UNIVERSITI TEKNOLOGI MARAFACULTY OF CHEMICAL ENGINEERINGPROCESS ENGINEERING LABORATORY II(CPE 554)

NAME : AMIR FADZRUL BIN AB RAHMAN STUDENT NO : 2012289094GROUP : EH2214C (1) EXPERIMENT : MEMBRANE SEPARATION UNITDATE PERFORMED : 16 APRIL 2013SEMESTER : MARCH- JULY 2013PROGRAMME/ CODE : EH221SUBMIT TO : SITI SHAWALLIAH IDRIS

No.TitleAllocated marks (100%)Marks

1. Abstract/summary5

2. Introduction5

3. Objectives/aims5

4. Theory5

5. Materials and apparatus5

6. Methodology/procedure10

7. Result10

8. Calculation10

9. Discussion20

10. Conclusion10

11. Recommendation5

12. References5

13. Appendix5

TOTAL MARKS100

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CONTENT

TitlePage Number

Abstract1

Introduction2

Objectives3

Theory 3-5

Apparatus6

Methodology/Experimental Procedures7-8

Results9

Discussions10-11

Conclusion11

Recommendations12

References13

Appendices13

ABSTRACT

The objective of this experiment is to study the characteristic of four different types of membranes. This experiment is conducted to study thecharacteristics on 4 different types ofmembranes which are AFC 99 (polyamide film), AFC 40 (polyamide film),CA 202 (cellulose acetate) and FP 100 (PVDF) by using membrane test unit (TR14). This experiment requires approximately 100 gram of sodium chloride. The characteristics of the membranes could be reverse osmosis, nanofiltration, ultrafiltration microfiltration membrane. 10 minutes of time is required for every membrane in which the reading of the permeate is taken in every 1 minute. The data acquired were analysed and graphs of permeate weight versus time were plotted. Based on the characteristics of every membrane and the results of the permeates, it can be concluded that the type of membrane for membrane 1 is nanofiltration, membrane 2 is ultrafiltration, membrane 3 is reverse osmosis and membrane 4 is microfiltration

INTRODUCTION

Separations by the use of membranes are playing an important role in the process industries and biotechnology. In this relatively new separation process, 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, two gases phases, or a liquid and a gas phase. The two fluid phases are usually miscible and the membrane barrier prevents actual, ordinary hydrodynamic flow. In this experiment, there are four types of membrane separation process that are used. There are reverse osmosis, ultrafiltration, microfiltration and nanofiltration membrane process.

Reverse osmosis is one of the types of membrane separation process. This membrane separation process impedes the passage of low molecular weight solute which is placed between a solute-solvent solution and a pure solvent. The solvent diffuses into the solution by osmosis. In reverse osmosis, a reverse pressure difference is imposed which causes the flow of solvent to reverse, as in the desalination of seawater. This process is also used to separate other low molecular weight solutes, such as salts and sugars. Other type of membrane separation process is ultrafiltration. This process use pressure to obtain a separation of molecules by means of semipermeable polymeric membrane. The membrane discriminates on the basis of molecular size, shape or chemical structures and separates relatively high molecular weight solutes such as proteins, polymers and colloidal materials. The osmotic pressure is usually negligible because of high molecular weights.

Microfiltration is also one of the membrane separation processes. In microfiltration, pressure-driven flow through the membrane is used to separate micron-size particles from fluid. The particles are usually larger than those in ultrafiltration. Examples are separation of bacteria, paint pigment, yeast cells, and so on from solutions.

OBJECTIVES

The aim of this experiment is to study the characteristics on four different types of membrane separation process for the removing of the solute from the solution.

THEORY

Numerous theoretical models for ultrafiltration, nanofiltration, and reverse osmosis have been proposed along with the identification of new factor of controlling flux or mass transfer through membranes. The basic operating patterns are best outlined in terms of the hydrodynamic resistance resulting from the build-up of deposited materials on the membrane surface. The flux, J will be given by

(1)

For most biological materials, is a variable depending on the applied pressure and time (the compressible deposit), so that the expression requires a numerical solution. A useful method for the effects of cross-flow removal of depositing materials is to write:

(2)

Removal of solute by cross-flow is sometimes assumed constant, and equal to the convective particle transport at steady state (JssCb), which can be obtained experimentally or from an appropriate model. In many situations however, steady state of filtration is seldom achieved. In such cases, it is possible to describe the time dependence of filtration by introducing an efficiency factor , representing the fraction of filtered material remaining deposit rather than being swept along by the bulk flow. This gives:, where 0 < < 1 (3)Although deposition also occurs during ultrafiltration, an equally important factor controlling flux is concentration polarization. Solution containing macromolecular gel-forming solute will form a gel on the surface of the membrane. The gel formation will contribute to formation of dynamics membranes.

Due to convective flux through the membrane a concentration of the solution at the surface Cw increases and eventually reaches a gel formation concentration Cg. The flux, J through the membrane depends on a concentration according to the relationship:

(4)Combining equations (1) and (4),

(5)

As long as concentration Cw is less than Cg, Cw will increase with pressure, but the moment Cw equals Cg, an increase in P brings about an increase of the layer resistance Rp, and the flux will no longer vary with pressure. Assuming no fouling effect, the membrane resistance Rm can be calculated from the flux equation below:

(6)

The slope obtained from the plot of flux, J versus P is equal to . The retention of any solute can be expressed by the rejection coefficient, R.

(7)

where, Cf is final macrosolute concentration in the retentate Co is initial macrosolute concentration Vo is initial volume Vf is final retentate volumeThis expression assumes complete mixing of retentate seldom accomplished due to concentration polarization. The apparent rejection coefficient depends on factors affecting polarization including UF rate and mixing. For material entirely rejected, the rejection coefficient is 1 (100%) rejection; for freely permeable material it is zero.

Rejection is a function of molecular size and shape. Nominal cut-off levels, defined with model solute, are convenient indicators. Fractional rejection by membranes with low MW cut-off spans a narrower range of molecular size than by more open membranes. For maximum retention of a solute, select a membrane with nominal cut-off well below the MW of the species.

Many biological macromolecules tend to aggregate so that effective size may be much larger that native molecule, causing increased rejection. Degree of hydration, counter ions and steric effects can cause molecules with similar molecular weights to exhibit very different retention behaviour.

APPARATUS AND MATERIALS

TR 14 Membrane Test Unit apparatus. 500 mL beakers. Electronic balance. Sodium Chloride Water

Figure 1: TR 14 Membrane Test Units

PROCEDUREOPERATING PROCEDUREGeneral start-up procedure1. All the valves were ensured initially closed.2. A sodium chloride solution was prepared by adding 100g of sodium chloride into 20L of water.3. The tank was filled up with the salt solution that prepared in step 2. The feed was maintained at room temperature.4. The power for control panel was turn on. All sensors and indicators were check to functioning properly.5. Thermostat was switch on and the thermo oil level was making sure above the coil inside thermostat. Thermostat was checked if connections were properly fitted.The temperature was adjusted at the thermostat to maintain feed temperature.6. The unit is now ready for experiments.

General shut-down operation1. The plunger pump was switch off.2. Valve 2 was closed.3. All liquid in the feed tank and product tank were drain by opening valves V3 and V4.4. The entire pipes were flush with clean water. V3 and V4 were closed; the clean water was filled to the feed tank until 90% full.5. The system was run with the clean water until the feed tank nearly empty for cleaning purposed.

EXPERIMENT PROCEDURES1. The general start-up procedures were performed.2. The experiment for membrane 1 was start. Valves V2, V5, V7, V11, and V15 was opened.3. The plunger pump (P1) was switch on and slowly closed valve V5 to set the maximum working pressure at 20 bars.4. Valve V5 was opened. Then, membrane maximum inlet pressure was set to 18 bars for membrane 1 by adjusting the retentate control valve (V15).5. The system was allowed to run for 5 minutes. Sample was start to collect from permeate sampling port and the sample was weight by using digital weighing balanced. The weight of permeates was record every 1 minute for 10 minutes.To collect sample, valve V19 was opened nad simultaneously closed valve V11.6. The step 1 to 5 was repeated for membrane 2, 3, and 4. The valves was opened and closed respectively and the inlet pressure in membrane was adjusted for every membrane.

MembraneOpen valves (step 2)Sampling valvesRetentate control valveMembrane maximum inlet pressure (bar)

1V2, V5, V7, V11 and V15Open V19 and close V11V1518

2V2, V5, V8, V12, and V16Open V20 and close V12V1612

3V2, V5, V9, V13, and V17Open V21 and close V13V1710

4V2, V5, V10, V14, and V18Open V22 and close V14V188.5

7. The graph of permeates weight versus time was plotted.

RESULTS

Time (min)Weight of permeates (g)

Membrane 1Membrane 2Membrane 3Membrane 4

146.5964.3240.31432.67

285.09124.8771.41867.23

3124.50184.06103.981294.82

4162.41244.23135.381720.33

5203.26304.73167.512146.62

6243.11364.97199.572825.60

7283.11425.86231.233247.61

8323.55486.14263.273664.47

9364.01548.08295.484082.05

10404.19608.89328.074496.90

DISCUSSIONS

The aim of this experiment is to study the characteristics on 4 different types of membranes which are AFC 99 (polyamide film), AFC 40 (polyamide film), CA 202 (cellulose acetate) and FP 100 (PVDF). From the graph, we can observe that the slope of the membrane 4 is the steepest compared to other membranes. This is followed by membrane 2, membrane 1 and membrane 3 respectively.

Membrane 4 has the steepest slope compare to the other membranes. Therefore, membrane 4 is the microfiltration. This is because the weight of permeates for membrane 4 have the heaviest weight. In microfiltration, the size of the membrane has large membrane pore size. Thus, this will allow particles in the range of 0.1 to 10 micrometres to pass through. The pressure used is basically in between 0.5 to 2 bars. The membrane configuration is usually cross-flow. This membrane is symmetric and asymmetric porous.

While membrane 3 has the least steep slope compare to the other membranes. Therefore, membrane 3 is the reverse osmosis. This is because the weight of permeates for membrane 3 have the lightest weight. Reverse osmosis operates at very high pressure which is more than 20 bras. Reverse osmosis require the greatest operating pressure as it has the smallest pore-size range and has the ability to remove solids as small as salts. Only small amounts of very low molecular weight solute can pass through the membranes. Membrane 3 is nonporous, asymmetric, and composite with homogeneous layer which has dense pore size.

Membrane 2 operates in ultrafiltration. Ultrafiltration designates a membrane separation process, driven by a pressure gradient, in which the membrane fractionates components of a liquid as a function of their solvated size and structure. The membrane configuration is usually cross-flow. The feed water flows across the membrane surface by limiting the extent of particle deposition and formation on the membrane surface. The membrane pore size is larger allowing some components to pass through the pores with the water. Ultrafiltration operates at lower pressure compared to nanofiltration and reverse osmosis. A type of membrane 3 is asymmetric microporous and the size of pore is 5-100nm. The driving force for this membrane is between 1-9 bars.

Nanofiltration is a type of membrane process that uses membrane 1. This is also same as reverse osmosis that operates at high pressure but not as higher as pressure used in reverse osmosis. The driving force used in nanofiltration is between 4 to 20 bars. Nanofiltration is used for organic, color and contaminant removal as well as for softening. Membrane 3 is also asymmetric, microporous which has pore size between 1 to 5 nm. Main application of nanofiltration is to separate small organic compounds and multivalent ions.

CONCLUSIONS

From this experiment, it can be concluded that membrane 3 is operate in reverse osmosis process while membrane 1 is in nanofiltration process. Both of this membrane process operate at very high pressures and are typically deployed for the removal of dissolved inorganic and organic constituents. While the membrane 2 and membrane 4 has been used in ultrafitration and microfiltration respectively. Both of this membrane process are applied for the removal of particulate and microbial contaminants and can be operated under negative or positive pressure. The objective of this experiment is achieved and the type of the membrane for all four membranes had been determined.

RECOMMENDATIONS

In this experiment, there are some recommendations that can be done in order to get the best results which are: During taking the weight of permeates by using digital weighing balance, the reading should be taking in more significant figures so that the reading of the actual weight of permeates are more accurate and the value of true error could be minimized. The average weight of permeates should be calculated by taking the weight of permeates in three times in order to get more accurate value of weight of permeates. When collecting the sample from permeates sampling port, make sure that we used a big container to support the volume of the sample and to avoid the sample from spill out in order to get more accurate weight of permeates. The system should be run in more than 5 minutes so that the system and membrane maximum inlet pressure is more stabilized in order to get the accurate value of weight of permeates. To collect the sample, the sampling valves should be open and close simultaneously so that there is no interruption during collecting the sample from permeates sampling port. The digital weighing balance should not be put near the pump as it is shaking while taking reading. Thus, error could be happened.

REFERENCES

C.J Geankoplis, Transport Processes and Separation Process Principles, 4th edition (Prentice Hall,2003) http://www.solution.com.my/pdf/TR14(A4).pdf. (n.d.). membrane test unit. Retrieved 20 April, 2013, from solteq: http://www.solution.com.my/pdf/TR14(A4).pdf Zeman, Leos J., Zydney, Andrew L. (Inc,1996). Microfiltration and Ultrafitration, Principles and Applications. In M. Dekker, Microfiltration and Ultrafitration, Principles and Applications. New York. Eliane Rodrigues dos Santos Goes,Elisabete Scolin. Mendes, Nehemias Curvelo Pereivela, Sueli Teresa Davantel de Barros. (2005). influence at different condition on the concentration by reverse osmosis. Retrieved 9 april, 2012, from Alim.Nutr.Araquara: http://serv bib.fcfar.unesp.br/seer/index.php/alimentos/article/viewFile/489/452

APPENDICES