Shells, coconut

Typical adsorption isotherms for light hydrocarbons on activated carbon prepared from coconut shells ate shown in Figure 11 (46). The polarizabihties and boiling points of these compounds increase in the order... 

In carbon adsorption, contaminants are physically attracted or adsorbed on the surface of the carbon. Adsorption capacities are high for carbon because its porous nature provides a large surface area relative to its volume. Activated carbon is prepared from lignite, bituminous coal, coke, wood, or other organic materials such as coconut shells. 

The process for the thermal activation of other carbonaceous materials is modified according to the precursor. For example, the production of activated carbon from coconut shell does not require the stages involving briquetting, oxidation, and devolatilization. To obtain a high activity product, however, it is important that the coconut shell is charred slowly prior to activation of the char. In some processes, the precursor or product is acid-washed to obtain a final product with a low ash content (23,25). 

Adsorption. Adsorption (qv) is an effective means of lowering the concentration of dissolved organics in effluent. Activated carbon is the most widely used and effective adsorbent for dyes (4) and, it has been extensively studied in the waste treatment of the different classes of dyes, ie, acid, direct, basic, reactive, disperse, etc (5—22). Commercial activated carbon can be prepared from lignite and bituminous coal, wood, pulp mill residue, coconut shell, and blood and have a surface area ranging from 500—1400 m /g (23). The feasibiUty of adsorption on carbon for the removal of dissolved organic pollutants has been demonstrated by adsorption isotherms (24) (see Carbon, activated carbon). Several pilot-plant and commercial-scale systems using activated carbon adsorption columns have been developed (25—27). 

Another commonly employed low-cost organic filler is coconut shell flour. This can be incorporated into the moulding composition in large quantities and this results in cheaper mixes than when woodflour is used. The mouldings also have a good finish. However, coconut shell flour-filled mouldings have poor mechanical properties and hence the filler is generally used in conjunction with woodflour. 

The adhesive resins are of the novolak type and generally hardened by paraformaldehyde (which may be supplied mixed with coconut shell flour or diatomaceous earth) in conjunction with an accelerator such as magnesium oxide. 

Activated carbon is an amorphous solid with a large internal surface area/pore strucmre that adsorbs molecules from both the liquid and gas phase [11]. It has been manufactured from a number of raw materials mcluding wood, coconut shell, and coal [11,12]. Specific processes have been developed to produce activated carbon in powdered, granular, and specially shaped (pellet) forms. The key to development of activated carbon products has been the selection of the manufacturing process, raw material, and an understanding of the basic adsorption process to tailor the product to a specific adsorption application. 

In a recent study for the US Department of Energy [61], AGLARG have shown that suitable adsorbents for ANG can be produced from peach pit or coconut shell using KOH as the activating agent. These carbons, like all KOH produced carbons, were low in bulk density. Densities of greater than 0.6 g/ml were possible with compaction in small vessels (<50 ml) and deliveries of greater than 150 V/V methane could be obtained from 3.4 MPa at 298 K. 

Critoph and Turner [15] carried out similar direct measurements for ammonia and 208C (coconut shell based) carbon manufactured by Sutcliffe Speakman Carbons. The bed conductivity was found to be around 0.165 W/mK at concentrations less than 20% and to rise to 0.19 W/mK at 25% concentration. The corresponding grain conductivities rose from 0.85 to 1.25 W/mK respectively. The higher grain conductivity than that found by Gurgel and Grenier may reflect the different structures present within the extmded and nut shell carbons. 

Adsorption is the process by which liquid or gaseous molecules are concentrated on a solid surface, in this case activated carbon. This is different from absorption, where molecules are taken up by a liquid or gas. Activated carbon can made from many substances containing a high carbon content such as coal, wood and coconut shells. The raw material has a very large influence on the characteristics and performance activated carbon. 

Activated carbon or activated charcoal Carbon in the form of charcoal granules, which has an affinity to adsorb many gases and vapors and, in so doing, removes odors. It is manufactured by exposing coal, coconut shells, or peat to steam at 800 to 900 C. 

One of several species of seaside grass, among which are the Lygeum Spar turn or hooded mat-weed of the Mediterranean and Anophilia Are-naria of Holland, The name Esparto is used for the fibers covering coconut shells. The dried weed may be nitrated to give an expl compd (see below)... 

Nitromatweed (Matweed Nitrate, Nitrosparte in Fr). Prepd by nitration of dried matweed with mixed nitric-sulfuric acids in a manner similar to the prepn of NC. Trench, Faure and MacKie (Ref 2), in 1876, patented expls containing as a base nitrosparte (or other nitrated cellulosic material such as cotton, hay, agave, hemp, flax, straw, aloe, yucca, etc) together with resin, ozokerite, collodion, glycerin, charcoal and soot. Hengst (Ref 3), in 1898, patented a smokeless powd containing nitrosparte prepd by nitration of fibers covering the coconut shell Refs 1) Merriam Webster s Diet, 2nd Ed (1963), ... 

Smokeless powders prepd by gelatinizing with a vol solvent, NC s prepd from such materials as corozzo, coconut shells, etc, together with Nitrostarch or Nitrodextiin 1888 Invention of Ballistite, the first successful smokeless powder contg NG, described in BritP 1471 of 1888 (Ref 1, p 51)... 

There are various grades of activated carbon, depending on the carbon source and the ultimate application types include coconut shells,... 

Use hard, abrasion-resistant grades of carbon such as bituminous coal and coconut shell for raw water pretreatment to avoid the production of fines resulting from erosion. 

The AC used in this study was a granular type (30 35 mesh) prepared from coconut shell. The purified AC (PAC) was prepared by boiling the AC for 5 hr in a water bath. The acidic and alkaline solutions for preparation of MACs were made with HNO3 (NA), H2SO4 (SA), HCl (HA), H3PO4 (PA), CH3COOH (AA), KOH (PH), and NaOH (SH). The AC was modified into each solution according to the conventional wet process. The specific surface area of the adsorbents was measured by BET method (ASAP 2020, Micrometries, USA). 

Amuda, O.S., Giwa, A.A., and Bello, I.A., Removal of heavy metal from industrial wastewater using modified activated coconut shell carbon, Biochemical Engineering Journal, 36, 174-181, 2007. 

Certain types of adsorption media have been shown to preferentially adsorb certain contaminants. For example, research has shown that, in some cases, coconut shell-based GAC removes MTBE better than typical coal-based GAC. In addition, synthetic resins have been developed to preferentially adsorb some oxygenates, such as TBA, that are less absorbable by GAC. Often, adsorption processes also take advantage of the biodegradability of MTBE and other oxygenates by promoting bacterial growth on the adsorption. 

Filter through a 0.5-pm Zefluor absorb on a solid sorbent tube containing coconut shell charcoal desorb with ammonia hydroxide and hydrogen peroxide dilute. 

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