Application of deep eutectic solvents in biomass valorization Yang G.H., Wu T.Y., Loow Y. L., Ang L. Y.
Outline 01 02 03 04 Introduction Literature Review Case study Conclusion Types and Case study: Properties of Delignification of DES OPF via DES in Problem improving xylose Current Statements Recent extraction from Limitations Developments of Oil Palm Fronds DES in Biomass (OPF) Introduction of Processing Contributions of DES Methodology Research Applications of DES in other Quantitative and industries qualitative results 2
01 Introduction Problem Statement Introduction of DES 3
Introduction Projected Growth in Global Energy Demand Renewable Non- renewable Fig. 1 Projected Growth in Global Energy Demand (adopted from IEA, 2016) Breakdown of solid waste generated in Malaysia Organic waste • Plant biomass • Organic waste Sugars Energy • Renewable source of energy • Potential sustainable solution Fig. 2 Segregation of solid waste in Malaysia (adopted from Agamuthu and Fauziah, 2010 ) 4
Introduction (Continued…) Structural Component of Lignocellulosic Biomass Necessity of a pretreatment process to improve overall sugar recovery and extraction process via removal of lignin components Fig. 3 General components in lignocellulosic biomass (adopted from Loow et al., 2015) Glucose Xylose Arabinose Fig. 4 Structural arrangement of lignin, hemicellulose Physical seal that and cellulose (adopted from Loow et al., 2015) protects cellulose and hemicellulose
Introduction (Continued…) Pretreatment method Table 1 Comparison of conventional pre-treatment methods of lignocellulosic biomass (adopted from Amirkhani et al., 2015) Advantages Pretreatment Disadvantages • Similar physiochemical properties as ILs Low cost of alkaline materials Alkaline pretreatment Formation of inhibitors • Green solvent due to low toxicity and is biodegradable Energy intensive • Low vapor emission Harsh operating condition • Easy to synthesize Simple pretreatment procedure Dilute acid pretreatment Production of inhibitors Hazards due to strong acid use Deep Mild operating conditions Ionic Liquid Expensive High yield of sugar Eutectic Difficult to synthesize High toxicity Solvent Non-biodegradable (DES) Sharp decrease in melting point than its constituents Fig. 5 Phase diagram showing the eutectic composition of DES (adopted from Abbott, 2007) 6
02 Literature Review Synthesis of DES Types and Properties of DES Recent Developments of DES in Biomass Processing
Literature Review Synthesis of DES (Heating with agitation) Choline chloride Urea Mixing of a Hydrogen bond (HBA) (HBD) donor (HBD) and Hydrogen bond acceptor (HBA) in solid phase Molar ratio: 1:2 Agitation speed: 150 – 200 rpm Gentle agitation of 150 - 200 rpm at moderate temperature of 60 - Temperature: 60 - 80°C 80°C for 2 hours Duration: 2 hours + N Formation of liquid DES OH ChCl- Urea DES
Literature Review (Continued…) Types of DES Table 2 Types of DES segregated into 4 groups (adopted from Smith et al., 2014) Type Terms General Formula Example Cat + X - zMClx ; M = Zn, Sn, Fe, Al, Ga, Metal salt + organic ZnCl 2 + ChCl Composed of environmentally 1 and economically benign salt In materials Cat + X - zMClx·yH2O; M = Cr, Co, Cu, Metal salt hydrate + CoCl 2 ·6H 2 O + 2 organic salt Ni, Fe ChCl Cat + X - zRZ; Z = CONH 2 , COOH, OH Hydrogen bond urea + ChCl 3 donor + organic salt − ; M Zinc/Aluminium MCl x + RZ = MCl x−1 + ·RZ +MCl x+1 ZnCl 2 + urea 4 chloride + Hydrogen = Al, Zn & Z = CONH 2 , OH bond donor
Literature Review (Continued…) Properties of DES Melting point • Sharp decrease in melting point • Example: Pure ChCl: 302ºC Pure urea: 135ºC ChCl-urea DES: 12ºC Fig. 6 Schematic representation of eutectic point on a two component phase diagram (adopted from Smith et al., 2014) Delocalization of charge due to hydrogen bonding between HBD and halide ion. Dependent variables Types of HBD and HBA used Composition of HBD in mixture
Literature Review (Continued…) Properties of DES Surface Tension • Higher surface tension than most ILs • Surface tension is closely related to intermolecular forces Dependent variables Type of cation in HBA Presence of hydroxyl groups in cation led to high surface tension Temperature of system Increase of temperature resulted in decrease of surface tension. Gain of energy by halide salt that broke up the intermolecular forces i.e. hydrogen bonding
Literature Review (Continued…) Properties of DES Density Viscosity • Higher density than water • Higher viscosity than ILs (Type IV DES density > 1.3 g/cm 3 ) (except ChCl-ethylene glycol) Dependent Variables • High viscous property Types of HBD and HBA used accompanied with a low Temperature of system conductivity Water content Hole Theory Formation of DES resulted in decrease of average hole radius as it is composed of holes and empty vacancies, hence affecting density and viscosity considerably upon formation.
Literature Review (Continued…) Recent Developments of DES in Biomass Processing Solubilization of Lignin Extraction of Phenolic Compound Table 3 Summary of lignin solubilization methods with different DES reagents Mol Lignocellulo wt% DES reagent Operating Conditions References ratio sic Biomass Delignification Lactic acid - 2:1 52 ± 6 Betaine 5:1 56 ± 3 60 ° C for 12 h in with Kumar et 2:1 Rice straw agitation of 100 rpm in a 51 ± 1 al., 2015 Lactic acid – screw capped conical flask. 5:1 60 ± 2 ChCl 9:1 59 ± 3 130 ° C for 2 h with agitation Formic acid – Xu et al., - Corn stover of 100 rpm in a three 23.8 ChCl 2016 necked flask. Imidazole – ChCl 2:1 70 Procentese Urea – ChCl 2:1 Corncob 115 ° C for 15 h in an oil bath. 24.8 et al., 2015 Glycerol - ChCl 7:3 4.4
Literature Review (Continued…) Recent Developments of DES in Biomass Processing Secondary Lignin wall Primary wall Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Cl - Hemicellulose Cellulose Plasma Membrane Fig. 7 Reaction mechanism of DES in extraction of lignin compound 14
Literature Review (Continued…) Recent Developments of DES in Biomass Processing Fig. 9 Reactions occurred between halogen anion of DES with lignin 15
Literature Review (Continued…) Recent Developments of DES in Biomass Processing DES delignification damaged the protection barrier provided by lignin via dissolution of lignin Formation of hydrogen bond between Cl - and hydroxyl group of lignin led to dissolution of lignin from lignocellulose Fig. 8 Structural change of DES and solid biomass after proposed reaction mechanism 16
03 03 Case study: Extraction of lignin compound from OPF to improve xylose recovery Case study: Delignification of OPF via DES in improving xylose extraction from Oil Palm Fronds (OPF) Methodology Quantitative Results OPF Characterization (XRD, FT-IR, FE- SEM)
Case study Overview Type of lignocellulosic biomass: Oil Palm Fronds (OPF) Type of DES used: ChCl-urea with molar ratio of 1:2 Fig. 10 Oil palm fronds (OPF), with leaflets removed Aim: To determine the recovery of xylose sugar (adapted from http://www.mightyjacksparrow.com) via inorganic salt hydrolysis enhanced by DES delignification Control set Inorganic salt pre- Xylose recovery OPF treatment Real sets Delignification Inorganic salt OPF of OPF via Xylose recovery pre-treatment DES
Case study (Continued…) Methodology Supernatant ChCl-Urea DES liquid (25 ml) (DES + Lignin) Synthesis of Delignification of Inorganic salt Monomeric Characterization Grinding of OPF DES OPF pre-treatment sugars analysis of OPF • Equipment: • Equipment: Oil • Equipment: • Equipment: • Equipment: • Equipment: Siever / Bath Autoclave HPLC FESEM, FT-IR Magnetic Grinder Stirrer • Biomass • Biomass • Quantification • Compare the • Particle Size < loadings at 10 loadings at 10 Solid residue of xylose morphology, • Raw 0.5 mm feedstock: w/v% to DES w/v% to 0.4 M crystallinity CuCl 2 solution index and ChCl and Urea functional • Mix at molar groups of OPF ratio of 1:2 before and after each Solid Oil Palm Frond stage of pre- (Holocellulose) Hydrolysate (2.5 g) treatment (1 g) 0.4 M CuCl2 solution (10 ml) 19
se study (Continued…) antitative Result (Xylose Recovery from OPF) Removal percentage of lignin: 28.42% Fig. 11 Effect of temperature and duration of reaction on xylose yield Operating condition: 120 ° C, 4 hours
se study (Continued…) F Characterization (FE-SEM) ol - (0.4 M CuCl 2 inorganic salt pre-treatment) Raw OPF After inorganic salt pre-treatment Fig. 10 Morphology of OPF in control set l-urea DES delignification + 0.4 M CuCl 2 inorganic salt pre-treatment)
se study (Continued…) F Characterization (FT-IR) Table 5 Assignment of bands wavelength of solid biomass at various stage of pre-treatment 1735cm -1 1050cm -1 Notation Band Assignment wavelength 1600cm -1 (cm -1 ) 1235cm -1 ~900 Small sharp band A indicates cellulose ~1235 C-O-C indicates B ether bond in lignin ~1508-1600 C=C double bond C indicates the stretching of aromatic ring in lignin ~1735 C=O double bond D denotes hemicellulose ~1033 Represents E cellulose and hemicellulose
04 Conclusion Current Limitations & Future Improvements Contributions of Proposed Research
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