Extraction of Vanillin from Alkali Lignin by Water-based Deep Eutectic Solvent Md Sajjadur Rahman and Douglas E. Raynie Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007
[email protected] ABSTRACT
GC-MS ANALYSIS
GC-MS METHOD
Vanillin is the major component of vanilla flavoring, a very prominent precursor of many organic syntheses, and a
✓ The GC-MS chromatogram shows qualifying result of the extraction of vanillin from alkali lignin
key intermediate for the synthesis of bio-based polymers. It has many applications in various fields like fragrance
✓Gaussian 09 software [3]
and flavors, pharmaceuticals, and others. The aim of this study was to develop a simple method to extract vanillin
✓Density functional theory: B3LYP
from an available and inexpensive source lignin by dichloromethane (DCM), after exposure to the eco-friendly
✓Basis set: 6-31G(d)
deep eutectic solvent (DES) (choline chloride : water = 1:4). Sample preparation was carried out by mild heating
✓Optimization of molecules,
(up to 90°C) of the lignin-DES solution and continuously stirred for a 3 to 6 hours in a covered beaker. After extraction with DCM, samples were analyzed by GC-MS. This DES system which demonstrates high affinity and selective separation for vanillin is reported for extraction for the first time. Another advantage is that no further
✓ Instrument ✓ Detector
vibrational frequency calculation ✓Gibbs free energy, dipole moment and HOMO-LUMO gap calculation
dilution is required for the treated solution. It does not form any emulsion layer between DES and DCM layers. Both the solvents and source of vanillin are affordable and produce less waste. This extraction method is non-
Agilent 7890A Agilent 5975C triple-axis mass detector with EI (full scan, m/z = 50-600)
Parameters
Conditions
✓ Flow rate of carrier gas
2.4 mL/min
✓ Injection volume
1 µL
✓ Solvent Delay
1.0 min
✓ Injection mode
Splitless
✓ Oven Temperature
Initial temperature: 40°C held for 1 min. It was increased at a rate of 20°C/min up to 200°C.
destructive and simple. Although this method still requires optimization but it looks promising.
INTRODUCTION
✓ Fig. 4 shows chromatogram of the extract from (a) Lignin-DES reaction in presence of CuO and (b) Lignin-DES reaction in absence of CuO, where vanillin is the target analyte and o-Terphenyl is the internal standard. ✓ Reaction with oxidizing agent CuO found more efficient but higher waste production.
o-Terphenyl
✓ Column
DB5 column (30m×250μm×0.25μm)
✓ Carrier gas
Hydrogen
o-Terphenyl
Vanillin
Vanillin
✓ Lignin is a complex biopolymer and potential building block of different aromatic compounds. It is also an alternative renewable energy source which could replace fossil fuel.[1] Among a thousand tons of lignin produced in different industries, only very small portion of it is used to make different products.
RESULTS AND DISCUSSION
source lignin by the exposure to the eco-friendly deep eutectic solvent (DES) could give two major benefits: ▪First, it could help to decrease the production cost of this value-added product vanillin.
(b)
(a)
✓ So that development of a simple extraction method to extract vanillin from such a potent and inexpensive
QUANTUM MECHANICAL CALCULATION
Fig 4: Chromatogram of the extract from (a) Lignin-DES reaction in presence of CuO, (b) Lignin-DES reaction in absence of CuO, where Vanillin is the target analyte and o-Terphenyl is the internal standard
▪Secondly, the development of a eco-friendly extraction method. ✓ Density Functional Theory (DFT) has widely been used for chemical and material simulation to predict and observe the physical and chemical properties of many inorganic or organic combinations.[2] ✓ GC-MS method is an excellent way to study of the success of an extraction
method.[1]
✓ Therefore, the aims of the study were to observe molecular level interaction of Vanillin, DES and Vanillin-DES by quantum mechanical calculation to predict the feasibility of this extraction method and to develop a new eco-friendly and simple method to extract vanillin from lignin.
CONCLUSION
✓ Fig. 2 shows frontier orbital which is presenting distribution of charge densities on DES, Vanillin and DES-Vanillin in HOMO and LUMO.
In this study, molecular level interaction of vanillin, DES and vanillin-DES were observed by DFT calculation to predict the
✓ Gibbs free energy graph shows that, the combined state of DES-Vanillin has higher negative value, so it is thermodynamically more favorable. Whereas vanillin has positive Gibbs free energy which means
feasibility of this extraction method. GC-MS Chromatograms showed that the extraction was successful. Moreover, both the
thermodynamically unfavorable before reaction (Fig. 3)
solvents DES, DCM and source of vanillin were affordable and produced less waste. This extraction method was nondestructive and simple.
✓ Fig.3 also shows dipole moment is higher during interaction between DES and Vanillin. ✓ HOMO-LUMO graph shows that the gap between HOMO and LUMO decreases for DES-Vanillin combination which means higher chemical reactivity and lower kinetic stability. So it is energetically more favorable. (Fig. 3) LUMO
HOMO
✓ Preparation of a new DES ✓ Use of this DES to develop a simple
Gibbs Free Energy (KJ/mol)
OBJECTIVES
during the reaction by DFT calculation ✓ Extraction of vanillin from lignin
Vanillin
ChCl:4H2O
0 -500
ChCl:4H2OVANILLIN
VANILLIN
-1000
1. Marino, D. D.; Stöckmann, D.; Kriescher, S.; Stiefel, S.; Wessling, M. Green Chem. 2016, 22, 6021-6028.
-1500
DOI: 10.1039/C6GC01353H
Name of Chemical Species
1. Rahman, M.S.; Hossain, S.M.; Rahman, M.T. et al. Environ Monit Assess. 2017, 189, 618.
Dipole Moment (Debye)
✓ Study of molecular level interaction
500
-2000
ChCl: 4H2O
extraction method
REFERENCES
1000
DOI: 10.1007/s10661-017-6328-1 3. Frisch, M. J., et al. 2009. Gaussian 09, Revision A.02. Gaussian 09, Revis. A.02. http://gaussian.com/g09citation. (accessed on 4 May, 2018) VANILLIN
ChCl:4H2O
ChCl:4H2OVANILLIN
4. https://www.kyarazen.com/secrets-tea-seasons-aging (accessed on 4 May, 2018)
ChCl:4H2O -Vanillin [4]
HOMO-LUMO Gap (eV)
Name of the Chemical Species 0.3 0.25
0.15 0.1 0.05 0
Fig. 1: Schematic diagram of the extraction method
Fig. 2: Frontier molecular orbitals (HOMO and LUMO) of DES, Vanillin and DES-Vanillin calculated at B3LYP/6-31G(d)
ACKNOWLEDGEMENT
0.2
VANILLIN
ChCl:4H2O
ChCl:4H2OVANILLIN
Name of Chemical Species
Fig. 3: Gibbs free energy, dipole moment, and the HOMO-LUMO gap of DES, vanillin and DES-vanillin
✓ Department of Chemistry and Biochemistry, South Dakota State University for the lab support. ✓ Dr. Mohammad A. Halim, CEO, The Red-Green Research Centre (RGRC) for giving permission to use gaussian 09 software.
