Activated carbon, also called activated charcoal, is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Activated is sometimes substituted with active. Due to its high degree of microporosity, just one gram of activated carbon has a surface area in excess of 1,300 m2 (14,000 sq ft), as determined by gas adsorption. An activation level sufficient for useful application may be attained solely from high surface area; however, further chemical treatment often enhances adsorption properties.Activated carbon is usually derived from charcoal and is sometimes utilized as biochar. Those derived from coal and coke are referred as activated coal and activated coke respectively.
The activation of carbons involves the exposure of carbon to an atmosphere of CO2, CO, O2, H2O vapor and sometimes other specified gases, at temperatures between 300°C and 800°C. This is followed by quenching of the carbon in air or water. Activated carbons are generally used as adsorbents or catalysts. They can be used in the removal of dyes, odors, tastes, and contaminants. They are, therefore, also used in water decontamination and purification processes.Activated carbon is available in a variety of grades for purification and, particularly, for decoloration applications, as well as for specialized uses.
What is activated carbon made from ?
Activated carbon (activated charcoal) can made from many substances containing a high carbon content such as coal, coconut shells and wood. The raw material has a very large influence on the characteristics and performance of the activated carbon (activated charcoal).
Forms of activated carbon
There are three main forms of activated carbon (activated charcoal).
Granular Activated Carbon – irregular shaped particles with sizes ranging from 0.2 to 5 mm. This type is used in both liquid and gas phase applications.
Powder Activated Carbon – pulverised carbon with a size predominantly less than 0.18mm (US Mesh 80). These are mainly used in liquid phase applications and for flue gas treatment.
Extruded Activated Carbon – extruded and cylindrical shaped with diameters from 0.8 to 5 mm. These are mainly used for gas phase applications because of their low pressure drop, high mechanical strength and low dust content.
Customized Shape & Size – Activated carbons can be formed into a variety of shapes and sizes per customers’requests.
The uses of Activated Carbon
Activated carbon is used in gas purification, decaffeination, gold purification, metal extraction, water purification, medicine, sewage treatment, air filters in gas masks and respirators, filters in compressed air and many other applications.
Activated Charcoal AC-05 is specially developed for PSA hydrogen purification which used to remove the impurities such as CO2, CO, N2 from the industrial gas stream. Pressure swing adsorption is a widely used technology for the purification of gases. This regeneration process is accomplished by reducing the pressure. At the moderate pressures found in compressed air systems, such as 100 pounds per square inch, an adsorbent can support a certain amount of moisture. When that pressure is dropped to ambient air pressure, the adsorbent can only support a smaller amount of moisture. By swinging the pressure from high to low, it is possible to adsorb large quantities of moisture at the higher pressure, and then release that moisture at the low pressure. This technique is called pressure swing adsorption. By alternating between two adsorbent filled vessels, one vessel being on line and removing moisture at high pressure, and the other off line releasing the trapped moisture at low pressure, it is possible to thoroughly dry a gas.
There are many remediation and industrial process applications at municipal sewage treatment plants and industrial facilities where odor removal is the primary reason for treating the air. These odors are generally present in the vapor phase and can be due to sulfur compounds such as H2S and other sulfur compounds, ammonia, amines, etc.Activated carbon is an effective adsorbent media for odor removal from vapor phase streams. SINOCATA’s vapor phase activated carbon adsorbers return cleaner air while capturing the elements that can cause the odor.
SINOCATA offers a variety of activated carbon equipment, vessels, and filter media specifically designed for odor removal. The vapor phase activated carbon adsorbers are excellent for odor removal applications.
Mercury emissions from coal-fired generators, cement kilns, industrial boilers, waste incinerators and steel mills are a serious environmental concern due to the toxicity and persistence of mercury that creates air pollution and accumulates in our waterways.Mercury, a toxic and corrosive material, must be removed from various gas and liquid streams. Since it is always present in very low concentrations, adsorption processes are most suitable for mercury removal. Activated carbon serves as an excellent carrier for various impregnates, which physically react with the mercury and hold it within the adsorbent particles. Very high levels of purity can be attained because of the high mercury removal efficiency attained by the adsorption process.
Activated carbon, often infused with sulfur or iodine, is widely used to trap mercury emissions from coal-fired power stations, medical incinerators, and from natural gas at the wellhead. AC-08 mercury Activated Carbon adsorbent products are used for removing mercury from gas phase hydrocarbons such as natural gas. Since mercury corrodes the aluminum heat exchangers used to liquefy natural gas, it must be removed before the low temperature condensation step. Mercury removal is also necessary to protect downstream equipment from corrosion such as compressors and pipelines.
Hydrogen sulfide (H2S) is a poisonous, highly flammable, colorless gas that is associated with a ‘rotten egg’ odor. Somtimes, it is a by- product from industrial processes such as natural gas processing, petroleum refining and petrochemical plants. A filtration apparatus or breathing device should be used at all times when encountering air containing H2S. Possible side effects of inhaling hydrogen sulfide include reduced oxygen intake, central nervous system failure, eye irritation, respiratory system complications, shock, coma, and even death.
So treating the effluent gas stream with activated carbon has been found to be one of the best ways to remove hydrogen sulfide. Most standard activated carbons have little capacity for H2S. However, General Carbon carries both impregnated and non-impregnated high H2S capacity carbons.
AC-10 is large surface area, large pore volume, high sulfur adsorption capacity adsorbent, a metal oxide impregnated activated carbon for bulk removal of sulfur species, especially H2S from natural gas, refinery gases, liquid HC, CO2 and other types of industrial gases. The high metal content impregnated activated carbon allows it to absorb a large amount of sulfur; up to 10 wt%. Also it is fully re-generable to save operation cost.
Shape: Irregular Mesh or Pellet Sizes: 4×8 – 10 mesh or 12×30 mesh or 2.5mm or 4.0mm Material Composition: min.12% metal oxide Surface Area: 400 – 600 m2/g Bulk Density: 520 – 600 kg/m3 Optimum Operating Temperature: 32 – 80 deg C
Removal of sulfur species, especially H2S from natural gas, refinery gases, liquid HC, CO2 and other types of industrial gases.
Activated carbon is the most common material used for such adsorption because it is versatile and inexpensive. Typically, a carbon-containing material: such as coal, wood or coconut shells; is reacted with heat and steam. This produces a highly porous substance that preferentially adsorbs organic compounds from both gaseous and liquid streams. If air containing solvent vapor is passed through a bed of activated carbon several inches thick, the solvent molecules are adsorbed by the carbon. Carbon bed adsorption systems operate on this principle.
The carbon bed can be arranged for either batch or continuous operation. In batch type adsorbers, the carbon bed is usually spread on metal supports in a vertical or horizontal steel tank. The adsorbed solvent is recovered by blowing steam through the bed of carbon and condensing the vapors. The solvent is then separated from the condensed steam through decantation or distillation. In continuous adsorbers, the carbon bed is arranged in a large wheel that rotates in a vertical or horizontal plane. Air containing solvent vapors is blown through one side of the wheel, which adsorbs the solvents. The wheel rotates continuously, bringing the solvent saturated carbon bed into a second stream of hot air that strips the solvents from the activated carbon. The second stream, which has a lower flow rate than the first stream, has a correspondingly higher vapor concentration. This stream is typically sent to an incinerator.
The batch type adsorber is older technology and is used where vapor concentrations are high enough to justify solvent recovery and recycling. The continuous adsorber is used where the solvent concentrations are low and the goal is to concentrate the vapors to make disposal by incineration easier.
An entire carbon bed adsorption system consists of: • Duct work carrying the vapor-laden air from the point of vapor generation. • Filtration by water wash, electrostatic precipitators or mechanical filters. • Carbon bed adsorbers. • Solvent disposal or recycling (incinerating, distilling, decanting, etc.).