Parametric Investigation of Biochar Yield from Microwave Pyrolysis of Corn Cob Wastes

Author : Lawas, Kristine Iannah Aparri
Major Adviser : Carpio, Rowena B. 
Committee Members : Alfafara, Catalino G.; Migo, Veronica P. 
Year : 2018
Month : June
Type : Thesis
Degree: BS
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A parametric investigation of the effect of exposure time, microwave absorber concentration, catalyst concentration, polymerization time and microwave output power on biochar yield was performed using a half resolution (2ᵏ⁻¹) factorial design. Statistical analysis showed that exposure time and microwave output power, as well as their interaction, are significant in the yield of biochar. A general decreasing effect was observed from increasing exposure time and output power. This was due to the rapid heating experienced by the corn cob wastes causing the hydrocarbons to react and transform into permanent gases at high temperatures. The increase in temperature was attributed to the oscillation of the dielectric molecules of the biomass and the microwave absorber. Characterization analyses showed progression of various functional groups during pyrolysis, presence of pre-graphitic and graphitic properties and development of pores within the samples. Elemental analysis showed an average of 67.11 % C at 450 W for 5 min (LTLP) and 81.32 % C for the samples operated at 700 W for 10 min (HTHP). Moreover, cost analysis showed that conventional pyrolysis consumes 18.72 times more energy than microwave-assisted method per gram of corn cob fed and is 4.72 times costlier. Both characterization and cost analysis suggested that microwave pyrolysis was successful in creating porous graphitic carbon at faster, more cost-effective and more efficient method.

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