification efficiency of the equipment is basically lost. For this reason, the system sets a differential pressure measurement system at the inlet and outlet of the equipment to detect and display the pressure difference of the exhaust gas at the inlet and outlet of the device, and replace the activated carbon in time.

Since activated carbon has the characteristic of being regenerated, when the amount of activated carbon is large, the exhaust gas concentration is high, and the activated carbon adsorption saturation time is short, the activated carbon desorption device can be used to regenerate and recycle the activated carbon (steam can be used as the desorption medium). The use of an activated carbon desorption device can not only save operating costs, but also recycle the adsorbed exhaust gas, while avoiding secondary pollution. In the case of not recycling the solvent, a photocatalytic oxidation activated carbon regeneration device can also be used to regenerate and recycle the activated carbon. The nano-photocatalytic catalyst material (GC-100) in the core of the automobile spray paint room exhaust gas treatment equipment is a substance that can produce a catalytic reaction on its surface after absorbing light energy, and its function is similar to the chlorophyll of plants. When ultraviolet light of a specific nano-wavelength irradiates the photocatalytic catalyst material (GC-100), a photocatalytic redox reaction occurs on its surface. Finally, carbon dioxide and water are formed.