Activation time

The objective of this study is to relate textural and surface characteristics of microporous activated carbon to their methane adsorption capacity. Oil palm shell was used as a raw material for the preparation of pore size controlled activated carbon adsorbents. The chemical treatment was followed by further physical activation with CO2. Samples were treated with CO2 flow at 850°C by varying activation time to achieve different burn-off activated carbon. H3PO4 chemically activated samples under CO2 blanket showed higher activation rates, surface area and micropore volume compared to other activation methods, though this sample did not present high methane adsorption. Moreover, it was shown that using small proportion of ZnCl2 and H3PO4 creates an initial narrow microporosity. Further physical activation grantees better development of pore structure. In terms of pore size distribution the combined preparation method resulted in a better and more homogenous pore size distribution than the conventional physical activation method. Controlling the pore size of activated carbon by this combined activation technique can be utilized for tuning the pore size distribution. It was concluded that the high surface area and micropore volume of activated carbons do not unequivocally determine methane capacities. © 2010 The Institution of Chemical Engineers.

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http://www.sciencedirect.com/science/article/pii/S0263876210002923

Cocoa shell (CS) was used as a low-cost precursor for production of activated carbon (AC) and evaluated for its ability to adsorb Methylene Blue (MB) dye. Cocoa shell-based pellets were carbonized at 800°C and subjected to 850°C under a flow of CO 2 in different activation times. The cocoa (Theobroma cacao) shell-based activated carbon (CSAC) showed moderate surface area with the average pore size 2.7nm. CSAC also displays the presence of aliphatic, aromatic hydrocarbons and near absence of C-O, carboxylic acid, and the -COOH functional group. Only the presence of O-H groups was detected. The influences of adsorption time and initial dye concentration on adsorption performance have been measured in a batch system. The results are well described by the Freundlich and Langmuir isotherms. The results from the kinetic study show that MB adsorption follows pseudo-second-order and Boyd models, which indicated the MB adsorption on the CSAC was controlled by film diffusion. © 2012 The Institution of Chemical Engineers.

http://ac.els-cdn.com/S0263876212000457/1-s2.0-S0263876212000457-main.pdf?_tid=b9eaf67a-2363-11e4-98d9-00000aacb361&acdnat=1407987375_480d7e9a640abdbade404c6702c9e41b 
http://www.sciencedirect.com/science/article/pii/S0263876212000457