Activated carbon

Activated carbon is also called activated carbon black. It is black powdered or granular amorphous carbon. In addition to carbon, the main component of activated carbon contains elements such as oxygen and hydrogen. This is why activated carbon is a hydrophobic adsorbent.

Activated carbon classification: Due to the different sources of raw materials, manufacturing methods, appearance and shape, and application occasions, there are no fewer than 1,000 types of activated carbon. 1.1 According to the source of raw materials, it can be divided into wooden activated carbon (such as coconut shell activated carbon, apricot shell activated carbon, wood powder charcoal, etc.), mineral raw material activated carbon (active carbon made from various coal and petroleum and their processed products as raw materials), other raw materials Activated carbon made (such as activated carbon made of waste rubber, waste plastic, etc.). 1.2 According to the manufacturing method, it can be divided into chemical activated carbon (chemical charcoal). The carbon-containing raw material is mixed with certain chemicals and then heat treated. The method of preparing activated carbon is called chemical method. Activated carbon produced by chemical method is also called chemical activated carbon or chemical carbon. Chemicals that can be used as chemical methods are also called activators. Activators include zinc chloride, calcium chloride, potassium carbonate, phosphoric acid, potassium dihydrogen phosphate, potassium sulfide, sulfuric acid, potassium hydroxide, sodium hydroxide, boric acid, etc. In short, many acids, bases, and salts can be used as activators, and which activator is used mainly from the performance and economy of activated carbon. Generally speaking, the secondary micropores and mesopores (pores with pore diameter or pore width greater than 1.5 nanometers) in chemical carbon pores are more developed, and they are mainly used for liquid phase adsorption refining and solvent recovery for gas (vapor) adsorption occasions. Due to the addition of chemicals in the production of activated carbon by chemical methods, great attention should be paid to environmental protection and the influence of trace elements that may not be introduced in the product. 1.2.2 Physical activated carbon uses carbon as raw material, water vapor, carbon dioxide, air (mainly oxygen) or their mixture (flue gas) as the activation medium, and is activated at high temperature (600~1000℃) to prepare activated carbon. Called physical law. Activated carbon manufactured by physical method is called physical activated carbon, also known as physical carbon. Generally speaking, physical carbon has well-developed micropores (pore diameter or pore width less than 1.5 nanometers), which is mainly used for gas phase adsorption or small molecule liquid phase adsorption. 1.2.3 Chemical-physical or physical-chemical activated carbon While understanding chemical and physical carbon, we should also mention chemical-physical or physical-chemical activated carbon. The selection of different raw materials and the use of different combinations of chemical and physical methods can control the pore structure of activated carbon, thereby preparing activated carbons with different properties. This chemical-physical method or physical-chemical method is a method of preparing activated carbon that has been of great concern to activated carbon workers from all over the world for many years and for a long time in the future. 1.3 Divided by appearance and shape 1.3.1 Powdered activated carbon Generally, more than 90% of activated carbon that has passed through an 80-mesh standard sieve or whose particle size is less than 0.175mm is generally called powdered activated carbon or powdered carbon. Powdered carbon has the advantages of faster adsorption speed and sufficient adsorption capacity when used, but it requires a proprietary separation method. With the advancement of separation technology and the emergence of certain application requirements, the particle size of powdered carbon tends to become more and more refined, and in some cases it has reached the micron or even nanometer level. 1.3.2 Granular activated carbon Generally, activated carbon with a particle size greater than 0.175mm is called granular activated carbon. Granular activated carbon is divided into the following categories. Unshaped granular activated carbon Unshaped granular activated carbon is generally made from granular raw materials that are carbonized and activated, and then crushed and sieved to the required particle size. It can also be made by adding powdered activated carbon with an appropriate binder and processing. to make. Cylindrical activated carbon Cylindrical activated carbon, also known as columnar carbon, is generally made from powdered raw materials and binders through kneading, extrusion molding, and carbonization and activation. It can also be extruded with powdered activated carbon and binder. Columnar charcoal can be divided into solid and hollow. Hollow columnar charcoal has one or more regular small holes in the columnar charcoal. Spherical activated carbon Spherical activated carbon, hence the name implies, is spherical activated carbon. Its preparation method is similar to that of columnar carbon, but there is a pelletizing process. It can also be made from liquid carbon-containing raw materials through spray granulation, oxidation, carbonization, and activation, or it can be processed by powdered activated carbon and binder into balls. Spherical activated carbon is also divided into solid and hollow spherical activated carbon. 1.3.3 Activated carbon in other shapes In addition to powdered activated carbon and granular activated carbon, there are other shapes, such as activated carbon fiber, activated carbon fiber blanket, activated carbon cloth, honeycomb activated carbon, activated carbon board and so on. 1.4 According to the application occasions. As mentioned before, activated carbon is widely used in almost all sectors of the national economy and people’s daily life. Because of this, it is difficult to classify activated carbon by application occasions. The problem is that the same activated carbon can be used in many occasions. , And a variety of activated carbon can be used to achieve the same purpose in certain occasions. People often get their knowledge of activated carbon by application, so it is often preceded by the word “×××” activated carbon is also used as a customary fuzzy classification method for activated carbon. Such as sugar activated carbon, injection activated carbon, monosodium glutamate activated carbon, water purification activated carbon and so on.

Activated carbon purchase tips: 1. Iodine value: Iodine value is a poor performance of activated carbon. The iodine value of nut shells, bamboo charcoal, and coal are all in the hundreds. The iodine value of activated carbon raw materials ranges from 800, 850, 900, 950, 1000, 1100mg/g, etc., the adsorption capacity is also different! The cost and price are also different! Activated carbon with the same iodine value only has the best effect with coconut shell. 2. Weight by hand: As mentioned above, if you want to improve the adsorption performance of activated carbon, you can only create as much pore structure on the activated carbon as possible. The more pores, the looser the activated carbon and the lighter the relative density. Good activated carbon will feel lighter in hand. In the case of the same weight, activated carbon with good performance will be much larger than inferior activated carbon. Three. Look at the bubbles: Put a small amount of activated carbon into the water. Due to the penetration of water, the water will gradually immerse into the pore structure of the activated carbon, forcing the air in the pores to expel, thereby generating a series of extremely small bubbles, which are pulled out in the water. The tiny bubble line will make a slight bubble sound at the same time, which is very interesting. The more intense this phenomenon occurs and the longer the duration, the better the adsorption of activated carbon. 4. Look at the decolorization ability: Another performance of the adsorption capacity of activated carbon is the decolorization ability. Activated carbon has the magical ability to turn colored liquids into light or colorless. This is actually caused by activated carbon adsorbing pigment molecules in colored liquids. of. V. Important reminder: At present, consumers do not know enough about activated carbon. They often mistake the unactivated bamboo charcoal, charcoal, coconut shell charcoal and other carbonized materials as activated carbon; secondly, they regard low adsorption value carbon carving and ordinary activated carbon as high-quality Activated carbon. Therefore, please distinguish between them when purchasing and do not be fooled.

The effect of activated carbon: 1. The first role of activated carbon in the world was to make gas masks. Later, the role of activated carbon was mainly to deodorize activated carbon in water plants. Activated carbon has a wide range of applications, such as: sugar decolorization, military gas masks, cigarette filters, air purifiers, water treatment in water plants, drinking water purification, detoxification, sobering, treatment of radioactive element pollution, reduction of residual pesticides in the soil, and conditioning of soil performance , Treat indoor formaldehyde, keep vegetables fresh, etc. 2. The unique pore structure of activated carbon: Activated carbon is a kind of microcrystalline carbon material that is mainly made of carbon-containing materials and has a black appearance, developed internal pore structure, large specific surface area, and strong adsorption capacity. There are a large number of micropores invisible to the naked eye in the activated carbon material. The surface area of ​​the micropores in 1 gram of activated carbon material can be as high as 800-1500 square meters, which is even higher for special purposes. In other words, in an activated carbon particle the size of a rice grain, the inner surface area of ​​the micropores may be equivalent to the size of a living room area. It is these highly developed, human capillary-like pore structures that make activated carbon possess excellent adsorption properties. 3. The interaction force between activated carbon molecules: also called “van der Waals gravity”. Although the speed of molecular motion is affected by factors such as temperature and material, it is always in motion in the microenvironment. Due to the mutual attraction between the molecules, when a molecule is captured by the inner pores of the activated carbon and enters the pores of the activated carbon, due to the mutual attraction between the molecules, more molecules will be attracted continuously until the activated carbon is filled. Up to the inner pore. 4. Activated carbon can adsorb various harmful substances: Activated carbon of different materials and uses has different inner pore sizes. Generally speaking, the quality of high-quality coconut shell activated carbon adsorbing harmful substances can approach or even reach its own quality. The characteristics of activated carbon to adsorb harmful substances. Activated carbon is based on the principle of physical adsorption. In the process of action, it relies on air as a medium, so it is defined as a passive air purification material.

Precautions for activated carbon: 1. Clean and remove dust before use, otherwise these black dust may temporarily affect the cleanliness of water quality. However, it is not recommended to rinse directly with fresh tap water, because once the porous activated carbon absorbs a large amount of chlorine and bleach in the tap water, it will damage the water quality when it is placed in the filter for use. 2. It is impossible to clean the clogged debris in the porous pores of activated carbon by simple cleaning. Therefore, the activated carbon must be replaced regularly to prevent the activated carbon from losing its efficacy due to “saturation of adsorption”. And the timing of the replacement is best not to wait for it to fail before replacing it, so as to ensure that the activated carbon can continuously remove the harmful substances in the water quality of the aquarium. It is recommended to replace the activated carbon 1-2 times a month. 3. The efficiency of activated carbon to treat water quality is related to its treatment dosage, usually “the effect of treating water quality with more dosage is relatively good.” 4. After the quantitative activated carbon is used, you should always observe the changes in water quality in the early stage of use, and pay attention to the observation results, as the basis for judging the time for the replacement of activated carbon after failure. 5. When using medicines for the treatment of fish diseases, the activated carbon should be temporarily taken out and the use should be suspended. In order to prevent the drug from being adsorbed by the activated carbon and reducing the therapeutic effect.