ABSTRACT This is a report from the experiment to study the characteristics of different types of membran membrane. e. The The develo developme pment nt of the filter filter medium medium has helped helped the indust industry ry,, specifi specificall cally y filtration industry to achieve very fine levels of separation today. In its early days as a separating medium, the membrane as a thin flexible sheet or a thin!alled flexible tube, rendered semi!permeable by its production process. Its earlier applications covered reverse osmosis and ultrafiltration. Then, the appearance of nanofiltration has overlapped the top end of revers reversee osmo osmosis sis and and the the loe loerr end end of ultra ultrafil filtr trati ation on.. "urt "urthe herm rmor ore, e, appe appear aran ance ce of microf microfiltr iltratio ation n has greatly greatly increa increased sed the applica applicabil bility ity of membran membranee media media in separati separation on processes. In addition, though membranes are better #non for li$uid separation, they are also idely used for gas and vapour separations. %en Sutherland &'(()* stated that, the ability to ma#e smart of functional membranes is an important development in membrane materials, and the rotating or vibrating membrane unit offers a great promise. +ven the application of membrane has also been developed, as such sterilisation of a li$uid flo or treating aste li$uid.
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Semipermeable membranes involve in many separation processes of gaseous or li$uid mixture. Semipermeable membranes hich usually are of thin layers of a rigid material such as porous glass or sintered metal allo one or more constituents of a mixture to pass through more readily than the others. 2oever, in some cases, the membranes are purposely designed to be of flexible films hich have a high permeability for certain types of molecules, and made from synthetic polymers. &3arren 4., '((5* /ut of the three groups of filtration, the principle of crossflo filtration membrane filtration as applied in this e$uipment, 6embrane Test 1nit &6odel 7 TR -8*. The membrane in crossflo filtration is made up of ceramic, metal or polymer. The pores are small enough to exclude most of the suspended particles. The feed suspension, in a crossflo filter flos across the filter medium under pressure at a moderate velocity. There may be a build up of a thin layer of solids on the surface of the medium, but the formation of the layer is prevented by the high li$uid velocity. &3arren 4., '((5* There are severel types of filters involve in the crossflo filtration. The first one is the microfiltration. This type of filter is generally used for particles of the si9e range beteen (.5 to
. Besides that, ultrafiltration is also one of the types of filter in crossflo
filtration. It covers a ider range of particles si9es, from
of about
to molecules ith the si9e
. ext, for the separation of small molecules or ions, hyperfiltration and
nanofiltration is used. 2oever, in such operation, reverse osmosis ould also be applied hen the osmotic pressure has a ma:or effect on the flux. The difference beteen these to filters is their type of membrane. &3arren 4., '((5*
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This experiment as carried out to study the characteristics of four different types of membrane.
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The term membrane most commonly refers to a thin, film!li#e structure that separates to fluids. It acts as a selective barrier hich allo some particles or chemicals to pass through but not others. In anatomy cases, membrane may refer to a thin film that is primarily a separating structure rather than a selective barrier. A membrane is a layer of material hich serves as a selective barrier beteen to phases and remains impermeable to specific particles, molecules, or substances hen exposed to the action of a driving force. Components that are not alloed to pass through the membrane membrane retained in the retentate stream hile the other alloed components pass through the membrane into a permeate stream. In reverse osmosis membrane process, a membrane must allo passage of certain molecules and exclude or greatly restrict passage of others. In osmosis, a spontaneous transport of solvent occurs from a dilute solute or salt solution to a concentrated solute or salt solution across a semipermeable membrane hich allos passage of the solvent but impedes passage of the salt solutes. The solvent ater normally flos through the semipermeable membrane to the salt solution. The solvent can be reduced by exerting a pressure on the salt solution, e$uilibrium is reached and the amount of solvent passing in opposite direction is e$ual. The chemical potentials of the solvent on both sides of the membrane are e$ual. 1ltrafiltration membrane procedded has $uite similarity ith reverse osmosis. It is pressure driven process here the solvent and small solute molecules pass through the membrane and are collected as a permeate. 4arger solute molecules do not pass through the membrane and recovered in a concentrated solution. The solutes or molecules to be separated generally have molecular eights greater than 5(( and up to - ((( ((( or more. 1ltrafiltration membranes are too porous to be used for desalting. It is also used to separate a mixture of different molecular eight proteins. In microfiltration membrane processes, pressure!driven flo through a membrane is used to separate micron!si9ed particles from li$uids. The si9e range of particles ranges from
(.('
to -(
. This microfiltration separates particles from solutions. The particles
are usually larger than the solutes in reverse osmosis and ultrafiltration. 2ence, osmotic pressure is negligible. At the very lo end of the si9e range, very large soluble macromolecules are retained. The dividing line beteen ultrafiltration and microfiltration is not very distinct. The pore si9es of the membranes and the permeate flux are typically larger than for reverse osmosis and ultrafiltration. 1sually the pressure drop used across the membranes varies from - psi to 5( psi.
8.( A??ARAT1S A0 6AT+RIA4S 8.- 6embrane Test 1nit & 6odel TR -8 * 8.' 0igital eighing balance 8.= Stopatch 8.8 Bea#er 8.5 Sodium Chloride and 3ater
5.( +@?+RI6+TA4 ?R/C+01R+S 5.- The general start!up procedures had been performed by the laboratory technician. 5.' The experiment for 6embrane - as started.
/pen
Sampling
&step '*
Retentate
6embrane
Control
6aximum Inlet ?ressure
-
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/pen
<-),
close
<-5
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'
<--, <-5 <', <5, <,
<-/pen
<'(,
close
<-
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=
<-', <- <', <5, <),
<-' /pen
<'-,
close
<-
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8
<-=, <- <', <5, <-(,
<-= /pen
<'',
close
<-
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<-8
Table 5.1 : Respective sets of valves for every membrane
5. The graph of eight of permeate versus time as plotted. .( R+S14TS
Time &min*
6embrane -
3eight of ?ermeates &gram* 6embrane ' 6embrane =
6embrane 8
-.( '.( =.( 8.( 5.( .( .( .( ).( -(.(
'.( 55.( .5 -.5 -(.) -='. -5.)) -'. '(. '==.8'
.8' -8.5 '-.8 '8.'=5'.( 8'-.-5 8.8= 555.) '5.-8 )=.(
'-(.( 8=.8( 8-.)5 =.5 -(-5.( --8. -=8(.=8 -8).-5 -=5.= -(.'
(.)) -=-.8' '(('.( '55. '(=.' ==. =)'. 888).') 85').-= 5'8).8
Table 6.1 : Table of experimental results
Weight of Permeates VS Time 6000
Weight of Permeates (g)
5000
Weight of Permeates(gram) Membrane 1
4000
Weight of Permeates(gram) Membrane 2
3000
Weight of Permeates(gram) Membrane 3
2000
Weight of Permeates(gram) Membrane 4
1000 0 Time (min) Graph 6.1 : Graph of Weight of Permeates ! Time
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The experiment as conducted to distinguish beteen four types of membranes. In this experiment, the 6embrane Test 1nit &6odel 7 TR -8* used has four membranes. They are reverse osmosis &R/*, nanofiltration &"*, ultrafiltration &1"* and microfiltration &6"*. This experiment as started by preparing the sodium chloride solution first, by adding -(( gram of sodium chloride into '( litre of ater. The solution as then filled into the feed tan# of the unit. Then, the experiment as conducted as in the experimental procedures.
The membranes that ere used in this experiment ere different from each other. They ere manufactured by ?CI system, and ere categori9ed according to their membrane types. The type of membrane used in membrane -, ', = and 8 ere made up of mostly polyamide film and cellulose acetate. ?olyamide film as idely used to ma#e membrane because of its permeability to ater and its relative impermeability to various dissolved impurities including salt ions and other small non!filtrable molecules. /n the other hand, cellulose acetate has an extremely lo binding characteristic. This as hy it is suitable and an ideal type of membrane to be used for protein and en9yme filtrations. Another material that made up the membrane is polyvinylidene difluoride &?<0"*, a material that can provide high protein and nucleic acid binding capacity. /ne of the characteristics of membrane is hydrophilic membrane, hich it has an attractive response to ater and can readily absorb ater. This allos the material to be etted forming a atter film or coating on the surface of the membrane. In contrast, hydrophobic membrane does not absorb ater and have less charge than hydrophilic. Based on the plotted graph, it can be seen that the permeation rate differs for each of the membrane. 6embrane 8 had the highest permeation rates. ext, it folloed by 6embrane =, then 6embrane ' and lastly, 6embrane -. 2ence, permeates moves fastest through 6embrane 8 and sloest through membrane -. The high permeation rate of 6embrane 8 is most li#ely due to its hydrophobic property, hile as for membrane =, its hydrophilic property caused its permeation to be the sloest. There ere several errors occurred during the experiment hich affect the results obtaind. /ne of the errors is the digital eighing scale cannot measure the accurate eight of the permeate due to the vibration of the pump, hich made the reading of the eighing scale as inconsistent. In order to reduce this error, the eighing scale should be put outside of the unit. Besides that, the eight of the permeate that as permeated from the membrane changed too fast, hich eventually causing the eight recorded to be less accurate. Then, to reduce this error , the experiment need to be repeated three time to get tha average reading of the permeate eight.
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Based on the results obtained, it as observed that permeation rate differs for each membrane. 6embrane 8 has the highest permeation rates, folloed by 6embrane =, then 6embrane ', and lastly 6embrane -. Since 6embrane 8 has the highest permeation rates, then, permeate moves fastest through it. /n the other hand, the permeate moves the sloest through 6embrane -.
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).- The pressure must be ensured to be measured according to the experimental procedure. ).' All valves must be ensured to be ell functioning to avoid pressure drop during experiment. ).= The eighing balance should be put outside of the unit to avoid inaccurate measurement due to vibration. ).8 Repeat the experiment = times to get more accurate permeate eight measurements
R+"+R+C+S
Christie ;ohn Dean#oplis, Transport Processes and Separation Process principle 4 th Edition, ?earson +ducation Inc, 1nited States, '((= 3arren 4. 6cCabe, Unit Operations of Chemical Engineering 7 th Edition, 6cDra!2ill Companies, Inc., '((5 %en Sutherland, Membrane Filtration : Whats !e" in Membrane Filtration# , accessed from http7EEac.els!cdn.com.e9access.library.uitm.edu.myES((-5-'()(-)=8E-!s'.(! S((-5-'()(-)=8!main.pdfFGtidH5(b5de'!dc(d!--e8!b5-! (((((aab(f'acdnatH-8'')-''Ge5f'e'(=(=)afca8a5'f)f5=5'fd at th April '(-5
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