Charcoal filter beds

Recently, two alterations to the baseline incineration process have been considered, charcoal filter beds or a hold, test, and release system. In February 1994, NRC recommended the study of activated charcoal filter beds as an addition to the baseline incineration process. The Army and EPA also endorse the addition of charcoal filter beds to baseline incineration because it would further eliminate the risk of toxic air... 

The arrangement and distribution of anodes in gravel and activated charcoal filters is different. Cathodic protection of activated charcoal filters is basically feasible but requires a large number of electrodes and high protection current densities that are twice those for gravel bed filters, so that an electrically insulating layer can be deposited on the steel wall. 

The pale yellow product was dissolved in warm, absolute methanol, and the solution after mixing with decolorizing charcoal was filtered through a bed of filter aid. The filter bed was washed with warm absolute methanol, and the combined methanolic filtrate and... 

An impurity in a water stream at a very small concentration is to be removed in a charcoal trickle bed filter. The filter is in a cylindrical column that is 2 ft in diameter, and the bed is 4 ft deep. The water is kept at a level that is 2 ft above the top of the bed, and it trickles through by gravity flow. If the charcoal particles have a geometric surface area to volume ratio of 48 in.-1 and they... 

At this point I don t have to give up much, but I still take precautions. When we go to concerts or movies, I hold a charcoal filter tight to my nose. When we travel, I take my own bedding and an air purifier, even to Europe. I can go for months without getting a headache. When I do get one, it s mild—nothing like having severe ones two or three days a week. Unlike many, I m able to lead a fairly normal life. I m very fortunate. 

A mixture of ethyl (acetylamino)(cyano)acetate (5.10 g, 30 mmol), 80 (5.46 g, 20 mmol), 18-crown-6 (528 mg, 2 mmol), and finely powdered K2C03 (8.28 g, 60 mmol) in MeCN (60 mL) was stirred overnight at rt. The mixture was filtered through a Celite bed and the cake was washed with CHC13. The residue obtained after rotary evaporation was dissolved in hot EtOH (100 mL), treated with activated charcoal, filtered, and diluted with hexanes (100 mL) affording 81 as bright yellow crystals yield 6.01 g (83%) mp 162-163°C. 

Synthesis of 5-(4-cyano-phenyl)-indole 1. A double jacket reactor was charged with 5-bromo-indole 3 (50 g, 250 mmol), 4-cyano-benzene-boronic acid 4 (38.7 g, 263 mmol), and isopropanol (393 g). The reactor was purged with nitrogen. Pd(PTol3)2Cl2 (0.2 g, 0.25 mmol) was added, and the reaction mixture was heated to reflux. Sodium carbonate solutimi (2 M, 250 ml, 500 mmol) was dosed within 2 h. The reaction was stirred for additional 90 min at reflux. The isopropanol was distilled off until the temperature of the distillation residue reached lOO C. The reaction mixture was cooled to room temperature and was extracted with dichloromethane (1,000 ml). The organic phase was extracted with water (250 ml) and was filtered slowly through a bed of silica (40 g) and charcoal (4 g). The filter bed was washed with dichloromethane (100 ml). To the combined dichloromethane phases, toluene (500 ml) was added and dichloromethane was distilled of until the distillation residue reached a temperature of 110°C. The product solution was cooled to 95°C and was seeded. The suspension was cooled slowly (l°C/min) to room temperature. The product is filtered, washed with toluene (50 ml), and dried at 60°C. 5-(4-cyano-phenyl)-indole 1 was obtained as colorless crystals (42.6 g, 188 mmol, 75%). 

In order to remove radioactive substances potentially present in the air flow, most of the ventilation systems are equipped with filter units consisting of high-efficiency particulate filters (HEPA filters, class S) and iodine adsorbers (activated charcoal, KI impregnated). These filters are monitored, either continuously or at regular intervals the filter efficiency of the iodine adsorbers is determined by taking charcoal samples from the filter beds at regular intervals and analyzing them in the laboratory (see Section 6.2.1.5.). 

Because the filter flask is attached to a source of vacuum, a solution poured into a Hirsch funnel or Buchner funnel is literally sucked rapidly through the filter paper. For this reason, vacuum filtration is generally not used to separate fine particles such as decolorizing charcoal, because the small particles would likely be pulled through the filter paper. However, this problem can be alleviated, when desired, by the use of specially prepared filter beds (see Section 8.4). 

The release of radioiodine has generally been controlled by means of two methods (1) holdup for decay and (2) collection by scrubbing systems and solid sorbents. Both holdup and collection have been practiced. But the former is not suitable for I. When only small amounts of radioiodine are involved, as with reactor effluents, the holdup method may be adequate and charcoal filters or charcoal delay beds can be utilized. In fuel reprocessing plants, both holdup and collection have been used with more recent effort concentrating on collection and disposal. 

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