MEMBRANE TECHNOLOGY by G1A988C3

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									MEMBRANE TECHNOLOGY
              By :
 Prof. Dr. Tien R. Muchtadi
            DEFINITIONS
•   INTRODUCTION
•   CLASSIFICATION OF MEMBRANE PROCESS
•   TYPES OF MEMBRANE
•   REJECTION COEFFICIENT
•   NOMINAL MW CUT-OFF
•   GENERAL MEMBRANE EQUATION
                    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 :
    a.   Finely dispersed solids, especially those which are compressible,
         have a density close to that of the liquid phase, have high viscosity,
         or are gelatinous
    b.   Low molecular weight, non-volatile organics or pharmaceuticals and
         dissolved salts
    c.   Biological materials which are very sensitive to their physical and
         chemical environment
• 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
      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
  Table 1. Classifocation of membrane separation process for
                               liquid systems

Name of process     Driving force       Separation size   Examples of
                                        range             materials
                                                          separated
Microfiltration     Pressure gradient   10 – 0.1µm        Small particles,
                                                          large
                                                          colloids,microbial
                                                          cells

Ultrafiltration     Pressure gradient   < 0.1 µm – 5 nm   Emulsions,
                                                          colloids,
                                                          macromolecules,
                                                          proteins
Reverse osmosis     Pressure gradient   < 5 nm            Dissolved salts,
(hyperfiltration)                                         small organics

Electrodialysis     Electric field      < 5 nm            Dissolved salts
                    gradient

Dialysis            Concentration       < 5 nm            Treatment of renal
                    gradient                              failure
 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
     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
• 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
• 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
           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
         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
The advantage of cross-flow filtration over
   conventional filtration are :
a. A higher overall liquid removal rate is
   achieved by prevention of the formation of
   an extensive filter cake
b. The process feed remains in the form of
   mobile slurry suitable for further
   processing
c. The solids content of the product slurry
   may be varied over a wide range
d. It may be possible to fractionate particles
   of different sizes
             Membrane
                          Permeate



Processing                                              Retentate
feed
crossflow




                           Permeate


       Figure 1. The Concept of Cross-Flow Filtration
Figure 2. Flow diagram for a simple cross-
               flow system
                                                    C


 Membrane
 permeation
                                                    b
 rate

                                                    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”
     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
         ELECTRODIALYSIS
• OUTLINE OF MEMBRANE OPERATION
• MEMBRANE TYPE AND TRANSPORT
  MECHANISM
• APPLICATIONS
         LIQUID MEMBRANES
•   TYPES
•   OPERATING MECHANISM
•   PRODUCT RECOVERY
•   APPLICATIONS
         GAS SEPARATIONS
• MECHANISM
• TYPES OF MEMBRANE
• APPLICATIONS
 CONCENTRATION OR GEL POLARISATION
             MODEL
• APPLICATION OF THE DESIGN MODEL TO THE
  ULTRAFILTRATION CONCENTRATION AND
  SEPARATION OF GEL FORMING PROTEIN
  SOLUTION
• CALCULATIONS AND ASSUMPTIONS
        APPLICATIONS OF MEMBRANE
               TECHNOLOGY
•   FOOD PROCESSING AND ENGINEERING
•   BIOTECHNOLOGY, MEMBRANE REACTORS
•   BIOMEDICAL ENGINEERING
•   PROCESS DEVELOPMENT
•   GROUP DISCUSSTION AND PROBLEM SOLVING
      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)
       KLASIFIKASI PROSES MEMBRAN

Berdasarkan pada driving force yang digunakan :
1.Mikrofiltrasi
2.Ultrafiltrasi
                          Paling banyak digunakan untuk
3.Reverse osmosis         pengolahan produk pangan
4.Elektrodialysis
5.Dialysis
          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.
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).
        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
• Karakteristik membran ultrafiltrasi : nilai
  MWCO (Molecular Weight Cut Off)
• MWCO           batas toleransi berat
  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
    Tabel 1. Aplikasi Teknik Separasi Membran
        pada Pengolahan Produk Pangan
N      Teknik             Tujuan Proses            Pustaka
o      Proses
1 Mikrofiltrasi    Penghilangan pektin pada sari   Zakoer and Mc.
                   buah apel                       Lelan (1993)

2 Ultrafiltrasi    Pemurnian isolat protein        Debra and
                   kedelai                         Cheryan (1981)

3 Ultrafiltrasi    Penyederhanaan proses           Thomas, et.al.
                   produksi sari buah apel         (1986)
4 Ultrafiltrasi    Pemisahan komponen kasein       Woychik et.,al
                                                   (1992)
5 Ultrafiltrasi    Penurunan kandungan bakteri     Tien and
                   pada kecap                      Chiang (1992)
6 Ultrafiltrasi & Pengembangan berbagai            Lawhon, et., al
  reverse osmosis produk tepung protein dari       (1981)
                  kacang tanah
   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
         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
     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
Polimer      Pelarut                   Aditif




            Pencampuran


          Pendiaman/relaxing


               Casting         Gambar 4. Diagram
                               Alir proses
             Penguapan         pembuatan membran


             Koagulasi


            Membran sheet
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
Gambar Alat separasi membran skala
          laboratorium

                       Keterangan :
                       A. Beaker geals pyrex
                       B. Tutup bagian atas
                       C. Tutup bagian bawah
                       D. Tutup pengatur tekanan
                       E. Aliran tekanan
                       F.   Saluran bahan
                       G. Pengaduk magnetis
                       M. Modul membran ultrafiltrasi
                       O. Saluran pengeluaran
                       P. Disk Polietilen penyangga
                          membran
                       S. Pemanas/hot plate
        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.
• 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
    Hasil analisis HPLC karakteristik membran campuran
  polisulfon, DMAc, dan NMP pada perbadingan 22 : 62,4 :
                             15,6

Jenis feed Lama proses    Peak area   Peak area       %
            annealing     pada feed     pada      rejection
                                      permeate
1, PEG,    Non annealing 16271913     4237323     73.96
BM = 20000 5 menit       16439954     2295437     86.03
           15 menit      16641256     2161709     87.01
2. Dx,     Non annealing 15075104     7099627     52.90
BM = 71400 5 menit       16433516     1503613     90.85
           15 menit      16870494     527375      96.87
  Gambar 5. Hubungan antara waktu annealing dan %
rejection membran polisulfon terhadap dekstran (BM =
                       71400)


                 120

                 100                                       96.87
                                           90.85
   % rejection




                 80

                 60                   y = 21.985x + 36.237
                           52.9
                                           R2 = 0.8505
                 40

                 20

                  0
                       0               5              15
                            Waktu annealing (menit)
              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
• 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.)
                         Substrat
Substrat + enzim         Produk                Produk
                         Enzim



                                     Membran



Gambar 6. Prinsip separasi membran untuk imobilisasi
        enzim
Tabel 2. Aplikasi proses separasi membran untuk imobilisasi
                      enzim secara fisik
  Jenis       Jenis enzim      Karakteristik     Jenis        Jenis     Pustaka
 proses      terimobilisasi     membran         retentat     permeat
                                               komponen     komponen

Produksi     Glukoamylase      MWCO 5000 -Oligosaka Sirup               Sims
sirup        dari Baciluss               rida       glukosa             and
glukosa      lichenifor, mis             -Glucoamy                      Cheryan
             : termamyl                  lase                           (1992)

Produksi     Protease dari     MWCO 10         -protein     Asam-       Zhang
hidrolisat   Aspergillus       kDa             -protease    asam        et al.
protein      Oryzae                                         amino       (1996)

Hidrolisis β-                  MWCO            -laktosa     Glukosa,    Sheth et
laktosa    galactocidase       > 30000         - β-         galaktosa   al.
           dari                                galactocid               (1988)
           Aspergillus                         ase
           oryzae
Karakteristik membran untuk imobilisasi enzim
               tergantung pada :

1. Jenis enzim yang akan diimobilisasi
2. Jenis substrat yang diharapkan akan
   tertahan (retentate) pada membran
3. Produk yang diharapkan melewati
   (permeate) membran
           HASIL PERCOBAAN
1. Enzim yang akan diimobilisasi dan retentate
   substrat memiliki berat molekul lebih dari
   71400, dan
2. Produk hasil reaksi enzimatis (permeate)
   memiliki berat molekul lebih kecil dari 71400

								
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