5. 2017 2(4) research, determination of furfural and ...€¦ · (gc-ms)3,17-19 and high...

Journal of Bioresources and Bioproducts. 2017, 2(4): 170-174

www.Bioresources-Bioproducts.com 170

Determination of Furfural and Hydroxymethyl furfural by UV Spectroscopy in ethanol-water hydrolysate of Reed

Haiyang Zhanga, Qingwei Pinga,*, Jian Zhanga and Na Lia

a) Dalian Polytechnic University, Liaoning Province Key Laboratory of pulp and paper, Dalian, Liaoning, 116034, China.

*Corresponding author: [email protected]

ABSTRACT

In this paper a quick method was developed to determine separate furfural and HMF concentrations simultaneously in ethanol-water hydrolysate of reed based on UV spectroscopy. Acid soluble lignin and other interfering substances were first removed by distillation as residue. The distillate was then used for the determination of furfural and HMF by measuring the maximum absorption wavelength and the absorbance at the wavelength. Results showed that the maximum absorption wavelength of the characteristic peak correlated well with the composition of furfural and HMF mixture in an ethanol-water solution, and the absorbance at the maximum absorption wavelength also had an excellent linear relationship with the sum concentration of furfural and HMF in the solution. The separate concentrations of furfural and HMF in a mixture solution could be determined by applying these correlations.

Keywords: Furfural; HMF; ultraviolet visible spectroscopy; lignocellulose biomass

1. INTRODUCTION

Today global development is facing resource shortageand energy crises due to the foreseeable depletion of fossil oil reserves.1 Development of technologies to utilize renewable biomass feedstock based on the biorefinery concept holds an important practical significance in a long-term strategic approach to substitute chemicals and fuels from fossil resources. The biorefining process includes extraction and fractionation of valuable biopolymers and bio-chemicals from biomass.2-4 The high value by-products of furfural (F) and 5-hydroxymethyl furfural (HMF) can effectively be obtained in the auto-catalyzed ethanol-water refining system at high temperatures.5 Furfural and HMF can readily be formed from water-soluble monomers and oligomers of pentose and hexose, respectively, which are derived from biomass.

Furfural and HMF are used extensively as organic solvents and reagents in the production of medicines, resins, food additives, fuel additives and other special chemicals6-8. The derivatives of furfural and HMF are also high value products.9-10 A number of studies in the literature associated with biomass refinery focused on the isolation, purification and application of furfural and HMF.10-13

The conventional methods to determine furfural and HMF concentration in hydrolysate include capillary electrophoresis,14-15 Mn(II)-catalyzed B-Z oscillating system,13 gas chromatography–mass spectrometry (GC-MS)3,17-19 and high performance liquid chromatography (HPLC).20-27 HPLC along with a UV detector is commonly used to determine furfural and HMF, but the calibration procedure is time-consuming.28 UV spectroscopy method is relatively simple and rapid.

Our previous studies revealed that furfural and HMF have maximum absorption at 276 nm and 284 nm, respectively, which can be used to determine their concentrations in solutions. However, the measurement of mixture of furfural and HMF in hydrolysate is interfered by acid soluble lignin and overlap of the absorption peaks of furfural and HMF. In current study, we explored a novel method to analyze both furfural and HMF in hydrolysate while avoiding the interference of inter-superimposed absorbed peaks of the furan compounds in the UV spectra.

2. EXPERIMENTAL

2.1. Materials and Methods

2.1.1. Materials

Furfural (>99.5%) purchased from Ziyi chemicals and HMF (HPLC grade, >98%) from Xiya chemicals Inc. (China) were used without further purification. 95% ethanol was purchased from Tianyuan Pharmaceutical Co. (Panjin, China). Reeds received from Xishan reservoir (Dalian, China) were cut to 2~3 cm length chips and then air dried.

2.1.2. Sample Preparations

The furfural, HMF and compound (furfural + HMF) standard solutions of various concentration (0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 and 0.5 mg/L) were prepared with 30% alcohol (V/V) as the solvent. The reed chips were hydrolyzed in a 500-mL reactor with 50% (V/V) ethanol water solution at 185℃ for 30 min, 120 min or 210 min. The obtained hydrolysate was diluted and centrifuged to

Peer-Reviewed

ORIGINAL PAPER DOI: 10.21967/jbb.v2i4.84



remove suspended solid particles. The supernatant was distilled, and the obtained distillate and residual were diluted 1000-fold with 30% ethanol.

2.1.3. UV Spectroscopy

Ultraviolet visible spectroscopy carried out with a Cary 100-300 spectrophotometer (VARIAN, USA), with data interval of 0.0200 nm, scan rate of 12.000 nm/min and average time of 0.0100 s. The samples were scanned from 350 nm to 200 nm. The sample was scanned three times to determine the wavelength for the maximum absorption. Samples were diluted to obtain absorbance values between 0.2 and 0.8. 3. RESULTS AND DISCUSSION 3.1. Influence of soluble lignin

A small amount of lignin is dissolved in the hydrolysis of reed with ethanol-water solution. Lignin has a characteristic absorption at 280 nm, which may interfere with testing of furfural and HMF by UV spectroscopy. Previous results have shown that furan compounds (furfural and HMF) accounted for about two-thirds of the absorbance at 280 nm, and the rest was attributed to acid soluble lignin and other phenolic compounds.29 Syringyl and coniferyl aldehyde structure and α-keto groups of lignin have conjugated carbonyl groups that can interfere with the testing.30 Therefore, distillation of the hydrolysate is needed to exclude the interference of lignin on the testing of furfural and HMF. 3.2. Effects of distillation time

To eliminate or largely inhibit the interference of other compounds (acid-soluble lignin and other phenolic compound), the hydrolysate was distilled at atmospheric pressure. The UV spectra of the distillates and residual liquor at various distillation time (5, 10, 15, 20, 25 and 30 min) were shown in Figure 1. The distillate and residue were diluted 1000-times with 30% (V/V) ethanol water solution. As the distillation time increased from 5 to 20 minutes, the maximum absorption position drifted slightly from 280 nm to higher wavelength, and the absorbance value increased, which can be explained by the changes of furfural and HMF concentrations in the distillate as well as the removal of acid-soluble lignin. However, the changes were negligibly small when the distillation time was increased to 25 or 30 minutes (figure 1A). On the other hand, the absorbance of the distillation residue at 280 nm decreased with increasing distillation time and remained almost constant when the distillation time was further increased from 20 to 25 and 30 minutes min (Fig. 1B).

In fact, after 20 minutes of distillation, no more distillate was coming out from the residue, indicating that most of

furfural and HMR had been distilled out to the distillate. The residue was essentially acid soluble lignin and lignin like substances which also had strong absorption at 280 nm as furfural and HMF. Therefore, distillation was effective method to remove the interference of acid soluble lignin and lignin like substances on the measurement of furfural and HMF in the hydrolysate.

Fig. 1. UV spectra of the distillate (A) and residual liquor (B) of

ethanol-water hydrolysate at various distillation time. 3.3. Determination of furfural and HMF concentrations

The UV spectra of furfural (0.45 mg/L), HMF (0.45 mg/L) and their compound (0.225 mg/L furfural and 0.225 mg/L HMF) solutions are shown in Fig. 2. The maximum absorption positions for furfural and HMF were at 276.78 nm and 284.28 nm respectively. For the compound of furfural and HMF, the two individual absorption peaks for furfural and HMF superimposed into a single peak with a maximum absorption between 276.78 and 284.28 nm.

To investigate the influence of HMF content on the maximum absorption wavelength of the compounds (mixture of furfural and HMF), in Figure 2, the total concentration of furfural and HMF was fixed at 0.45 mg/L,



while the mass ratio of HMF in the mixture was varied from 0 to 1.0. The results in Figure 2 show that the maximum absorption wavelength increased linearly from 276.78 nm to 284.28 nm as the HMF mass ratio increased from 0 to 1.0, with a very good regress coefficient.

Fig. 2. UV spectra of the furfural (0.45 mg/L), HMF (0.45 mg/L)

and compound (0.225 mg/L+0.225 mg/L HMF) solutions

Fig. 3. Correlation of the maximum absorption wavelength and

the mass ratio of HMF to furfural

Fig. 4. UV spectra of the mixture of F and HMF at different

concentrations (the constant proportion of HMF)

To further validate the correlation of the maximum

absorption wavelength and the mass ratio of HMF at other concentrations, in Figure 4, the mass ratio of HFM in the mixture of furfural and HMF was fixed at 0.5, while the total concentration of furfural and HMF was varied from 1 mg/L to 5 mg/L. The results in Figure 4 show that in spite of the concentration difference, the peak absorption was constantly at 280.39 nm, indicating that the concentration of the mixture of furfural and HMF had no effect on the maximum absorption wavelength.

3.4. Identification of the linear correlation coefficient

Table 1. Effect of HMF mass ration on the liner correlations of UV absorbance at the maximum absorption wavelength versus the total concentration of furfural and HMF in the mixture

Mass ratio of HMF in the

mixture Intercept (b) Slope（k） Regression

coefficient (R2)

0 0.01842 0.1345 0.9998 0.1 -1.744*10-4 0.1344 0.9999 0.2 -0.00608 0.1374 0.9992 0.3 -0.00430 0.1337 0.9995 0.4 -0.00860 0.1331 0.9997 0.5 0.01080 0.1343 0.9986 0.6 -3.711*10-4 0.1318 0.9996 0.7 0.00150 0.1313 0.9999 0.8 -0.00470 0.1333 1.0000 0.9 -0.00478 0.1333 1.0000 1.0 0.01525 0.1334 0.9999

In Table 1, at each HFM mass ratio of 0, 0.1, 0.2, 0.3,

0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0, the total concentration HFM and furfural in the mixture was varied from 1 to 5 mg/L (1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 mg/L), and the absorbance was determined at the corresponding maximum wavelength. The data were linearly regressed, and the results were summarized in Table 1. It can be seen that the absorbance had an excellent correlation with the sum concentration of furfural and HMF in the mixtures, with a regression coefficient of 0.999 or larger in all cases. The slopes of all the correlations were very similar (about 0.133), regardless of the HMF mass ratio in the mixture. Therefore, the sum concentration of HMF and furfural can be determined by measuring the absorbance at the maximum absorption wavelength and using the linear correlation.

3.5. Calculation of furfural and HMF concentrations

Based on the linear regression fit, a correlation between HMF mass ratio and the maximum absorption wavelength was formulated as follows.

W =𝜆 − 276.657.48602

(1)



Where W is the mass ratio of HMF in the mixture, and λ is maximum absorption wavelength found for the mixture.

The sum concentration (as mg/L) of the mixture is correlated with the absorbance at the maximum wavelength. Therefore the total concentration of the mixture can be determined by following equation:

C =𝐴 − 𝑏𝑘

(2)

Where C is the concentration of the mixture, A is the

absorbance of the mixture measured at the maximum absorption wavelength, b and k are coefficients derived from the linear regression fit, as shown in Table 1.

Then the individual HMF and furfural concentrations can be calculated as mg/L by following equations:

𝐶678 = 𝐶𝑊𝐷(3)

𝐶8 = 𝐶(1 −𝑊)𝐷(4)

Where CHMF and CF are the individual concentrations of

HMF and furfural, respectively, in the mixture, and D is the dilution factor.

3.6 Precision and validation

Table 2. Recovery rate and relative standard deviation of the UV spectroscopy method for the determination of furfural and HMF in ethanol-water system Mixture 1 Mixture 2 Mixture 3

HMF added, mg/L 0.10 0.15 0.20 Furfural added, mg/L 3.0 4.0 5.0 HMF found, mg/L 0.089 0.136 0.182 Furfural found, mg/L 2.881 3.751 4.724 HMF Recovery, % 89.1 90.7 91.2 Furfural recovery, % 96.0 93.8 94.5 HMF RSD, % 0.21 0.25 0.65 Furfural RSD, % 0.40 0.85 0.68

In Table 2, three mixture samples of furfural and HMF of various concentrations were prepared by mixing known amounts of furfural and HMF with 30% ethanol-water solution, and then the UV spectroscopy method developed in this study was applied to determine the amount of furfural and HMF in the prepared samples. As shown in Table 2, the recovery rates for furfural and HMF ranged from 93% to 96% and 89% to 92%, respectively, indicating the method reasonably accurate. The relative standard deviation (RSD) of the testing was less than 1% for both furfural and HMF.

4. CONCLUSIONS

A rapid method was developed to determine individual furfural and HMF concentrations simultaneously in

ethanol-water hydrolysate of reed, based on UV spectroscopy. The hydrolysate was distilled for 20 minutes under atmospheric pressure to separate furfural and HMF as the distillate. Acid soluble lignin and other interfering substances as residue. The distillate was then used for the determination of furfural and HMF by measuring the maximum absorption wavelength and the absorbance at the maximum wavelength. It was found that the absorption wavelength of the characteristic peak correlated well with the composition of the furfural and HMF mixture in an ethanol-water solution, and the absorbance at the maximum absorption wavelength also had an excellent linear relationship with the sum concentration of furfural and HMF in the solution. Based on these correlations, the separate concentrations of furfural and HMF in a mixture solution could be determined. The precision of this method was found to be reasonably good in terms of recovery rates and relative standard deviation.

ACKNOWLEDGMENTS

The authors would like to thank the National Natural Science Foundation of China for financial support for this research (Grant #: 31270634). REFERENCES 1. Nirmal Uppugundla1, Leonardo da Costa Sousa1, Shishir PS

Chundawat, et al. A comparative study of ethanol production using dilute acid, ionic liquid and AFEX™ pretreated corn stover [J]. Biotechnology for Biofuels 2014, 7: 72.

2. Wang Z., Zhang L., Fan Y., Yang Y*., Matsumoto Y. Solubilization and Fractionation of Japanese Beech Wood with LiCl and DMSO. J. Bioresour. Bioprod, 2016, 1(2): 38-45.

3. Zheng X., Ma X., Chen L., Huang L., Cao S., Nasrallah J. Lignin extraction and recovery in hydrothermal pretreatment of bamboo. J. Bioresour. Bioprod, 2016, 1(3): 145-151.

4. Li B*, Liu C., Yu G., Zhang Y., Wang H., Mu X., Peng H*. Recent progress on the pretreatment and fractionation of lignocelluloses for biorefinery at QIBEBT. J. Bioresour. Bioprod, 2(1): 4-9.

5. Pan X., Arato C., Gilkes N., etal. Biorefining of Softwoods Using Ethanol Organosolv Pulping: Preliminary Evaluation of Process Streams for Manufacture of Fuel-Grade Ethanol and Co-Products: Biotechnology and Bioengineering ,2005,90: 473–481

6. Panagiotopoulou P., Dionisios G. Liquid phase catalytic transfer hydrogenation of furfural over a Ru/C catalyst. Applied Catalysis A: General, 2014, 480: 17–24

7. Su Y., Heather M., Huang X., Zhou X. Single- step conversion of cellulose to 5-hydroxymethylfurfural (HMF), a versatile platform chemical.

8. Jin H., Li Y., Liu X. Recovery of HMF from aqueous solution by zeolitic imidazolate frameworks. Chemical Engineering Science, 2015, 124: 170-178

9. Sánchez C., Serrano L., Andres M. Furfural production from corn cobs autohydrolysis liquors by microwave technology. Industrial Crops and Products, 42:513-519



10. Liu W., Holladay J. Catalytic conversion of sugar into hydroxymethylfurfural in ionic liquids. Catalysis Today , 2013, 200:106-116

11. Lu Q., Liao H., Zhang Y. Reaction mechanism of low-temperature fast pyrolysis of fructose to produce 5-hydroxymethyl furfural. Journal of fuel chemistry and technology, 2013, 41:1070-1076

12. López F., García M., Feria M. Optimization of furfural production by acid hydrolysis of Eucalyptus globulus in two stages. Chemical Engineering Journal, 2014, 240:195-201

13. Tong X., Wang Y., Nie G. Selective Dehydration of Fructose and Sucrose to 5-Hydroxymethyl-2-Furfural with Heterogeneous Ge (IV) Catalysts. Environmental Progress & Sustainable Energy, 2015, 34:207-210.

14. Hyvärinen S., Mikkola J., Murzin D. Sugars and sugar derivatives in ionic liquid media obtained from lignocellulosic biomass: Comparison of capillary electrophoresis and chromatographic analysis. Catalysis Today, 2014, 223:18-24.

15. Vaher M., Helmja K., Käsper A. Capillary electrophoretic monitoring of hydrothermal pre-treatment and enzymatic hydrolysis of willow: Comparison with HPLC and NMR. Catalysis Today, 2012, 196:34-41

16. Gao J., Dai H., Yang W. Determination of furfural in an oscillating chemical reaction using an analyte pulse perturbation technique. Ana Bioanal Chem, 2006,384:1438-1443

17. Lu Q., Dong C., Zhang X. Selective fast pyrolysis of biomass impregnated with ZnCl2 to produce furfural: Analytical Py-GC/MS study. Journal of Analytical and Applied Pyrolysis, 2011, 90:204-212

18. Hrivňák J., Tölgyessy P., Figedyová S., Katuščák S. A Solid-Phase Microcolumn Extraction Method for the Analysis of Acetic Acid and Furfural Emitted from Paper. Chromatographia, 2009, 70: 619–622

19. Hu X., Gunawan R., Mourant D. Acid-catalysed reactions between methanol and the bio-oil from the fast pyrolysis of mallee bark. Fuel, 2012, 97:512-522

20. Petisca C., Henriques A., Pe´rez-Palacios T. Assessment of hydroxymethylfurfural and furfural in commercial bakery

products. Journal of Food Composition and Analysis, 2014, 33:20-25

21. Nabarlatz D., Ebringerová A., Montané D. Autohydrolysis of agricultural by-products for the production of xylo-oligosaccharides. Carbohydrate Polymers, 2007, 69:20-28

22. Garrote G., Domínguez H., Parajó H. Generation of xylose solutions from Eucalyptus globulus wood by autohydrolysis-posthydrolysis processes: posthydrolysis kinetics. Bioresource Technology, 2001, 79:155-164

23. Jensen J., Juan M., Aglan A. Kinetic Characterization of Biomass Dilute Sulfuric Acid Hydrolysis:Mixtures of Hardwoods, Softwood, and Switchgrass. Environmental and energy engineering, 2008, 54:1637-1645

24. Nabarlatz D., Farriol X., Montane D. Kinetic Modeling of the Autohydrolysis of Lignocellulosic Biomass for the Production of Hemicellulose-Derived Oligosaccharides. Industrial engineering chemistry research, 2004, 43: 4124-4131

25. Eliana V., George J., George J. Evaluation of the Kinetics of Xylose Formation from Dilute Sulfuric Acid Hydrolysis of Forest Residues of Eucalyptus grandis. Industrial engineering chemistry research, 2007, 46: 1938-1944

26. Jenny S., Tiia N., Herbert S. Comparative evaluation of autohydrolysis and acid-catalyzed hydrolysis of Eucalyptus globulus wood. Bioresource Technology, 2012, 109: 77–85

27. Tunc M., Chheda J., Heide E. Two-Stage Fractionation and Fiber Production of lignocellulosic Biomass for Liquid Fuels and Chemicals. Industrial engineering chemistry research, 2013, 52: , 13209 −13216

28. Nabarlatz D., Farriol X., Montane D. Autohydrolysis of Almond Shells for the Production of Xylo-oligosaccharides: Product Characteristics and Reaction. Industrial engineering chemistry research, 2005, 44:7746-7755.

29. Martinez A., Rodriguez M., York S., et al. Use of UV Absorbance to Monitor Furans in Dilute Acid Hydrolysates of Biomass [J]. Biotechnology Progress, 2000, 16:637-641.

30. Dence C. Determination of lignin [J]. Methods in Lignin Chemistry, 1992: 33–61.

5. 2017 2(4) research, determination of furfural and ...€¦ · (gc-ms)3,17-19 and high...

Documents