Preparation of Activated Carbons from Macadamia Nut Shell and Coconut Shell by Air Activation

Abstract

A novel, three-step process for the production of high-quality activated carbons from macadamia nut shell and coconut shell charcoals is described. In this process the charcoal is (i) heated to a high temperature (“carbonized”), (ii) oxidized in air following a stepwise heating program from low (ca. 450 K) to high (ca. 660 K) temperatures (“oxygenated”), and (iii) heated again in an inert environment to a high temperature (“activated”). By use of this procedure, activated carbons with surface areas greater than 1000 m2/g are manufactured with an overall yield of 15% (based on the dry shell feed). Removal of carbon mass by the development of mesopores and macropores is largely responsible for increases in the surface area of the carbons above 600 m2/g. Thus, the surface area per gram of activated carbon can be represented by an inverse function of the yield for burnoffs between 15 and 60%. These findings are supported by mass-transfer calculations and pore-size distribution measurements. A kinetic model for gasification of carbon by oxygen, which provides for an Eley−Rideal type reaction of a surface oxide with oxygen in air, fits the measured gasification rates reasonably well over the temperature range of 550−660 K.

Performance of a First-Generation, Aqueous-Alkaline Biocarbon Fuel Cell

“…[7][8][9][10] Finally, carbonized charcoal is a good electrical conductor, 4 has a high surface area, and contains many dangling bonds that cause it to be extremely reactive at modest temperatures. 9,[12][13][14][15] Despite these attractive features, most researchers have emphasized carbon fuel cells that use fossil carbons (e.g., graphite, coke, and coal) as the consumable anode 1,2,16 with a variety of electrolytes as the charge carrier, including aqueous alkaline, [16][17][18][19] molten potassium hydroxide at >400°C, 16,[20][21][22][23][24][25][26] solid zirconia stabilized with magnesia or yttria at >1000°C, 27,28 molten lead at >500°C, 29,30 and molten carbonates at >560 °C. [31][32][33][34] In a recent paper, Cooper, Cherepy, and their coworkers 35 at the Lawrence Livermore National Laboratory described the performance of a molten carbonate carbon fuel cell that used nine different carbons (including two biocarbons) and a porous nickel electrode.…”

Adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions bioremediation from aqueous solution using unmodified and EDTA-modified maize cob

“…Recently, non-conventional and low cost agricultural by-products have been employed. This includes nut shells, wood, bone, peat processed into activated carbons [9][10][11][12][13][14][15][16][17][18][19]; maize cob and husk [20][21][22][23]; cassava waste [24]; sawdust and coconut fibre [25]; and so on. Biomasses such as Aspergillus tereus [26]; Pseudomonas sp.…”

Waste Water: Treatment Options and its Associated Benefits

“…Besides, previous researches on the removal of COD from industrial wastewater using coagulation/flocculation, membrane filtration and oxidation processes etc., reveal that the technology of these methods are generally expensive, complicated, time consuming and required skilled personnel (Galambos et al, 2004;Peres et al, 2004). However, low cost and non-conventional adsorbents such as nut shells, wood, bone, peat, processed into activated carbons and biomass such as Aspergillum tereus, Peusodomonas sp., Rhizopus arrhizus are better (Okieimen et al, 1985;Tam and Antal, 1999;Bansode et al,2004;Nomanbhay and Palanisamy, 2005;Preetha and Viruthagiri, 2005). Again, ultraviolet (UV) lamp has also been used to treat textile wastewater.…”