Energy & Fuels 2007, 21, 1165-1168
1165
Dewaxing from Stalks with Petroleum Ether by Different Methods Wei Zhao,* Zhi-Min Zong, Juan Lin, Yan-Min Song,† Xiang-Feng Guo, Zi-Shuo Yao, Li-Ning Zhang, Ren-Ling He, Jing-Pei Cao, and Xian-Yong Wei School of Chemical Engineering, China UniVersity of Mining and Technology, Xuzhou 221008, Jiangsu, China ReceiVed May 22, 2006. ReVised Manuscript ReceiVed October 9, 2006
Soxhlet, ultrasonic-, and microwave-assisted extractions for dewaxing from rice, wheat, and corn skin stalks with petroleum ether were compared. The results show that microwave-assisted extraction is the most effective method for dewaxing from the stalks. The yields and compositions of the waxes extracted by different methods were determined gravimetrically and by GC/MS analysis.
Introduction Stalks are an important biomass resource. Even only in China, annual production of stalks is estimated to be over 0.8 Gt and will increase in the future. Therefore, great attention has been paid to the development of a technology for the efficient use of the stalk resource. At present, in addition to use as fuel, stalks are mainly used to produce fertilizer, edible fungus, and industrial chemicals.1-11 All nonfuel uses are affected by the surface properties of stalks. Most of the stalk surface is covered with waxy layers. Wax coverage decreases the permeation of water and organic solvents in stalks, preventing the stalks from efficient use, especially use as potential feedstocks for valueadded chemicals. On the other hand, the wax itself in stalks usually consists of various organic compounds,12-17 including many value-added chemicals. Hence, exploring methods of * Corresponding author. E-mail:
[email protected]. † Present address: School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China. (1) Lv, P. M.; Chang, J.; Wang, T. J.; Wu, C. Z. Energy Fuels 2004, 18 (6), 1865-1869. (2) Bharadwaj, A.; Baxter, L. L.; Robinson, A. L. Energy Fuels 2004, 18 (4), 1021-1031. (3) Demirbas, A. Energy ConVers. Manage. 2001, 42 (11), 1357-1378. (4) Mφller, H. B.; Sommer, S. G.; Ahring, B. K. Biomass Bioenergy 2004, 26 (5), 485-495. (5) Dalai, A. K.; Sasaoka, E.; Hikita, H.; Ferdous, D. Energy Fuels 2003, 17 (6), 1456-1463. (6) Asadullah, M.; Miyazawa, T.; Ito, S.; Kunimori, K.; Tomishige, K. Energy Fuels 2003, 17 (4), 842-849. (7) Iranza, M.; Canizares, J. V.; Roca-Perez, L.; Sainz-Pardo, I.; Mormeneo, S. Bioresour. Technol. 2004, 95 (1), 107-112. (8) Di Blasi, C.; Branca, C.; Teislev, B. Bioresour. Technol. 2004, 91 (3), 263-271. (9) Wu, Z. S.; Wu, C. Z.; Huang, H. T.; Zheng, S. P.; Dai, X. W. Energy Fuels 2003, 17 (3), 619-624. (10) Gea, G.; Murillo, M. B.; Arauzo, J. Energy Fuels 2003, 17 (1), 46-53. (11) Calvo, L. F.; Otero, M.; Jenkins, B. M.; Moran, A.; Garcia, A. I. Fuel Process. Technol. 2004, 85 (4), 279-291. (12) Sylwia, K. W.; Jakub, N.; Edyta, W.; Jan, H.; Jan, D. M. Colloids Surf. B: Biointerfaces 2003, 29 (2-3), 131-142. (13) Taner, F.; Eratik, A.; Ardic, I. Fuel Process. Technol. 2005, 86 (4), 407-418. (14) Adam, J.; Blazso, B.; Meszaros, E.; Stocker, M.; Nilsen, M. H.; Bouzga, A.; Hustad, J. E. Fuel 2005, 84 (12-13), 1494-1502. (15) Klinke, H. B.; Ahring, B. K.; Schmidt, A. S.; Thomsen, A. B. Bioresour. Technol. 2002, 82 (1), 15-26. (16) Lequart, C.; Nuzillard, J. M.; Kurek, B.; Debeire, P. Carbohydr. Res. 1999, 319 (1-4), 102-111. (17) Sun, R. C.; Sun, X. F. Ind. Crops Prod. 2001, 14 (1), 51-64.
Table 1. Proximate Analysis (percent by Mass) of Different Stalk Powder Samples stalk sample powder
moisture (ad)
ash (ad)
volatile matter (daf)
rice wheat corn skin
5.6 5.3 4.8
7.2 6.1 3.6
86.8 88.2 88.6
efficient isolation of wax from stalks and understanding the detailed composition of the wax in stalks are of importance. In this paper, the effects of different extraction techniques on the yields of extracts were compared and the compositions of the wax extracted were determined. Experimental Section Samples and Solvent. Rice, wheat, and corn skin stalks were collected from the field in the vicinity of Xuzhou City, Jiangsu, China. They were washed with water, air-dried (ad) in sunlight, chopped into small pieces, and pulverized to pass through an 80mesh sieve (
