1. Activated carbon packaging is preferably sealed and packaged. Because the organic macromolecular substances are more or less permeated in the air, especially in the storage cabinets of the newly renovated shops or homes, the concentration of phenolic substances is extremely high, and these substances are absorbed by the activated carbon, which accumulates over time. The adsorption properties of activated carbon are reduced or even unusable due to the adsorption of these substances. Therefore, the more activated carbon with higher adsorption value, the more sealed packaging should be used to prevent the performance of activated carbon from being disturbed by the outside.
2. The counterfeit activated carbon that appears on the market now is pretending to be a semi-finished “carbonized material†of activated carbon. The carbonized material can only become a real activated carbon through the “activation†process, and the activation process is the most important pore structure in the activated carbon manufacturing process. the process of. The carbonized material that lacks this process can be said to have almost no adsorption performance, which is not harmful to consumers. Since the carbonized material is not subjected to the process of activation and pore formation, the surface is smoother than the activated carbon, and the color is white, slightly metallic, and the handle is harder than the activated carbon, and the weight is also much heavier. A considerable part of the fake activated carbon is produced by inferior raw materials, diatomaceous earth, which has extremely low carbon content, and most of them are inactive substances. The carbon color is relatively white, the hand feel is very heavy, and the particle length is long. The strength is also very high, and the collision will give a crisp sound similar to that of a ceramic tap. The hand rubs the meeting and finds that there are white fine particles on the section. When buying, you must pay attention to avoid being fooled.
[Coal activated carbon treatment petrochemical plant sewage report]
Coal-based activated carbon treatment of refinery wastewater is different from that of petrochemical plant wastewater. In the refinery wastewater, the activated carbon adsorbed substances are treated with hydrocarbons, and in the petrochemical plant wastewater, according to the results of the Japanese scholars' penetration of COD adsorption at various depths of the activated carbon layer, the activated sludge method is used as a pretreatment. The adsorption effect of the activated carbon is greatly enhanced; however, there are exceptions, and when the substance having a large adsorption property contained in the drainage becomes hydrophilic and difficult to adsorb, the adsorption performance of the activated carbon is lowered.
It can be seen that it is very important to understand as much as possible the behavior of COD components in the drainage in various treatment methods. For details, see the article on the important drainage treatment system using coal-based activated carbon adsorption. In addition, it should be emphasized that the BOD/COD ratio does not change when the raw water is treated with activated carbon or when the activated sludge treatment water is treated, but the BOD can be selectively removed during the activated sludge treatment. There are many types of adsorbed substances and they are complicated. The compounds contained in these drainages include ethanol, diethyl ether, butyraldehyde, benzene, etc., and their general tendency to adsorb varies depending on the type of compound, molecular weight, and the like.
Coal-based activated carbon is more easily adsorbed than aromatics in general aromatics; linear compounds have weaker adsorption capacity than side chain compounds; in the substituents, the adsorption capacity of the compounds is lowered by the base and amine groups, and the nitro group and the sulfonic acid group The adsorption capacity increases; the influence of adsorption of light base, halogen, double bond and the like varies with the compound; the compound with high solubility usually has low adsorption force; the strong electrolyte has lower adsorption force than the weak electrolyte; the substance with larger molecular weight has larger adsorption capacity than the small component. .
In refinery wastewater and petrochemical plant wastewater, process wastewater or oily drainage is the usual treatment target. Because this type of sewage contains floating oil and suspended matter, direct treatment with coal-based activated carbon is not suitable. Therefore, in the refinery sewage and petrochemical plant sewage treatment, it is necessary to pretreat with coagulation sedimentation, coagulation and uplift, sand filtration and its combination method to remove oil and suspended matter first, and then treat it with activated carbon. effective. In petrochemical plant wastewater, there is often no floating matter, but sometimes the BOD value is high or the BOD/COD ratio is high. Therefore, it is not necessary to pretreat by coagulation or filtration. However, it is necessary to use activated carbon adsorption method and activated sludge method. The chemical treatment method is used in combination.
[Activated activated carbon produced by gas activation method]
The gas activation method is a method for preparing activated carbon by using a gas activator such as steam, carbon dioxide or the like to oxidize a gas at a high temperature after the carbonaceous raw material is carbonized, since the activation does not require inorganic chemicals, and thus Called the physical method, the gas activation method is one of the widely used methods in the production of activated carbon. Most of the granular activated carbon is produced by the gas activation method, and it is also used for the production of powdered activated carbon.
1. Basic knowledge of gas activation
The formation and properties of raw material carbon: When carbon is used as raw material, such as wood, nut and coal, the activated carbon is activated by gas activation method, firstly carbonized at a temperature of 400-600 ° C to prepare a raw material carbon suitable for activation. In the carbonization process, non-carbon elements such as oxygen and hydrogen contained in the raw materials, most of the low-molecular product gaseous states (such as carbon monoxide, carbon dioxide, water and low-molecular organic substances) are volatilized, and finally a solid carbonized product is formed, that is, Raw material charcoal.
The nature of the raw material carbon is closely related to the type of raw materials and the carbonization conditions. They have a common carbon content and contain some volatile components and volatiles at high temperatures. From the perspective of microstructure, they are composed of carbon basic crystallites (also known as graphite-like crystallites), single-network planar carbon and non-organized carbon. They belong to microcrystalline carbon (formerly known as amorphous). carbon). In microcrystalline carbon, the irregular arrangement of the basic crystallites of carbon causes many pores to form between the crystallites, but most of these pores are occupied by non-organized carbon. Therefore, the pores of the raw material carbon are not developed, and the pores are not developed. The volume is small, the specific surface area is small, and it needs to be activated to be converted into activated carbon.
2. Gas activation process
The process of gas activation is a process in which the gas activator acts on the carbon at the high temperature and the raw material carbon to gradually develop the pore structure of the carbon. In the process of gas activation, the following functions are used: the non-organized carbon such as tar is removed, and the original blockage is caused. The pores are open and unobstructed. The non-composed carbon, such as tar, which is formed during the carbonization process and which does not remain in the pores of the raw material carbon, can be removed from the raw material carbon with the inert gas under the condition of heating and introducing an inert gas. As a result, the pores that were originally blocked by them were opened and unblocked, and the raw material charcoal was activated to a certain extent.
Under the conditions of activation, the combination of high temperature and gas activator makes this process easier. It is believed that this effect mainly occurs when the weight reduction rate is within 10% during reactivation.
When the activated carbon is produced by the gas activation method, the activated carbon is called the activated material, and the percentage of the difference between the weight of the dry raw material carbon and the dry activated material is the weight reduction rate. The weight reduction rate is an important indicator. When the activation process proceeds normally, it embodies the degree of activation of the raw material carbon. Therefore, it is commonly used as a measure of the degree of activation in production.
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