Activated carbon purification adsorber (Dongguan Meijun Automation Equipment Co., Ltd.)
Activated carbon is a very small carbon particle with a large surface area, and because the surface area of the carbon particle is large, it is very important to study the surface area of activated carbon
Activated carbon is a hydrophobic adsorbent made from carbon-containing materials as raw materials, which is carbonized and activated at high temperature. It is a very small carbon particle with a large surface area.
Activated carbon carbon particles also contain a large number of smaller pores-capillaries. This capillary has a strong adsorption capacity. Micropores have a large specific surface area, so they can be fully contacted with gases (impurities). Once the capillary is adsorbed, it can play a purification role, can effectively remove chroma and odor, and can remove most organic pollutants and certain inorganic substances in the secondary effluent, including some toxic heavy metals.
Storage tanks made of activated carbon, plus other auxiliary facilities, enable activated carbon to adsorb more harsh gases in a short period of time, purify more impurities and flavors in polluted gases, and achieve the purpose of exhaust gas treatment.
The factors that affect the adsorption of activated carbon are: the characteristics of activated carbon; the characteristics and concentration of the adsorbed substance; the pH value of the wastewater; the characteristics of the suspended solids content; the contact system and the operation mode. Activated carbon adsorption is the most important and effective treatment technology in the advanced treatment of urban sewage and has been widely used.
Activated carbon can effectively adsorb chlorinated hydrocarbons, organophosphorus and urethane insecticides. It can also adsorb phenyl ether, n-nitrochlorobenzene, naphthalene, ethylene, xylenol, benzene powder, DDT, alzheimer, alkyl Benzenesulfonic acid and many esters and aromatic compounds. The secondary effluent also contains organic substances that are not adsorbed by activated carbon, such as intermediate degradation substances of proteins, which are more difficult to be adsorbed by activated carbon than the original organic substances, and the removal capacity of activated carbon for THMS is low, only 23-60%. The activated carbon adsorption method is used in combination with other treatment methods. Ozone-activated carbon method, coagulation-adsorption activated carbon method, Habberer process, activated carbon-diatomite method, etc. have appeared, which significantly prolonged the adsorption cycle of activated carbon, reduced the amount of use, and the treatment effect and scope. substantial improvement.
Adsorption is a slow-acting process in which one substance adheres to the surface of another substance. Adsorption is an interface phenomenon activated carbon adsorption method, which is related to changes in surface tension and surface energy. There are two kinds of driving forces that cause adsorption, one is the repulsive force of solvent water to hydrophobic substances, and the other is the affinity and attraction of solids to solutes.
Adsorption in wastewater treatment is mostly the result of a combination of these two forces. The specific surface area and pore structure of activated carbon directly affect its adsorption capacity. When selecting activated carbon, it should be determined through experiments according to the water quality of the wastewater. For printing and dyeing wastewater, carbon species with well-developed transition holes should be selected. In addition, ash also has an effect. The smaller the ash, the better the adsorption performance; the closer the size of the adsorbent molecules to the diameter of the carbon pores, the easier it is to be adsorbed; the concentration of the adsorbent also affects the amount of activated carbon adsorbed. Within a certain concentration range, the amount of adsorption increases with the increase of the concentration of the adsorbate. In addition, water temperature and pH also have an effect. The amount of adsorption decreases with increasing water temperature and increases with decreasing pH. Therefore, low water temperature and low pH value are favorable for the adsorption of activated carbon.
Adsorption of activated carbon Adsorption refers to the action of liquid or gas adhering to a solid surface, which can occur in general activated carbon. Adsorption is different from absorption. Absorption refers to the entry of liquid or gas into the solid atomic structure, but activated carbon does not have this ability. Its adsorption is only a surface phenomenon, so it only occurs on its surface.
The formation of adsorption mainly comes from the London dispersion force, which is another manifestation of van der Waals force. This force is common among molecules that do not have a permanent dipole moment, and it is a natural attraction. As long as the molecules are close enough, this force will naturally occur. Any action that can use this force to attract matter is called physical adsorption. This force is independent of temperature and is therefore not affected by temperature.
The London dispersion force must take place after the distance between the surface of the carbon and the adsorbed molecules has reached. The magnitude of the force relates to the extent to which all relevant atoms in the adsorbed molecules are in close contact with the carbon atoms on the surface of the activated carbon. The higher the degree of contact, the greater the force, and the stronger the adsorption capacity of activated carbon for the molecule.
① Properties of activated carbon adsorbent The larger the specific surface area of activated carbon, the stronger the adsorption capacity; activated carbon is a non-polar molecule, which is easy to adsorb non-polar or low-polar adsorbents; the size of activated carbon adsorbent particles, and the structure of fine pores And distribution, as well as surface chemistry, have a great impact on adsorption.
② The nature of the adsorbent depends on its solubility, surface free energy, polarity, the size and unsaturation of the adsorbent molecules, and the concentration of the attached substances. ③ Wastewater PH activated carbon is generally more acidic than in alkaline. High adsorption rate.
The pH value will affect the state and solubility of the adsorbate in water, which will affect the adsorption effect.
④ When coexisting substances coexist with multiple adsorbents, the adsorption capacity of activated carbon for a certain adsorbent is worse than that with only that adsorbent. ⑤ Temperature and temperature have less influence on the adsorption of activated carbon. There is a certain contact time to make the adsorption close to equilibrium and make full use of the adsorption capacity.
Chemical properties of activated carbon
In addition to physical adsorption, activated carbon also has chemical adsorption. The adsorption of activated carbon depends on both the pore structure and the chemical composition.
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