Filters activated carbon

If more active treatment is required, such as pump-and-treat, it is possible that biological reactors will be a cost-effective replacement for activated carbon filters (63). 

Three approaches have been identified that reduce susceptibility of CA resists to airborne contamination. In the first, process engineering changes such as the addition of special activated carbon filters to the environmental chambers surrounding the exposure tools (76,79), overcoating the resist with a soluble protective film to isolate the resist from the environment (77,80,81), or modifications of the process flow to minimize the time interval between exposure and post-exposure bake have been shown to improve CA resist processibibty. 

Other industries of interest are (1) the manufacturing of spices and flavorings, which may use activated carbon filters to remove odors from their exhaust stream (2) the tanning industry, which uses afterburners or activated carbon for odor removal and wet scrubbers for dust removal and (3) glue and rendering plants, which utilize sodium hypochlorite scrubbers or afterburners to control odorous emissions. 

The alcoholic filtrate is evaporated to 50 cc., and 50 g. of barium hydroxide and 150 cc. of distilled water are added (Note 4). The mixture is refluxed for two hours and the excess barium hydroxide is precipitated with carbon dioxide. The barium carbonate is removed by filtration and washed with hot distilled water. A slight excess of sulfuric acid is added to the filtrate to liberate the amino acid from its barium salt, and an excess of barium carbonate is added to remove sulfate ion. The mixture is digested on the steam bath until effervescence ceases, and it is then filtered and the precipitate is washed with hot distilled water. The filtrate and washings are concentrated on the steam bath to a volume of 100 cc., decolorized with i g. of active carbon, filtered, and concentrated to the point of crystallization (about 25 cc.). The amino acid is precipitated by the addition of 150 cc. of absolute alcohol and the product is collected and washed with absolute alcohol. 

Medicine Single faucet activated carbon filter or whole-house tank-type activated absorption filter... 

Chemical Tastes (Other) Pesticides-herbicides Activated carbon filter will absorb limited amount. Must continue to monitor the product water closely... 

O Troublesome organics Activated carbon filters are required where soluble organic constituents are present because many will pass straight through standard plants, e.g. pesticides, phenols, MTBE and so forth. 

Adsorption efficiency can be optimized by using finer particle size products which will improve the diffusion rate to the surface of the activated carbon. However, there is a tradeoff in using finer particles with pressure drop and, hence energy use. Note that during start-up of an activated carbon filter bed, a bed expansion of 25 to 35 % is recommended in order to remove soluble matter and to stratify particles in order to ensure that the MTZ is maintained when future backwashing is performed. 

Activated carbon filter A canister I ilter containing activated carbon. 

The methionine nitrile (20 g) is dissolved in a solution prepared from 50 ml of aqueous 5N sodium hydroxide solution and 65 ml of ethanol. The solution is then refluxed for 24 hours ammonia is evolved. The solution is treated with activated carbon, filtered, acidified with glacial acetic acid (17 ml), chilled to -10°C and filtered to give crude product. This crude product is then slurried with a solution made up of 20 ml of water and 20 ml of methanol, filtered at -5° to -H0°C and dried to give dl-methionine as white platelets. 

After the said 2 to 3 hours the liquid is cooled and the bottom sediment, which has a greenish color, is filtered off. The liquid sucked off eventually is treated with active carbon, filtered and made slightly acid by means of acetic acid, at which 2-amino-benzolsulfon-amido-5-methyl-1,3,4-thiodiazol (melting point 204° to 206°C) is precipitated. 

Ion exchangers in general and cation resins in particular are liable to chemical attack by chlorine. The very small residual of chlorine in public supply (typically, 0.2mg/l) has only a mineral effect, but if more chlorine has been added it must be removed (e.g. with an activated carbon filter) before ion exchange. 

Activated carbon filters remove a wide range of organic matter by adsorption onto the carbon bed. The bed may be derived from a number of different carbon sources, and the correct selection of bed type, capacity, and porosity is a specialized function. Activated carbon may be usefully employed in organic traps, complementing the resin bed, but its capacity and organic removal rate characteristics are flow-dependent. Excessive flows may compromise the rate of adsorption of organic matter. 

Activated carbon filters are employed primarily as RW contaminant removal systems for chlorine (by chemisorption) and various organics such as trihalomethanes (THMs), petroleum products, and pesticides (by adsorption). In addition, they act as physical filters and therefore incorporate sufficient freeboard in their designs to permit periodic backwashing. 

Finally, an accident involved an active carbon filter, which contained potassium iodide and through which gas containing ozone was passing. The detonation of the filter was explained by ozone oxidising iodide into iodate and by the iodate interacting to produce an explosion with the active carbon (see the effect of iodates on metalloids above). 

In the Boliden process, developed by Boliden Kemi Company in Sweden, filter beds containing amorphous selenium are used to filter the gases. Mercury in the gas is deposited in the filter as mercury selenide (HgSe). Alternatively, the gases can be scrubbed with a slurry of amorphous selenium, whereupon mercury is precipitated as HgSe. Activated carbon filters are also useful for absorbing mercury vapor from the gas. 

In-tank filtration. Steel finishing electroplating and alkaline cleaning operations use in-tank filters to extend process bath life by removing contaminants in the form of suspended solids. Solids are usually disposed of offsite. Devices such as granular activated carbon filters remove dissolved contaminants, such as organic constituents. 

It safely treats process offgases using a combination of thermal treatment, catalytic oxidation, activated carbon filters, and treatment of the munitions demilitarization building (MDB) HVAC system ventilation air through activated carbon filter media prior to release. 

In addition to the removal of solids from gases, the problem of small quantities of compounds causing odour nuisance must frequently be handled. Activated carbon filters are used for this purpose and, in continuous operation, gaseous impurities from the air-stream are adsorbed on the activated carbon granules. The carbon will frequently adsorb contaminants until they reach a level of 20-30 per cent of the mass of the carbon. 

---