Chemical properties and application characteristics of activated carbon
Chemical properties of activated carbon: adsorption of activated carbon in addition to physical adsorption, as well as chemical adsorption. The adsorption of activated carbon depends on both the pore structure and the chemical composition.
Activated carbon not only contains carbon, but also contains a small amount of chemically bonded, functional group-starting oxygen and hydrogen, such as carbonyl, carboxyl, phenols, lactones, terpenes, ethers. Some of the oxides and complexes contained on these surfaces are derived from derivatives of raw materials, some of which are formed by the action of air or water vapor upon activation and activation. Surface sulfides and chlorides are sometimes formed. In the activation, the minerals contained in the raw materials are concentrated into activated carbon to become ash, and the main components of the ash are salts of alkali metals and alkaline earth metals, such as carbonates and phosphates.
These ash contents can be lowered by washing with water or pickling.
The inorganic components in activated carbon can be seen from the analysis of four kinds of powdered charcoal products.
The production of activated carbon is generally divided into two processes, the first step, carbonization, drying the raw material at a temperature of 170 to 600, and carbonizing 80% of the organic structure in the same amount. In the second step, the carbonized material which has been carbonized in the first step is sent to the reaction furnace, reacted with the activator and water vapor to complete the activation process, and the finished product is prepared. In the endothermic reaction process, a combination of CO and H2 is mainly produced to heat the carbonized material to an appropriate temperature (800 to 1000 degrees) to remove all decomposable substances, thereby producing a rich pore structure and a large specific surface area. The activated carbon has a strong adsorption force. The activated carbon produced by different raw materials has different pore diameters, wherein the activated carbon with coconut shell as the raw material has the smallest pore size, the wood activated carbon also has a larger pore diameter, and the pore size of the coal activated carbon is between the two. The activated carbon pore size is generally divided into three categories: large pore A transition pore: 20-1000A microporous: 20A According to the above characteristics, it can be seen that for different adsorption targets, the corresponding activated carbon should be selected to achieve the best cost performance, therefore, Generally, in the liquid phase adsorption, more activated carbon with a larger transition pore diameter and a larger average pore diameter should be used.
Activated carbon application
According to the adsorption characteristics of activated carbon, activated carbon is mainly used to remove pollutants from water, decolorize, filter and purify liquids and gases, and also be used for air purification and waste gas recovery (such as the recovery of gas "benzene" in the chemical industry). Recovery and refining of precious metals (such as the absorption of gold).
With the development of science, the use of activated carbon has become more and more extensive. With the country's emphasis on the ecological environment, activated carbon has also played an increasingly important role.
Question 1: Can activated carbon be used to absorb formaldehyde in new houses?
Answer: Activated carbon can not only be used to adsorb formaldehyde, but also to purify a variety of harmful gases. Activated carbon used for household air purification generally uses coconut shell activated carbon, and the particles generally require less than 40 mesh, which is somewhat demanding. Can use the well-known brand "Xinjubao activated carbon"
Question 2: What is activated carbon?
Answer: Activated carbon is a black powder, granular or pelletized or amorphous with porous carbon. The main component is carbon, and also contains a small amount of oxygen, hydrogen, sulfur, nitrogen, chlorine. It is mainly composed of wood, nut shell, coal and the like which are activated by high temperature. Carbon is the most stable element in nature, and activated carbon has this feature. Activated carbon has a well-developed pore structure with a large surface area (500-1000 m 2 /g), or even higher, has strong physical adsorption properties, can adsorb gas, liquid or colloidal solids; for gases, liquids, adsorbed substances The quality can be close to the quality of the activated carbon itself. Its adsorption is selective, and non-polar substances are more easily adsorbed than polar substances. In the same series of substances, the higher the boiling point, the easier the adsorption is. The higher the pressure, the lower the temperature, the higher the concentration, and the larger the adsorption amount. On the contrary, decompression and temperature rise are beneficial to the desorption of gas.
Activated carbon is commonly used in gas adsorption, separation and purification, solvent recovery, sugar liquid, grease, glycerin, drug decolorizer, deodorant for drinking water and refrigerator, filter in gas mask, air purification, and can also be used as A carrier or the like of a catalyst or a metal salt catalyst.
The main purpose:
1. New home: It is used to adsorb toxic and harmful gases such as formaldehyde, benzene, ammonia and hydrazine in the air of new homes and continuously released into the air, and quickly remove the decoration odor.
2, new furniture: used to absorb the continuous release of formaldehyde, benzene, and various odors.
3, wardrobe, bookcase, shoe cabinet: smell, detoxification, dehumidification, pest control, deodorization, sterilization, preservation of calligraphy and so on.
4, the bathroom: deodorization sterilization, fresh air.
5, the floor: astringent, moisture-proof, mildew-proof, anti-insect, protect the floor from deformation.
6. Car: Adsorb various harmful gases in the new car and various odors in the old car.
7, computers, household appliances, etc.: adsorption, reduce the harm of radiation gases to people.
8. Offices, hotels and other public places: purify the air and eliminate odors.
[Manufacturing method of coal-based activated carbon particle]
1, method summary
A certain amount of purified water is sampled by using a coal granular activated carbon sample on a vibrating screen, and the mass of the sample remaining on each sieve layer as a percentage of the mass of the original sample indicates the particle size distribution of the sample.
2, measuring step
1) According to the technical requirements of the product, select a corresponding set of sieve layers, arranged according to the size of the mesh holes, arranged from top to bottom, and placed on the vibrating screen machine.
2) Weigh 100 g of the sample into the uppermost sieve of the vibrating screen, cover the sieve cover, and fasten the complete sieve. Start the vibrating screen and start the timer (or bully stopwatch) at the same time.
3) Vibrating screen (600 ± 10) s.
4) Loosen the shaker clip, take off the sieve cover, gently remove the layers in turn and collect the samples in each layer separately with a porcelain plate. The activated carbon stuck on the sieve hole is gently shaken by a screen frame or brushed, and also sieved on the sieve layer.
5) Weigh each sieve layer and the screening quality in the chassis (accurate to o.1 e),
6) Repeat steps s. l to s. 5 and make another sample.
7) Particle size calculation formula of coal granular activated carbon: Li (%) = mi / m × 100% Li - mass fraction of the i-th layer, %; mi - mass of the sample on the i-th sieve, B: m - the mass of the original sample, g.
Optical Microscopy
In optical microscopy different filters are used to improve contrast and emphasize specific features based on material properties. This can be achieved with magnifications typically ranging from 2.5 times up to 1,000 times. In materialography, reflected light is the most commonly used type of light optical microscopy. Transmitted optical microscopy is also used, but mainly for mineralogy specimens.
Stereo Optical Microscopy
The stereo microscope is an optical microscope variant, designed for low magnification observation of a specimen, using the light reflected from the specimen surface.
Scanning Electron Microscopy
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a specimen by scanning the specimen surface with a focused beam of electrons. The electrons interact with the atoms in the specimen, producing various signals that can be translated into information about the surface topography and the composition of the specimen.
Transmission Electron Microscopy
Transmission electron microscopy (TEM) uses a beam of electrons transmitted through an ultra-thin specimen and that interacts with the specimen as it passes through it. Generated signals can be translated into various types of information, including information on the type and orientation of individual crystals.
metallographic sample preparation for microscopy,sample preparation for metallurgical microscope,optical microscope for metallurgy
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