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Mass Transfer Operations in Food Industry: Solid-Liquid Extraction

Explore the separation processes in the food industry, focusing on solid-liquid extraction as an essential method. Learn about the phases involved and the various contact methods. Discover the factors influencing extraction efficiency and operational techniques.

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Mass Transfer Operations in Food Industry: Solid-Liquid Extraction

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  1. Extraction

  2. INTRODUCTION • Perpindahanmassaantarfasedalamindustripangan, merupakansesuatu yang seringterjadidanmenarikuntukdipelajari. • Fase-faseyang adameliputi gas, cair, padatdangabunganlebihdarisatufase. • Padapengetahuanbahan, satufaseterdiridaribeberapakomponendansetiapkomponenmempunyaitendensi yang berbedaterhadap yang lain dalamperpindahanmassa. • Suatukomponenmudahlarutdalamsuatucairantertentu, makakondisiinimerupakansuatudasaruntukmelakukanekstraksidenganmenggunakanpelarut.

  3. Separation processes - general • Mechanical separations e.g. filtration of a solid from a suspension in a liquid, centrifugation, screening etc • Mass transfer operations e.g. distillation, extraction etc Paul Ashall 2007

  4. Mass transfer operations – nature of interface between phases • Gas-liquid contact e.g. absorption, evaporation, distillation etc • Liquid-liquid contact e.g. extraction • Liquid-solid contact e.g. crystallisation, adsorption • Gas-solid contact e.g. adsorption, drying etc Paul Ashall 2007

  5. Mass transfer operations – controlling transport phenomenon • Mass transfer controlling e.g.distillation, absorption, extraction, adsorption etc • Mass transfer and heat transfer controlling e.g. drying, crystallisation • Heat transfer controlling e.g. evaporation Paul Ashall 2007

  6. Methods of operation • Non steady state – concentration changes with time e.g. batch processes • Steady state • Stage • Differential contact Paul Ashall 2007

  7. When both phases are flowing: • Co-current contact • Cross flow Counter-current flow Stage 1 Stage 2 etc 1 2 1 2 Paul Ashall 2007

  8. EKSTRAKSI PADAT-CAIR • Ekstraksipadatan-cairanadalahsuatucontohoperasipemisahankomponen yang diinginkan (solute) dalamfasepadatandipisahkandenganmengontakkanpadatandancairan (solvent) yang manakomponen yang diinginkandapatlarut. • Prosesoperasinyadapatsatutahapan (stage) ataubeberapa (multi) stage

  9. Istilah • Stage dalamkeseimbangan: Komponen-2 dari fase-2 yang dikontakkansecaraintimbercampurdandijagatetapkontakdenganwaktu yang cukupdan agar terjadikeseimbanganthermodinamikantara komponen-2 tersebut. • Effisiensi stage : merupakanrasiodariperubahankomposisi yang terjadidalam stage aktualdenganperubahankomposisidalam stage teoritispadakondisi yang sama.

  10. MacamAliran Dalamekstraksipadatan-cairan yang keluar ada duamacamyaitu : • alirancairanbersih (overflow), yaitularutan solute dalam solvent dan • aliranresidu (underflow), yaitupadatan yang tidakdapatlarutdanbeberapalarutan yang bersamanya. Padastage aktualkonsentrasi solute dalamalirancairanbersih (overflow) akanlebihkecildalamlarutan yang bersamapadapadatandalamaliran underflow.

  11. PrinsipEkstraksi Maserasi Perkolasi Soxhletasi Refluks DestilasiUap-Air Rotavapor EkstraksiCair-Cair Kromatografi Lapis Tipis Penampakan Noda

  12. JenisEkstraksi • EkstraksiSecaraDingin Maserasi, Soxhletasi, Perkolasi • EkstraksiSecaraPanas Refluksi, DestilasiUap

  13. LIQUID-LIQUID EXTRACTION

  14. INTRODUCTION • Ekstraksi cair-cair adalah pemisahan komponen dari suatu campuran cair dengan mengontakkan pada cairan lain • Sering disebut juga Ekstraksi cair atau ekstraksi pelarut (solvent extraction) • Pemisahan berdasar perbedaan kelarutan Dr.-Ing. Misri Gozan

  15. Separatory funnel for use in a liquid–liquid extraction.

  16. Two phase system, hydrophobic (top) and hydrophilic (bottom) for measuring the partition coefficient of compounds.

  17. Extraction equipment Batch: Continuous: single-stage: column: separatory funnel mixer-settler rotating-disk contacter a. agitator; b. stator disk

  18. Mixer-settler column Mixer-settlers operate with a purely stage-wise contact. After every mixer there is a settler. Mixer-settlers can be operated in a multistage, co- or countercurrent fashion.

  19. Agitated column In extraction with high mass transfer and/or changing physical properties, this is the column of choice. The geometry of the agitated compartments can be adapted for changing hydrodynamic conditions. Other main features are the special mixing turbines and the perforated partition plates.

  20. Packed extraction column

  21. Schematic diagram of a Soxhlet extractor.

  22. Faktor-faktor yang mempengaruhilajuekstraksimeliputi : • Luasan interface padatan - cairan. • Gradienkonsentrasi. • Temperatur • Lajualiran solvent.

  23. V = mass flow rate of the light stream, L = flow rate of the heavy stream, y = concentration of the component being exchanged in the light stream x = concentration of the component being exchanged in the heavy stream n = conditions at equilibrium in the nth stage n + 1 = conditions at equilibrium in the (n + 1)th stage a = the conditions of the streams entering and leaving stage 1, one being raw material and one product from that stage

  24. A simplified equation can be written for such cases:

  25. Example. Single stage steam stripping, of taints from cream A continuous deodorizing system, involving a single stage steam stripping operation, is under consideration for the removal of a taint from cream. If the taint component is present in the cream to the extent of 8 parts per million (ppm) and if steam is to be passed through the contact stage in the proportions of 0.75 kg steam to every 1 kg cream, calculate the concentration of the taint in the leaving cream. The equilibrium concentration distribution of the taint has been found experimentally to be in the ratio of 1 in the cream to 10 in the steam and it is assumed that equilibrium is reached in each stage. Call the concentration of the taint in the cream x, and in the steam y, both as mass fractions, From the condition that, at equilibrium, the concentration of the taint in the steam is 10 times that in the cream: 10x = y and in particular, 10x1 = y1 Now, y1 the concentration of taint in the steam leaving the stage is also the concentration in the output steam y1 = ya = 10x1

  26. The incoming steam concentration = y2 = 0 as there is no taint in the entering steam. The taint concentration in the entering cream is xa = 8 ppm. These are shown diagrammatically in Fig. 9.3. Basis is 1 kg of cream The problem is to determine x1 the concentration of taint in the product cream. The mass ratio of stream flows is 1 of cream to 0.75 of steam and if no steam is condensed this ratio will be preserved through the stage. 1/0.75 = 1.33 is the ratio of cream flow rate to steam flow rate = L/V.

  27. to the one stage n = 1, y2 = x1(L/V) + ya – xa(L/V) y2 = 0 = x1. 1.33 + 10.x1 - 8 . 1.33 x1 = 10.64/11.33 = 0.94 ppm which is the concentration of the taint in the leaving cream, having been reduced from 8 ppm.

  28. Rate of Extraction Rate of Solution = Driving Force / Resistance where : dw/dt = rate of solution, Kl = mass-transfer coefficient, A = interfacial area, ys and y = the concentrations of the soluble component in the bulk of the liquid and at the interface. It is usually assumed that a saturated solution is formed at the interface and ys is the concentration of a saturated solution at the temperature of the system.

  29. EXAMPLE . Counter current extraction of oil from soya beans with hexane Oil is to be extracted from soya beans in a counter current stage-contact extraction apparatus, using hexane. If the initial oil content of the beans is 18%, the final extract solution is to contain 40% of oil, and if 90% of the total oil is to be extracted, calculate the number of contact stages that are necessary. Assume that the oil is extracted from the beans in the first mixer, that equilibrium is reached in each stage, and that the crushed bean solids in the underflow retain in addition half their weight of solution after each settling stage. The extraction plant is illustrated diagrammatically in Fig. 9.5.

  30. Overall mass balance In 100 kg raw material there will be 18% oil, that is 82 kg bean solids and 18 kg oil. In the final underflow, 82 kg beans will retain 41 kg of solution, the solution will contain 10% of the initial oil in the beans, that is, 1.8 kg so that there will be (18 - 1.8) = 16.2 kg of oil in the final overflow, Extract contains (16.2 x 60/40) = 24.3 kg of solvent Total volume of final overflow = 16.2 + 24.3 = 40.5 kg Total solvent entering = (39.2 + 24.3) = 63.5 kg MASS BALANCE Basis: 100 kg beans

  31. Oil concentration in underflow = product concentration = 0.4. It is an equilibrium stage, so oil concentration in underflow equals oil concentration in overflow. Let y2 represent the concentration of oil in the overflow from stage 2 passing in to stage 1. Then oil entering stage 1 equals oil leaving stage 1. Therefore balance on oil:

  32. Extraction of Nicotine with Immisible Liquids • An inlet water solution of 100 kg/h containing 0.01 wt fraction nicotine (A) in water is stripped with a kerosene stream of 200 kg/h containing 0.0005 wt fraction nicotine in a countercurrent stage tower. The water and kerosene are essentially immiscible in each other. It is desired to reduce the concentration of the exit water to 0.0010 wt fraction nicotine. Determine the theoretical number of stages needed. The equilibrium data are as follows (C5), with x the weight fraction of nicotine in water solution and y in the kerosene.

  33. Terima kasih

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