Membrane technology
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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.

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MEMBRANE TECHNOLOGY

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Membrane technology

MEMBRANE TECHNOLOGY

By :

Prof. Dr. Tien R. Muchtadi


Definitions

DEFINITIONS

  • INTRODUCTION

  • CLASSIFICATION OF MEMBRANE PROCESS

  • TYPES OF MEMBRANE

  • REJECTION COEFFICIENT

  • NOMINAL MW CUT-OFF

  • GENERAL MEMBRANE EQUATION


Introductions

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


Membrane technology

  • 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

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

Table 1. Classifocation of membrane separation process for liquid systems


The nature of synthetic membranes

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

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


Membrane technology

  • 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


Membrane technology

  • 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

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

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


Membrane technology

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


Membrane technology

Membrane

Permeate

Processing feed crossflow

Retentate

Permeate

Figure 1. The Concept of Cross-Flow Filtration


Figure 2 flow diagram for a simple cross flow system

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


Membrane technology

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”


Membrane fouling and effects

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

ELECTRODIALYSIS

  • OUTLINE OF MEMBRANE OPERATION

  • MEMBRANE TYPE AND TRANSPORT MECHANISM

  • APPLICATIONS


Liquid membranes

LIQUID MEMBRANES

  • TYPES

  • OPERATING MECHANISM

  • PRODUCT RECOVERY

  • APPLICATIONS


Gas separations

GAS SEPARATIONS

  • MECHANISM

  • TYPES OF MEMBRANE

  • APPLICATIONS


Concentration or gel polarisation model

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

APPLICATIONS OF MEMBRANE TECHNOLOGY

  • FOOD PROCESSING AND ENGINEERING

  • BIOTECHNOLOGY, MEMBRANE REACTORS

  • BIOMEDICAL ENGINEERING

  • PROCESS DEVELOPMENT

  • GROUP DISCUSSTION AND PROBLEM SOLVING


Teknologi separasi membran

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

KLASIFIKASI PROSES MEMBRAN

Berdasarkan pada driving force yang digunakan :

  • Mikrofiltrasi

  • Ultrafiltrasi

  • Reverse osmosis

  • Elektrodialysis

  • Dialysis

Paling banyak digunakan untuk pengolahan produk pangan


What is reverse osmosis

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.


Membrane technology

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

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


Membrane technology

  • 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


Tabel 1 aplikasi teknik separasi membran pada pengolahan produk pangan

Tabel 1. Aplikasi Teknik Separasi Membran pada Pengolahan Produk Pangan


Contoh percobaan separasi membran

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 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

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


Membrane technology

Polimer

Pelarut

Aditif

Pencampuran

Pendiaman/relaxing

Casting

Gambar 4. Diagram Alir proses pembuatan membran

Penguapan

Koagulasi

Membran sheet


Membrane technology

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

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


Hasil dan pembahasan

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.


Membrane technology

  • 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


Membrane technology

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


Membrane technology

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


Aplikasi membran pada pengolahan pangan

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


Membrane technology

  • 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.)


Membrane technology

Substrat

Produk

Enzim

Substrat + enzim

Produk

Membran

Gambar 6. Prinsip separasi membran untuk imobilisasi enzim


Tabel 2 aplikasi proses separasi membran untuk imobilisasi enzim secara fisik

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


Karakteristik membran untuk imobilisasi enzim tergantung pada

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


Hasil percobaan

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


Membrane technology

TERIMA KASIH


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