Effects of microwave heating on porous structure of regenerated powdered activated carbon used in xylose

Abstract

The regeneration of spent powdered activated carbons used in xylose decolourization by microwave heating was investigated. Effects of microwave power and microwave heating time on the adsorption capacity of regenerated activated carbons were evaluated. The optimum conditions obtained are as follows: microwave power 800 W; microwave heating time 30 min. Regenerated activated carbon in this work has high adsorption capacities for the amount of methylene blue of 16 cm³/0.1 g and the iodine number of 1000.06 mg/g. The specific surface areas of fresh commercial activated carbon, spent carbon and regenerated activated carbon were calculated according to the Brunauer, Emmett and Teller method, and the pore-size distributions of these carbons were characterized by non-local density functional theory (NLDFT). The results show that the specific surface area and the total pore volume of regenerated activated carbon are 1064 m²/g and 1.181 mL/g, respectively, indicating the feasibility of regeneration of spent powdered activated carbon used in xylose decolourization by microwave heating. The results of surface fractal dimensions also confirm the results of isotherms and NLDFT.

Keywords:

• spent powdered activated carbon
• regeneration
• microwave heating
• porous structure
• surface fractal dimensions

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Acknowledgements

The support of National Natural Science Foundation of China (21061007), the Analysis Testing Foundation of Kunming University of Science and Technology, Research Fund for Ph.D. Programs Foundation of Ministry of Education of China (20115314120014) and Reserve Talents of Middle-aged and Young Academic Technology Leaders in Yunnan Province (2011CI010) is gratefully acknowledged.