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Journal of Environmental Science and Technology
  Year: 2008 | Volume: 1 | Issue: 3 | Page No.: 124-134
DOI: 10.3923/jest.2008.124.134
 
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Adsorption Characteristics of Active Carbons from Pyrolysis of Bagasse, Sorghum and Millet Straws in Ortho Phosphoric Acid

J.A. Lori, A.O. Lawal and E.J. Ekanem

Abstract:
Pyrolysis of bagasse, sorghum and millet straws impregnated with ortho phosphoric acid, produced carbon with heterogeneous pore structure and high adsorption capacities. Carbon precursors with particle size of 1180 μm were pyrolysed, to overcome difficulties caused by low density and high ash content. The active carbons obtained from low impregnation ratios (<13.6) were largely microporous. Higher impregnation ratio did not substantially benefit the evolution of micropores in the pyrolysed samples. Fast attainment of sorption equilibrium was skewed towards high initial concentrations of methylene blue. The impregnation ration, controlled by varying the proportion of H3PO4, had strong influence on the yield of carbon. Equilibrium yields were highest at 450°C, with impregnation ratio of 13.6. Production of active carbons was completed in 45 min. The adsorptive capacities of the active carbons for large molecular weight compounds such as methylene blue were 502, 662 and 390 mg g-1 for bagasse, sorghum and millet straws, respectively. The iodine numbers which indicate the adsorptive capacities for low molecular weight substances were 626, 667 and 593 mg g-1 for bagasse, sorghum and millet straws, respectively. These iodine numbers are more than 18% higher than the value recommended for low molecular weight compounds by American Water Works Association.
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How to cite this article:

J.A. Lori, A.O. Lawal and E.J. Ekanem, 2008. Adsorption Characteristics of Active Carbons from Pyrolysis of Bagasse, Sorghum and Millet Straws in Ortho Phosphoric Acid. Journal of Environmental Science and Technology, 1: 124-134.

DOI: 10.3923/jest.2008.124.134

URL: https://scialert.net/abstract/?doi=jest.2008.124.134

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