Presentation on theme: "Week 3 Collection and Analysis of Biodiesel"— Presentation transcript:
1 Week 3 Collection and Analysis of Biodiesel Biodiesel and SoapWeek 3Collection and Analysis of Biodiesel
2 Getting biodiesel Siphon off the biodiesel Wash with water until May be contaminated withSoapUn-reacted acidWash with water untilAllow to separateMeasure pH of waterRepeat until pH ~7Collect biodieselDry biodiesel
3 Analytical Techniques % yieldCalorimetryViscometrySingle temp or as a function of temperatureFreezing pointFTIRVolatility analysisThin layer chromatographyGC-MS
4 % Yield Product yield Good for comparing yield from different methods Mass of biodiesel produced as a percentage of mass of oil usedGood for comparing yield from different methods
5 CalorimetryBurn biodiesel and used heat given off to raise the temperature of water (NOT BOIL).Monitor the starting temp and final temperature of waterBiodiesel + O2 CO2 + H2O + heatHeat given off will be used to heatqwater (J) = m (g) * C (J/g.K) * ΔT (K)
6 CalorimetryHow does this work? This is a quick and dirty method - good for comparison but not research gradeGet a canAdd known weigh to water to the canCan also make use of density of water and measure volumeWeigh biodiesel into a crucible (use crucible which is already black- do not use pristine ones). Place a wick in oilPlace can over crucibleSet biodiesel alight while monitoring the change in temperature of the water. Ideally don’t want > 60CCalculate J/g or J/mg ofC for water is J/(g.K)
7 Volatility Heat the sample to see if volatile impurity is lost EthanolWater?Will have oven set to 75 C for this (Felizardo et al., Waste Management 26 (2006) 487–494)Don’t want to use Bunsen (flames)
8 FTIR Look for presence (or absence of functional groups) Good way to comparereactants and productsDifferent biodieselKnow how to use the FTIR instrument
9 Viscometry Will use Varnish Viscometer Tubes flat bottom with graduation lines at 27, 100 and 108mm from the outside bottomApproximate I.D.=10.74 ± mm, length=114 mmHow do you useFill to 2nd lineTurn up side down and allow liquid to completely settleTurn right side up and note the bubble time which is the time bubble rises from the bottom-line (27) to the middle line (100).The length of time, in seconds, required for an air bubble to pass from the 27mm to 100mm score mark, a distance of 73mm, is approximately equal to the viscosity of the liquid in "Stoke" units; alternatively, viscosity may be expressed in "Bubble Seconds." It is important to note that the position of the air bubble in relation to the 27mm score should be similar at the end of the test on the 100mm score.
10 Thin Layer Chromatography (TLC) A good way to check for impuritiesHow many different compounds are in a sampleVery small quantities of the samples is placed on the special TLC platesThe plate is put in a container with a solvent or solvent mixtureThe solvent runs up the plate and will separate the different kinds of molecules based on polarity differences and size differences
11 Chromatography Two types which essentially uses the same principles Thin Layer ChromatographyGas Chromatography
12 Thin Layer Chromatography (TLC) There are two phasesa stationary phase (a solid, or a liquid supported on a solid)and a mobile phase (a liquid or a gas).The mobile phase flows through the stationary phase and carries the components of the mixture with it. Different components travel at different rates.The stationary phase in this case is silica gel coated on a thin piece of rigid plasticThe mobile phase in this case is a mixture of solvents hexane and ethyl acetate in a 80:20 ratio (v/v)
13 Thin Layer Chromatography (TLC) How does it work?Get a cut piece of TLC plateMark a line (in pencil at the ¼ inch from the bottom)Place a small dots of the biodiesel and oils on the line.There should be sufficient space between the dotsWhen the sample is dry, place the plate in a shallow layer of solvent in a covered beaker. Make sure that the solvent level is below the line.As the solvent moves up the plate, different components will move at different rates.When the solvent reaches the top, remove the plate from the solvent.Place the plate in an iodine chamber and allow the color to developMark the various spots on the plateCalculate the Rf value for each componentRf = distance traveled by component distance traveled by solventIonic compounds will be more tightly held by the plate and will have a lower Rf value.
14 What is going on? The sample is first dissolved in the mobile phase The compounds present will then tend to get carried up the chromatography plate as the solvent continues to move upwards.How fast the compounds get carried up the plate depends on two things:The solubility of the component which is dependent o the Inter molecular Forces between the compound and the mobile phase.How much the compound sticks to the stationary phase is dependent on the IMF the compound and the silica gel.A compound which can form H-bonds ( N-H, O-H), will tend to stick to the stationary phase and will have lower Rf values
15 Gas Chromatography (GC-MS) Separates components of samples based on their boiling point or volatility. This tends to be far more effective than TLCThe sample is injected on a column and a carrier gas (N2) is passed over the column while the column is being heated. The more volatile compounds will be eluted (washed off the column) first.Mobile phase is called carrier gas is N2The compounds are identified by mass spectroscopy. To see how this works visit the web site at:The settings we will be using is optimized for examining acids and their esters.
16 Prep of sample for GC-MS Each lab group may submit up to 5 samples for analysis by GC-MSYou first need to make a 1:100 dilution of your sample in methanol (not water)You will be provided with 10 ml volumetric flasks for this.Place ~2 mL of diluted sample in labeled vialClose vials tightly and place in vial holder