This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.
The activated carbon's adsorption properties had contributed to various kind of application. The below following are three of the major uses of activated that used in our real life.
The water industry uses activated carbon in several forms, typically powdered and granular, to deal with a variety of undesirable aspects in raw water. To the right is an image of pilot scale carbon columns at a water treatment plant. Seasonal application of powdered activated carbon (PAC) at the raw water intake or rapid mix unit is used by some plants to correct short term raw water quality problems such as algal blooms. PAC is basically used to correct taste and odor problems which are primarily an aesthetic quality of the water. Contact time is needed to allow adsorption to occur. The PAC is removed from the water by the processes of coagulation, flocculation, and sedimentation. Once the PAC has been separated from the water it is disposed of along with sedimentation sludge.
Active carbon filters also have been used in home water purification systems primarily to remove taste and odor. Taste and odor, although undesirable, are generally not considered unhealthy. In recent years, however, AC filters have been used to remove some of the contaminants that have been discovered in water supplies. Many organic compounds, such as chlorinated and non-chlorinated solvents, gasoline, pesticides and trihalomethanes can be adsorbed by AC. AC is effective in removing chlorine and moderately effective in removing some heavy metals. AC will also remove metals that are bound to organic molecules. Fluoride, chloride, nitrate, hardness (calcium and magnesium) and most metal ions are not removed by AC to any significant degree.
Activated carbon, also known as activated charcoal in medical field can treat poisonings and overdoses following oral ingestion. Activated charcoal has been scientifically proven to bind, and thus prevent the absorption of, many ingested drugs and chemicals from the gastrointestinal tract. In cases of suspected poisoning, medical personnel administer activated charcoal on the scene or at a hospital's emergency department. Dosing is usually empirical at 1 gram/kg of body weight (for adolescents or adults, give 50-100 g), usually given only once, but depending on the drug taken, it may be given more than once. In rare situations activated charcoal is used in Intensive Care to filter out harmful drugs from the blood stream of poisoned patients.
Activated charcoal has become the treatment of choice for many poisonings, and other decontamination methods such as ipecac-induced emesis or stomach pumping are now used rarely. The efficacy of activated charcoal in the treatment of poisonings and overdoses is due to direct adsorption of the toxic substance in the gastrointestinal tract. Activated charcoal will adsorb most drugs and toxins, but not all compounds are well adsorbed. Activated charcoal can interfere with the enterohepatic or gastroenteral recirculation, back-diffusion or both of toxic substances out of the systemic circulation into the gut via the gastrointestinal mucosa.
For the use of activated charcoal in poisoning involves the concept of lowering serum concentrations of already systemically absorbed drugs or poisons. This tends to reduce the serumhalf-life of the toxin. This effect has been demonstrated after experimental administration of toxic levels of phenobarbitaland phenobaritone, theophylline, digoxin and diazepam. The reduction in serum half-life after oral administration of activated charcoal was nearly 50% for each drug compared with controls. With some toxins such as atenolol, charcoal reduces intestinal absorption by as much as 95%. One explanation for this effect is the ability of activated charcoal to bind conjugated drug before hydrolysis or to free conjugated drug before reabsorption. Back-diffusion of free drug from the systemic circulation across the gastrointestinal tract into the intestinal fluids, and finally, binding to the activated charcoal in the gut. Coma due to diazepam toxicity was completely reversed within 12 hours after adminstration of activated charcoal, and the serum half-life of the drug was dramatically reduced from 195 to 18 hours during charcoal administration.
Treatment of VOC emission
Volatile organic compounds (VOCs) are compounds that have a high vapor pressure and low water solubility. Many VOCs are human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals, and refrigerants. VOCs typically are industrial solvents, such as trichloroethylene; fuel oxygenates, such as methyl tert-butyl ether (MTBE); or by-products produced by chlorination in water treatment, such as chloroform. VOCs are often components of petroleum fuels, hydraulic fluids, paint thinners, and dry cleaning agents. VOCs are common ground-water contaminants. Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors. VOCs are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.
For the treatment of the VOC emission, the activated carbon used is in vapor phase. The gas phase activated carbon are used for removal of volatile organic compounds such as hydrocarbons, solvents, toxic gases and organic based odors. In addition, chemically impregnated activated carbons can be used to control certain inorganic pollutants such as hydrogen sulfide, mercury, or radon.
In the adsorption process, molecules of a contaminated gas are attracted to and accumulate on the surface of the activated carbon. Carbon is a commonly used adsorbent due to its very large surface area. It can be made from a variety of base materials including coal, wood and coconut shells, and is manufactured or activated in a high temperature controlled oxidation process. 0.45kg of highly activated carbon has a surface area approaching 574 km².
Activated carbons used in the air pollution control field are normally supplied in a granular form with a particle size ranging from 1 to 5 millimetres. In the granular form activated carbon can easily be packed into a containment device through which a contaminated gas stream can be processed for purification. An adsorption system in its simplest form is made of a containment device, distribution and collection devices to effect proper circulation of the gas stream through the activated carbon bed, and a means for moving the gas stream through the bed (such as a fan, a blower, or pressurized gas displacement). Packed activated carbon beds can be conveniently configured into small transportable drums or tanks, or into large fixed contacting devices depending on the application.
Following is the brief list of the application and examples of activated carbon in gas phase and liquid phase
Gasoline Vapor Recovery
Gasoline Fuel recovery,ELCD
MEK, Cyclohexanone, CS2, Furon, Trichloroethane
Room Order Removal
Tobacco, CO, Room filters, Toilet Odor, Pet Odor
Cabin air filters
Anesthetic gas removal
Copiers, Laser Printers
Dioxin removal,Space Ships, Underground CO2
Nitrogen Gas Separation
Radio Active Gas
Factory Waste Water
Cleaning Waste Water
Drinking Water Treatment
Trihalomethane, Chlorine, VOCs, Lead, Arsenate removal
Decolorization of Indusrial Chemicals
Sugar refinement, Pharmaceutical use, Whisky distilment
Medical and Nursing
Kidney machine, Nursing supplies, Respirators
Double Layer Capacitors, Hardisks