The commonly used activation gases are carbon dioxide, water vapor, oxygen, etc., due to the oxidation reaction of these gases on the surface of the carbonized substance, eroding the carbonized substance, thus producing a rich porous structure.(2) Chemical method.hsl fused alumina
Chemical activation method is a method of preparing activated carbon by adding chemicals to the raw materials used or impregnation into the raw materials or carbonized materials, and then heating it at high temperature in inert gas.The chemicals used in chemical activation are generally dehydrating.The more commonly used activator is: inorganic acid varieties have phosphoric acid, sulfuric acid and boric acid, salt varieties have zinc chloride, calcium carbonate and potassium sulfate, alkali varieties have sodium hydroxide, potassium hydroxide, etc.https://www.hslabrasive.com
The main principle of chemical activation method is the raw materials in 0.5~5 times the chemical activator impregnation for a certain time, in the process of heating, because of the dehydration of chemicals, the H and О elements in the raw materials in the form of water vapor released, the results produced a developed porous structure of activated carbon.The method requires the oxygen content in the raw material.25%, hydrogen content ≥5%[4], and most of the materials that can meet the requirements of this index are rice husk, wood and coalCombined Equations (5) and (10) can calculate the total amount of Pb and 21Bi atoms in activated carbon after adsorption for any length of time (i.e., the total number of activated carbon Y).Let n=0 in Equation (10), then the accumulation and attenuation of total atomic amount of 2Pb and 2Bi (total number of activated carbon Y) after the removal of activated carbon can be calculated in Equation (10).In fact, if thin layer activated carbon is used, the value of N should be equal to the product of the adsorption coefficient of activated carbon and radon concentration, while the radon adsorption coefficient of activated carbon mainly depends on the type of activated carbon and is affected by temperature, humidity and other factors.
When the radon adsorption coefficient of activated carbon is constant,n is proportional to the concentration of radon. In this case, Equation (10) represents the functional relationship among the total number of activated carbon V, radon concentration and adsorption (or exposure) time. Therefore, the concentration of radon in the environment can be calculated according to the total number of activated carbon and adsorption time.Simulation calculation and result analysis of total number of activated carbon According to Equations (5) and (10), a computer program can be written to calculate the relationship between the total number of Y in the process of radon adsorption on activated carbon and the relationship between the total number of Y after the removal of activated carbon and the change of time.When the adsorption time is 85 min, take n-600), and the calculated theoretical curve is shown in FigureIt can be seen from the figure that the measured curve is in good agreement with the theoretical curve.Fig. 2 is the simulation result of the total number of Y taken out over time after activated carbon adsorbs 1 radon atom from the environment every second and continues to adsorb for 3 days.After the activated carbon was taken out, the total number of V reached the maximum after t time, and then the total number became smaller. After about 50 min, the total number of V decreased by a negative exponential function.
The curve can be divided into a stationary area and a measuring area. The width of the stationary area (i.e. the duration of the stationary area) is set at (t+50) min, followed by the measuring area.
There is no obvious rule of counting in the standing zone. Should be avoided during this period of time.Total number of;The measurement area is counted by