Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals

Nanjing, China

Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals

Nanjing, China
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Yang J.,Nanjing Forestry University | Rong Y.,Nanjing Forestry University | Gao L.,Nanjing Forestry University | Zhu J.,Nanjing Forestry University | And 7 more authors.
Huagong Xuebao/CIESC Journal | Year: 2016

Aiming at the effect of inhibitors on yeast ethanol fermentation during the fuel ethanol biorefinery process, a new green detoxification technology-ionic liquid extraction was developed for detoxification of the prehydrolyzate obtained from washed acid-catalyzed steam-exploded corn stover (ASC). The extractive performances of two kinds of imidazolium-based ionic liquids (alkylimidazolium hexafluorophosphate [Cnmim][PF6] (n=4,6,8) and alkylimidazolium tetrafluoroborate [Cnmim][BF4] (n=6,8)) for the ASC prehydrolyzate were investigated and compared. The results indicated that the extraction efficiency of the inhibitors decreased with the increase of alkyl chain length on the cation of ionic liquids. Ionic liquid with BF4 - anion had much higher extraction efficiency for the inhibitors than those with PF6 - anion because of the stronger effective charge in BF4 -. Compared to the extraction efficiency of sugars and inhibitors, [C8mim][BF4] was selected as the extractant for detoxification of the ASC prehydrolyzate. Its detoxification results indicated that 85.13% of 5-hydroxymethylfurfural, 53.22% of formic acid, 47.53% of acetic acid and 65.05% of total phenols could be removed, while the loss of sugars was less than 6%. © All Right Reserved.


Rong Y.,Nanjing Forestry University | Shi L.,Nanjing Forestry University | Zhang C.,Nanjing Forestry University | Zou L.,Nanjing Forestry University | And 8 more authors.
Huagong Xuebao/CIESC Journal | Year: 2016

Aiming at the effect of lignin-degradation products on ethanol fermentation during the bioethanol production process, six kinds of typical lignin-degradation products (vanillin, syringaldehyde, 4-hydroxybenzaldehyde, vanillic acid, syringic acid and 4-hydroxybenzoic acid) were selected to oxidative removal by a new detoxification technology-advanced oxidation process of heat-activated persulfate. The oxidation removal conditions and its oxidation mechanism were also investigated. The results indicated that the optimal oxidation conditions were pH 6.0, 80℃, and the persulfate concentration of 1.5 g·L-1 based on 0.1 g·L-1 vanillin. On the basis of the optimized conditions, the oxidation effect of other five of typical lignin-degradation products was studied. The results showed that the effects of oxidation removal were obvious. The removal ratio of vanillin, 4-hydroxybenzaldehyde, vanillic acid and syringic acid reached to 100% within 1 h, while that of syringaldehyde reached to 100% within 2 h. The study of oxidative mechanism was to indirectly decide which the main active species was in the reaction process by the addition of radical scavengers of methanol and t-butanol. The results showed that the main active species were sulfate radicals. Therefore, using heat-activated persulfate is a good way for oxidative removal of the lignin-degradation products. © All Right Reserved.


Zhu J.,Nanjing Forestry University | Zhu J.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | Yang J.,Nanjing Forestry University | Zhu Y.,Nanjing Forestry University | And 6 more authors.
Bioprocess and Biosystems Engineering | Year: 2014

The prehydrolyzate obtained from acid-catalyzed steam-exploded corn stover (ASC) mainly contains xylose and a number of inhibitory compounds that inhibit ethanol fermentation by Pichia stipitis. In this study, the effects of the ASC prehydrolyzate, specifically those of the carbohydrate-degradation products, lignin-degradation products (which were extracted from ASC prehydrolyzate using ethyl acetate), and six major phenolic compounds (added to pure-sugar media individually or in combination), on ethanol fermentation were investigated. Results indicate that the effects of the carbohydrate-degradation products were negligible (10 h delayed) compared with those of pure-sugar fermentation, whereas the effects of the lignin-degradation products were significant (52 h delayed). Meanwhile, the inhibitory effects of the major phenolic compounds were not caused by certain types of inhibitors, but were due to the synergistic effects of various inhibitors. © 2014 Springer-Verlag.


Zhu J.,Nanjing Forestry University | Zhu J.,Jiangsu Key Laboratory of Biomass Based Green Fuel and Chemicals | Zhu Y.,Nanjing Forestry University | Zhang L.,Nanjing Forestry University | And 6 more authors.
Separation and Purification Technology | Year: 2014

Trialkylamine was an effective extractant for the removal of inhibitors from corn stover prehydrolyzate. Ethanol fermentability of the extracted prehydrolyzate was improved significantly. An approach for regeneration and valuable solutes (mainly acetic acid) recovery from such extractant was to back-extract the extractant containing inhibitors with sodium hydroxide. The influences of NaOH concentration, aqueous-organic phase ratio (A/O) on the extractant regeneration were investigated. The results indicated that 17.5 g/l NaOH could remove 100% acetic acid at A/O of 1:1. 175 g/l NaOH at A/O of 1:10 could also reach the same effect. Likewise, the results of 175 g/l NaOH at A/O of 1:1 repeatedly back-extracted the extractant for ten cycles were the same as before. The performance of regenerated extractant on extraction the corn stover prehydrolyzate showed almost no change after reused ten cycles. So NaOH was very suitable to regenerate the extractant containing inhibitors in bioethanol industry. © 2014 Elsevier B.V. All rights reserved.


Zhu J.,Nanjing Forestry University | Zhu J.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | Rong Y.,Nanjing Forestry University | Yang J.,Nanjing Forestry University | And 8 more authors.
Applied Biochemistry and Biotechnology | Year: 2015

High-efficiency xylose utilization is one of the restrictive factors of bioethanol industrialization. However, xylonic acid (XA) as a new bio-based platform chemical can be produced by oxidation of xylose with microbial. So, an applicable technology of XA bioconversion was integrated into the process of bioethanol production. After corn stover was pretreated with acid-catalyzed steam-explosion, solid and liquid fractions were obtained. The liquid fraction, also named as acid-catalyzed steam-exploded corn stover (ASC) prehydrolyzate (mainly containing xylose), was catalyzed with Gluconobacter oxydans NL71 to prepare XA. After 72 h of bioconversion of concentrated ASC prehydrolyzate (containing 55.0 g/L of xylose), the XA concentration reached a peak value of 54.97 g/L, the sugar utilization ratio and XA yield were 94.08 and 95.45 %, respectively. The solid fraction was hydrolyzed to produce glucose with cellulase and then fermented with Saccharomyces cerevisiae NL22 to produce ethanol. After 18 h of fermentation of concentrated enzymatic hydrolyzate (containing 86.22 g/L of glucose), the ethanol concentration reached its highest value of 41.48 g/L, the sugar utilization ratio and ethanol yield were 98.72 and 95.25 %, respectively. The mass balance showed that 1 t ethanol and 1.3 t XA were produced from 7.8 t oven dry corn stover. © 2015, Springer Science+Business Media New York.


Zhu J.,Nanjing Forestry University | Zhu J.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | Shi L.,Nanjing Forestry University | Zhang L.,Nanjing Forestry University | And 5 more authors.
Bioprocess and Biosystems Engineering | Year: 2016

The difference in the enzymatic hydrolysis yield of acid-catalyzed steam-exploded corn stover (ASC) before and after washing with water reached approximately 15 % under the same conditions. The reasons for the difference in the yield between ASC and washed ASC (wASC) were determined through the analysis of the composition of ASC prehydrolyzate and sugar concentration of enzymatic hydrolyzate. Salts produced by neutralization (CaSO4, Na2SO4, K2SO4, and (NH4)2SO4), sugars (polysaccharides, oligosaccharides, and monosaccharides), sugar-degradation products (weak acids and furans), and lignin-degradation products (ethyl acetate extracts and nine main lignin-degradation products) were back-added to wASC. Results showed that these products, except furans, exerted negative effect on enzymatic hydrolysis. According to the characteristics of acid-catalyzed steam explosion pretreatment, the five sugar-degradation products’ mixture and salts [Na2SO4, (NH4)2SO4] showed minimal negative inhibition effect on enzymatic hydrolysis. By contrast, furans demonstrated a promotion effect. Moreover, soluble sugars, such as 13 g/L xylose (decreased by 6.38 %), 5 g/L cellobiose (5.36 %), 10 g/L glucose (3.67 %), as well as lignin-degradation products, and ethyl acetate extracts (4.87 %), exhibited evident inhibition effect on enzymatic hydrolysis. Therefore, removal of soluble sugars and lignin-degradation products could effectively promote the enzymatic hydrolysis performance. © 2016 Springer-Verlag Berlin Heidelberg


Yang J.,Nanjing Forestry University | Cheng Y.,Nanjing Forestry University | Zhu Y.,Nanjing Forestry University | Zhu J.,Nanjing Forestry University | And 7 more authors.
Shengwu Gongcheng Xuebao/Chinese Journal of Biotechnology | Year: 2016

Lignin degradation products are toxic to microorganisms, which is one of the bottlenecks for fuel ethanol production. We studied the effects of phenolic ketones (4-hydroxyacetophenone, 4-hydroxy-3-methoxy-acetophenone and 4-hydroxy-3,5-dimethoxy-acetophenone) derived from lignin degradation on ethanol fermentation of xylose and cellular lipid composition of Pichia stipitis NLP31. Ethanol and the cellular fatty acid of yeast were analyzed by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Results indicate that phenolic ketones negatively affected ethanol fermentation of yeast and the lower molecular weight phenolic ketone compound was more toxic. When the concentration of 4-hydroxyacetophenone was 1.5 g/L, at fermentation of 24 h, the xylose utilization ratio, ethanol yield and ethanol concentration decreased by 42.47%, 5.30% and 9.76 g/L, respectively, compared to the control. When phenolic ketones were in the medium, the ratio of unsaturated fatty acids to saturated fatty acids (UFA/SFA) of yeast cells was improved. When 1.5 g/L of three aforementioned phenolic ketones was added to the fermentation medium, the UFA/SFA ratio of yeast cells increased to 3.03, 3.06 and 3.61, respectively, compared to 2.58 of the control, which increased cell membrane fluidity and instability. Therefore, phenolic ketones can reduce the yeast growth, increase the UFA/SFA ratio of yeast and lower ethanol productivity. Effectively reduce or remove the content of lignin degradation products is the key to improve lignocellulose biorefinery. © 2016 Chin J Biotech, All rights reserved.


Wang X.,Nanjing Forestry University | Wang X.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | Zhou X.,Nanjing Forestry University | Zhou X.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | And 4 more authors.
Chemistry and Industry of Forest Products | Year: 2014

Five calcium aldonates were firstly produced from glucose, xylose, arabinose, galactose and mannose respectively by whole cell catalysis using Gluconobacter oxydans in the shake-flask liquid system. Their purities were detected by high performance anion-exchange chromatography coupled with pulsed amperometric detector (HPAEC-PAD), and the molecular structures were identified by infrared spectroscopy (IR) and electrospray ionization mass spectrometry (ESI-MS). The results indicated that a strong absorbance of COO- deprotonated carboxylic group characteristic peak located at 1600 cm-1 was observed in IR. In ESI-MS spectra, the characteristic molecule-mass peaks in pentonic acids and hexonic acids were identified at 165.1 and 195.1, respectively. These values were consistent with the theoretical values.


Chen X.-P.,Nanjing Forestry University | Chen X.-P.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | Zhang L.,Nanjing Forestry University | Zhang L.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | And 8 more authors.
Chemistry and Industry of Forest Products | Year: 2014

The main factors affecting self-immobilization of Rhizopus oryzae NLX-M-1 for L-lactic acid production were studied in present study. The optimum fermentation conditions utilizing wood fiber-based glucose for R. oryzae self-immobilization were obtained. The optimal results were achieved as 100 g/L initial glucose, 2 g/L (NH4)2SO4, 2%inoculum size (value fraction), 30 g/L CaCO3, 0.1 g/L KH2PO4, 0.25 g/L MgSO4·7H2O and 0.1 g/L ZnSO4·7H2O. Under this optimal condition, R. oryzae formed pellets with an average diameter of about 1 mm during the fermentation, the production of L-lactic acid was 76.6 g/L and the conversion rate was 81.6%. R. oryzae in acid explosive residue hydrolyzate containing 60 g/L glucose became 1.2 mm pellets, and produced 36.4 g/L L-lactic acid with a conversion rate of 63.5%.


Li Q.,Nanjing Forestry University | Li Q.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | Song X.-Y.,Nanjing Forestry University | Song X.-Y.,Jiangsu Key Laboratory of Biomass based Green Fuel and Chemicals | And 6 more authors.
Chemistry and Industry of Forest Products | Year: 2015

Mixed sugars (glucose and xylose)consumption patterns by the following three fermentation methods, i.e., single bacterium fermentation by Candida shehatae, successive fermentation by C. shehatae and Saccharomyces cerevisiae, as well as synchronization (fermentation by these two), were investigated. The results showed that the fermentation by synchronization pattern can effectively terminate the inhibition of glucose, and accelerate the xylose utilization at the same time. The fermentation medium of mixed yeast was optimized by Plackett-Burman design, steepest climbing experimental design, and central composite design. The optimal culture conditions were (NH4)2SO4 9.09 g/L, KH2PO4 8.96 g/L and CaCl2 0.34 g/L. Under the above conditions of fermentation, the ethanol yield was 21.71 g/L, which is 9.4% higher than before. Under the optimized medium, the yeast turbidity (OD) increased from 12.12 to 21.87, and the conversion of xylose also increased from 82% to 93%. ©, 2015, Edited & Published by Editorial Board of «Chemistry and Industry of Forest Products». All right reserved.

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