Get to Know a Different Carbon Fiber – Activated Carbon Fiber

 

Activated Carbon Fiber (ACF), also known as fibrous activated carbon, is a highly efficient active adsorption material and environmental engineering material with better performance than activated carbon. More than 50% of its carbon atoms are located on the inner and outer surfaces, forming a unique adsorption structure, which is called a surface solid.

 

It is made of a fibrous precursor, which is activated by carbonization in a certain procedure. The more developed specific surface area and narrow pore size distribution make it have a faster adsorption and desorption rate and a larger adsorption capacity. Moreover, since it can be easily processed into different shapes such as felt, cloth, paper, etc., and has acid, alkali and corrosion resistance, it has received widespread attention and in-depth research since its launch. It has been widely used in gas phase recovery, water treatment, air purification and other fields.

 

Activated carbon (GAC) is a porous carbon that has been activated and has a strong adsorption capacity. It has been used in military, chemical, environmental protection and other fields for a hundred years.

 

Traditional activated carbon is powdery or granular, while activated carbon fiber (fibrous) is covered with micropores. Its adsorption capacity is 20 times higher than that of granular activated carbon, and its adsorption speed is 1000 times faster! It has only been used for the past 20 years. Its super adsorption capacity is used in industry to recycle organic solvents, purify air, and purify water.

 

Activated carbon fiber is a high-tech product that can only be produced in a few countries in the world. Its products can be in the form of silk, paper, felt, cloth, etc. The market price of activated carbon fiber is 100 times that of bamboo charcoal and granular activated carbon.

 

 

Adsorption Capacity

After high-temperature activation of carbon fiber, the fiber surface is covered with micropores (i.e. the positions occupied by hydrogen and oxygen atoms before volatilization), and the pore size is one hundred thousandth of a hair. If the inner surface of these micropores is unfolded, the unfolded area of ​​1g activated carbon fiber felt is as high as 1600㎡. These micropores play the role of odor adsorption. From physics, we know that the surface of an object has external gravity. The larger the surface, the greater the adsorption force. Activated carbon adsorbs surrounding molecules and firmly adheres to the micropores through the action of this van der Waals force and chemical bonds.

 

It can absorb organic matter such as: hydrocarbons (benzene, toluene, xylene, trimethylbenzene, n-hexane, cyclohexane, etc.), halogenated hydrocarbons (chloromethane, dichloromethane, trichloromethane, trichloroethylene, trichloroethane, bromomethane, tetrachloride, etc.), aldehydes and ketones (acetone, cyclohexanone, formaldehyde, acetaldehyde, furfural, etc.), esters (ethyl acetate, butyl acetate, etc.), ethers (methyl ether, ethyl ether, methyl ethyl ether, etc.), alcohols (methanol, ethanol, isopropanol, butanol, etc.), polymerization monomers (vinyl chloride, etc.)

 

Application of Activated Carbon Fiber Felt

Activated carbon fiber is a high-performance adsorption material with micropores all over its surface. Compared with traditional granular carbon, it has the advantages of faster adsorption and desorption speed and convenient operation and maintenance. It can be divided into felt, cloth, and filament according to its form. Activated carbon fiber has a large adsorption capacity, and its adsorption capacity for organic gases and odorous substances is several to dozens of times greater than that of granular activated carbon. It also has good adsorption capacity for inorganic gases, so activated carbon fiber has a wide range of uses.

 

Solvent Recovery

Activated carbon fiber felt can be used for the recovery of organic solvents, such as benzene, ketones, esters, and petroleum waste gases can be recovered from the gas phase by adsorption. Using activated carbon fiber as a solvent recovery material has a fast adsorption and desorption speed, a large processing capacity, and a high quality of recovered solvents. The recovery rate can reach more than 90%. The newly designed solvent recovery production lines in China mostly use activated carbon fiber adsorbers, and some old production lines that originally used activated carbon adsorbers will also be converted to activated carbon fiber adsorbers.

 

Activated Carbon Fiber Adsorption Device

 

Activated Carbon Fiber Cotton Filter

 

Water Treatment

The adsorption characteristics of activated carbon fiber depend not only on its pore structure, but also on its surface chemical properties – surface chemical functional groups, surface heteroatoms and compounds. Different surface functional groups, heteroatoms and compounds have obvious adsorption differences for different adsorbates.

 

During the activation process, a large number of oxygen-containing surface complexes such as hydroxyl, carboxyl and phenolic groups are formed on the surface of activated carbon fiber. Different types of oxygen-containing groups are the main active sites on activated carbon fiber, which can make the surface of activated carbon fiber present weak acidity, alkalinity, oxidizing, reducing, hydrophilicity and hydrophobicity.

 

These constitute the diversity of activated carbon fiber properties and affect the binding ability of activated carbon fiber with active components.

 

Generally speaking, the richer the acidic compounds in the oxygen-containing functional groups on the surface of activated carbon fiber, the higher the efficiency of adsorbing polar compounds; while activated carbon fiber with more alkaline compounds is easy to adsorb less polar or non-polar substances.

 

At present, in order to enhance the adsorption capacity of activated carbon fiber, it is often modified. The chemical properties of the surface of activated carbon fibers can be changed by chemical oxidation, reduction, loading and other modification methods. Increasing the relative content of acid and base groups can selectively adsorb substances with different polarities, or by adding specific surface heteroatoms or compounds to enhance the adsorption capacity of specific adsorbates, thereby coping with diverse water treatment environments, such as sewage treatment, drinking water purification and other fields.

 

Water Purifier Filter Element

 

Air Purification

The fiber diameter of activated carbon fiber is 5~20μm, the average specific surface area is about 1000~3000m2/g, the average pore size is 1.0~4.0nm, the micropores are evenly distributed on the fiber surface, and the adsorption rate of small molecular substances is fast and the adsorption speed is high. The contact area with the adsorbate is large, and it can be evenly contacted and adsorbed, so that the adsorption material can be fully utilized.

 

The adsorption efficiency is high, and it has various fine surfaces such as fiber, felt, cloth and paper. The pores are directly opened on the fiber surface. The diffusion path of the adsorbate to the adsorption position is short, and the surface area itself is two orders of magnitude higher than the internal surface area.

 

For some macromolecules or particulate substances, such as dioxins, dust, etc., they are widely used in clean workshop ventilation duct air filtration.

 

Activated carbon fiber also has the functions of anti-toxicity, deodorization, bacterial filtration, and dust blocking. It is especially used in occasions containing organic gases, acid volatiles, pesticides, and sulfur dioxide irritating gases.

 

Activated carbon fiber can also effectively absorb harmful gases such as benzene, ammonia, formaldehyde, odor, and bad smell in the air to improve the indoor environment. Most brands of purifiers use activated carbon fiber materials.

Activated Carbon Fiber Filter

 

Air Purifier

 

AFC regeneration conditions are not harsh. Due to its high carbon content and conductive properties, it can be directly heated and regenerated by using this property. It can also be quickly regenerated by hot steam or hot air above 100 degrees, greatly reducing production costs. At present, the application of activated carbon fiber is an increasingly mature industry. From a sewage treatment system to an air purifier, AFC materials account for a large proportion. It can be said to be a very cost-effective material with broad market prospects.