What kind of material is activated carbon fiber?
What is activated carbon fiber? What is the material of activated carbon fiber? Activated carbon fiber (ACF), also known as fibrous activated carbon, is a highly efficient active adsorbent material and environmentally friendly engineering material with superior performance to activated carbon. More than 50% of its carbon atoms are located on the inner and outer surfaces and are constructed into a unique adsorption structure called surface solids. It is made up of a fibrous precursor that is activated by a certain program of carbonization. The more developed specific surface area and narrower pore size distribution make it have faster adsorption desorption speed and larger adsorption capacity, and because it can be easily processed into different shapes such as felt, cloth, paper, etc., and has acid resistance. The corrosion resistance of the alkali has made it widely concerned and in-depth research. At present, it has been widely used in environmental protection, catalysis, medicine, military and other fields.
Since the first US patent in 1962 involved the subsequent US ORNL using activated carbon fiber to filter radioactive iodine radiation, the research and application of different precursor organic fibers and their activated carbon fibers have developed rapidly. The United States, the United Kingdom, the former Soviet Union, and especially Japan, are big countries that research and use ACF, with an annual output of nearly 1,000 tons. The domestic ACF study began in the late 1980s, and industrial devices appeared in the late 1990s. Most are in the laboratory research stage.
Manufacturing method: The difference in the raw material of the precursor, the production process of ACF and the structure of the product are also significantly different. The production of ACF is generally carried out by stabilizing organic precursor fibers at a low temperature of 200 ° C to 400 ° C, followed by (carbonization) activation. Commonly used activation methods are: physical activation method using CO2 or water vapor and chemical activation method using ZnCI2, H3PO, H2PO4, KOH, treatment temperature between 700 °C and 1 000 °C, different treatment processes (time, temperature, The activation dose, etc.) corresponds to different pore structures and properties. The organic fibers used as the ACF precursor mainly include cellulose-based, PAN-based, phenolic-based, pitch-based, polyvinyl alcohol-based, styrene/olefin copolymers, and lignin fibers. Commercialization is mainly the first four.
Structural features: Activated carbon fiber is a typical microporous carbon (MPAC), which is considered to be “superfine particles, irregular surface structure and a combination of extremely narrow spaces†with a diameter of 10 μm to 30 μm. The pores are directly open to the surface of the fiber, and the ultrafine particles are combined in various ways to form a rich nano-space, and the space formed is of the same order of magnitude as the ultrafine particles, thereby creating a large specific surface area. It contains many irregular structures - heterocyclic structures or microstructures containing surface functional groups, which have great surface energy, and also make micropores work together with pore wall molecules to form a strong molecular field, providing an adsorption state molecular physics. And high pressure systems with chemical changes. The diffusion path of the adsorbate to the adsorption site is shorter than that of the activated carbon, the driving force is large, and the pore size distribution is concentrated. This is the main reason why the ACF has a larger specific surface area, a faster adsorption and desorption rate, and a higher adsorption efficiency than the activated carbon.
Functionalization: Functionalization is mainly through the pore structure control and surface chemical modification to meet the efficient adsorption conversion of specific substances.
ACF is generally suitable for adsorption of gas phase and liquid phase low molecular weight molecules (MW = 300 or less). When the pore size of the adsorbent is about twice the critical size of the adsorbate molecule, the adsorbate is more easily adsorbed. The purpose of the pore size adjustment is to make the pores of the ACF equivalent to the size of the adsorbate molecules. The following methods are usually used: 1) activation process or change of activation degree (to the nanometer scale); 2) addition of metal compounds or other substances to the fibrils by carbonization Activated, or activated by adding ACF to the metal compound (mesoporous), the raw fiber has a pore size close to the macroporous (macroporous); 3) Hydrocarbon pyrolysis is deposited on the pore wall, and high temperature post treatment The pore size becomes smaller).
Surface chemical modification mainly changes the surface acidity and basicity of ACF, and introduces or removes some surface functional groups. The surface oxygen-containing group (reduction) can be removed by high temperature or hydrogenation treatment; an acidic surface can be obtained by gas phase oxidation and liquid phase oxidation. Modification needs to take into account the effects of physical and chemical structures.
Cey Fabric,Air Flow Woven Fabric,Muslim Clothing Fabric,Polyester Woven Fabric
SHAOXING KAIMING TEXTILES CO.,LTD , https://www.sxruiqi.com