Charcoal coconut

The above methods for obtaining D, as well as other ones, are reviewed in Refs. 3-12, and Refs. 7-9 give tables of D values for various adsorbents. For example, D is close to 3 for the highly porous silica gels and close to 2 for nonporous fumed silica and for graphitized carbon black coconut charcoal and alumina were found to have D values of 2.67 and 2.79, respectively [7]. 

Fig. 4.2 Adsorption isotherms of benzene at 25°C on (1) a charcoal from anthracite coal, activated to 56% yield (2) an activated coconut charcoal. (After Cadenhead and Everett.)...

The same author (25) has shown that sulfur is bound to carbon blacks by the action of carbon disulfide at 150°. In the presence of hydrogen sulfide, less carbon disulfide will react with activated carbon (129). The interaction of carbon disulfide and sulfur with coconut charcoal was studied by Sykes and White (130) at low pressures in the temperature... 

Table V compares the degradation of total 2,4-D and 2,4,5-T (n-butyl esters and acids) over six years of observations In the Kansas and Florida locations. Although the rates of application were similar, the method of application, preplant Incorporation versus subsurface Injection, resulted In significant differences In the Initial concentrations of herbicides In the plots. The acid of 2,4,5-T comprised most of the total residue after the first two years. Although some residues were recovered, especially In later years, at depths below 15 cm, the majority (90 percent) of residue was confined to the top 15 cm of soil profile. The addition of soil amendments such as lime, organic matter and fertilizer did not appreciably Increase the overall rate of disappearance of the herbicide. The addition of activated coconut charcoal, however, significantly decreased the rate of disappearance of herbicide. Six years after the charcoal plots were established, residues (primarily 2,4,5-T acid) were still present.

The addition of coconut charcoal Increases persistence of phenoxy herbicide residues, especially residues of 2,4,5-T. 

Activated carbon adsorption, treatment of wastewater, 125-50,155 Activated coconut charcoal, effect, degradation In soil, 168... 

Charcoal. Activated coconut charcoal has gained the status as the almost universal solid sorbent. Petroleum-based charcoal is less active, but is also widely used. Charcoal is a very effective sorbent and is generally used for collection of nonpolar organic solvent vapors. It also collects polar organics, but they frequently cannot be recovered. However, many organic substances that are reactive, polar, or oxygenated (e.g., chloroprene, acetic acid, and acetone) have been successfully collected and recovered from charcoal. Substances for which charcoal tube methods have been validated are listed in Table II. 

An earlier study at SRI concluded that diphenyl could not be collected on activated coconut charcoal because recovery was poor. The recovery of diphenyl from coconut charcoal is given below. 

The report (5) on the study recommended that a less active charcoal be tested. A literature survey did not yield any conclusive evidence for successful collection by recovery from alternative sorbents. On the basis of the little information available, we selected petroleum charcoal and three porous polymers to test (petroleum charcoal is less active than coconut charcoal). All the porous polymers were based on aromatic monomers, and they should be good collectors for nonpolar aromatics. Aliquots of 113 pg diphenyl were spiked onto these sorbents, and the samples were desorbed with various solvents. The results are given below. 

It appears to us that the most simple, and best developed reagent for the carbonyl-chelates is the red carbonyl solution. A convenient method has been reported for preparing such solutions105, but since this method requires the preparation of coconut charcoal, it may be preferable to employ the original Chatt procedure. 

The trap should consist of 2,6-diphcnylcnc oxide polymer (Tenax GC grade), silica gel, and coconut charcoal, each constituting a one third portion. A methyl silicone packing at the inlet can extend the life of the trap. Tenax alone may be used if only compounds boiling above 35°C are to be analyzed. A silica gel trap is required for highly volatile compounds, while charcoal effectively adsorbs dichlorodifluoromethane and related compounds. 

Adsorbed over coconut charcoal (100 mg/50 mg) desorbed with CS2 and analyzed by GC-FID recommended flow rate 200 mL/min sample volume 20 L. 

Air drawn through a solid sorbent tube packed with coconut charcoal (400 mg/200 mg) 1,3-butadiene desorbed with 4 mL methylene chloride (more than 30 min standing) analyzed by GC-FID (NIOSH Method 1024, 1987) recommended air flow rate 0.2L/min sample volume 20 L. 

The use of charcoal tubes for the collection of solvent vapors is recommended in the NIOSH method. The charcoal tubes presently used contain 150 milligrams (mg) of coconut charcoal. Figure 1 illustrates the charcoal tube subdivided into two sections of 100 mg and 50 mg of charcoal. The front portion of 100 mg is used to collect the solvent vapors while the 50 mg backup section is intended to determine if solvent breakthrough occurred on the front portion. This is a built-in quality control check. (6)(14)... 

Liquid air is now a common commercial product and can be applied to various useful purposes. An obvious application is to the production of low temperatures for experimentation work,2 and a valuable extension is to the production of high vacua by filling with carbon dioxide the apparatus which has already been attached by hermetically sealing to a bulb of coconut charcoal when this bulb is immersed in liquid air, the carbon dioxide is absorbed so rapidly and completely that the pressure may be almost immediately reduced to a fraction of a millionth of an atmosphere. 

Phosphine is only slightly soluble in alcohol or ether. It is readily absorbed by wood charcoal, to the extent of about 500 volumes by 1 volume of the charcoal. Coconut charcoal absorbs 69 volumes of the gas at 0° C.3... 

Use a trap not shorter than or narrower than 25 cm x 2.67 mm (id). Pack the trap to contain the indicated minimum lengths of adsorbents in the following order, beginning at the trap inlet 7.7 cm of 2,6-diphenylene oxide polymer (TENAX GC, or equivalent), 7.7 cm of silica gel, and 7.7 cm of coconut charcoal. 

Tenax, silica gel, coconut charcoal, 3% OV-1 on Chromosorb WHP, molecular sieves, and carbo traps. 

In the Dewar s method, the mixture of noble gases is introduced from a gasholder into a bulb filled with coconut charcoal. This bulb is placed in a cold bath (-100°C). The mixture of gases is allowed to remain there for about half an hour during which time Ar, Kr and Xe get adsorbed. He and Ne, which remain unadsorbed, are pumped out of the bulb and kept in contact with another lot of charcoal maintained at -180°C whereby Ne is adsorbed, leaving He in the free state and the latter is pumped out. Ne is recovered by heating the charcoal. 

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