At present, every household uses coal-based columnar activated carbon, because activated carbon has strong adsorption capacity, adsorption and drying, and good effect. Activated carbon has no effect on human body, and the physical effect of activated carbon has deodorization and moisture resistance. Currently used in automotive or indoor purification. Because activated carbon is a very fine carbon particle with a large surface area, and there are more fine pores in the carbon particles - capillary, and this capillary has a strong adsorption capacity, coupled with the large surface area of ​​activated carbon carbon particles , so it can be in full contact with gases (impurities). When these gases (impurities) are adsorbed against the capillary, the purification effect is obtained.
The coal-based columnar activated carbon produced by Keyuan after many years of research is a porous carbonaceous material, and its prosperous leisure structure in the production process makes it have a large surface area. It is easy to contact with the toxic and harmful gases in the air, and the strong adsorption capacity around the activated carbon pores. To meet this requirement, the requirements for the selection and processing of activated carbon materials are extremely severe. That is, the skill of activated carbon molding can not be dealt with constantly, so that it can be used in practice by using activated carbon powder or granules. Zhongyi is scattered. Easy to pollute. Not easy to keep. Use short defects such as time.
Several methods for surface structure reduction of activated carbon are as follows
1) Keyuan Water Purification Plant has decided to reduce the relative content of basic groups by reducing the relative content of basic groups by reducing agents, increasing the non-polarity of the surface and improving the adsorption capacity of activated carbon for non-polar substances. Activated carbon after surface reduction exhibits different characteristics when treated with dyes. For anionic dyes, there is a close relationship between the surface alkalinity of the activated carbon and the adsorption effect. The adsorption mechanism is the interaction between the anaerobic Lewis base of the activated carbon surface and the free electrons of the adsorbed dye. For cationic dyes, the oxygen-containing functional groups on the surface of activated carbon play an active role, but the heat-treated activated carbon still has a good adsorption effect on cationic dyes, indicating that electrostatic adsorption and dispersion adsorption are two comparable adsorption mechanisms.
2) Branch source activated carbon can introduce specific heteroatoms and compounds on the surface of activated carbon by liquid-phase deposition adsorption, and use the combination of these substances and adsorbate to increase the adsorption capacity of activated carbon. In the case of liquid phase deposition, the type of impregnant is a major factor affecting the adsorption effect. For different adsorbed substances, activated carbon can be treated with different impregnating agents to obtain good adsorption effect.
3) The activated carbon of Keyuan Water Purification Plant tells everyone that it is worth noting that when the surface functional group of activated carbon is modified, it is accompanied by changes in surface chemistry, and its surface area, pore volume and pore size distribution will change. It also affects the adsorption of activated carbon. Therefore, when modifying the surface functional groups, different modifications are applied to different adsorption conditions and adsorbates, and the effects of the physical and chemical structures of the activated carbon should be considered comprehensively.
[Overview of activated carbon wastewater treatment technology]
The technology of activated carbon in sewage treatment is to separate the pollutants contained in the sewage by various methods, or convert it into harmless and stable substances, thereby purifying the sewage.
I. Classification of sewage treatment methods
Modern sewage treatment technologies can be divided into four categories according to their working principles: physical law, chemical method, physical chemical method and biological treatment method.
(1) Physical law
Through physical action, to separate and recover the insoluble suspended pollutants (including oil film and oil beads) in the sewage, the chemical properties are not changed during the treatment. The physical method is simple and economical to operate. Gravity separation methods, centrifugal separation methods, filtration methods, evaporation, crystallization methods, and the like are often used.
Gravity separation (ie precipitation)
Using the principle of different suspended pollutants and water density in the sewage, the suspended solids in the water are separated by gravity sedimentation (or floating). The sedimentation (or floating) treatment equipment has a grit chamber, a sedimentation tank and a grease trap.
In the sewage treatment and utilization method, activated carbon precipitation and floating method are often used as pretreatment before other treatment methods. If the biological treatment method is used to treat sewage, it is generally necessary to remove most of the suspended matter in the pre-sinking tank to reduce the treatment load of the biochemical treatment structure, and the biologically treated effluent still has to be treated by the secondary sedimentation tank to ensure the separation of the muddy water. Water quality.
2. Filtration method
The filter medium is used to intercept the suspended matter in the sewage. The filter medium has steel bars, screens, abrasive cloth, plastics, microporous tubes, etc. Commonly used filtration equipments include grids, grids, microfilters, sand filters, vacuum filters, filter presses, etc. (the latter two filters) The machine is mostly used for sludge dewatering).
3. Air flotation (flotation)
The air is introduced into the sewage and precipitated from the water as a carrier in the form of tiny bubbles. The fine particulate pollutants (such as emulsified oil) whose relative density is close to water adhere to the bubbles and rise to the surface with the bubbles. The pollutants in the sewage can be separated from the sewage. Depending on the way the air is driven in, the air floatation method includes a pressurized dissolved air floatation method, an impeller air floatation method, and a jet air floatation method. In order to improve the air flotation effect, it is sometimes necessary to add a coagulant to the sewage.
4. Centrifugal separation
When the sewage containing suspended pollutants is rotated at a high speed, the suspended particles (such as emulsified oil) and the sewage are separated by different centrifugal force. The commonly used centrifugal equipment can be divided into two types according to the centrifugal force generation method: the centrifugal separator is generated by the rotation of the water flow itself, and the centrifugal separator is driven by the rotation of the device while also driving the liquid to generate centrifugal force.
The cyclone separator is divided into two types: pressure type and gravity type. Because of its small volume and high capacity per unit volume, it has been widely used in steel rolling wastewater treatment and high turbidity river water treatment in recent decades. There are many types of centrifuges, and there are constant speed centrifuges and high speed centrifuges according to separation factors. The normal-speed centrifuge can be used to separate low-slurry wastewater by up to 60% to 70%, and can also be used for sedimentation and dewatering of sedimentation tanks. The high-speed centrifuge is suitable for the separation of emulsions. For separation of wool wastewater, it can recover 30% to 40% of lanolin.
(2) Chemical law
A chemical substance is added to the sewage, and a chemical reaction is used to separate or recover certain pollutants in the sewage or convert them into harmless substances. Commonly used methods include chemical precipitation, coagulation, neutralization, redox (including electrolysis), and the like.
Chemical precipitation method
A method of adding a chemical substance to the sewage to cause it to exchange with a dissolved substance in the sewage to form a precipitate that is hardly soluble in water to reduce dissolved substances in the sewage. This treatment is commonly used in the treatment of industrial production wastewater containing heavy metals, cyanides and the like. Depending on the precipitant used, the chemical precipitation method can be divided into a lime method (also known as a hydroxide precipitation method), a sulfide method, and a bismuth salt method.
2. Coagulation method
Adding a coagulant to the water can make the colloidal particles in the sewage lose stability and condense into large particles and sink. Finely dispersed solid particles, emulsion oil and colloidal substances in sewage can be removed by coagulation. The method can be used to reduce the turbidity and chromaticity of sewage, remove a variety of high molecular substances, organic matter, certain heavy metal poisons (mercury, cadmium, lead) and radioactive materials, and can also remove eutrophic substances such as phosphorus. Soluble inorganic substances can also improve the dewatering performance of sludge. Therefore, the coagulation method is widely used in industrial wastewater treatment, and can be used as an independent treatment process or in combination with other treatment methods as pretreatment, intermediate treatment or final treatment. Coagulants commonly used at present are aluminum sulfate, basic aluminum chloride, iron salts (mainly ferrous sulfate, ferric chloride and ferric sulfate).
When the coagulant is used alone to achieve the desired water purification effect, in order to strengthen the coagulation process and save the amount of coagulant, it is often possible to add a coagulant at the same time.
3. Neutralization method
Used to treat acidic wastewater and alkaline wastewater. Alkaline substances such as lime, sodium hydroxide, limestone, etc. are added to the acidic wastewater to make the wastewater neutral. The alkaline wastewater can be neutralized by blowing flue gas containing CO2, and other acidic substances can be used for neutralization.
4. Redox method
Oxidizing and decomposing harmful substances in waste water into harmless substances by using strong oxidants such as liquid chlorine, ozone, potassium permanganate or by anodic reaction during electrolysis; and causing harmful substances in waste water by using a reducing agent or a cathodic reaction during electrolysis Reducing to harmless substances, the above methods are collectively referred to as redox methods.
Examples of application of redox method in sewage treatment include: air oxidation treatment of sulfur-containing sewage; alkaline chlorination treatment of cyanide-containing sewage; ozone oxidation method for deodorization, decolorization, sterilization and removal of phenol, cyanide and iron , manganese, reduce the BOD and COD of sewage have significant effects. The reduction method is currently mainly used for chromium-containing sewage treatment.
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