UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN KIMIA CHEMICAL ENGINEERING LABORATORY 2 (CHE 523) NAME GROUP EXPERIMENT SEMESTER PROGRAMME / CODE LECTURER No.
Title
: MUHAMMAD SOLAHUDIN BIN MUSA : EH 220 3 : LAB 6: MEMBRANE SEPARATION :3 : EH220 : MADAM NURHASLINA CHE RADZI Allocated Marks (%)
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Abstract/Summary
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Introduction
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Aims
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Theory
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Apparatus
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Methodology/Procedure
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Results
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Calculations
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Discussion
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Conclusion
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Recommendations
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Reference / Appendix
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TOTAL MARKS
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Date : 1.0 ABSTRACT The experiment is carried out to study on four different types of membranes by using Membrane Test Unit model TR14.The experiment is conducted to study characteristics based on 4 different types of membrane which are AFC99(polyamide film),AFC 40 (polyamide film),CA 202 (cellulose acetate) and FP 100 (PVDF),by using Membrane Test Unit model TR14. In plus, this experiment was made to determine the characteristics of 4 types of membranes which different in term of pore size by separation driving force is namely as reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF) membranes. Besides that, another aim in this experiment is to calculate the composition of solid salt at product. The experiment was run using approximately sodium chloride solution. The pressure supply for each membrane is different at maximum pressure for at which is 18 bar, 12 bar, 10 bar and 8.5 bar for membrane 1, 2, 3, and 4 respectively. For every 1 minute to 10 minutes, the permeate sample is collected and its weight was recorded for each type of membrane use. As the experiment goes, the solution will permeate through the membrane leaving only macromolecules behind. The sample of permeates were taken too made up the weight of permeates per time. The highest amount of permeate during 10 minutes is 6221.85 g that is for membrane 4 and the lowest is about 325.53 g that is membrane 1. The graph of permeate weight versus time then is plotted. From the graph, when the time increase, the permeate weight also increases. For the membrane 4, the line increases gradually. For the membrane 1, 2 and 3 the lines show sloppier with increase in the percentage of composition of salt at product. The experiment was completely and successfully conducted.
2.0 INTRODUCTION In our real life, the membrane technology is mostly used in transport of substances between two fractions with the help of permeable membranes for separation of gaseous or liquid streams .Membrane technology are available in variety of separation capabilities have become the technology .It used not only removal of turbidity, precursors, microorganism relating to underground , surface water supplies and other. But for our experiment, the Membrane Test unit Model TR 14 shown in Figure 2.1 has been designed to demonstrate the technique of membrane separations which highly popular as they provided effective separation without the use of heating energy as in distillation process, sublimation or crystallization . This type of membrane is mostly used among industry in biotechnology and process industry.
Figure 2.1:- Membrane Test unit Model TR 14
This self- contained unit on a mobile epoxy coated steel framework, it requires only connection to a suitable electricity supply and a normal cold water supply to be fully operational. It consists of a feed tank, a product tank, a feed pump, a pressure regulator, a water bath, and a membrane test module. All parts in contact with the process fluid ate stainless steel, PTFE, silicone rubber or nitrile rubber. The unit comes with a high pressure feed pump for delivering the feed to the membrane unit at the desired flow rate and pressure. The retentate line can be either returned to the feed tank or straight to the drain. Appropriate sensors for flow, pressure and temperature are installed at strategic locations for process monitoring and data acquisitions. This TR 14 consists of a test module supplied with four different membranes, namely the reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF) membranes as shown in Figure 2.2
Figure 2.2: Comparison for 4 types of membranes
. The TR 14 unit is supplied with 4 membranes which are:
Membrane Membrane Membrane Membrane
1: 2: 3: 4:
AFC 99 (polyamide film) AFC 40 (polyamide film) CA 202 (cellulose acetate) FP 100 (PVDF)
The AFC 99 is rated with 99% NaCl rejection at maximum pressure and temperature which is 64 bar and 80 ℃
whereas the AFC 40 has 60% CaCl 2 rejection at 60 bar
and 60 ℃ . Both of these membranes use in operation of reverse osmosis. Meanwhile, the CA 202 is rated with apparent retentation of 2000 MWCO and the FP 100 is 100000 MWCO. Both of these two membranes use in ultrafiltration process which CA 202 operates at 25 bars and 30 ℃
while the FP 100 is at 10 bar and 80 ℃ .
Many processes for separation of gaseous or liquid mixtures use semi permeable membranes that allow one or more constituents of the mixture to pass through more readily than the others. The membrane may be thin layers of a rigid material such as porous glass or sintered metal, but more often they are flexible films or synthetic polymers prepared to have a high permeability for certain types of molecules.
Figure 2.3: Closed look In permeate
of membrane reverse
is
about 1 atm, and very high
nearly
pure
osmosis, water
at
pressure is applied to the feed
solution to make the activity of the water slightly greater than that in permeate. This provides an activity gradient across the membrane even through the concentration of water in the product is higher than in the feed.
There are several processes for the separation of liquid mixtures using porous membranes
or
asymmetric
polymer
membrane.
With
porous
membranes,
separation may be depending just on differences in diffusivity, as is the case with dialysis, where aqueous solutions at atmospheric pressure are on both sides of the membrane. For liquid-liquid extraction using porous membranes, the immiscible raffinate and extract phases are separated by the membrane, and differences in the equilibrium solute distribution as well as differences in diffusivity determine the extract composition. Microfiltration (MF) and ultra-filtration (UF) systems used a lower pressure compare to reverse osmosis (RO) and nanofiltartion (NF). Both the MF and UF have been shown to exceed the removal efficiencies. MF and UF membrane system generally use hallow fibers that can be operated in the outside in or inside out direction of flow. In desalination, salt water on one side of a semi-permeable RO membrane is subjected to high pressure. This cause fresh water to diffuse through the membrane and leaves behind more concentrated solution that the source supply, containing the majority of the dissolved minerals and other contaminants. A loose version of RO called Nanofiltration typically operates at 85to 95% recovery, without pressures. Nanofiltration and reverse osmosis membranes are mainly used for water purification purposes. Reverse osmosis separates aqueous ionic solutions of different concentration. In osmosis, solvent transports from a dilute solute or salt solution to a concentrated solute or salt solution across a semipermeable membrane which allows passage of the solvent but impedes passage of the salt solutes. When the solvent moves from an area of high water potential to low water potential, there exist an osmotic pressure so that equal ionic concentrations on each side of membranes. Water molecules will pass to dilute solution side through the membrane if when a hydraulic pressure is applied to the concentrated solution which is greater and in reverse to the osmotic pressure. Thus, by using this process it can be separate water from ions and low-molecular weight organic constituents. As a result, the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be "selective," this membrane should not allow
large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as the solvent) to pass freely. Nanofiltration is about a process of water purification that use to remove contaminates from the water to produce clean, clear and pure water. Nanofiltration is is a form a reverse osmosis, that function to remove bivalent hardness, calcium, and magnesium plus sulphate but leave in most of the single valent sodium ion. Ultrafiltration is a type of separation process by using membranes with pore sizes in the approximately range is 0.1 to 0.001 micron. Basically, ultrafiltration mostly use by industry is to remove high molecular-weight substances, colloidal materials, and organic and inorganic polymeric molecules. But, the type like low molecular-weight organics and ions such as sodium, calcium, magnesium chloride, and sulphate are not removed. Thus, this is because ultrafiltration will remove only high-molecular weight species .To achieve high flux rates from an ultrafiltration membrane ,then the low applied pressures are apply.
Flux of a membrane is
defined as the amount of permeate produced per unit area of membrane surface per unit time. Meanwhile, microfiltration is a membrane technical filtration process which removes contaminants from a fluid (liquid and gas) by passage through a microporos membrane. This type of membrane pore size range is 0.1 to 10 micrometers (µm). Microfiltration is fundamentally different from reverse osmosis and nanofiltration because those systems use a pressure as a means of forcing water to go from low pressure to high pressure. Microfiltration can use a pressurized system but it does not need to include pressure.
3.0 OBJECTIVES The experiment is conducted in order:
To study the characteristics of membrane by performing a characteristic study on 4 different types of membranes.
To calculate the composition of solid salt at product.
4.0 THEORY There are several types of equipment for membrane processes. The membrane acts as a semipermeable barrier and separation occurs by the membrane controlling the rate of movement of various molecules between two liquid phases. The two fluid phases are usually miscible and the membrane barrier prevents actual, ordinary hydrodynamic flow. First is flat membrane is usually to characterize the permeability of the membrane. The modules are easy to fabricate and use and the areas of the membranes are well defined. Next, spiral wound membranes and this configuration retains the simplicity of fabricating flat membranes while increasing markedly the membrane area per unit separator volume. Third is hallow fibre membranes and the membranes are in the shape at very small diameter hollow fibres. The graph of permeate weight versus time that should we get is increase in permeate weight as time increase. But at certain time, the curve shape will be seen as time of separation increase. This is due to the fouling effect that occurs inside the
membrane
and
will
cause
increases
expenditure, reduce flux, membrane failure.
pressure
drop,
increases
energy
Figure 4.1 :The figure above shown that ,the filtration range for every each type of membrane.
Figure 4.2 : The figure shown that type of membrane use to separate components.
Membrane separation can be classified by pore size and by the separation driving force for example Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF), IonExchange (IE) and Reverse Osmosis (RO).
Figure 4.3 : This figure is examples of different substance that correspondence to the pore size of the membrane separation method.
The membrane separation techniques utilized in the dairy industry serve different purposes:
RO –mostly it used for dehydration of whey, UF permeate and condensate.
NF –mostly it used when partial desalination of whey, UF permeates or retentate is required.
UF -typically used for concentration of milk proteins in milk and whey and for protein standardization of milk intended for cheese, yoghurt and some other products.
MF -basically used for reduction of bacteria in skim milk, whey and brine, but also for defatting whey intended for whey protein concentrate (WPC) and for protein fractionation.
Membrane processes are characterized by the fact that a feed stream is divided into 2 streams: retentate and permeate. The retentate is that part of the feed that does not pass through the membrane, while the permeate is that part of the feed that does pass through the membrane. The optional "sweep" is a gas or liquid that is used to help remove the permeate. The component(s) of interest in membrane separation is known as the solute. The solute can be retained on the
membrane and removed in the retentate or passed through the membrane in the permeate.
Figure 4.4 : This figure is process of membrane technology Some components are allowed passage by the membrane into a permeate stream, whereas others are retained by it and accumulate in the retentate stream. Some advantages of membrane separation are less energy-intensive, since they do not require major phase changes, do not demand adsorbents or solvents, which may be expensive or difficult to handle and the equipment simplicity and modularity, which facilitates the incorporation of more efficient membranes. The particular advantage of membrane separation processes is that it operate without heating and thus are energetically usually lower than conventional thermal separation processes (distillation, Sublimation or crystallization).
5.0 APPARATUS AND MATERIALS 1) 2) 3) 4) 5) 6) 7)
TR 14 model (membrane test unit) Digital weighing balance Jars Stopwatch 20 L of tap water Sodium chloride solution water
Figure 5.1:The figure shown that Membrane Test Unit model TR14.
6.0 PROCEDURES 6.01 General Start-Up Procedures: 1. Ensure all valves are initially closed. 2. A sodium chloride solution was prepared by adding 100 gram of sodium chloride into 20L of water. 3. The feed tank was filled up with salt solution prepared in step 2. The feed shall always be maintained at room temperature. 4. The power was turned on for the control panel. All sensors and indicators are checked for functioning properly. 5. The thermostat was switched on and make sure the thermo oil level was above the coil inside thermostat. Thermostat connections are checked so that they are properly fitted. 6. The unit is now ready for experiment
6.02 Experimental Procedure: 1. The general start-up procedure was performed. 2. The experiment for Membrane 1 was started. Open valves V2, V5, V7, V11 and V15. 3. The plunger pump (P1) was switched on to set the maximum working pressure at 20 bars, and slowly close valve V5. Observe pressure value at pressure gauge and the pressure regulator was adjusted to 20 bars. 4. Valve V5 was opened. Then, membrane maximum inlet pressure was set to 18 bars for Membrane 1 by adjusting the retentate contral valve (V15). 5. The system was allowed to run for 5 minutes. The sample was start to collect from permeate sampling port and the sample was weight using digital weighing balance. The weight of permeates was recorded every 1 minute for 10 minutes. 6. Step 1 to 5 was repeated for Membrane 2, 3 and 4. Open and close the respective sets of valves and the membrane maximum inlet pressure was adjusted for every membrane. 7.
Membrane
Open Valves
Sampling
Retentate
Membrane
(step 2)
Valves
Control Valve
maximum inlet
1
V2,V5,V7,V11
Open V19 and
V15
pressure (bar) 18
2
and V15 V2,V5,V8,V12
close V11 Open V20 and
V16
12
3
and V16 V2,V5,V9,V13
close V12 Open V21 and
V17
10
4
and V17 V2,V5,V10,V14
close V13 Open V22 and
V18
8.5
and V18
close V14
8. Plot the graph of permeate weight versus time
6.03 General Shut-Down Procedure: 1. The plunger pump was switched off (P2) 2. Valve V2 was closed. 3. Drain all liquid in the feed and product tank by opening valves V3 and V4. 4. Flush all the piping with clean water. Close V3 and V4, fill the clean water to feed tank until 90% full. 5. The system was run with the clean water until the feed tank is nearly empty this is for cleaning purpose).
7.0 RESULTS Time (min) Membrane 1 1 2 3 4 5 6 7 8 9 10
Max P=18 49.07 95.57 138.60 182.57 225.00 267.79 312.23 356.68 401.99 446.00
Weight of Permeates (g) Membrane 2 Membrane 3 Max P=12 70.95 134.80 198.53 261.90 325.20 389.30 459.63 519.49 582.07 647.58
Max P=10 32.09 57.65 89.91 121.73 155.67 190.73 223.47 257.20 291.28 325.53
Membrane 4 Max P=8.5 559.16 1168.04 1779.58 2386.42 2974.54 3587.32 4194.05 4802.24 5622.92 6221.85
8.0 CALCULATION
Membranes of permeate(g) versus time(min) 7000 6000 5000 Membrane 1(P=18)
4000 Membranes of permate(g)
Membrane 2(P=12) 3000
Membrane 3(P=10) Membrane 4(P=8.5)
2000 1000 0 0
2
4
6
8
10
12
Time(min)
9.0 DISCUSSION In this experiment, we were to characterize the differences between four types of membranes, which are the reverse osmosis (RO), nanofiltration (NF),
ultrafiltration (UF), and microfiltration (MF). In doing this experiment, the apparatus used to accomplish the objective is SOLTEQ Membrane Test Unit (Model: TR14). This unit has been designed to demonstrate the technique of membrane separations which has become highly popular as it provide separation in effective way without using heat energy as used in distillation process. Heat sensitive materials, such as fruit juices can be separated or concentrated by virtue of their molecular weight.Membrane separation is a process of which a solution sample and water is run through a semi permeable membrane that allows them to separate. The separated water will equilibrate the system, which is commonly known as osmotic pressure. When a mechanical force is applied to exceed the osmotic pressure, the water is forced to move from low concentration to higher concentration. Permeates designates the liquid passing through the membrane and retentate, or concentrate designates the fraction to not pass through the membrane. Thus, sodium chloride is used to pump from feed tank and pass through each membrane and the weight of permeate collected was recorded. The weight of permeate collected shows the efficiency for of each the membrane. The experiment is started with sodium chloride was passed through membrane 1 with the pressure inlet of 18 bar. After 10 minutes, permeate collected is 446.00g. The pressure is decrease to 12 bar for the membrane 2 and permeate collected is 647.58 g after 10 minutes. Lowest pressure was set for membrane 4 which is only 8.5 bar and highest permeate is recorded for about 6221.85 g. However, when the pressure is 10 bar for the membrane 3, permeate collected is 325.53 g after 10 minutes. Second objective of this experiment is to determine the composition of solid salt at product. With same amount of salt at the feed which is 0.02 m 3, but due to the difference in pressure for each membrane results in difference amount of permeate flowed. The composition of salt at product is not same for the each type of membrane. This is because of the effectiveness of each membrane it has. For example, type of material they use, the membrane may be thin layers of a rigid material such as porous glass or sintered metal, but more often they are flexible films or synthetic polymers prepared to have a high permeability for certain types of molecules
Overall, from all 4 membranes, membrane 3 has lowest amount of permeates which is only 325.53 g. While amount of permeate of membrane 4 is the highest with 6221.85 g. This is due to the difference in pressure supply to the system and the size of pore depends on the type of membrane used. Pressure inlet for membrane 1 is the highest with 18 bar and membrane 4 is lowest with 8.5 bar. Also depending to the flow rate, if the flow rate is slower, then the solution has more time to permeate. The solution will not react thoroughly with the pore and it also caused the solution difficult to pass through the pore, size of pore in membrane also can effect amount of permeate collected. If the size of pore is too small, the solution cannot pass through the pore and amount of permeates also will less. The graph plotted shows that the permeates weight is proportional with the time. When the time is increases, the permeates weight also increasing. Besides that, the highest line from the graph is during the membrane 4 and the lowest line is when the membrane 3 is using. While conducting this experiment, there must be theoretical errors. General step up must be conducted as given to ensure that the experiment can be run smoothly and are save to use. When taking the reading, the observer must be faster because the value changes as fast as the flow of permeates. The jar used must be clean and dry to avoid inaccurate data.
10.0 CONCLUSION This experiment was a quite success and conclusions can be made. Firstly, based on the theory, the weight of permeates collected from membrane 1 to 4 can be different due to different maximum inlet pressure of each membrane. The highest amount of permeate at product is 6221.85 g and the lowest is about 325.53 g. It can be seen that the forth membrane carried the largest value of weight of the collected. This shows that every membrane will give out the same pattern at the outlet however, only the values of the weight were different from each other. Therefore, this shows that the separation process was the fastest in the forth membrane and the first membrane was the slowest. From the graph, the permeate weight increases while the time increases. For the membrane 4, the line increases steadily. For the membrane 1, 2 and 3 the lines show sloppier with increase in the percentage of composition of salt at product. Therefore, the objectives of this experiment are successfully achieved.
11.0 RECOMMENDATIONS In carried out the experiment, there are a few steps of recommendation that can be considered in order to get accurate data and smoothly in progressing the experiment. Firstly, general step-up must be conducted as given then followed by the experiment procedures and end with the general shut-down procedures. This is to ensure that the experiment can be progress successfully. During taking the reading of weight permeates by using digital weighing balance, the reading of weight should be taking in more significant figures so that to avoid any error and to get result more accurate in order word the true values could be minimized. Moreover, the average weight of permeates should be calculated by taking weight of permeates in three or two times in order to get more accurate value of result. The system should run more than 5 minutes so that the system can work more stabilized in order to get more accurate value of weight of permeates. During collect the samples, the sampling valves should be open and close simultaneously and immediately so that no occur in term of interruption during collecting samples. Besides that, leftover sodium chloride in membrane 1 should be dried first before the starting of experiment for others membrane to avoid leaking during the experiment. Before conducting to next experiment, every each of membranes must be cleaned before and after usage to avoid fouling which might affect the final results. The amount of permeates should be recorded at the approximate moment to avoid inaccuracy. Furthermore, used the suitable size of jar based on the amount of permeate to avoid spillage and affect the permeate weight of solution.
12.0 REFERENCES CHE 554 Lab Manual McCabe,w.L Smiths,J.C and Harriott (2001), Unit Operations Of Chemical Engineering, McGraw-Hill,7th Edition STI International membrane Separation Tecnologies Ridgway, Harry F. (Ph.D) (Advanced Membrane Technologies Stanford University, 2008) http://www.lenntech.com/membrane-technology.htm ,Retrieved at 24/5/2014 http://www.kochmembrane.com/PDFs/Membrane-Filtration-Technology---KochMembrane-Sys.aspx, Retrieved at 24/5/2014 13.0 APPENDIX
Figure 13.1:The figure shown that Membrane Test Unit model TR14.
Figure 13.2 :The figure shown that jars and Digital weighing balance
