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In recent years, the use of honeycomb activated carbon to treat waste gas has been a more common way. Honeycomb activated carbon relies on its own developed void structure and large specific surface area, and the pore structure and specific surface are very decisive factors in waste gas treatment. It is exposed to air to a large extent and carries out contact adsorption on a large area. They then adsorb toxic and harmful substances into their pores. And "save" it. The size of the iodine adsorption value also has a great relationship with the adsorption performance, that is, the adsorption of small iodine adsorption value is not entered, and the adsorption of large iodine adsorption value can be absorbed and stored in large quantities. It is theoretically proved that the greater the iodine adsorption value, the easier it is to be adsorbed by honeycomb activated carbon. The adsorption capacity of honeycomb activated carbon has a great relationship with temperature, and the temperature determines the adsorption capacity and workload of honeycomb activated carbon. Honeycomb activated carbon has a high adsorption capacity when the temperature is 10, which is its preferred temperature. At 30 degrees, the adsorption performance of honeycomb activated carbon is very small.Honeycomb activated carbon used in activated carbon adsorption box, is a kind of organic waste gas filtration adsorption environmental protection equipment products, honeycomb activated carbon adsorption box can be made of stainless steel, carbon steel, PP plate and other materials. Honeycomb activated carbon adsorption box has the advantages of high adsorption efficiency, wide application, easy maintenance, and can handle a variety of mixed waste gases at the same time, honeycomb activated carbon has the effect of removing formaldehyde, benzene, TVOC and other harmful gases and disinfection and deodorization, etc. Honeycomb activated carbon adsorption tower is now widely used in the production of electronic components, battery (battery) production, pickling operations, laboratory exhaust, metallurgy, chemical industry, medicine, painting, food, brewing and other organic waste gas treatment.Organic waste gas is powered by the fan, positive pressure or negative pressure into the honeycomb activated carbon adsorption box, because there is an unbalanced and unsaturated molecular gravity or chemical strength on the solid surface of the honeycomb activated carbon, therefore, when the solid surface is in contact with the gas, it can attract gas molecules, so that it is concentrated and maintained on the solid surface, polluting substances are absorbed. After the exhaust gas is adsorbed by the filter, it enters the dust removal system of the equipment, and the purified gas is discharged to the standard at high altitude. The saturated honeycomb activated carbon can be recycled and recycled, reducing the cost, so the honeycomb activated carbon has become the mainstream product of the current exhaust gas treatment.

Columnar activated carbon adsorption pretreatment technology refers to the method of removing pollutants in water by using the adsorption property or exchange action of substances. Among them, the most used are hydrophobic substances which have strong adsorption effect on organic pollutants and odors in water. However, after the columnar activated carbon participates in the coagulation and precipitation process, it remains in the sludge, and there is no good recovery and regeneration method at present, resulting in high treatment costs and difficult to popularize and apply. Although the clay mineral adsorbents are abundant in supply, cheap in price and have good adsorption properties, a large amount of clay is put into the coagulant to increase the sludge discharge of the sedimentation tank, which brings certain difficulties to the production and operation.France generally uses granular activated carbon in the drinking water treatment process, when used for odor removal and deodorization, the sand filter is placed before the activated carbon adsorption step, so that the water treatment effect is better, and the activated carbon life is more than three years. When activated carbon is used to remove all organic matter in the water, the sand filter is used as the second stage, and the activated carbon adsorption method or the biological activated carbon method used in combination with aeration is used as the first stage, so that the water treatment effect is increased by 20% to 40%.In order to protect the drinking water in a low-lying area from benzene, toluene, chloroform, dichloroethylene and other organic matter pollution, the United States Environmental Protection Agency has built two activated carbon adsorption devices, using the granular activated carbon produced by Calgore company, each adsorption tower is filled with activated carbon 9t, and the drinking water is treated every day (the water plant mixes surface water with groundwater) 4546t.In 1979, a dye factory in Dalian, China used cooling, settling, activated carbon adsorption, expanded limestone neutralization process to treat 1000-2000mg dinitrochlorobenzene containing 0.5% acid washing wastewater. The content of dinitrochlorobenzene in the effluent reached 5mg/L. The saturated carbon was desorbed with chlorobenzene, and was regenerated in the tower by purging steam regeneration.Activated carbon adsorption method is an effective way to treat water, in recent years, activated carbon water treatment application methods continue to deepen the research, and gradually widely used, but it should be emphasized that activated carbon adsorption method for sewage treatment, often used as a secondary treatment, or even tertiary treatment. Wastewater treatment in the world's industrial developed countries is characterized by a large proportion of secondary treatment, such as the United States and the former West Germany in more than 70%, the United Kingdom accounted for almost 100%, many countries have begun to study the application of sewage treatment, including activated carbon adsorption, the wastewater as a second water source to be used. In addition, it should be pointed out that the combined water treatment process, including activated carbon adsorption method, has better water treatment effect and wider application range.At present, the adsorbents used for water treatment are columnar activated carbon, diatomite, silica, activated alumina, zeolite and ion exchange resin. In recent years, some new adsorption materials have been developed, such as porous synthetic resin, columnar activated carbon fiber and so on.

First, the nature of activated carbon1. AdsorptionThe adsorption property is the primary property of activated carbon. Activated carbon has microcrystals that resemble graphite grains but are arranged randomly. During the activation process, pores of different shapes and sizes are generated between microcrystals. Assuming that the pores of activated carbon are cylindrical pores, the radius of the pores can be divided into two categories according to a certain method:(1) According to IUPAC score:Micropore <1.0nmCenter hole 1-25nmLarge hole >25nm.(2) According to habits:Micropore <150nmMiddle hole 150-20000nmLarge hole >20000nm.Because these pores, especially micropores, provide a huge surface area.The pore volume of micropores is generally only 0.25-0.9mL/g, the number of pores is about 1020 /g, and the surface area of all micropores is about 500-1500m2/g, which is usually measured by BET method, and there are also as high as 3500-5000m2/g. Almost 95% or more of the surface area of activated carbon is in micropores, so in addition to some macromolecules can not enter, micropores are an important factor in determining the adsorption performance of activated carbon. The pore volume of the middle hole is generally about 0.02-1.0mL/g, and the surface area can reach several hundred square meters, which is generally only about 5% of the total activated carbon silkworm species. Its function can adsorb steam, and can provide a channel for the adsorption into the micropore, and can directly adsorb larger molecules.The pore volume of large pores is generally about 0.2-0.5mL/g, and the surface area is only about 0.5-2m2/g. One of its functions is to enable adsorbent molecules to quickly penetrate into the smaller pores inside the activated carbon. Second, when the catalyst is used as a catalytic carrier, a small amount of catalyst is often precipitated in micropores, mostly in large and medium pores.The surface area of the activated carbon should include the internal surface area and the external area, in fact, the adsorption properties are mainly from the huge internal surface area, so it can not be mistaken for: grinding the activated carbon will significantly improve the surface area to improve the adsorption force.Many adsorption is reversible physical adsorption, that is, the adsorbed material is a fluid, at a certain temperature and pressure is adsorbed by activated carbon, at high temperature and low pressure adsorbed material and desorption, activated carbon inner surface return to its original state. This is a widely used physical adsorption, also known academically as van der Waals adsorption.2. ChemistryAdsorption of activated carbon in addition to physical adsorption, there are chemical adsorption. The adsorbability of activated carbon depends on both pore structure and chemical composition.Activated carbon not only contains carbon, but also contains a small amount of chemical binding, functional groups of oxygen and hydrogen, such as carbonyl, carboxyl, phenols, lactones, quinones, ethers. Some of the oxides and complexes contained on these surfaces are derived from the derivatives of raw materials, and some are formed by the action of air or water vapor during and after activation. Sometimes surface sulfides and chlorides are also formed. In the activation, the minerals contained in the raw material are concentrated in the activated carbon to become ash, and the main components of ash are alkali metals and alkali earth metal salts, such as carbonate and phosphate.The ash content can be reduced by washing or pickling.The inorganic composition of activated carbon can be seen from the analysis of four kinds of powdered carbon products in Table 3-1. (Schedule omitted)3, catalyticActivated carbon is associated with catalytic abandonment in many adsorption processes, showing the activity of catalyst. For example, activated carbon adsorbs sulfur dioxide by catalytic oxidation into sulfur trioxide.Due to the presence of specific surface oxygen-containing compounds or complexes, activated carbon has catalytic activity for a variety of reactions, such as the formation of phosgene from chlorine and carbon monoxide.Due to the formation of a complex between activated carbon and the carrier, this complex catalyst greatly increases the catalytic activity, such as palladium salt-holding activated carbon, even if there is no copper salt catalyst, the oxidation reaction of olefin can be catalyzed, and the speed is fast and the selectivity is high.Activated carbon can be used as catalyst carrier because of its well-developed porous structure, huge internal surface area and good heat resistance, acid resistance and alkaline resistance. For example, in the hydrogenation, dehydrogenation cyclation, isomerization and other reactions in organic chemistry, activated carbon is an excellent carrier of platinum and palladium catalysts.4. MechanicalThe following items represent the mechanical properties of activated carbon, which are valued by activated carbon users, especially by a large number of industrial users.(1) Particle size: Using a standard screening method to find the weight of activated carbon left in and through each sieve, indicating the particle size distribution.(2) Static density or pile density: the weight of activated carbon per unit volume of dietary pore volume and intergranular void volume.(3) Bulk density and particle density: the weight of activated carbon per unit volume of the pore volume without the void volume between the particles.(4) Strength: the crushing resistance of activated carbon.(5) Wear resistance: that is, wear resistance or anti-friction performance.These mechanical properties directly affect applications, for example: density affects container size; The thickness of powdered carbon affects the filtration; The distribution of carbon particle size affects the fluid resistance and pressure drop. Fragmentation affects service life and waste carbon regeneration.

The adsorption of solute molecules in water by powdered activated carbon is a complex process, which is the result of the combined action of several forces, including ion attraction, van der Waals force and chemical impurity force. According to the two-rate diffusion theory of adsorption, adsorption is a two-speed process consisting of two stages of rapid diffusion and slow diffusion, and rapid diffusion is completed within a few hours, playing 60% to 80% of the adsorption capacity of activated carbon. Rapid diffusion is a process in which solute molecules are diffused in large pores with low resistance distributed radially in carbon particles. These large pores create radial diffusion resistance. When the molecule diffused further from the macropore into the micropore connected with the macropore, it was extremely slow due to the great resistance generated by the narrow aperture. The micropores are also evenly distributed within the carbon particles, but do not constitute radial diffusion resistance. The factors affecting the adsorption of powdered activated carbon involve the polarity, molecular weight and spatial structure of solute, which depend on the characteristics of water quality. Activated carbon has selective adsorbability to different substance molecules.

Activated carbon selection is not good attenuation obvious life is not long, generally 6 months to 1 year or so to change once, change the cost of activated carbon is very high. The adsorption force of the special activated carbon can reach more than 100%, and the desorption and stability are good, so the life span is more than 2-3 years, and the cost can be saved. The specific surface area of activated carbon has a great relationship with the pore structure, and different organic solvents use activated carbon with different pore sizes, so as to ensure that the attenuation is not obvious, has the characteristics of small piezoresistivity through the gas, strong adsorption capacity, and easy desorption, ensure that the gas overflow rate is faster, and eliminate the local temperature rise.Organic waste gas treatment activated carbon has the advantages of reasonable pore size distribution, high adsorption capacity, fast adsorption speed, large mechanical strength, used in a fixed bed, low airflow resistance, easy desorption and regeneration, and has a strong adsorption capacity for most inorganic gases (such as sulfides, nitrogen oxides, etc.) and most organic vapors and solutes in a wide concentration rangeSpecific indicators are as follows:Adsorption index: CTC good more than 100% benzene adsorption: good more than 50% acetone adsorption: more than 50%Strength: 70-90% or 95% later, depending on the specific application. Not the higher the better, the higher the strength of the adsorption may decrease.Specific gravity: The higher the specific gravity, the greater the cost, indicating that the smaller the specific surface area, the more solid. The heavier a cube is, the heavier it is.Ash content: less than 6%, moisture < 5% impurities are too high will also affect adsorption and cost.Ignition point: > 450 degreesMaterial: The main choice of wood or coal, coconut shell is not suitable because the organic solvent needs mesoporous activated carbon, if the coal quality to achieve the above index cost is higher than wood. Ordinary coal-based activated carbon CTC50-70% benzene adsorption: 20-40% lignin chemical activated carbon: CTC: 100%-140% benzene adsorption: 45-60% The proportion of only half of coal.Organic waste gas treatmentsummarizeOrganic waste gas treatment refers to the use of a variety of technical measures, through different ways to reduce oil consumption, reduce the amount of organic solvents or exhaust gas purification to eliminate organic waste gas pollution. Organic waste gas pollution sources are widely distributed. In order to prevent pollution, in addition to reducing oil consumption, reducing the amount of organic solvents to reduce the production and emission of organic waste gas, exhaust gas purification is a practical approach. The commonly used methods are adsorption, absorption, catalytic combustion, thermal combustion and so on. When selecting the purification method, the county should choose the method with low cost, less energy consumption and no secondary pollution according to the specific situation, try to turn the harm into benefit, and fully recover the components and waste heat. In most cases, the petrochemical industry adopts condensation, absorption, direct combustion and other methods because of the high exhaust concentration. Coating construction, printing and other industries due to low exhaust concentration, the use of adsorption, catalytic combustion and other methods.Management method1, condensation recovery method: the organic waste gas directly into the condenser through adsorption, absorption, plate, separation, can recover valuable organic matter, the method is suitable for high concentration of organic waste gas, low temperature, small air flow conditions, need to attach refrigeration equipment, mainly used in pharmaceutical, chemical industry, printing enterprises less.2, absorption method: The general use of physical absorption, that is, the waste gas into the absorption liquid into purification, to be saturated after the absorption liquid by heating, analysis, condensation recovery; This method is suitable for large gas volume, low temperature and low concentration of waste gas, but it needs to be equipped with a heating analysis recovery device, which is large in volume and high in investment.Generally, activated carbon adsorption method is used: exhaust gas is absorbed by activated carbon, when the adsorption is saturated, activated carbon desorption regeneration, catalytic combustion of the exhaust gas after blowing off, converted into harmless substances, and the regenerated activated carbon continues to be used. When the activated carbon is regenerated to a certain number of times, the adsorption capacity is significantly reduced, and the activated carbon needs to be regenerated or renewed.Activated carbon is the most used method to treat organic waste gas. It has good adsorption performance for benzene waste gas, but poor adsorption for hydrocarbon waste gas. The main disadvantage is that the operation cost is high and it is not suitable for the environment with high humidity, but for the current market application, the use of activated carbon adsorption is more commonly used. Activated carbon is used more: activated carbon particles and activated carbon fiber, the price of activated carbon particles is cheaper, but the effect is poor, compared with the price of activated carbon fiber is relatively high, the effect is better.Xinsen organic gas special activated carbon:(1) Large specific surface area, high effective adsorption capacity. Since the surface area of the same weight of Xinsen activated carbon is nearly ten times that of the coal-based activated carbon particles, the weight of the Xinsen activated carbon that needs to be filled is very small, but the adsorption efficiency is very high, and the adsorption efficiency is between 85% and 98% according to the organic gas content and other physical characteristics of the processed waste gas. The multistage adsorption process can reach 99.99%, which is much higher than the higher adsorption rate of 88% of the ordinary activated carbon particle adsorption method, and the volume and total weight are also very small.(2) Short travel of adsorption and desorption, fast speed; Low energy consumption for desorption and regeneration. The organic gas adsorption capacity of Xinsen activated carbon is several times to dozens of times larger than that of ordinary granular activated carbon (GAC), and it also has a good adsorption capacity for inorganic gases, and can maintain a high adsorption and desorption speed and a long service life. If heated with water vapor for 10-30 minutes, it can be completely desorption, good heat resistance, high temperature resistance in inert gases above 1000 ° C, and ignition point in the air above 450 ° C.(3) Variable shape, easy to use. It has columnar and spherical particles, so it is very convenient to replace and will not cause any harm to the human body.(4) Can produce special activated carbon with special properties according to needs; Good strength, will not cause secondary pollution.3, direct combustion method: the use of gas or fuel and other auxiliary fuel combustion, the mixed gas heating, so that harmful substances under the action of high temperature decomposition into harmless substances; The process is simple, the investment is small, suitable for high concentration, small air volume of waste gas, but the safety technology, operation requirements are high.4, catalytic combustion method: the waste gas heating through catalytic combustion into harmless odorless carbon dioxide and water; This method has the advantages of low ignition temperature, energy saving, high purification rate, convenient operation, small footprint and large investment, and is suitable for high temperature or high concentration of organic waste gas.5. Adsorption method:(1) Direct adsorption method: organic waste gas is adsorbed by activated carbon, which can reach a purification rate of more than 95%. The equipment is simple and the investment is small, but the activated carbon is frequently replaced, which increases the working procedures such as loading and unloading, transportation, and replacement, resulting in an increase in operating costs.(2) Adsorption-recovery method: The use of fiber activated carbon to adsorb organic waste gas, after close to saturation with superheated water steam blowback, desorption regeneration; This law requires the supply of the necessary steam.(3) New adsorption-catalytic combustion method: This method combines the advantages of adsorption method and catalytic combustion method, using a new adsorption material (honeycomb activated carbon) adsorption, hot air is introduced to desorption and analysis after approaching the drink and after desorption, the exhaust gas is introduced into the catalytic combustion bed flameless combustion, which is completely purified, and the hot gas is recycled in the system, greatly reducing energy consumption. This method has the characteristics of stable and reliable operation, low investment, low operating cost, convenient maintenance, etc. It is suitable for the waste gas treatment of large air volume and low concentration, and is a relatively mature and practical method for the treatment of organic waste gas in China

Activated carbon is a kind of microcrystalline carbon material made of carbon-containing materials with black appearance, developed internal pore structure, large surface area and strong adsorption capacity. It is a commonly used adsorbent, catalyst or catalyst carrier, widely used in almost all sectors of the national economy and People's Daily life.Activated carbon classification - There are no less than thousands of activated carbon varieties due to different raw material sources, manufacturing methods, appearance shapes and application occasions.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 (various coal and petroleum and its processing products are made of raw materials), and activated carbon made of other raw materials (such as activated carbon made of waste rubber, waste plastic, etc.).According to the manufacturing method, it can be divided into chemical activated carbon (chemical carbon)The method of preparing activated carbon by heat treatment after mixing carbon-containing raw materials with certain chemicals is called chemical method. Activated carbon produced by chemical process is also known as chemical activated carbon or chemical carbon.Chemicals that can be used as chemical methods are also called activators, activators are 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, salts can be used as activators, mainly from the performance and economy of activated carbon to consider what kind of activator.In general, the secondary micropores and mesoporous pores (that is, pores with pore diameter or pores wider than 1.5 nanometers) of chemical carbon are more developed, mainly used for liquid phase adsorption refining and solvent recovery gas phase (vapor) adsorption occasions.Chemical manufacturing of activated carbon due to the addition of chemicals in the manufacturing process should pay great attention to environmental protection and the impact of trace elements brought into the product may exist.