Destilasi Destilasi sederhana, terjadi satu kali penguapan, satu kali kondensasi, cross current process. Untuk pemisahan cairan dengan Td 40-150 0 C dengan beda Td 80 0 C. Destilasi kolom (Rektifikasi), berulang kali penguapan dan kondensasi. Terjadi lintas arus fasa uap dan fasa cair kondensat dalam kolom, counter current process. Destilasi uap, continue process.
Dasar Fisika Proses Pemisahan p A = P A x X A p B = P B x X B P A, P B : tekanan uap senyawa murni X A,X B : fraksi mol dalam cairan p A /p B = P A /P B x X A / (1 – X A ) p A = pY A ; p B = pY B p A /p B = p/p x Y A /(1-Y A ) Y A / (1 – Y A ) = P A /P B x X A / (1-X A ) Y A / (1 – Y A ) = x X A / (1-X A ) Y A, Y B : fraksi mol dalam ruang penguapan
Hubungan Titik didih dengan Tekanan Atmosfir Setiap Penurunan tekanan atmosfir menjadi setengahnya, akan mengakibatkan penurunan Td sekitar 15 0 C. 1. Dietileter, 2. Aseton, 3. Benzen, 4. Air, 5. Khlorbenzen, 6. Brombenzen, 7. Anilin, 8. Nitrobenzen, 9. Chinolin, 10. Dodesilalkohol, 11. Trietilglikol, 12. Dibutilesterftalat, 13. Tetracosan, 14. Octakcosan.
Destilasi sederhana sistem vakum: Dengan aliran air kran sampai 8-15 mm. Dengan pompa vakum : sampai 0,01-1 mm. Bila bekerja dengan vakum dan tekanan, Jangan lupa pakai kaca mata pengaman !
Distillation was developed into its modern form with the invention of the alembic by Islamic alchemist Jabir ibn Hayyan in around 800 AD. He is also credited with the invention of numerous other chemical apparatus and processes that are still in use today. alembic alchemistJabir ibn Hayyan800 The design of the alembic has served as inspiration for some modern micro- scale distillation apparatus such as the Hickman stillhead.
As alchemy evolved into the science of chemistry, vessels called retorts became used for distillations. Both alembics and retorts are forms of glassware with long necks pointing to the side at a downward angle which acted as air-cooled condensers to condense the distillate and let it drip downward for collection.alchemychemistryretortsglassware Later, copper alembics were invented. Riveted joints were often kept tight by using various mixtures, for instance a dough made of rye flour. These alembics often featured a cooling system around the beak, using cold water for instance, which made the condensation of alcohol more efficient. These were called pot stills.pot stills
Distillation was mentioned by Aristotle (384-322 B.C.) as a method of purifying water, and Pliny the Elder (23-79 A.D.) recorded one of the earliest references to a rudimentary still, the apparatus used to perform a distillation. In its most basic form, distillation requires: –a container for the original mixture—called a retort. –a condenser to cool the vapors a receiver to collect the distillate
Miriam the Prophetess is considered the mother of the protoscience of alchemy. Also called “Maria the Jewess,” she is believed to have lived in the first century A.D. Writing 500 years later, the Egyptian alchemist Zosimos credits her with inventing the kerotakis, an early forerunner of the modern still. It had characteristics of what we know as a double boiler, and in France the double boiler is still called a bain- marie—Maria's bath. An early drawing of a distillation apparatus
Steam Distillation A new technique that arises in this experiment is that of steam distillation. When you isolate the clove oil (eugenol and acetyl eugenol) from cloves, you will not have a solution. Instead, you will have two layers. Unlike the distillation of a solution (e.g., cyclohexane/toluene), these two layers will behave as distinct entities and there will be no dependence on how much of each species is present. The total pressure of the pot liquids can be defined by the following equation.
Notice there are no mole fraction terms in the equation. This means that if you have lots of water or just a little it will make the same contribution to the vapor pressure. What will happen when you distill? The mixture will heat up and eventually boil. Please recall that boiling occurs when the pot liquids have a vapor pressure equal to the external pressure. In steam distillation, the pressures of the two components must add up to 760 torr.
Throughout the heating process, water and clove oil molecules will escape in proportion to their respective vapor pressures at the distilling temperature. Since water has a significantly lower boiling point than eugenol or acetyl eugenol, a much greater proportion of water molecules will be vaporizing at any time during the distillation. Even though the components of clove oil have low vapor pressures, they are volatile enough to vaporize to some extent and a small amount will lift off with the water molecules.
Since the water and organic components are not interacting with each other, no enrichment occurs and they will co-distill at a single temperature until all of one component is completely distilled over. Normally, steam distillations are carried out with a large excess of water. When all the organic component has been distilled, pure water begins to distill. How is this situation reflected in the appearance of the liquid and in the still head temperature?
While the steam distillation is occurring, the boiling point of the two together will be lower than the boiling point of the more volatile component. Why? At the end of the distillation, you will have two layers in the receiver which can be separated. A helpful relationship when considering steam distillation in a theoretical sense is the ideal gas law, PV = nRT, where P = pressure, V = volume, n = moles, R = the gas constant and T = temperature. It is important to remember that all of these parameters refer to gaseous molecules.
Since distillation involves the expansion of a liquid into a gas in a fixed volume (the still), the gas law can be useful in predicting the amount of water needed to complete a steam distillation or to figure out the proportion in which the organic and aqueous layers will co-distill. To gain a more practical expression, take the ratio of a gas law written for the gaseous water and one written for the organic gas. If this is done, one obtains the following expression.
Fortunately, several of the terms in the above expression cancel. The volumes cancel because both gases occupy the same space, i.e., the still. The temperature terms cancel because the two components are co-distilling at the same temperature. The R terms obviously cancel.
The equation therefore reduces to:
This simple equation sums up steam distillation because it demonstrates that the amount of water obtained is directly proportional to the vapor pressure of water at the distillation temperature. The same is true of the organic component. Therefore, if the organic component has a higher boiling point than the aqueous component, it will contribute fewer molecules to the overall push against the atmosphere. Nonetheless, the two components are working together.
You can think of the system as being like two people trying to push a broken down car. The weaker person may not be contributing much, but is still reducing the work for the stronger person. Because the organic is there, the water does not have to push as hard against atmosphere and this is why the overall temperature is the below the boiling point of pure water.
Now with all this sophisticated theory stated, why is steam distillation useful? You might wonder why you would not just take the cloves and press the oil out of them or extract the cloves directly with an organic solvent such as methylene chloride or ether. The problem with pressing the oil out (and this can be done) is that the yield is very low. You might be able to imagine that much of the material would get caught up in the solid matrix that constitutes most of the mass of the cloves.
The problem with a direct organic extraction is that many other nonvolatile organic components of the clove would also dissolve in the solvent resulting in a much more complex mixture. Purification would become time consuming and material would lost with each added step. With steam distillation, only the volatile components are collected and they can be isolated exhaustively if enough water is used.
Summary In summary, steam distillation is an ideal way to separate volatile compounds from nonvolatile contaminants in high yield. For these reasons it has been used extensively in the isolation of natural products.
DISTILLATION- / RECTIFICATION PLANTS
DISTILLATION AND RECTIFICATION PLANT Concentration increase of 2-component solutions Separation of solutions into its single components Draw-off of waste components Purification of liquid products
E&E distillation and rectification E&E distillation and rectification plants are designed tailored to your needs. The capacities vary from pilot to small scale up to high production scale. Nearly every kind of liquid can be handled in our columns. Our plants operate at vacuum or overpressure conditions. Ex-proof execution is our daily job. In connection with our extraction plants rectification plants are used to recover and concentrate the used solvents: yield colors aromas ethereal oils oleoresins others
Distillation Services Every distillation pilot test involves a setup customized for the application at hand. Varying configurations are available for flashing, steam stripping, vacuum, azeotropic, multi-component and non-ideal processes. Column internals can be either trays or packing. Flanged column sections are used to provide maximum flexibility for arrangement of internals. Both stainless steel and glass sections can be used. Provisions can be made for multiple feed point locations, as well as vapor or liquid sidedraw. Reboilers can be kettle, thermosiphon, forced circulation or falling film, heated by steam, hot oils, or electricity. Alternatively, direct steam addition can be utilized. Operating pressures from 30 PSIG to 1 mmHg absolute are possible. Heat loss is minimized by means of heat tracing and insulation. The pilot column is run over a range of operating conditions to measure separation performance and help determine optimum conditions. Other observations, such as operating stability, foaming, fouling, or thermal degradation, are also made and recorded. This type of data and information is extremely important for process scale-up.
Distillation Capabilities Column Configurations - Packed, Trays, Multiple Feeds, Sidedraw - Sizes range from 1" to 4" and up to 60 theoretical stages Operating Pressures - Pressure to 30 PSIG, Vacuum to 1 mmHG Reboiler Types - Kettle, Thermosiphon, Forced Circulation, Falling Film Heat Sources - Steam, Hot Oil, Electric