Comparison on the Characteristics of Bio-Based Porous Carbons by Physical and Novel Chemical Activation

Abstract

There is significantly abundant portion of waste agricultural materials in the world serving as environmental challenge, however, they could be converted into useful value added products like activated carbon. Coconut shell based carbons were synthesized using physical activation by CO2 and chemical activation with potassium hydroxide and potassium acetate. The BET surface areas and pore volumes are 361m2/g and 0.19cm3/g for physical activation, 1353m2/g and 0.61cm3/g for activation with KOH and 622m2/g and 0.31cm3/g for potassium acetate activated carbon. From the Fourier Transform Infrared Spectroscopy analysis, hydroxyls, alkenes and carbonyl functional groups were identified with more prominence on the chemically activated porous carbons. Thermogravimetric analysis (TGA) results showed occurrence of moisture pyrolysis at 105°C, the pyrolysis of hemicellulose and cellulose occurred at 160–390°C and lignin at (390-650°C). Carbonization at 700°C and 2hrs had highest yield of 32%. Physical activation yielded lower surface area with approximately 88% micropores. On the other hand, chemically activation yielded higher surface area with elevated mesopores. The porous carbons can be applied to salvage pollution challenges.