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MEMBRANE TECHNOLOGY

MEMBRANE TECHNOLOGY

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MEMBRANE TECHNOLOGY

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  1. MEMBRANE TECHNOLOGY By : Prof. Dr. Tien R. Muchtadi

  2. DEFINITIONS • INTRODUCTION • CLASSIFICATION OF MEMBRANE PROCESS • TYPES OF MEMBRANE • REJECTION COEFFICIENT • NOMINAL MW CUT-OFF • GENERAL MEMBRANE EQUATION

  3. INTRODUCTIONS • Effective product separation is crucial to economic operation in process industries • However, certain types of materials are inherently difficult and expensive to separate • Prominent examples include : • Finely dispersed solids, especially those which are compressible, have a density close to that of the liquid phase, have high viscosity, or are gelatinous • Low molecular weight, non-volatile organics or pharmaceuticals and dissolved salts • Biological materials which are very sensitive to their physical and chemical environment

  4. A membrane may be defined as “an interphase separating two phases and selectively controlling the transport of materials between those phases • Since 1960s a new technology using synthetics membrane for process separations has been rapidly developed by materials scientist, physical chemist and chemical engineers • Such membrane separations have been widely applied to a range of conventionally difficult separation

  5. CLASSIFICATION OF MEMBRANE PROCESSES • Industrial membrane process may be classified according to the size range of materials which they are to separate and the driving force used in separations. • There is always a degree of arbitrariness about such classification and the distinction which are typically drawn are shown in Table. 1

  6. Table 1. Classifocation of membrane separation process for liquid systems

  7. THE NATURE OF SYNTHETIC MEMBRANES • Membrane used for separation process are most commonly made of polymeric materials • Membrane have most commonly been produced by a form of phase inversion known as immersion precipitation • This process has four main steps : • The polymer is dissolved in a solvent to 10-30 per cent by weight • The resulting solution is cast on suitable support as film of thickness ~ 100 µm • The film is quenched by immersion in non-solvent bath, typically water or an aqueous solution • The resulting membrane is annealed by heating

  8. GENERAL MEMBRANE EQUATION • The general membrane equation is an attempt to state the factor which may be important in determining the membrane permeation rate for pressure driven processes • Form : J = |Δ P| - |ΔΠ| (Rm + Rc + Rf‘)µ

  9. J : the membrane permeation rate (flux expressed as volumetric rate per unit area) • Δ P : the pressure difference applied across the membrane (trans membrane pressure) • ΔΠ : the difference in osmotic pressure across the membrane • Rm : the resistance of the membrane • Rc : the resistance of the layers depasited on the membrane (filter cake, gel foulants) • Rf‘ : the resistance of the film layer

  10. If the membrane is only exposed to pure solvent, exp water the equation become : J = |ΔP|/Rmµ • For microfiltration and ultrafiltration membranes where solvent flow is most often essentially laminar through an arrangement of tortous channels, this is analogous to the Carman-Kozeny equation • Knowledge of such as water fluxes is useful for characterising new membrane and also for assesing the efectiveness of membrane cleaning procedures

  11. MEMBRANE PROCESS • MICROFILTRATION • ULTRAFILTRATION (U/F) • REVERSE OSMOSIS (R/O) OR HYPERFILTRATION (H/F) • MEMBRANE MODULES AND CONFIGURATIONS • MEMBRANE FOULING, FLUX RATE REDUCTION, CLEANING AND PROCESS ECONOMICS

  12. MICROFILTRATION • Such filters use filter cloths as the filtration medium and are limited to concentrating particles above 5 µm in size • Dead end membrane microfiltration, in which the particle containing fluid is pumped directly through a polymeric membrane, is used for industrial clarification and sterilization of liquids

  13. The advantage of cross-flow filtration over conventional filtration are : • A higher overall liquid removal rate is achieved by prevention of the formation of an extensive filter cake • The process feed remains in the form of mobile slurry suitable for further processing • The solids content of the product slurry may be varied over a wide range • It may be possible to fractionate particles of different sizes

  14. Membrane Permeate Processing feed crossflow Retentate Permeate Figure 1. The Concept of Cross-Flow Filtration

  15. Figure 2. Flow diagram for a simple cross-flow system

  16. C Membrane permeation rate b a Time Figure 3. The time-dependence of membrane permeation rate duringcross-flow filtration : a. low cross-flow velocuty, b. increased cross-flow velocity, c. back-fushing at the bottom of each”saw-tooth”

  17. MEMBRANE FOULING AND EFFECTS • MEMBRANE FOULING • FLUX RATE REDUCTION • CLEANING METHODS • PROCESS ECONOMICS : EFFECT OF FLUX RATE REDUCTION AND MEMBRANE LIFE ON OPERATING COSTS AND RETURN ON CAPITAL INVESMENT

  18. ELECTRODIALYSIS • OUTLINE OF MEMBRANE OPERATION • MEMBRANE TYPE AND TRANSPORT MECHANISM • APPLICATIONS

  19. LIQUID MEMBRANES • TYPES • OPERATING MECHANISM • PRODUCT RECOVERY • APPLICATIONS

  20. GAS SEPARATIONS • MECHANISM • TYPES OF MEMBRANE • APPLICATIONS

  21. CONCENTRATION OR GEL POLARISATION MODEL • APPLICATION OF THE DESIGN MODEL TO THE ULTRAFILTRATION CONCENTRATION AND SEPARATION OF GEL FORMING PROTEIN SOLUTION • CALCULATIONS AND ASSUMPTIONS

  22. APPLICATIONS OF MEMBRANE TECHNOLOGY • FOOD PROCESSING AND ENGINEERING • BIOTECHNOLOGY, MEMBRANE REACTORS • BIOMEDICAL ENGINEERING • PROCESS DEVELOPMENT • GROUP DISCUSSTION AND PROBLEM SOLVING

  23. TEKNOLOGI SEPARASI MEMBRAN • Proses pemisahan komponen berdasarkan perbedaan berat dan ukuran molekul melalui suatu membran semipermeabel, dimana akan diperoleh komponen dengan ukuran molekul besar akan tertahan (retentate) dan komponen yang melewati membran (permeate)

  24. KLASIFIKASI PROSES MEMBRAN Berdasarkan pada driving force yang digunakan : • Mikrofiltrasi • Ultrafiltrasi • Reverse osmosis • Elektrodialysis • Dialysis Paling banyak digunakan untuk pengolahan produk pangan

  25. What Is Reverse Osmosis? Reverse osmosis, as form of water treatment, is a technology in its infancy. The first membrane was developed in 1958. In the years following, membrane technology has grown a great deal and will continue to grow in the future. In fact, some of the membranes that are currently in use may be obsolete in a very short time, in favor of some new membrane material that is more resistant to a particular fouling contaminant. The reverse osmosis membrane is used for various applications from precious metal reclamation, to chemical reclamation, food processing nuclear waste reclamation, laboratory water purification, and on and on. We will limit our discussion to water purification and its laboratory applications.

  26. To fully understand the technology of reverse osmosis, you must first understand the concept of normal osmosis. Simply put, in normal osmosis, water flows from a less concentrated solution through a semi-permeable membrane to a more concentrated solution (see figure 1). Reverse osmosis utilizes pressure to reverse normal osmotic flow, thus in reverse osmosis water flows from a more concentrated solution across semipermeable membrane to a less concentrated solution (see figure 2).

  27. BAHAN BAKU MEMBRAN ULTRAFILTRASI • Polimer (misal Polisulfon, Poliacrilonitril) dan keramik (Zirconium oxide, Aluminium oxide) • Untuk memperoleh struktur membran dgn karakteristik tertentu selain bahan baku tadi juga diperlukan campuran pelarut dan aditif

  28. Karakteristik membran ultrafiltrasi : nilai MWCO (Molecular Weight Cut Off) • MWCO batas toleransiberat molekul (BM) senyawa yang dapat dipisahkan oleh suatu membran • MWCO 10,000 membran dapat menahan (reject) sebanyak 95% komponen-komponen dengan BM ≥ 10,000, sedangkan komponen-komponen dengan BM lebih rendah akan melewati membran

  29. Tabel 1. Aplikasi Teknik Separasi Membran pada Pengolahan Produk Pangan

  30. CONTOH PERCOBAAN SEPARASI MEMBRAN Tujuan percobaan : • Melakukan pembuatan membran ultrafiltrasi dari polimer polisulfon • Melakukan annealing untuk menghasilkan membran dengan karakteristik tertentu • Melakukan pengujian kinerja membran yang diperoleh untuk memisahkan senyawa dekstran (Dx) (BM = 71400) dan polietilen glikol (PEG) (BM= 20000), dan • Melakukan studi literatur apliaksi membran yang dihasilkan pada pengolahan pangan

  31. BAHAN DAN ALAT Bahan : polimer polisulfon (PS), pelarut dimetyhl-acetamide (DMAC), aditif nourmal methyl pirolidon (NMP), dekstran (BM=71.400) dan polietilen glikol (BM= 20000) Alat : alat separasi membran, alat casting, water bath, HPLC waters dan detektor refraktometer

  32. METODOLOGI PERCOBAAN • Pembuatan membran (Gambar 4) • Pengujian karakteristik membran • proses annealing • proses separasi membran • Pengujian selektifitas membran • mengamati prosentase rejeksi komponen dekstran dan polietilen glikol

  33. Polimer Pelarut Aditif Pencampuran Pendiaman/relaxing Casting Gambar 4. Diagram Alir proses pembuatan membran Penguapan Koagulasi Membran sheet

  34. Prosentase rejeksi dihitung dengan rumus : Rejeksi (%) = [ 1-Cp/Cf ] x 100 % Dimana : Cp = konsentrasi solute pada permeate Cf = konsentrasi pada feed • Penentuan konsentrasi solute pada feed dan permeate dilakukan dengan metode HPLC menggunakan eluen aquadest, dgn flow rate 0.8 ml/menit dan volume injeksi 200 ml

  35. Gambar Alat separasi membran skala laboratorium • Keterangan : • Beaker geals pyrex • Tutup bagian atas • Tutup bagian bawah • Tutup pengatur tekanan • Aliran tekanan • Saluran bahan • Pengaduk magnetis • M. Modul membran ultrafiltrasi • Saluran pengeluaran • Disk Polietilen penyangga membran • S. Pemanas/hotplate

  36. HASIL DAN PEMBAHASAN • Membran dari polisulfon, pelarut dimetil acetamide (DMAc) dan aditif normal methyl pirolidon (NMP) dengan rasio 22: 62,4:15,6 hanya cocok untuk memisahkan dekstran dan senyawa lain dengan BM > 71400. • Dengan menghitung waktu annealing saat persen 95% didapatkan MWCO membran polisulfon 71400 dan waktu annealing sebesar 6 menit.

  37. Annealing akan memperbesar daya rejection • Peningkatan daya rejection diduga akibat perendaman dalam air hangat selama proses annealing sehingga pori-pori membran lebih teratur dalam jarak dan ukurannya

  38. Hasil analisis HPLC karakteristik membran campuran polisulfon, DMAc, dan NMP pada perbadingan 22 : 62,4 : 15,6

  39. Gambar 5. Hubungan antara waktu annealing dan % rejection membran polisulfon terhadap dekstran (BM = 71400)

  40. APLIKASI MEMBRAN PADA PENGOLAHAN PANGAN Kelebihan metoda separasi membran : • Mampu memisahkan secara sempurna suatu campuran yang terdiri dari komponen-komponen dengan berat molekul yang berbeda-beda • Untuk memisahkan komponen bernilai ekonomis tinggi Kelemahan : • Memerlukan biaya yang relatif tinggi dibandingkan dengan cara ekstrasi ataupun distilasi konvensional

  41. Salah satu contoh komponen dgn nilai ekonomis tinggi adalah ENZIM • Enzim : komponen protein (makromolekul) dgn BM besar (104 – 109) • Proses imobilisasi menggunakan membran untuk enzim dg BM > 71400 • Proses imobilisasi secara fisik berarti membran akan bersifat tidak permeable bagi enzim sehinga enzim dapat didaur ulang maupun dipalikasikan untuk proses produksi secara kontinu (Gambar 6.)

  42. Substrat Produk Enzim Substrat + enzim Produk Membran Gambar 6. Prinsip separasi membran untuk imobilisasi enzim

  43. Tabel 2. Aplikasi proses separasi membran untuk imobilisasi enzim secara fisik

  44. Karakteristik membran untuk imobilisasi enzim tergantung pada : • Jenis enzim yang akan diimobilisasi • Jenis substrat yang diharapkan akan tertahan (retentate) pada membran • Produk yang diharapkan melewati (permeate) membran

  45. HASIL PERCOBAAN • Enzim yang akan diimobilisasi dan retentate substrat memiliki berat molekul lebih dari 71400, dan • Produk hasil reaksi enzimatis (permeate) memiliki berat molekul lebih kecil dari 71400

  46. TERIMA KASIH