Activated carbon is the most important and most used adsorbent material in water purifiers. It is made of coconut shell, husk, etc., through carbonization (steaming furnace), activation (activation at 800 °C high temperature steam in Slep activation furnace), crushing, screening, air separation, water washing, drying, etc. Got it. As early as the 1930s, activated carbon was used to adsorb phenol from wastewater from coking plants. Therefore, the application of activated carbon in water treatment has been nearly 80 years old.
Classification of activated carbon
1. According to the different raw materials of activated carbon, activated carbon can be divided into:
(1) Wood charcoal: It can be divided into charcoal (made from wood chips), bamboo charcoal (made from bamboo as raw material), shell charcoal (made from walnut shell or apricot kernel), coconut shell charcoal ( Made from coconut shell)
(2) Coal charcoal (made of anthracite, with better quality in Ningxia)
(3) bone charcoal (made of animal bones)
(4) Silver-loaded activated carbon: Generally, the shell-shell activated carbon is used as a raw material, and the silver is loaded by a special process. The silver content is usually 0.1-0.3%, and it will slowly release silver ions (Ag) in water, while silver ions have The bactericidal effect, therefore, in addition to the adsorption function of ordinary activated carbon, the silver-loaded activated carbon also has the function of inhibiting the growth of bacteria. The water purifier must use high-quality silver-loaded activated carbon, otherwise the silver ions in the effluent will exceed the standard at the beginning, and no silver will be dissolved after a long time. I once asked the director of an activated carbon production plant, how do you produce silver-loaded activated carbon? He said that the activated carbon is washed, soaked in silver nitrate solution, removed, filtered, and then soaked in hydrochloric acid or brine. Drain, wash and dry. I said that you are carrying silver chloride. Silver chloride has a high solubility in water. The above situation will occur. At the beginning, the silver ion in the effluent exceeds the standard. Drinking this water is harmful to the human body. After a long time, the silver chloride is completely dissolved. When it is finished, there will be no silver ions dissolved, and there will be no bacteriostatic effect. Therefore, such silver-loaded activated carbon is definitely not acceptable, and it is recommended to use it with caution.
2. According to the different forms of activated carbon, the activated carbon commonly used in household water purifiers can be divided into:
(1) Powdered activated carbon (PAC). Powdered activated carbon is actually a granular activated carbon with a finer particle size. Due to the small size of the particles and the large specific surface area, its adsorption effect is superior to that of the commonly used granular activated carbon. Germany Shibaokang and US Aihuipu use powdered activated carbon.
(2) Granular activated carbon (GAC). This is the most commonly used activated carbon in water purifiers. The smaller the particle, the better the adsorption effect, but the greater the resistance of the water (inlet and outlet pressure difference), the easier it is to leak carbon. Therefore, the water purifier manufacturer should select the particles with the appropriate particle size. In large-scale water treatment equipment, 10~24 mesh (Φ2.0-0.8mm) is often used. The small household water purifier is recommended to use 16~32 mesh due to the short carbon column height, fast flow rate and short contact time between water and activated carbon. Φ1.3 to 0.6 mm).
(3) Activated carbon fiber felt (ACF), according to different raw materials, it has two kinds: one is made of viscose-based fiber filament as raw material, processed into cloth, carbonized, activated and treated at high temperature; It is made of polyacrylonitrile-based fiber as raw material, processed into felt, pre-oxidized, charred, activated and treated at high temperature. The average pore size is 17 to 26 A, and the latter is 10 to 20 A.