Más contenido relacionado


Presentation extraction ms. juhi bandre

  1. Prepared by Guided by Ms. Juhi Bandre Ms. Neha Raut M.Pharm 2nd Sem. (2019-2020) Pharmaceutical Chemistry Department. Smt.Kishoritai Bhoyar College of Pharmacy, Kamptee.
  2. ©JUHIBANDRE INDEX 1.Introduction 2.Liquid-liquid equilibria 3.Extraction with Agitation 4.Counter-current extraction 5.Reference 2
  3. ©JUHIBANDRE • Extraction is a process where one or more solute(s) are removed from one liquid phase (technically called a diluent) by transferring that/those the solute(s) to another liquid phase (or a solvent). • Since this is the operation between the two liquid phases, no vaporisation is needed; thus, extraction can be performed at low temperatures. • Accordingly, extraction is suitable for separating materials that may decompose or denature at elevated temperatures. 3
  4. ©JUHIBANDRE Liquid – Liquid Extraction (LLX) • Liquid-liquid extraction(LLX) is a mass transfer operation in which a solution (feed: a mixture of solute and carrier liquid) is brought into intimate contact with a second immiscible or slightly miscible liquid (solvent) in order to achieve the transfer of solute (s) from the feed to solvent. • The solute rich phase is called the extract. • The residual liquid (feed stream) that may have the little of the left in it is called the raffinate. 4
  5. ©JUHIBANDRE Liquid-liquid Equilibria(LLE) • According to the phase rule there are three degrees of freedom (three independent variables) for a ternary(three-component) system consisting of two liquid phases at equilibrium. • At any temperature and pressure, therefore, only one degree of freedom remains. If the composition of one of the liquid phase is specified or fixed, and the composition of the second liquid is also fixed and is not an independent variable provided that equilibrium condition exist. • Classification of Ternary Systems - • A liquid-liquid extraction system contains at least three components –Solute (A), Carrier liquid in the feed (B), Extracting material (C) may be regarded as composed of three binary system – A and B, B and C, and A and C. 5
  6. ©JUHIBANDRE Fig.,Triangular diagram for one pair of partially miscible liquids. Pyridine –water –chlorobenzene at 25℃. 6
  7. ©JUHIBANDRE Categories- 1. The component A and B are completely miscible. 2. The component A and C are completely miscible. 3. The component B and C are partially miscible. • In fig. the triangular diagram for the system pyridine-water-chlorobenzene at 25℃. • Pyridine and water are completely miscible (A and B), Pyridine and chlorobenzene are completely miscible ( A and C ), while water and chlorobenzene (B and C) are practically immiscible at this temperature. • The curve labeled EFG, called the “solubility curve,” separates the two-phase region from the single-phase region. 7
  8. ©JUHIBANDRE • Any point inside the boundary of the solubility curve, such as point H, represents the composition of a mixture consisting of two liquid phases. • If equilibrium is attained, the composition of two liquid phases is represented by the intersection of the tie line (shown as dotted line) with two branches, I -EF and II –FG of the solubility curve. • Any straight lines such as PQ, RS, TV, or EG joining two points on the solubility curve which represent the composition of liquid phases in equilibrium is called a “tie line.” • Examination of the tie lines shows that the length of the tie lines decreases and that the Compositions of the two liquid phases in equilibrium approach each other as the pyridine concentration increases. 8
  9. ©JUHIBANDRE • Liquid phase having composition on the branch of the solubility curve EF corresponding to the higher solute compositions are called extract phases, while those corresponding to compositions on the branch FG are called raffinate phases. 9
  10. ©JUHIBANDRE • Liquid-liquid extraction is an easy method which is generally preferred over other methods. • This method is used for heat sensitive materials or when components to be separated have very close boiling points. • When there are expensive disposal problems for by products then this method can be used as a substitute. • This method has less chemical consumption and also less formation of by products. • This method is cost effective unlike other methods of separation in which capital is required for setting up various incentives. Application of Liquid-liquid Equilibria - 10
  11. ©JUHIBANDRE Extraction With Agitation • Agitation is the movement of one or more components of a mixture to improve contact. • Putting into motion by shaking or stirring often to achieve mixing. • Rotary-agitated columns • Reciprocating columns • Examples of Rotary-agitated columns include: - Scheibelll columns, Rotating disk contactor (RDC), Oldshue-Rushton Columns, Kuhni columns, etc. - An example of the Reciprocating column is the Karr columns. Mechanically Agitated Extractors 11
  12. ©JUHIBANDRE Scheibel Extractor • This is probably the oldest of column having agitators. It operates on the mixer- settler principle. • There are many versions of this design, an example of which is shown in the Figure. The agitators are mounted at fixed intervals on a central vertical shaft, and wire-mesh packings are installed to improve coalescence and separation of the phases. 12
  13. ©JUHIBANDRE 13
  14. ©JUHIBANDRE Rotating Disk Contactor (RDC) • In this system, horizontal disks are used as agitating elements, which are mounted on a centrally supported shaft. • Mounted on the column wall and offset against the agitator disks are the stator rings, whose have aperture is greater than the agitator disk diameter. • This device uses the shearing action of the rapidly rotating disks to inter-disperse the phases. 14
  15. ©JUHIBANDRE Asymmetric Rotating Disk (ARD) Contactor • The column consists of an asymmetrically located mixing zone and a transfer- settling zone partially separated from each other by means of a vertical baffle. • The mixing zone contains a number of compartments, each of which is equipped with a disk-type mixing impeller mounted on a common rotor shaft. The transfer- settling zone consists of a series of compartments, separated by means of annular horizontal baffles. • Its design is aimed at retaining the efficient shearing action of the RDC by using rotating disks to produce dispersion while using the coalescence re-dispersion cycle produced in the separated transfer-settling zone to reduce back-mixing. 15
  16. ©JUHIBANDRE Karr Reciprocating-Plate Extractor • This is a "descendant" of the pulse column with fixed plates. Essentially, the reciprocating-plate column has sieve plates moving up and down (i.e. reciprocating motion) driven by an overhead motor. Thus its operation involves "pulsing" the plates in a steady flow liquid medium. • The Karr Extractor consists of a stack of perforated plates and baffles which have a free area of about 58%. The central shaft which supports the plates is reciprocated by means of a reciprocating drive mechanism located at the top of the column. The amplitude is adjustable generally from 3 to 50-mm and the speed is variable up to 1000 stokes/cm. • Perforated trayes moves up and down. • More uniform drop size distribution. 16
  17. ©JUHIBANDRE Counter current extraction 1. Counter-current extraction with filter. 2. Continuous counter-current decantation systems. • Counter-current extraction is a refinement of basic liquid-liquid extraction that permits separation of substance with very similar portioning behaviour. • The term counter-current indicates that the two phases move in opposite direction actually in the CCD procedure it is usually used one phase is stable and other moves hence the two phases are in relative motion. 17
  18. ©JUHIBANDRE Principle of counter-current extraction • The distribution of a single solute between two liquids the fraction p distribution into the upper phase is a function of the partition coefficient k and the U of upper to lower phase volume p=KU/KU+1 The fraction of solutes in the lower phase at equilibrium q is given by, q=1/KU+1 since p+q=1 The greater the value of KU the larger the fraction p of solutes that passes into the upper phase 18
  19. ©JUHIBANDRE • In these extraction wet raw material is pulverised using toothed disc disintegrators to produce the fine slurry. • The material to be extacted is moved in the one direction (generally in the form of fine slurry) within a cylindrical extractor where it comes in contact with extraction solvent. • The further the starting material moves the more concentrated the extract becomes. • Finally, sufficiently concentrated extract comes out at one end of the extractor while the marc falls out the other end. Procedure - 19
  20. ©JUHIBANDRE Counter – current extraction with filter 20
  21. ©JUHIBANDRE •, System for the manufacture of caustic soda by the reaction of sodium carbonate and milk of lime. • The two reagents in solution are mixed in agitator A, which may be a standard agitator of any type. • The volume of agitator A compared to the amount of solution being introduced is such that time is allowed for the reaction to become complete. • The agaitator overflows continuously to a thickener B where a preliminary separation is made, and from the launder of thickener B the clear solution of the same concentration as that produced in agitator A is taken off as the product of the process. Process for Counter current extraction 21
  22. ©JUHIBANDRE • The filter cake is washed with a solution so that a calcium carbonate precipitate,partly washed free from caustic,is obtained. • The filtrate from this filter is now added to the overflow of thickener B and becomes the product of the process. • The cake from filter C is altogether too thick to pump,and therefore it is dropped into a repulper D. • The underflow from thickener B, consisting now of calcium carbonate suspended in a caustic soda without introducing so much wash water that an undue load is placed on the evaporators for the solution. • This underflow is pumped by a diphragm pump to a rotatory continuous filter C. 22
  23. ©JUHIBANDRE • Repulper D is merely a half cylinder with paddles, in which a stream of solution is introduce until the mixture has been reduced to the thickest consistency that can be pumped with safety. This is then pumped to a second filter E. • Filter E is washed with fresh water; and, if the process has been properly designed,the cake leaving filter E contains so little caustic that it may be sent to waste. • The filtrate from filter E is the liquid that is used (a) to repulp the cake in repulper D, and (b) to wash the cake on filter C. • The systems of more than two filters are not common, but there may be any conceivable combination of thickeners and filters in series. 23
  24. ©JUHIBANDRE Advantages- • A much smaller amount of wash water theoretically required for unit quantity plant material extraction. The same degree of removal of solute as done in counter- current decantation system without filter but with much more water. • The filters take much less space than the equivalent thickeners. • CCE is commonly done at room temperature which spare thermolabile constitutes from exposure to heat which is employed in most other techniques. • CCE procedure has been rated to be more effective and efficient than continuous hot extraction. 24
  25. ©JUHIBANDRE Disadvantage- • The filter system is that the degree with which the wash water comes into equilibrium with the solution on the filter is questionable; and it depends to a considerable extent on the care taken in the maintenance of the filter cloth and the spray nozzles that supply the water. • If the filters are not properly operated,the cake thickness may be variable,in which case the wash water to largely through the spots in the cake and will not extract the thicker spots. • This is not applicable for colloidal or very slow – settling solids. Application- • DNA purification. • Food industry. • Examples citrus oils unsaturated fatty acids. • An important application is citrus oils processing. • An important subject in perfumes and food industry. 25
  26. Theory A method of multiple liquid-liquid extractions is counter current extraction, which permits the separation of substances with different distribution coefficients (ratios). A clever design known as Craig apparatus is used for this purpose (Lyman C. Craig, 1943). • It consists of 300-400 such chambers. • The organic solvent and the aqueous solution is introduced to tube and then it passes to B. Procedures 26
  27. ©JUHIBANDRE • When the apparatus is again made vertical. • The liquid passes through D into E in the next chamber of A and then into B. • The process is repeated till the two liquid gets almost separated. • It is allowed to attain the equilibrium.Now,the appartus is tilted so that the upper layer gets decanted through C and is collected in D. 27
  28. ©JUHIBANDRE Application- • With the help of this method we can have accurate quantitative analysis of a single as well as the mixture of components. • In this case, apparatus required are very simple ( separating funnel, burette, conical flask, etc). • Time required for analysis is very small. • The method is very well used for detection of traces quantity of substance where precipitation method, Gravimetry method not possible. • Fe+3 ferric ion can be easily extracted by ether from 6 Molar HCL solution of the ferrous alloy and iron core. 28
  29. ©JUHIBANDRE • In industrial and commercial field extraction by counter current extraction is frequently applied in the separation of components where the difference in the distribution coefficient small. • The phenomenon is widely applied in the drug analysis. • The solvent extraction is used in clinical laboratory. • Metal chelates are more soluble in non polar solvent.Thus Ni(ll) in it’s tetra co- ordinate complex with dimethyl glyoxime can be extracted into chloroform. In presence of citrate or tartrate the precipitation of Fe(lll) and Cr(lll) can be avoided. • The extract can also be used in the extraction of metal as metal chelate has high solubility in an immiscible solvent such as Chloroform and Benzene. 29
  30. ©JUHIBANDRE 30
  31. ©JUHIBANDRE Reference – 1.Introduction to chemical engineering TATA MC GRAW HILL Edition by Walter.Badger & Julius T. Banchero. 2. 3. Pharmaceutical Engeeneering New age international publishers by K.Sambamurthy. 4. Pharmaceutical analysis, Nirali Prakashan,Volume ll by Dr.A.V. Kasture, Dr.K.R.Mahadik, Dr.S.G.Wadodkar, Dr.H.N.More. 31
  32. ©JUHIBANDRE 32 Thank you!!