Date

2011

Author

Özsin, Gamzenur

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In this study production and characterization of activated carbon from an agricultural waste, pistachio-nut shells, was investigated. To determine optimum production conditions by chemical activation method, effect of tempreature (300, 500, 700 and 900 oC) and effect of impregnation ratio (1:1, 2:1 and 3:1 as activation agent:sample) were investigated by applying two different methods (raw material activation and char activation) and with two different activation agents (phosphoric acid and potassium hydroxide). To produce activated carbon, all the impregnated samples were heated to the final activation temperature under a continuous nitrogen flow (100 cm3/min) and at a heating rate of 10 oC/min and were held at that temperature for 1 hour. Pore structures of activated carbons were determined by N2 adsorption and micro-mesopore analysis was made by “Non-local Density Functional Theory” and “Monte Carlo Simulation” method (NLDFT-Monte Carlo Simulation Method). BET surface areas of produced activated carbons were found from N2 adsorption data in the relative pressure range of 0.01 to 0.15. BET surface areas of phosphoric acid activated carbons by raw material activation method were found between 880 and 1640 m2/g. The highest value of the BET surface area was obtained in the case of the activated carbon which was produced with an impregnation ratio of 3/1 (g H3PO4/g raw material), at an activation temperature of 500 oC. The repeatibility was also investigated on phosphoric acid activated carbons which were produced with conventional raw matererial activation method. Results showed that, both the BET surface area values and pore size distributions were consistent among themselves. On the other hand char activation experiments with phosphoric acid produced activated carbons having lower BET surface areas than the ones obtained with raw material activation method by creating mesoporous structure. When the same char activation method was tried with potassium hydroxide, it was concluded that elevated temperatures could help in producing activated carbons with high BET surface areas by creating microporous structure. Results also showed that properties of activated carbon such as ash content, slurry pH value, true density, elemental composition, methylene blue number and surface morphology were strongly affected by both production conditions and production method, as pore structure was affected considerably.

Subject Keywords

Chemical engineering., Carbon, Activated., Pistachio.

URI

http://etd.lib.metu.edu.tr/upload/12612892/index.pdf
https://hdl.handle.net/11511/20488

Collections

Graduate School of Natural and Applied Sciences, Thesis