Summary
Although cellulose is the most abundant organic molecule, its susceptibility to hydrolysis is restricted due to the rigid lignin and hemicellulose protection surrounding the cellulose micro fibrils. Therefore, an effective pretreatment is necessary to liberate the cellulose from the lignin–hemicellulose seal and also reduce cellulosic crystallinity. Some of the available pretreatment techniques include acid hydrolysis, steam explosion, ammonia fiber expansion (AFEX), alkaline wet oxidation, and hot water pretreatment. Besides reducing lignocellulosic recalcitrance, an ideal pretreatment must also minimize formation of degradation products that inhibit subsequent hydrolysis and fermentation. AFEX is an important pretreatment technology that utilizes both physical (high temperature and pressure) and chemical (ammonia) processes to achieve effective pretreatment. Besides increasing the surface accessibility for hydrolysis, AFEX promotes cellulose decrystallization and partial hemicellulose depolymerization and reduces the lignin recalcitrance in the treated biomass. Theoretical glucose yield upon optimal enzymatic hydrolysis on AFEX-treated corn stover is approximately 98%. Furthermore, AFEX offers several unique advantages over other pretreatments, which include near complete recovery of the pretreatment chemical (ammonia), nutrient addition for microbial growth through the remaining ammonia on pretreated biomass, and not requiring a washing step during the process which facilitates high solid loading hydrolysis. This chapter provides a detailed practical procedure to perform AFEX, design the reactor, determine the mass balances, and conduct the process safely.
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References
Gray, K.A. Zhao, L., Emptage, M. (2006) Bioethanol. Curr. Opin. Chem. Biol. 10, 141–146
Ragauskas, A.J., Williams, C.K., Davison, B.H., Britovsek, G., Cairney, J., Eckert, C.A., Frederick, W.J. Jr., Hallett, J.P., Leak, D.J., Liotta, C.L., Mielenz, J.R., Murphy, R., Templer, R., Tschaplinski, T. (2006) The path forward for biofuels and biomaterials. Science. 311, 484–489
Ohara, H. (2003) Biorefinery. Appl. Microbiol. Biotechnol. 62, 474–477
Mosier, N., Wyman, C., Dale, B., Elander, R., Lee, Y.Y., Holtzapple, M., Ladisch, M. (2005) Features of promising technologies for pretreatment of lignocellulosic biomass. Bioresour. Technol. 96, 673–686
Wyman, C.E., Dale, B.E., Elander, R.T., Holtzapple, M., Ladisch, M.R., Lee, Y.Y. (2005) Coordinated development of leading biomass pretreatment technologies. Bioresour. Technol. 96, 1959–1966
Dale, B.E. (1986) Method for increasing the reactivity and digestibility of cellulose with ammonia. US Patent 4,600,590
Teymouri, F., Laureano-Perez, L., Alizadeh, H., Dale, B.E. (2005) Optimization of the ammonia fiber explosion (AFEX) treatment parameters for enzymatic hydrolysis of corn stover. Bioresour. Technol. 96, 2014–2018
Gollapalli, L.E., Dale, B.E., Rivers, D.M. (2002) Predicting digestibility of ammonia fiber explosion (AFEX) treated rice straw. Appl. Biochem. Biotechnol. 98–100, 23–35
O’Connor, J.J. (1972) Ammonia explosion pulping: a new fiber separation process. Tappi, 55, 353
Sulbaran de Ferrer, B., Aristiguieta, M., Dale, B.E., Ferrer, A., Ojada de Rodriguez (2003) Enzymatic hydrolysis of ammonia-treated rice straw. Appl. Biochem. Biotechnol. 105–108, 155–164
Eggeman, T., Elander, R.T. (2005) Process and economic analysis of pretreatment technologies. Bioresour. Technol. 96, 2019–2025
Alizadeh, H., Teymouri, F., Gilbert, T.I., Dale, B.E. (2005) Pretreatment of switchgrass by ammonia fiber explosion (AFEX) Appl. Biochem. Biotechnol. 121, 1133–1142
Bals, B., Dale, B.E., and Venkatesh, B. (2006) Enzymatic hydrolysis of distiller’s dry grain and solubles (DDGS) using ammonia fiber expansion pretreatment. Energy Fuels, 20, 2732–2736
Chundawat, S.P.S., Balan, V. and Dale, B.E. (2007) Effect of particle size based separation of milled corn stover on AFEX pretreatment and enzymatic digestibility. Biotechnol. Bioeng. 96, 219–231
Klinke, H.B., Thomsen, A.B. and Ahring, B.K. (2004) Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass. Appl. Microbiol. Biotechnol. 66, 10–26
Zhu, Y., Lee, Y.Y. and Elander, R.T. (2005) Optimization of dilute-acid pretreatment of corn stover using a high-solids percolation reactor. Appl. Biochem. Biotechnol. 124, 1045–1054
Viamajala, S., Selig, M.J., Vinzant, T.B., Tucker, M.P., Himmel, M.E., McMillan, J.D. and Decker, S.R. (2006) Catalyst transport in corn stover internodes: elucidating transport mechanisms using Direct Blue-I. Appl. Biochem. Biotechnol. 129–132, 509–527
Laine, J., Stenius, P., Carlsson, G. and Strom, G. (1994) Surface characterization of unbleached kraft pulps by means of ESCA. Cellulose 1, 145–160
Brunner, E. (1988) Fluid mixtures at high pressures VI. phase separation and critical phenomena in 18 (n-alkane + ammonia) and 4 (n-alkane _ methanol) mixtures. J. Chem. Thermodyn. 20, 273
Gillespie, P.C., Wilding, W.V. and Wilson, G.M. (1987) Vapor-liquid equilibrium measurements on the ammonia-water system from 313 K to 589K. AICHE Symposium Series 83, 97–127
Smolen, T.M., Manley, D.B. and Poling, B.E. (1991) Vapor-liquid equilibrium data for the NH3-H2O system and Its description with a modified cubic equation of state. J. Chem. Eng. data 36, 202–208
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Balan, V., Bals, B., Chundawat, S.P.S., Marshall, D., Dale, B.E. (2009). Lignocellulosic Biomass Pretreatment Using AFEX. In: Mielenz, J. (eds) Biofuels. Methods in Molecular Biology, vol 581. Humana Press, Totowa, NJ. https://doi.org/10.1007/978-1-60761-214-8_5
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DOI: https://doi.org/10.1007/978-1-60761-214-8_5
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