Turner Gordon Green Chem Solvents - Lu
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Water, ethanol and supercritical carbon dioxide – are these solvents really green? Aim • To enhance the value of byproducts from agricultural and forestry industry by isolating high-value compounds. • To develop environmentally sustainable processes using “green” solvents – pressurized hot water, ethanol and supercritical CO 2 (scCO 2 ). • To evaluate if the developed processes are really green! C. Turner 1 , P. Börjesson 2 , M. Co 3 , A. Ekman 2 , S. Khan 1 , J. Samuelsson 4 , S. Lindahl 1 , L. Mijangos Trevino 1 , A. Mustafa 1 , E. Nordberg Karlsson 1 1 Lund University, Department of Chemistry; 2 Lund University, Environmental and Energy System Studies; 3 Uppsala University, Analytical Chemistry; 4 Karlstad University, Chemistry www.kilu.lu.se/cas , [email protected] Background There are large amounts of byproducts from agricultural and forestry industry, that is currently recycled for its energy value, or used as animal feed or for soil improvement. These materials contain valuable compounds, for instance pigments and antioxidants, which potentially could be isolated from the biomass before any final usage. Research is funded by the Swedish Research Council Formas – Sustainable Resource Technology (www.suretech.lu.se) Water is undoubtedly the most environmentally sustainable solvent, and when used at higher temperature and pressure, fast extraction can be obtained. For nonpolar compounds, scCO 2 is a more suitable solvent, while for “medium-polar” compounds, a better alternative could be ethanol. Case 1 – Carotenoids in carrots Carotenoids are antioxidants and pigments, traditionally extracted using an organic solvent such as hexane, petroleum ether or tetrahydrofuran. In an effort to establish “greener” methods, hot ethanol was tested as extraction solvent [1], as well as scCO 2 mixed with vegetable oil. Case 2 – Betulin in birch bark Betulin is an anti-inflammatory compound constituting 10-20 weight% of the birch bark. An extraction method using liquid CO 2 mixed with ethanol was used to extract betulin [3] (“developed method” in Fig. 2). Life cycle assessment (LCA) was applied to compare the developed method with a conventional one based on leaching into ethanol (Fig. 2, [3]). Conclusions Choosing a solvent for extraction should include both consideration of solubility of the compound to be extracted and “greenness” of the solvent. As demonstrated for β- carotene in Table 1, it is not certain which of the three methods is to prefer. Our study further shows that LCA is a useful tool to compare the environmental impact of different extraction methods, as demonstrated for betulin in birch bark and quercetin in onion byproducts. References 1. Mustafa, A. et al., Molecules, 2012, 17, 1809. 2. Craft, N.E. & Soares, J.H., J. Agric. Food Chem., 1992, 40, 431. 3. Ekman, A. et al., subm. to J. Cleaner Prod., 2012. pdf available 4. Lindahl, S. et al, Green Chem., 2010, 1, 159. Figure 1. Carrots, birch bark and onions – voluminous byproducts. Figure 2. Energy consumption (left) and global warming potential (right) for the extraction of 150 g betulin from birch bark. Developed method: CO 2 /ethanol (8:2, w/w) at 50 bar and 16 °C, 2-3 h extraction. Conventional: leaching into ethanol for 3-7 days. Three times more ethanol was used in the conventional method. Figure 3. Energy consumption (left) and global warming potential (right) for the extraction of quercetin from onion byproducts [5]. Developed method: water at 120 °C and 50 bar, 15 min, enzymatic reaction at 85 °C and 10 min. Conventional method: methanol with HCl, 80 °C and 2 h. Research group homepage: Poster pdf: Case 3 – Quercetin in onion Quercetin is an antioxidant present in onion (2 mg/g, f.w.). Pressurised hot water extraction (PHWE) with β-glucosidase- catalysed hydrolysis was used to isolate quercetin from onion waste and compared to a conventional method using LCA [4], see Fig. 3. Parameter Conven,onal method* Ethanol method** scCO 2 /oil method*** Solvent amount (kg) 0.09 / 1.1 1.4 0 Extrac:on :me per sample (min) 40 20 Table 1. Environmental performance of extraction methods, with the functional unit 1 g of β-carotene. For the scCO 2 -method, the carotenoids were recovered in vegetable oil. Carrots extracted contained around 28 mg β-carotene/100 g f.w. carrot [1]. *Based on solubility data for tetrahydrofuran respectively hexane, 20 °C [2] **Ethanol at 60 °C, 50 bar, using an ASE-200 (Thermo) system. Sample: 2 g of fresh carrot mixed with Hydromatrix. ***scCO 2 /vegetable oil (86/14, v/v), 400 bar, 40 °C (0.99 g/mL), 5 mL/min. Total usage of recyclable compressed CO 2 for 1 g of β-carotene was 341 kg. Sample: 1 g of freeze dried carrot. 0 20 40 60 80 100 120 140 160 Methanol + HCl PHWE + enzyme MJ/10 g quercetin Enzyme Energy for extraction HCl Methanol 0 100 200 300 400 500 600 Methanol + HCl PHWE + enzyme GWP (kg CO2-eq./10 g Q) Enzyme Energy for extraction HCl Methanol SuReTech homepage:
Transcript of Turner Gordon Green Chem Solvents - Lu
Water, ethanol and supercritical carbon dioxide – are these
solvents really green?
Aim • To enhance the value of byproducts from agricultural and
forestry industry by isolating high-value compounds. • To develop environmentally sustainable processes using
“green” solvents – pressurized hot water, ethanol and supercritical CO2 (scCO2).
• To evaluate if the developed processes are really green!
C. Turner1, P. Börjesson2, M. Co3, A. Ekman2, S. Khan1, J. Samuelsson4, S. Lindahl1, L. Mijangos Trevino1, A. Mustafa1, E. Nordberg Karlsson1
1Lund University, Department of Chemistry; 2Lund University, Environmental and Energy System Studies; 3Uppsala University, Analytical Chemistry; 4Karlstad University, Chemistry
www.kilu.lu.se/cas, [email protected]
Background There are large amounts of byproducts from agricultural and forestry industry, that is currently recycled for its energy value, or used as animal feed or for soil improvement. These materials contain valuable compounds, for instance pigments and antioxidants, which potentially could be isolated from the biomass before any final usage.
Research is funded by the Swedish Research Council Formas – Sustainable Resource Technology (www.suretech.lu.se)
Water is undoubtedly the most environmentally sustainable solvent, and when used at higher temperature and pressure, fast extraction can be obtained. For nonpolar compounds, scCO2 is a more suitable solvent, while for “medium-polar” compounds, a better alternative could be ethanol.
Case 1 – Carotenoids in carrots Carotenoids are antioxidants and pigments, traditionally extracted using an organic solvent such as hexane, petroleum ether or tetrahydrofuran. In an effort to establish “greener” methods, hot ethanol was tested as extraction solvent [1], as well as scCO2 mixed with vegetable oil.
Case 2 – Betulin in birch bark Betulin is an anti-inflammatory compound constituting 10-20 weight% of the birch bark. An extraction method using liquid CO2 mixed with ethanol was used to extract betulin [3] (“developed method” in Fig. 2). Life cycle assessment (LCA) was applied to compare the developed method with a conventional one based on leaching into ethanol (Fig. 2, [3]).
Conclusions Choosing a solvent for extraction should include both consideration of solubility of the compound to be extracted and “greenness” of the solvent. As demonstrated for β-carotene in Table 1, it is not certain which of the three methods is to prefer. Our study further shows that LCA is a useful tool to compare the environmental impact of different extraction methods, as demonstrated for betulin in birch bark and quercetin in onion byproducts. References 1. Mustafa, A. et al., Molecules, 2012, 17, 1809. 2. Craft, N.E. & Soares, J.H., J. Agric. Food Chem., 1992, 40, 431. 3. Ekman, A. et al., subm. to J. Cleaner Prod., 2012. pdf available 4. Lindahl, S. et al, Green Chem., 2010, 1, 159.
Figure 1. Carrots, birch bark and onions – voluminous byproducts.
Figure 2. Energy consumption (left) and global warming potential (right) for the extraction of 150 g betulin from birch bark. Developed method: CO2/ethanol (8:2, w/w) at 50 bar and 16 °C, 2-3 h extraction. Conventional: leaching into ethanol for 3-7 days. Three times more ethanol was used in the conventional method.
Figure 3. Energy consumption (left) and global warming potential (right) for the extraction of quercetin from onion byproducts [5]. Developed method: water at 120 °C and 50 bar, 15 min, enzymatic reaction at 85 °C and 10 min. Conventional method: methanol with HCl, 80 °C and 2 h.
Research group homepage:
Poster pdf:
Case 3 – Quercetin in onion Quercetin is an antioxidant present in onion (2 mg/g, f.w.). Pressurised hot water extraction (PHWE) with β-glucosidase-catalysed hydrolysis was used to isolate quercetin from onion waste and compared to a conventional method using LCA [4], see Fig. 3.
Parameter Conven,onal method*
Ethanol method**
scCO2/oil method***
Solvent amount (kg)
0.09 / 1.1 1.4 0
Extrac:on :me per sample (min)
-‐ 40 20
Table 1. Environmental performance of extraction methods, with the functional unit 1 g of β-carotene. For the scCO2-method, the carotenoids were recovered in vegetable oil. Carrots extracted contained around 28 mg β-carotene/100 g f.w. carrot [1].
*Based on solubility data for tetrahydrofuran respectively hexane, 20 °C [2] **Ethanol at 60 °C, 50 bar, using an ASE-200 (Thermo) system. Sample: 2 g of fresh carrot mixed with Hydromatrix. ***scCO2/vegetable oil (86/14, v/v), 400 bar, 40 °C (0.99 g/mL), 5 mL/min. Total usage of recyclable compressed CO2 for 1 g of β-carotene was 341 kg. Sample: 1 g of freeze dried carrot.
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