Estimation of measurement uncertainty for the determination of the ...

More documents

Recommendations

Info

CountsD:\Analytical\...\Me-Bs-6_111222170734 22.12.2011 г. 17:07:34Fatty acid content, %D. I. Yordanov, Z. B. Tsonev, T. V. Palichev, Z. A. Mustafa/Petroleum & Coal 55(2) 74-81, 2013 79RT: 0.20 - 38.001000000009500000090000000NL:1.34E8FIDAnalogMe-Bs-6_1112221707345045450 W 300 W Dried at 20°C 120-150°C 600W850000008000000040750000007000000015.3735650000006000000019.53305500000050000000450000004000000025203500000030000000250000002000000018.8218.481510150000001000000022.125500000001.335.6710.2522.56 27.1812.12 16.0830.61 34.925 10 15 20 25 30 35Time (min)Fig. 6. GC chromatogram of the lipid extractfrom coffee residue irradiated by 600Wmicrowave for 20 minutes0Fattyacid14:0 16:0 18:0 9-18:1 11-18:1 18:2 18:3 20:0 20:1 21:0 22:0 23:0 24:0Fig. 7. Fatty acid content based on the resultsfrom Table 3.From our study and the data shown in Figure 7, we observe that any type of pretreatment(microwave irradiation or heat treatment only) of coffee residue from vending automatincreases the amount of saturated fatty acids.The palmitic and linoleic acids have the highest percentage in the analyzed extracts.The amount of stearic, oleic and arachidic acids are significant. The percentage of all otherfatty acids is less than one.If the coffee residue is not processed in any way, the greatest is the amount of unsaturatedfatty acids with more than one double bond. The residue treated at 120-150 C have asignificant content of saturated fatty acids and those containing one double bond, andtherefore the least amount of fatty acids with two or more double bonds.The coffee residue that was treated at 600W microwave has the fatty acid compositionsimilar to those of residue processed at 120-150 C. The residue processed at 450W microwaveirradiation has the fatty acid composition similar to those of residue dried at 20 C. Thesample treated at 300W microwave irradiation has a similar composition as those processedat 450W microwave irradiation.The triacylglycerols have the higher content in the neutral lipids (over 45%). This rateis the lowest in the sample that was treated at 120-150 C (46.8%). The residue dried at20 C has the highest percentage of triacylglycerols (67.1%). The residues dried at 120-150 C and irradiated at 600W microwave have the higher percent of sterols, diacylglycerols,and free fatty acids in sum.The percentage of lipids is calculated from the original sample by the extraction thatwas made. In our case, when we were added the amounts of lipid classes and adjustment tolipid extract were obtained the percentages of dyes, etc. accompanying substances thatdiffer in polarity of the lipid classes. Based on the data from Figure 9 and Tables 5 and 6,we can say that the lipid extract derived from the processing of coffee residue with microwaveradiation power of 600W, contains the greatest amount of lipids (8.07%). This is probablydue to the flow of high-energy cracking under the influence of powerful microwave radiationto the molecules in the coffee residue, resulting in increased total lipid content.Due to the higher melting point of saturated fatty acids and correspondingly lower oxidativestability of the unsaturated fatty acids containing one or more double bonds have to findtheir balanced composition in the production of biofuels. The sample obtained at 600Wmicrowave has the balanced composition of saturated and unsaturated fatty acids ofapproximately 50%. This allows us to offer exactly this way of handling the raw materialto obtain the biodiesel.Table 5. Lipid content of the extracts from sources irradiated by microwave.Coffeeresidue,g.Microwaveirradiation,WTime ofirradiation,min.Rawmaterial forextraction,gTime ofextraction,hProduct, g.Total lipidcontent, %20 600 20 13.7527 2 1.5092 8.0720 450 20 16.4640 2 1.4276 5.9420 300 20 17.7204 2 1.5105 5.63
Content of neutral lipids, %Fatty acid content, %Lipid content of extracts, %Table 6. Lipid content of the extracts from dried sources.Coffeeresidue,g.D. I. Yordanov, Z. B. Tsonev, T. V. Palichev, Z. A. Mustafa/Petroleum & Coal 55(2) 74-81, 2013 80Temperatureof drying, CTime ofdrying, h.Rawmaterial forextraction,gTime ofextraction,hProduct,g.Total lipidcontent, %20 150 4 20 2 0.8577 2.2920 20 24 20 2 1.6805 5.6380Sterol esters Triacylglycerols Non identified8070Sterols+Diacylglycerols+FFAMonoacylglycerols+Polar lipids706060505040403030202010100450 W 300 W Dried at 20°C 120-150°C 600WFig. 8. Data for the content of neutral lipids frоmextracts based on the results for Table 40450 W 300 W Dried at 20°C 120-150°C 600WFig. 9. Lipid content of the extracts.100Sum of unsaturated fatty acidsSum of saturated fatty acids9080706050403020100450 W 300 W Dried at 20°C 120-150°C 600WFig. 10. Content of the unsaturated and saturated fatty acids in the extracts.5. Conclusions1. We were performed the microwave irradiation processing and drying at 120-150 C for4 hours of the coffee residue from the vending machine. The products obtained were usedas raw materials for the extraction of lipids by n-hexane.2. From our study we may conclude that microwave irradiation and heat treatment of thecoffee residue increase the amount of saturated fatty acids of the coffee oil.3. The lipid extract derived from the processing of coffee residue with microwave radiationpower of 600W, contains the greatest amount of lipids (8.07%). This is probably due tothe flow of high-energy cracking under the influence of powerful microwave radiation tothe molecules in the coffee residue, resulting in increased total lipid content.4. The sample obtained at 600W microwave has the balanced composition of saturatedand unsaturated fatty acids of approximately 50%. This allows us to offer exactly this wayof handling the raw material to obtain the biodiesel.
Page 1 and 2: Petroleum & CoalISSN 1337-7027Avail
Page 4 and 5: four CH 2 -groups present in the sp
Page 8: ReferencesD. I. Yordanov, Z. B. Tso

Estimation of measurement uncertainty for the determination of the ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?