Optimization of Activated Carbon Preparation Process from Sesame (Sesamum Indicum) Husks and Its Application for Adsorption of Cr(Vi) Ions from Aqueous Solution
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Date
2015-10
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Addis Ababa University
Abstract
The demand for activated carbon is increasing owing to the increased utility of the carbon
materials in pollution control. As a result, cost of activated carbon is also growing depending on
the application. Designing ways for the production of activated carbon through economic ways is
the need of the hour. A range of low cost, easily available, carbon rich and low ash precursors
and sources are being explored for the production of carbon materials. This research has
presented sesame (Sesamum indicum) husks as row material for preparation of low cost activated
carbon and assessed its potential application for adsorption of Cr(VI) from aqueous solution.
Process variables for sesame husk activated carbon preparation were optimized response surface
methodology (RSM). The effect of activating agent concentration, impregnation ratio,
carbonization temperature and holding time were analyzed as main factor variable based on
BBD. Adsorption % of Cr(VI) was used as response variable. The statistical significance of the
model was investigated by ANOVA. The optimum condition during sesame husk based activated
carbon preparations was found 30min, 614.70C, 1M, 1w/w and 76.41 for holding time,
Carbonization Temperature, Concentrations of Activating agent, Impregnations Ratio and
Adsorptions % respectively at pH 2, amount of adsorbent dosage of 0.5g in 100mL solutions and
temperature of 250C. Characterization result shows sesame husk can be used as row material for
productions of activated carbon with comparable property with other reported activated carbons.
The optimum pH value for the adsorptions of was determined to be 2, at which the Cr(VI)
removal of were determined to be approximately 76%. The uptake of chromium from solution by
SHAC increased with contact time and attained equilibrium at 360min for all of the temperatures
studied. The adsorptions kinetics of pseudo-first order and pseudo-second-order rate equations
were tested on the kinetic data and the adsorptions process was found to follow pseudo-secondorder
rate kinetics for all temperature. The Langmuir and Freundlich isotherm models were
applied to the experimental equilibrium data depending on temperature at 30, 40 and 50oC, and
the isotherm constants were determined by using linearized correlations coefficient. Equilibrium
data were represented better by the Freundlich model than the Langmuir model. Freundlich
equations was found to fit the equilibrium data for Cr(VI) adsorption with monolayer capacity of
18.34, 17.54 and 16.01 at 30, 40, and 500C respectively.
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Sesamum Indicum