Coconut-based activated carbon

Figure 5. A collection efficiency of activated coconut-base carbon and Saran carbon for vinyl chloride (4)...

Adsorption of Radionuclides. Other appHcations that depend on physical adsorption include the control of krypton and xenon radionuchdes from nuclear power plants (92). The gases are not captured entirely, but their passage is delayed long enough to allow radioactive decay of the short-hved species. Highly rnicroporous coconut-based activated carbon is used for this service. 

The vendor states that activated carbon systems can be used on liquid, vapor, and solid waste streams contaminated with organic materials. Calgon Chemical Corporation has patented activated carbon technology. The vendor states that they produce more than 40 specialized types and sizes of bituminous coal- and coconut-based activated carbons for over 700 applications. Calgon claims the following advantages for its activated carbon systems ... 

Bagreev, A., Rahman, H., and Bandosz, T.J. (2000). Study of H2S adsorption and water regeneration of coconut-based activated carbon. Environ. Sd. TechnoL, 34, 4587-92. 

Coconut shell-based carbon seems to be less susceptible to fouling by NOM and other background water quality parameters, e.g., the precipitation of manganese, iron, or calcium carbonate [28] however, a decrease in adsorption performance correlating with the TOC content of three different natural waters was observed as well [55]. Knappe and Rossner [54] found a reduction of adsorption capacity of up to 60% for the coal-based activated carbons, for the coconut shell-based carbons of around 20%. The presence of NOM in values of 0.5 mg/L TOC resulted in a decrease in adsorption capacity of coconut-based carbons [28,53]. 

The price for purchase of a 200 lb canister of virgin coconut-based activated carbon is about 500 to 600 ( 2.50 to 3.00 per pound). Acceptance of return of that canister, containing only non-hazardous contents, incurs a modest fee of 75 (plus transportation). 

Sigot et al. [7] tested three commercial adsorbents a coconut-based activated carbon (AC) obtained from Chemviron Carbon (930 m /g BET surface), 13X zeolite obtained from CECA (700 m /g BET surface) (Z), Chameleon silica gel obtained from BDH Prolabo (690 m /g BET surface) (SG). 

The capacity of activated coconut-shell charcoal for several common VOCs is indicated by the data of Table 12-28. The values given, which are based on the data of Lamb and Coolidge (1920), do not represent complete equilibrium, but are very close to it for the conditions 0°C (32°F) and 10 mm Hg pressure of solvent vapor over the carbon. More detailed data for one of the solvents (benzene) are presented in Figure 12-40 to illustrate the typical effects of the partial pressure of the solvent and the temperature on the quantity adsorbed. The two upper curves represent adsorber operating cmiditions and the two lower curves represent conditions during regeneration. Adsorption isotherms for other VOCs have generally similar shapes as discussed in the previous section entitled Properties of Gas-Adsorption Carbons. ... 

Coconut-shell-based GACs These have a high portion of micropores and present surface areas generally over 1000 m2/g and apparent densities of about 0.50 g/cm3. Being manufactured mainly from vegetative material, they do not exhibit the fully developed pore structure of coal-based carbons. They are used in both vapor- and liquid-phase applications. Coconut shell-based carbon is slightly more expensive to produce than coal-based GAC, since about only 2% of the raw material is recoverable as GAC, versus 8-9% for coal-based carbons. In Table 4.1, the basic properties of common materials used in the manufacture of activated carbon ate presented. 

Adsorption capacities for HCl on coconut-shell carbon (open circles) and on coal-base carbon (solid circles) in 0.01 molar solutions of NaCl are plotted as a function of the hydronium-ion activity at equilibrium. The solid lines represent the calculated Fruendlich isotherms, the equations for which are given on the... 

Table 1 summarizes the results of the N2 and H2 physisorption measurements of the materials analysed. All samples are highly micro-and mesoporous carbon materials. In our experiments four samples of carbon Busofit-AYTM (1 - 4) and three samples of wood-based activated carbon (5 - 7) obtained by new technology were investigated. The activated carbon 207C (8) is made in the Great Britain from coconut shell. Samples 9 and 10 - granular activated carbons, specially developed for effective storage of methane. 

In this work we developed a methodology to produce activated carbons of high adsorption capacity and with controlled pore size, based on the KOH catalysed gasification with CO2 of a coconut shell char. To study the effect of potassium in the activation step two series of activated carbons were prepared, with (CK1173) and without KOH (DC1173), The results obtained show that the size of the micropores is much smaller in the series CKl 173. 

By defined heating of the second stage, each temperature between 4 K and 100 K can be adjusted. The reference cryosorption material is a coconut-shell-based, highly activated granular charcoal (CHEMVIRON CARBON, type SC-II, US mesh size 12x30), with the sample masses being about 2.5 g. 

TABLE 12 Effects of pH and the Presence of O on the Adsorption and Desorption of Gold and Silver Cyanide for Two Coconut-Shell-Based Activated Carbons... 

---