Article pubs.acs.org/IECR
Acid Hydrolysis of Prehydrolysis Liquor Produced from the KraftBased Dissolving Pulp Production Process Guihua Yang,*,†,‡ M. Sarwar Jahan,*,‡,§ Haitang Liu,‡,⊥ and Yonghao Ni*,‡ †
Key Laboratory of Pulp & Paper Science and Technology (Shandong Polytechnic University), Ministry of Education, Jinan, Shandong 250353, P.R. China ‡ Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 § Pulp and Paper Research Division, BCSIR Laboratories, Dhaka, 1205, Bangladesh ⊥ Tianjin Key Laboratory of Pulp and Paper, Tianjin University of Science and Technology, Tianjin 300457, P.R. China ABSTRACT: Acid hydrolysis is an essential step in converting polysaccharides to monosaccharides for the production of fuels and chemicals. The prehydrolysis liquor (PHL) from the kraft-based dissolving pulp production process contains mainly oligosugars with a minor amount of monosugars. In this study, the influence of process conditions, including the sulfuric acid concentration, temperature, and time on the PHL hydrolysis was thoroughly investigated in order to get maximum monosugar concentration with minimal degradation of sugars. The maximum monosugar concentration was obtained at 130 °C for 20 min when the hydrolysis was carried out with 1.78% H2SO4. A high acid concentration (3.33%) increased furfural formation and decreased the monosugar concentration. Acetic acid is generated from the acetyl groups bound to the dissolved hemicelluloses, resulting in a significant increase in the acetic acid concentration in the PHL. ral,8,11 (iii) acetic acid is generated by the cleavage of acetyl groups in wood, which is responsible for the decrease in pH during the prehydrolysis, and thus facilitate the hemicelluloses removal.9,12,13 The PHL from the kraft-based dissolving pulp production process contains both mono- and oligosugars along with lignin, acetic acid, and some degradation products.8 These sugars need to be converted to monosugars for producing fuels and chemicals. Therefore, the optimization of PHL hydrolysis is needed in order to obtain good conversion to monosugars with minimum degradation. The objective of this study was to determine the effect of the acid concentration on the monosugar concentration in the hydrolysis of PHL. The effects of hydrolysis time and temperature were also studied.
1. INTRODUCTION The acid-catalyzed hemicellulose hydrolysis is effective in breaking down their long chains to shorter oligomers and monomeric sugars. Hydrolysis of hemicelluloses in the prehydrolysis liquor (PHL) to monomeric sugars in an economical way presents a promising research opportunity that could be built into a realistic biorefinery initiative. Many studies have been carried out on hemicellulose hydrolysis of wood and nonwood by weak acid preextraction.1−4 The literature work has so far focused on the hydrolysis of hemicelluloses in the raw materials. So the results obtained clearly depend on the raw material type and on the operational conditions. The amount of sugars recovered from the raw material is dependent on the reaction time, temperature, and acid concentration.3 The acid concentration is the most important parameter affecting sugar yield, while for the formation of sugar degradation products, such as furfural, temperature has the highest impact.3,5 Dilute-acid pretreatment has the advantage of not only solubilizing hemicellulose but also converting solubilized hemicellulose to fermentable sugars.6 Kamiyama and Sakai7 studied on acid hydrolysis kinetics of di- and pentaoligoxylose and showed that the rate of hydrolysis of oligoxylose depended on the acid concentration and temperature and also found that the rate of xylose disugar hydrolysis was 1.8 fold higher than the corresponding pentaoligoxylose. Prehydrolysis is carried out for producing dissolving pulp in kraft process to efficiently remove hemicelluloses. During the prehydrolysis step of such a process, hemicelluloses and other organics are dissolved in the prehydrolysate liquor (PHL). The major reactions include: (i) depolymerization and dissolution resulting in the formation of sugars, oligomers,8−10 (ii) further degradation of sugars to form monosaccharides and sugardecomposition products such as furfural, hydroxymethylfurfu© 2012 American Chemical Society
2. MATERIALS AND METHODS 2.1. Industrial Prehydrolysate Liquor (PHL) Sample. The PHL samples were collected from the bottom of digester (draining the whole digester after depressurizing) at the dissolving pulp mills in Eastern Canada. The prehydrolysis of wood chips (70 wt % maple, 20 wt % poplar, and 10 wt % birch) was carried out through steaming at 170 °C for 30 min. The detail chemical composition of the PHL is given in Table 1. 2.2. Hydrolysis. Hydrolysis of PHL was carried out in a Parr reactor. The required amount of sulfuric acid was added to PHL in an ample and sealed. A sealed sample was placed inside the parr reactor contained water. The sulfuric acid concentrations in the PHL were 0.67, 1.14, 1.50, 1.78 and 3.33% (w/ Received: Revised: Accepted: Published: 13902
August 28, 2012 October 9, 2012 October 10, 2012 October 11, 2012 dx.doi.org/10.1021/ie3023059 | Ind. Eng. Chem. Res. 2012, 51, 13902−13907
Industrial & Engineering Chemistry Research
Article
Table 1. Compositions of the Industrial PHL Sample sugar (g/L) arhamnose arabinose galactose glucose xylose mannose total
mono-
oligo-
total
solid content (g/L)
lignin (g/L)
acetic acid (g/L)
furfural (g/L)
0.44 0.85 0.70 1.16 4.99 0.26 8.4
0.28 0 1.72 6.61 30.94 2.38 41.93
0.72 0.85 2.42 7.77 35.93 2.64 50.33
80.5
10.2
11.2
1.43
80.5
10.2
11.2
1.43
w) at 121 °C for 60 min. The temperature and time were also varied from 121, 130, and 140 °C for 20−180 min. 2.3. Activated Carbon (AC) Treatment. The PHL was treated with activated carbon (AC) at room temperature for 300 min. The ratio of PHL to AC was 30:1 and the shaking speed was 150 rpm. For the AC treatment of PHL in sonication, the time was 30 min and all other parameters were kept the same. 2.4. Sugar Analysis. The sugar concentrations were determined by using an ion chromatography unit equipped with a CarboPac PA1 column (Dionex-300, Dionex Cooperation, Canada) and a pulsed amperometric detector (PAD). The acidic hydrolysis of PHL with the required amount of sulfuric acid was carried out at 121, 130, and 140 °C in an oil bath (Neslab Instruments, Inc., Portsmouth, N.H., USA) to convert oligosaccharide to monosaccharide. The PAD settings were E1 = 0.1 V, E2 = 0.6 V, and E3 = −0.8 V. Deionized water was used as eluant with a flow rate of 1 mL/min, 0.2 N NaOH was used as the regeneration agent with a 1 mL/min flow rate, and 0.5 N NaOH was used as the supporting electrolyte with a 1 mL/min flow rate. The samples were filtered and diluted prior to analysis. The sugar content in the prehydrolysis liquor before the acid hydrolysis represented the monomeric form while the polymeric sugars were calculated from the difference with and without the acid hydrolysis. 2.5. Proton NMR Analysis. A Varian 300 NMRspectrometer was employed for determining the furfural and acetic acid concentrations as described earlier.14,15 Calibration curves were made with the standard solutions of each component to determine the unknown concentration for each of these present in the PHL. The solvent suppression method was used with D2O to sample ratio of 1:4.
Figure 1. Effect of hydrolysis time on the monosugar and furfural concentration at 3.33% sulfuric acid (121 °C).
furfural concentration increased.16 The effect of sulfuric acid concentration in the PHL hydrolysis on the monosugars concentration was shown in Table 2, and it was carried out at Table 2. Effect of Sulfuric Acid Concentration on the Monosugar Concentration in the Hydrolysis Process of Original PHL (121 °C, 60 min)
3. RESULTS AND DISCUSSION 3.1. Characteristics of the Prehydrolysis Liquor (PHL). The properties and chemical composition of the prehydrolysate liquor are summarized in Table 1. The hydrolysis was done by conventional conditions at 3.33% sulfuric acid and 121 °C for 60 min. In the PHL, 8.0% of the wood component was present as observed from solid content data of PHL. As expected xylan/ xylose was the major component in PHL, it was about 45% of total solid content. Another important product is acetic acid, which was about 14% of the total components. The lignin content in the PHL was about 13% of the solid content. In order to maximize the monosugar concentration, the acid hydrolysis of PHL needs to be optimized so that the furfural formation and other side reaction can be minimized. 3.2. Effect of Acid Concentration. The acid hydrolysis results at 121 °C and 3.33% sulfuric acid but various times are shown in Figure 1. The total monosugar concentration decreased with increasing hydrolysis time, consequently the
H2SO4 concentration (%)
0.67
1.14
1.50
1.78
3.33
rhamnose (%) arabinose (%) galactose (%) glucose (%) xylose (%) mannose (%) total sugars (%)
0.06 0.06 0.07 0.15 0.83
0.07 0.10 0.21 0.53 3.76 0.28 4.95
0.11 0.11 0.23 0.72 3.90 0.34 5.41
0.15 0.15 0.24 0.85 4.12 0.41 5.92
0.11 0.10 0.23 0.83 4.08 0.43 5.78
1.17
121 °C for 60 min. Xylose is the dominant sugar, and all sugar concentration are increased with increasing the acid concentration in the hydrolysis system until 1.78% sulfuric acid concentration. At the acid concentration of 0.67%, the mono sugar concentrations were low, with the total monosugar concentration of 1.17%, with the increase of acid concentration to 1.14%, the total monosugar concentration increased to 4.95%. The maximum monosugar concentration of 5.92% was obtained at the acid concentration of 1.78%, a further increase of acid concentration to 3.33% led to a slight decrease in the total monosugar concentration. The H2SO4 acid concentration was known to have an enormous effect on the conversion of xylopentose to xylose as observed by Kamiyama and Sakai.7 The effectiveness of dilute acid hydrolysis in xylan depolime13903
dx.doi.org/10.1021/ie3023059 | Ind. Eng. Chem. Res. 2012, 51, 13902−13907
Industrial & Engineering Chemistry Research
Article
Table 3. Effect of Sulfuric Acid Concentration and Time on the Monosugar Concentration at 130 °C (%) H2SO4 concentration (%)
time (min)
rhamnose
arabinose
galactose
glucose
xylose
mannose
total sugars
1.78 3.33 1.78 3.33 1.78 3.33
20 20 30 30 40 40
0.15 0.11 0.16 0.11 0.11 0.12
0.11 0.10 0.11 0.10 0.11 0.11
0.29 0.26 0.28 0.25 0.28 0.28
0.99 0.93 1.00 0.93 1.01 1.00
4.89 4.31 4.70 4.27 4.80 4.36
0.52 0.46 0.50 0.47 0.53 0.57
6.94 6.17 6.75 6.13 6.84 6.44
rization in the lignocellulosic raw materials was reported by others.2,4,6,17 Neuriter et al.17 showed that the acid concentration had the highest effect on the xylose concentration when studying the dilute acid hydrolysis of bagasse under various conditions, and the best conditions of 4.5% acid concentration, 159 °C, and 17 min were identified to reach the maximum xylose concentration of 22.95 g/100 g for the 20% dry matter bagasse feed stock. The xylose recovery concentration from Cyanara cardunculas was about 80% of the content in dry untreated raw material under the conditions of 0.1−0.2% acid concentration and 180 °C.18 Kim et al. observed that the hydrolysis of xylo-oligomers derived from pretreated hardwood by dicarboxylic maleic and oxalic acids produced the highest xylose concentration compared to sulfuric acid with less xylose degradation.19 On the basis of the above results, it can be concluded that the acid hydrolysis of PHL can be performed in much milder conditions than that of raw lignocellulosic material due to the lower molecular weight of hemicelluloses in the PHL in comparison with raw lignocellulosic material. The effects of mass transfer are likely to be significantly reduced if the xylooligosaccharides are dissolved in a liquid, as opposed to being integrated into the solid wood materials from which they are derived. 3.3. Effect of Time and Temperature at Low Acid Concentration. The dilute acid hydrolysis of PHL was carried out with varying time and temperature, and the results are shown in Table 3. At 130 °C, the total sugar concentration was consistently higher at 1.78% sulfuric acid concentration than that at 3.33% sulfuric acid concentration. Lavarack et al. observed that the xylose concentration from the bagasse hydrolysis reached its maximum within a short time at higher temperature (200 °C).4 Horwath et al.20 observed that the xylose formation and degradation were higher at higher temperature of pentosan hydrolysis in the biomass. As shown in Figure 2, at 130 °C, extending the hydrolysis time from 20 to 40 min had a negligible effect on the total monosugar concentration, and this was true for the acid concentration of 1.78 and 3.33% (Figure 2). A slightly lower sugar concentration at the acid concentration of 3.33% as compared to 1.78% may be explained by the formation of furfural. The above results support the conclusion that the acid concentration played an important role than the hydrolysis time at 130 °C. 3.4. Furfural and Acetic Acid. The formation of furfural, acetic acid, and monosugar concentration at different temperature and time at the 3.33% acid concentration are shown in Figure 3a−c. The total monosugar concentration at 130 °C is higher than that of 140 or 121 °C (Figure 3a). A lower monosugar concentration at higher temperature can be explained by furfural formation. Furfural is an inhibitory agent for sugar fermentation if sugar is for fermentation and
Figure 2. Effect of sulfuric acid concentration and time at 130 °C on the total monosugars concentration in the original PHL hydrolysis process.
chemical industries.21 The objective of this study was to get maximum monosugar concentration with minimum furfural formation. From Figure 3a and b, it could be seen that the acid hydrolysis at 130 °C for 20 min produced less furfural and more monosugar concentration than the acid hydrolysis at 121 °C for 60 min. Acid hydrolysis at 140 °C is detrimental as sugar was converted to furfural. The temperature has the highest effect on the degradation of sugar to furfural. The furfural formation increased from 0.34% to 0.79% with the increase of temperature from 130 to 140 °C for 20 min hydrolysis (Figure 3b). Neureiter et al.17 also showed that temperature and acid concentration were main factor for the degradation of sugar to furfural. The free acetic acid in the PHL sample was 1.12%, and more acetic acid is generated during the PHL acid hydrolysis from the bound acetyl groups in the dissolved hemicelluloses in the PHL, as shown in Figure 3c. It can be found that under the conditions studied the temperature variation from 121 to 140 °C and time variation from 20 to 90 min did not affect the acetic acid formation, indicating that the bound acetyl groups are readily hydrolyzed to form acetic acid in the process. Acetic acid is a major commercial products, and it has a huge use in food products, solvent, reagent, etc. Acetic acid in the PHL can be a valuable coproduct from the forest biorefinery. For a dissolving pulp mill of 600 ton/day (210 000 ton/y), at a 39% yield, one can estimate that there will be about 27 500 ton acetic acid/y.8 The economic implications can be substantial. This is also observed in other studies, for example, Xing et al.22 reported that acetic acid and formic acid were generated in the hemicelluloses solution hydrolysis for furfural production. The complete conversion of oligosugar in the hydrolysis will lead to an increase not only the monosugar yield, but also in the 13904
dx.doi.org/10.1021/ie3023059 | Ind. Eng. Chem. Res. 2012, 51, 13902−13907
Industrial & Engineering Chemistry Research
Article
Figure 4. Acid hydrolysis of PHLs with different oligosugar concentrations and its effect on the (a) monosugar concentration and (b) furfural and acetic acid concentrations.
monosugar concentration was 20.8%. Therefore, the more concentrated PHL would need higher acid concentration to complete the hydrolysis. This result complies with the acid hydrolysis of bagasse by Neureiter et al.17 who demonstrated that the hemicellulose concentration had a negative effect on the xylose yield, and a higher concentration sulfuric acid would have to be used to reach the expected xylose concentration. Another possible reason may be the formation of reversion products of xylose as observed in the case of glucose, where reversion reactions occurred at high sugar concentration in mildly acidic condition.23 The reversion products observed were primarily disaccharides. As shown in Figure 4b, the more concentrated PHL consequently generated more acetic acid from the bound acetyl hemicelluloses if the sulfuric acid concentration in the hydrolysis increased. The furfural formation was less when hydrolysis was carried out with 1.78% H2SO4 concentration at 130 °C for 20 min and remained almost constant at different sugar concentrations, but hydrolysis at 3.33% H 2 SO 4 concentration increased the furfural formation at a higher sugar concentration, as observed from Figure 4b. In summary, higher PHL concentration would need higher sulfuric acid concentration to completely hydrolyze the bound acetyl groups in the dissolved hemicelluloses. 3.6. Acid Hydrolysis of Activated Carbon Treated PHL. The industrial PHL contains lignin, which can hinder the utilization of sugars in the PHL;8 therefore, its removal has been studied based on the adsorption concept by using activated carbon, lime, or other adsorbent and/or flocculation concept.23−26 Table 4 shows the effect of acid concentration on the hydrolysis of activated carbon (AC) pretreated PHL at 130 °C for 20 min. Similar to original PHL, for the AC treated PHL, 1.78% acid concentration can be sufficient to complete the
Figure 3. Effect of time and temperature on the formation of (a) furfural, (b) monosugar concentration, and (c) acetic acid concentration (sulfuric acid concentration 3.33%).
acetic acid concentration, which will increase the revenue of the biorefinery process. 3.5. Effect of PHL Concentration. The PHL was evaporated to different concentrations of 14%, 21%, and 35% solid content, and hydrolysis was carried out with 3.33% H2SO4 concentration at 121 °C for 60 min or 1.78% H2 SO 4 concentration at 130 °C for 20 min. The hydrolysis of 14% PHL was nearly completed by 1.78% acid at 130 °C for 20 min, as shown in Figure 4a. If the PHL is further concentrated to higher PHL concentrations, i.e., 21% or 35%, the hydrolysis cannot be completed under the conditions of 1.78% H2SO4 concentration at 130 °C for 20 min. In case of 21% PHL, the total mono- sugar concentration was only 16.2% at 1.78% acid concentration, while at 3.33% acid concentration the total 13905
dx.doi.org/10.1021/ie3023059 | Ind. Eng. Chem. Res. 2012, 51, 13902−13907
Industrial & Engineering Chemistry Research
Article
ultrasonic treatment in the AC adsorption process is useful to PHL hydrolysis efficiency and improving total sugars concentration, and decreasing the AC adsorbed time. Compared to the shaking treatment in AC adsorption of PHL, ultrasonic treatment increased total sugars concentration by 7%, and AC adsorbed time decreased by 90% using ultrasonic treatment in the AC adsorption process.
Table 4. Effect of Sulfuric Acid Concentration on Activated Carbon Treated PHL on the Monosugar Concentration (130 °C, 20 min) H2SO4 concentration (%)
1.14
1.5
1.78
3.33
rhamnose (%) arabinose (%) galactose (%) glucose (%) xylose (%) mannose (%) total sugars (%)
0.09 0.12 0.11 0.19 0.75
0.14 0.11 0.22 0.76 3.89 0.44 5.56
0.16 0.21 0.20 0.76 3.73 0.42 5.48
0.13 0.10 0.20 0.69 3.03 0.37 4.52
1.4
■
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected] (G.Y.),
[email protected] (M.S.J.),
[email protected] (Y.N.).
hydrolysis with a total monosugar concentration of 5.92%. It can also be seen from Table 5 that AC adsorption of PHL with
Notes
Table 5. Effect of Ultrasonic Treatment on the Active Carbon Adsorption of PHL Hydrolysis at 1.78% H2SO4 Concentration (130 °C, 20 min)a
ACKNOWLEDGMENTS The authors are grateful for the financial support from the National Science Foundation of China (Grant No.31070525, 31270627) and the Prior Special Study of 973 Program (Grant No.2011CB211705). This project was also funded by an NSERC CRD grant.
rhamnose (%) arabinose (%) galactose (%) glucose (%) xylose (%) mannose (%) total sugars (%) a
original PHL
adsorbed for 300 min at room temperature and shaking speed 150 rpm
ultrasonic treatment for 30 min at room temperature
0.02
0.33
0.45
0.09
0.13
0.20
0.34
0.23
0.25
1.05 4.51 0.42
0.72 3.95 0.56
0.79 4.21 0.45
6.43
5.92
6.35
The authors declare no competing financial interest.
■ ■
REFERENCES
(1) Carrasco, E.; Roy, C. Kinetic study of dilute-acid prehydrolysis of xylan-containing biomass. Wood Sci. Technol. 1992, 26, 189−208. (2) Gonzalez, G.; Lopez-Santin, J.; Caminal, G.; Sola, C. Dilute Acid Hydrolysis of Wheat Straw Hemicellulose at Moderate Temperature: A Simplified Kinetic Model. Biotechnol. Bioeng. 1986, 28, 288−293. (3) Roberto, I. C.; Mussatto, S. I.; Rodrigues, R. C. L. B. Dilute-acid hydrolysis for optimization of xylose recovery from rice straw in a semi-pilot reactor. Ind. Crops Products 2003, 17, 171−176. (4) Lavarack, B. P.; Griffin, G. J.; Rodman., D. The acid hydrolysis of sugarcane bagasse hemicellulose to produce xylose, arabinose, glucose and other products. Biomass Bioenergy 2002, 23, 367−380. (5) Neureiter, M.; Danner, H.; Thomasser, C.; Saidi, B.; Braun, R. Dilute acid hydrolysis of sugar cane bagasse at varying conditions. Biochem. Biotechnol. 2002, 98, 49−58. (6) Loyd, T. A.; Wyman, C. E. Combined sugar yields for dilute sulfuric acid pretreatment of corn stover followed by enzymatic hydrolysis of the remaining solids. Bioresour. Technol. 2005, 96 (18), 1967−1977. (7) Kamiyama, Y.; Sakai, Y. Rate of hydrolysis of xylooligosaccharides in dilute sulfuric acid. Carbohydr. Res. 1979, 73, 151−458. (8) Saeed, A.; Jahan, M. S.; Li, H.; Liu, Z.; Ni, Y; Heiningen, A. Mass balances of components dissolved in the pre-hydrolysis liquor of kraftbased dissolving pulp production process from Canadian hardwoods. Biomass Bioenergy. 2012, 39, 14−19. (9) Alfaro, A.; Rivera, A.; Pérez, A.; Yáñez, R.; García, J. C.; López, F. Integral valorization of two legumes by autohydrolysis and organosolv delignification. Bioresour. Technol. 2009, 100, 440−445. (10) Liu, C.; Wyman, C. E. Partial flow of compressed-hot water through corn stover to enhance hemicellulose sugar recovery and enzymatic digestibility of cellulose. Bioresour. Technol. 2005, 96, 1978− 85. (11) Garrote, G.; Domínguez, H.; Parajó, J. C. Kinetic modelling of corncob autohydrolysis. Process Biochem. 2001, 36, 571−578. (12) Mosier, N. S.; Hendrickson, R.; Brewer, M.; Ho, N.; Sedlak, M.; Dreshel, R.; Welch, G.; Dien, B. S.; Aden, A.; Ladisch, M. R. Industrial scale-up of pH-controlled liquid hot water pre-treatment of corn fiber for fuel ethanol production. Biochem. Biotechnol. 2005, 125, 77−97. (13) Sixta, H. Multistage kraft pulping. Handbook of pulp; Sixta, H., Ed.; Wiley VCH: Weinheim, 2006; pp 325−365. (14) Ni, Y.; Kang, G. J.; Van Heiningen, A. R. P. Are hydroxyl group responsible for degradation of carbohydrates during ozone bleaching of chemical pulp? J. Pulp Paper Sci. 1996, 22 (2), 53−57.
The ratio of PHL to AC was 30:1.
ultrasonic treatment is beneficial in improving the total sugars concentration in the PHL hydrolysis and decreasing the adsorption time. Compared to the shaking treatment in AC adsorption of PHL, the total sugar concentration increased by 7% and AC adsorption time can be decreased by 90% by using ultrasonic treatment. The fact that ultrasonic pretreatment is beneficial may be due to mixing effects, or perhaps helping to enhance the release of xylo-oligosaccharides from the solid particles where these might otherwise be absorbed. The increase of total sugars will improve value-added products yield, and consequently increase the revenue of the process.
■
CONCLUSION The oligosugars present in PHL can be hydrolyzed to monosugars with minimum formation of furfural at 1.78% sulfuric acid concentration. The hydrolysis time and temperature also influenced the sugar concentration, and the maximum sugar concentration was obtained at 130 °C for 20 min of hydrolysis. A higher acid concentration increased furfural formation at the expense of monosugar concentration. The hydrolysis of oligosugar under mild conditions was accompanied with the formation of more acetic acid from the bound acetyl groups. The sulfuric acid concentration played a significant role in completing the hydrolysis, a more concentrated PHL would need higher acid concentration to ensure a complete hydrolysis. A low acid concentration hydrolysis conditions is beneficial for the hydrolysis of activated carbon (AC) treated PHL. An 13906
dx.doi.org/10.1021/ie3023059 | Ind. Eng. Chem. Res. 2012, 51, 13902−13907
Industrial & Engineering Chemistry Research
Article
(15) Ni, Y.; Kang, G. Formation of Per-acetic Acid during Peroxide Bleaching of Mechanical pulps. Appita. J. 2007, 60, 70−73. (16) Zeitsch., K. J. The chemistry and technology of furfural and its many by-products; Elsevier Science: New York, 2000. (17) Neureiter, M.; Danner, H.; Thomasser, C.; Saidi, B.; Braun., R. Dilute-Acid Hydrolysis of Sugarcane Bagasse at Varying Conditions. Appl. Biochem. Biotechnol. 2002, 49, 98−100. (18) Ballesteros, M.; Negro, M. J.; Manzanares, P.; Ballesteros, I.; Sáez, F.; Oliva, J. M. Fractionation of Cynara cardunculus (Cardoon) biomass by dilute-acid pretreatment. Appl. Biochem. Biotechnol. 2007, 140, 239−252. (19) Kim, Y.; Kreke, T.; Ladisch, M. R. Reaction mechanisms and kinetics of xylo-oligosaccharide hydrolysis by dicarboxylic acids. AIChE J. 2012, DOI: 10.1002/aic.13807. (20) Horwath, J. A.; Mutharasan, R.; Grossmann, E. D. Pentosan hydrolysis in a concentrated slurry system. Biotechnol. Bioeng. 1983, 25 (1), 19−32. (21) Laser, M.; Schulman, D.; Allen, S. G.; Lichwa, J.; Antal, M. J., Jr.; Lynd, L. R. A comparison of liquid hot water and steam pretreatments of sugar cane bagasse for bioconversion to ethanol. Biores. Technol. 2002, 81 (1), 33−44. (22) Xing, R.; Qi, W.; Huber, G. W. Production of furfural and carboxylic acids from waste aqueous hemicelluloses solutions from the pulp and paper and cellulosic ethanol industries. Energy Environ. Sci. 2011, 4, 2193−05. (23) Pilath, H. M.; Nimlos, M. R.; Mittal, A.; Himmel, M. E.; Johnson, D. K. Glucose Reversion Reaction Kinetics. J. Agric. Food Chem. 2010, 58 (10), 6131−6140. (24) Liu, Z.; Fatehi, P.; Sadeghi, S.; Ni, Y. Application of hemicelluloses precipitated via ethanol treatment of pre-hydrolysis liquor in high-yield pulp. Biores. Technol. 2011, 102, 9613−18. (25) Shen, J.; Fatehi, P.; Soleimani, P.; Ni, Y. Lime Treatment of Prehydrolysis Liquor from the Kraft-Based Dissolving Pulp Production Procedd. Ind. Eng. Chem. Res. 2012, 51, 667−672. (26) Shi, H.; Fatehi, P.; Xiao, H.; Ni, Y. Optimizing the Poly Ethylene Oxide Flocculation Process for Isolating Lignin of Prehydrolysis Liquor of a Kraft-Based Dissolving Pulp Production Process. Ind. Eng. Chem. Res. 2012, 51, 5330−35.
13907
dx.doi.org/10.1021/ie3023059 | Ind. Eng. Chem. Res. 2012, 51, 13902−13907
