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PERPUSTAKAAN UMP
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HUMIC ACID REM(
MEMBRANE SYN1
LTRATION (NF)
AMINE (TEOA)
] - , PEPU5TAAAN(II UNIVERSTJ MALAYSIA PAHANG
P
No. Perojehan No. Panggllan 24fL 2 Taiikh
.2 3 MAY 2013 F33ot3
FADZILAH B1NTI ABDUL LATIF
A Thesis submitted in fulfilment of
the requirements for the award of the degree of
Bachelor of Chemical Engineering
Faculty of Chemical & Natural Resources Engineering
UNIVERSITI MALAYSIA PAHANG
FEBRUARY 2013
HUMIC ACID REMOVAL BY POLYESTER NANOFILTRATION (NF)
MEMBRANE SYNTHESIZED FROM TRIETHANOLAMINE (TEOA)
MONOMER
ABSTRACT
Humic substances present in water sources affect the water quality causing
undesirable color and taste, besides serving as food for bacterial growth in water
distribution system. In order to treat this kind of natural organic matter,
Nanofiltration (NF) Polyester membrane was produced by studying the effect of
interfacial polymerization reaction time at constant monomer concentration. The thin
film composite membranes were synthesized through interfacial polymerization with
monomer concentration of 4% w/v of triethanolamine (TEOA) at different reaction
time. The TEOA which was aqueous solution reacted with organic solution of
trimesoylchloride (TMC) to produce new layer polyester on top of polyethersulfone
(PES) microporous support. The thin film composite membrane was characterized in
term of water flux, permeability and also solute rejection. The performances of NF
membrane in terms of humic acid and NaCl rejection were increased as the reaction
time increased. The performances in terms of flux and permeability showed that the
flux and permeability were decreased as the reaction time increased. The longer
reaction time had increased the layer thickness on the surface of the NF membrane
which resulting the performances of the membranes.
vi
PENYINGKIRAN HUMIK ACID MENGGUNAKAN MIEMBRAN
POLIESTER NANO-PENIIRASAN
SINTESIS DA1UPADA MONOMER TRIETANOLAMIN
ABSTRAK
Bahan-bahan humus yang hadir di dalam sumber air menjejaskan kuailiti air
dengan menyebabkan warn, a dan rasa yang tidak diingini, selain digunakan sebagai
makanan untuk pembesaran bakteria di dalam sistem pengagihan air. Untuk merawat
bahan organic semulajadi ini,membran poliester Nano-penurasan dihasilkan dengan
mengkaji kesan masa tindakbalas proses pempolimeran permukaan pada kepekatan
monomer yang sama. Membran komposit filem nipis telah disintesis melalui process
pempolimeran antara permukaan dengan 4%w/v kepekatan trietanolamin (TEOA)
monomer pada masa tindakbalas yang berbeza. TEOA yang merupakan larutan
akueus telah bertindakbalas dengan larutan organic trimesilkiorida (TMC) untuk
menghasilkan lapisan poliester baru di atas permukaan membran polietersulfon
(PES). Membran TFC dicirikan berdasarkan fluk air, kebolehtelapan dan
penyingkiran bahan larut. Kebolehan membran NF dari segi humik acid dan
penyingkiran NaCl meningkat apabila masa tindakbalas bertambah. Kebolehan dan
segi fluk dan kebolehtelapan menunjukkan bahawa fluk dan kebolehtelapan menurun
apabila masa tindakbalas bertambah. Masa tindakbalas yang yang lebih lama telah
meningkatkan ketebalan lapisan pada permukaan membran yang mengakibatkan
kebolehan membran juga meningkat.
VII
TABLE OF CONTENTS
Page
SUPERVISOR'S DECLARATION
STUDENT'S DECLARATION
DEDICATION, iv
ACKNOWLEDGEMENTS v
ABSTRACT
ABSTRAK
TABLE OF CONTENTS viii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF SYMBOLS xiv
LIST OF ABBREVIATIONS xv
CHAPTER 1 INTRODUCTION
1.1 Research Background 1
1.2 Problem Statement 2
1.3 Research Objectives 3
1.4 Scope of Proposed Study 3
1.5 Significance of Proposed Study 3
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction to Membrane Process 4
2. 1.1 Key Developments in Membrane Technology 5
2.1.2 Advantages and Limitation in Membrane Process 5
2.2 Membrane Processes and Principle 7
2.2.1 Membrane separation process 7
2.2.2 Pressure-Driven Membrane Process 7 2.3 Nariofiltratjon Process 10
2.3.1 Nanofiltratjon membranes 10
2.3.2 Application of Nanofiltration Membrane 11
VIII
2.4 Interfacial Polymerization 12
2.4.1 Description of Process 12
2.4.2 Triethanolamine (TEOA) as Monomer 13
2.5 Membrane Characterization 14
2.6 Humic Acid 15
2.7 Technologies for Humic Acid Removal 16
2.7.1 Physical methods 17
2.7.1:1 "Adsôrptibn 17
2.7.1.2 Membrane Filtration Method 17
2.7.2 Physical and Chemical Method 18
2.7.2.1 Flocculation 18
2.7.2.2 'Oxidation Method 18
2.7.3 Other Combination Treatment 19
CHAPTER 3 METHODOLOGY
3.1 Chemicals 20
3.2 Equipment 21
3.2.1 Amicon Stirred Cell 21
3.2.2 Ultrasonic Water Bath 21
3.2.3 Pressure Supply 22
3.2.4 Fourier Transform Infrared (FTIR) Spectroscopy 22
3.2.5 UV/ Vis Spectrometry 23
3.2.6 PH Meter 23
3.2.7 Conductivity Meter 24
3.3 Interfacial Polymerization 24
3.4 Membrane Characterization 26
3.4.1 Pure Water Flux 26
3.4.2 Salt Rejection 28
3.4.3 Humic Acid Removal Process 28
3.4.4 Fourier Transform Infrared Spectroscopy (FTIR) 29
ix
CHAPTER 4 RESULT AND DISCUSSION
4.1 Introduction 30
4.2 Pure Water Flux and Permeability 31
4.3 Salt Rejection 33
4.4 Calibration Curve of Humic Acid 37
4.5 Hurnic Acid Removal 38
4.6 Surface Layer Characterization 40
CHAPTER 5 CONCLUSION
5.1 Conclusion 41
5.2 Recommendation 42
REFERENCES 43
APPENDICES
Appendix A 46
Appendix B 48
Appendix C 52
X
LIST OF TABLES
PAGE
Table 2.1 Classification of membrane processes according to tjfr 7
driving forces
Table 2.2 Examples of nanofiltration (NF) membrane applications 11
Table 2.3 Summary on Technologies for the Removal of Humic 16
Acid from Water
Table 4.1 Water flux for 4% TEOA Polyester Membranes at 31
different reaction time
Table 4.2 Rejection of membrane with 15 minutes reaction time 33
(MiS)
Table 4.3 Rejection of membrane with 25 minutes reaction time 34
(M25)
Table 4.4 Rejection of membrane with 35 minutes reaction time 35
(M35)
Table 4.5 Absorbance for each concentration 37
Table 4.6 Rejection of Humic Acid for the polyester membranes 38
Table B.1 Time recorded at different pressure for Ml 5, M25 and 48
M35
Table 13.2 Conductivity value of membrane with 15 minutes reaction 49
time (M15) at different concentration
Table B.3 Conductivity value of membrane with 25 minutes reaction 50
time (M25) at different concentration
Table 13.4 Conductivity value of membrane with 35 minutes reaction 51
time (M35) at different concentration
Table C.1 The absorbance (ABS) value for M15, M25 and M35 53
Table C.2 Concentration of feed, retentate and permeate solutions 54
A
LIST OF FIGURES
PAGE
Figure 2.1 Schematic representation of a two-phase system 8
separated by a membrane.
Figure 2.2 Schematic representation of microfiltration, 9
ultrafiltration, nano filtration and reverse osmosis
Figure 2.3 Nañó'filtration membrane process through semi- 10
permeable membrane
Figure 2.4 Shematic drawing of the formation of a composite 13
membrane via interfacial polymerization
Figure 2.5 Hypothetical structure of Humic Acid 15
Figure 3.1 Amicon Model 8200 21
Figure 3.2 Ultrasonic Water Bath 21
Figure 3.3 Nitrogen gas for pressure supply 22
Figure 3.4 Fourier Transform Infrared (FTIR) spectrometer 22
Figure 3.5 UV-Vis Spectrophotometer 23
Figure 3.6 Mettler Toledo pH meter 23
Figure 3.7 Preparation Polyester NF membrane through interfacial 25
polymerization
Figure 3.8 Flow chart of the water flux 27
Figure 3.9 Nitrogen Cylinder attached to Amicon Stirred Cell 27
Figure 4.1 Flux versus pressure for three polyester membranes 32
Figure 4.2 Rejection of Ml 5 for different NaCl concentration 34 Figure 4.3 Rejection of M25 for different NaCl concentration 35
Figure 4.4 Rejection of M35 for different NaCl concentration 36 Figure 4.5 Calibration Curve of Humic Acid 37 Figure 4.6 Rejection of all three polyester membranes at different 39
pressure
Figure 4.7 FTIR spectra of (a) TMC, (b) TEOA, (c) PSf support 40
membrane and (d) TFC membrane
XII
Figure A.1 The PES membranes were cut into round shape
Figure A.2 The PES membranes were immersed in the ultrasonic
water bath
Figure A.3 The membranes were immersed in organic solution at
different reaction time (1 5mm, 25min and 35mm).
Figure A.4 Three polyester NF membranes were labéldsM15,
M25 and M35
Figure A.5 Thefiltration process using aniicon beaker by
supplying nitrogen gas
Figure A.6 The permeate, retentate and feed solution which were
transferred into centrifugal tube after the filtration
46
46
46
47
47
47
XIII
LIST OF SYMBOLS
Cp Concentration of permeate
Gf Concentration of feed
Pm Permeability
J Permeate flux
L Liter
M Meter
JP Filtration pressure
R Rejection
At Filtration time
V Volume
xiv
LIST OF ABBREVIATIONS
FTIR Fourier Transform Infrared Spectroscopy
IP Interfacial Polymerization
MF Microfiltration
NaOH Sodium Hydroxide
NF Nanofiltration
NOM Natural Organic Matter
PES Polyethersuifone
RO Reverse Osmosis
TEOA Triethanolamine
TFC Thin Film Composite
TMC Trimesoylchloride
UF Ultrafiltration
xv
CHAPTER 1
INTRODUCTION
1.1 Research Background
Humic acid constitute a major class of natural organic metal (NOM) present
in natural water such as lakes, groundwater and rivers. The substances affect water
quality which causing undesirable color and taste, serving as food for bacterial
growth in water distribution system binding with heavy metals to yield high
concentration of these substances and enhance their transportation in water
(Jacangelo et al., 1995). It also reacts with chlorine in water treatment to produce
trihalomethane which is known as human carcinogens. There are some processes
developed to remove humic substances such as chemical coagulation, adsorption,
and membrane separation.
1
Various types of membrane with different specifications make it suitable for
specific industrial separation demands. The membrane characteristic is partially
permeable which is allows water to flow through, while catches the suspended solids
and other substances when a driving force is applied across it. Nanofiltration (NF) is
a membrane separation technique which is operates on the principle of diffusion and
it is developed based on reverse osmosis (Petersen, 1993). As found by Van Der
Bruggen & Vandecasteele (2003), NF membrane is suitable to remove the pollutants
from groundwater or surface water and also applied for the combined removal of
natural organic metals, micropollutants, viruses and bacteria. As in recent years, it is
apparent that membrane separation processes, which are reverse osmosis and
nanofiltration are becoming more popular for their ability to produce a high quality
of drinking water (Taylor & Jacobs, 1996; Wilbert et al., 1993).
1.2 Problem Statement
The high demand for clean potable drinking water has led to the increasing
development of membrane technology. As found by Duran & Dunkelberger (1995),
the drinking water has been the major application area for nanofiltration (NF)
membrane and the reason is that NF membranes were essentially, developed for
softening. Humic substances present in natural water such as lakes, groundwater and
rivers affect water quality which causing undesirable color and taste, serving as food
for bacterial growth in water distribution system (Jacangelo et al., 1995). Hence, it is
desirable to minimize the presence of humic substances in drinking water.
2
1.3 Research Objectives
The objectives of this research are to produce Nanofiltration (NF) Polyester
membrane for natural organic matter (NOM) removal and to study the effect of
reaction time on the production of thin film composite NF and its effects on the
NOM and salt (NaC1) removal performance.
1.4 Scope of Proposed Study
In order to achieve the objectives, the scope have been identified as follows:
i. Production and characterization (flux and permeability) of thin film NF composite
by interfacial polymerization method using 4 0/ow/v of triethanolamine (TEOA) as
monomer at different reaction time (15, 25 and 35 mm)
ii. Performance of salt removal (NaC1)
iii. Removal of NOM by the synthesized NF membrane
1.5 Significance of Proposed Study
Nowadays, nanofiltration (NF) membranes are widely known as the best
technology and energy efficient processes for production of potable water. The NF
Process becomes more important in water treatment for domestic and industrial water
supply. The membrane technology which is applicable for environmental application
can be applied in cleaning technology.
3
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction to Membrane Process
A membrane is defined as a thin layer of material which acts as a semi-
permeable barrier that allows some particles to pass through it, while hindering the
permeation of other components (Silva, 2007). The capability of membrane to
separate the substances is due to the driving force applied across the membrane. The
elements of modem membrane science had been developed 'since the nineteenth and
early twentieth centuries. The membrane had no industrial or commercial uses, but
was used as laboratory tools to develop physical and chemical theories. During
period of 1960 to 1980, there were a significant change in the membrane technology
include interfacial polymerization and multilayer composite casting and coating in
order to produce high performance membrane (Baker, 2004).
4
According to Jalil (2004), the membrane process plays important role in
industrial fields, such as textile, food and beverages processing, pharmaceutical,
environment, paper and as well as in water wastewater treatment process.
2.1.1 Key Developments in Membrane Technology
Emerging new technologies are often characterized by key discoveries
providing a breakthrough by their application and same goes to the membrane
science and technology. The seminal discovery for reverse osmosis was the
anisotropic concept achieved with asymmetric cellulose acetate membranes by Loeb
and Sourirajan (1962). Another breakthrough in reverse osmosis membrane
development was expanded by Cadotte and Petersen (1981), who made the first
really efficient composite membranes. There are many more key developments that
had a significant effect on the development of membrane technology such as the
preparation of the first efficient ion-exchange membranes by Juda and McRae (1953)
and the first tailor-made ultrafiltration membranes by Michaels and Baker in 1968. A
real breakthrough in the medical application of membranes was the first successful
hemodialysis treatment of patients suffering from renal failure by Kolif and Berk
(1944).
2.1.2 Advantages and Limitation in Membrane Process
Membrane process offers more benefits compared to the conventional
filtration. In water desalination and purification the membrane processes compete
directly with the more conventional water treatment techniques. However, compared
to these conventional procedures membrane processes are very energy efficient,
5
simple to operate and yield a high quality product. The membrane processes are
usually more costly but generally provide a better product water quality. Membrane
process shows the simplicity of operation which is the system is relatively less
complex and less sophisticated. Membrane systems consume less energy since
separation does not involve phase change. Thus the system driving force is mainly
pressure provided by using pump. The separation using membrane is done physically
thereby undesirable by products and no side reactions and no waste generation.
Membrane processes are potentially better for environment since the membrane
approach require the use of relatively simple and non-harmful materials. (Mustaffar,
2004).
The major disadvantage of membrane processes is that until today the long-
term reliability is not completely proven. Membrane processes sometimes require
excessive pretreatment due to their sensitivity to concentration polarization, chemical
interaction with water constituents, and fouling. Membranes are mechanically not
very robust and can easily be destroyed by a malfunction in the operating procedure.
The concentration polarization and membrane fouling can reduce membrane
performance, both selectivity and flux. The pH stability also is one of the membrane
limitations of polymeric membrane. The pH stability of cellulosic membrane is in pH
range of 4 to 8, while for polysulfone is pH 2 to 12. Membrane modules often cannot
operate at much above room temperature. This is related to the fact that most
membrane are polymer-based, and that a large fraction of these polymers do not
maintain their physical integrity at much above 100°C.
6
2.2 Membrane Processes and Principle
2.2.1 Membrane separation process
Separation process is defined as a process at which a mixture of chemical is
converted into two or more end-use products with respective (Soni et al., 2009).
There are various types of membrane separation process which are developed for
specific industrial applications and they are classified according pore size and
separation driving forces as shown in Table 2.1. The driven forces can be pressure,
temperature, concentration, or electrical potential (Scott & Hughes, 1996).
Table 2.1 Classification of membrane processes according to their driving forces
Pressure Temperature Electrical Potential Concentration
difference differences Differences
Microfiltration Gas separation Thermo-osmosis Electrodialysis
Ultrafiltration Diffusion dialysis Membrane distillation Electro-osmosis
Nanofiltration Pervaporation Membrane electrolysis
Reverse Osmosis Vapour permeation
2.2.2 Pressure-Driven Membrane Process
Process such as Microfiltration (MF), Ultrafiltration (UF), Nanofiltration
(NF), and Reverse Osmosis (RO) involve pressure driving forces. These processes
are appropriate to different size of molecules where the microfiltration differentiates
the largest size of molecules and reverse osmosis differentiating the smallest
molecules (Silva, 2007).
7
Figure 2.1 Schematic representation of a two-phase system separated by a membrane.
(Source: httjxHclxy.tjpu.edu.cn/mo/lljx/jj.files/imageOlOjpg).
Figure 2.1 represents the driving forces applied across the membrane from
phase 1 to phase 2 which is separated by a semipermeable membrane. According to
Mulder (2003), the membranes separation system separates an influent stream of
feed into effluent streams of permeate. Permeate is the liquid which is going through
the membrane. When a driving force is establish across the membrane, a flux will go
through the membrane from the feed solution to the permeate side (Bier, 2007).
Membrane separation processes cover the entire size range which is from
suspended solids to the mineral salts and small organic's but it depends on the
membrane process types. Four pressure driven membrane processes have been
distinguished. MF is a membrane process with the largest pore size which is
characterized by membrane pore size between 0.05pm and 29m where the operating
pressure applied is below 2bar. It can remove bacteria and "turbidity" from water
treatment. UF is characterized by membrane pore size between 2nm and 0.05tm.
The operating pressure is between ibar and lObar. It is used to remove
8
microorganism and viruses, as well as to separate colloids like proteins from small
molecules. NF is characterized by a membrane pore size between 0.5nm and 2nm
and operating pressures between 5bar and 40bar. RO is characterized by a membrane
pore size in the range of 0.0005microns. The operating pressure is between 7bar and
lOObar. Figure 2.2 represents the pressure applied on the microfiltration,
ultrafiltration, nanofiltration and reverse osmosis process and the difference permeate
that pass through the membrane after the pressure is applied (Schafer, 2001).
mkrofiUratjo
• •'• . feed
SohCnt
o solute (low mol. weiI) . • olut 'high rnol weighs) rtmeate
ulf.tafihllaliQn
AP led
ITh1Ac
reete osrnos,r,
A D ®' 0 fred •— '1 :.. @' •.
Figure 2.2 Schematic representation of microfiltration, ultrafiltration, nanofiltration and reverse osmosis
(Source: http://clxy.tjpu.edu.cn/mo/lljx/MGC.fileWl*mage048.jpg)
9
2.3 Nanofiltration Process
2.3.1 Nanofiltration membranes
Nanofiltration (NF) is a pressure driven membrane process which developed
in the 1980s based on reverse osmosis (Zhang et. al., 2003). The fundamental
principle of nanofiltration membrane's technology is based on the pressure which
applied across the semi-permeable membrane in order to separate soluble ions from
water as shown in Figure 2.3. Although the process is similar to reverse osmosis in
the way the ions were rejected, but nanofiltration membrane is more limited in size
and molecular weight of the ions it does reject. It is applicable in separating
dissolved components with molecular weight cut off (MWCO) of about 200-1 000Da
with molecular size of about 1 nm (Van Der Bruggen & Vandecasteele, 2003).
NanofiFtratoh Semiperrneabe Mernbae
Pressure
J 4`1 1 3 0 .—L-_ 0
$oftwatèri ' 60S . altZ 0water
o 0.2
Figure 2.3 Nanofiltration membrane process through semi-permeable membrane. (Souce: http://www.fumatech.com )
10
2.3.2 Application of Nanofiltration Membrane
According to Raman et al., (1994), nanofiltration (NF) membrane separation
plays an important role in various industrial fields and its applications are increasing
rapidly in chemical, biological and desalination industries, since the NF technology
overcomes the operational problems that are associated with the conventional
techniques. The example of applications of NF membrane process are water
softening, dyes recovery, treatment of metal contained wastewaters, demineralization
of whey, and antibiotics. Table 2.2 represents the examples of nanofiltration (NF)
membrane applications.
Table 2.2 Examples of nanofiltration (NF) membrane applications (Source: http://www.pure-aqua.comlnanofiltration-systems.html )
Application Permeate Concentrate Benefits of NF
Whey Salty Desalted whey Allows recovery of lactose and permeate wastewater concentrate whey protein concentrate with
reduced salt content
Textile Dyes Water, salts, NF is used to desalt dyes BOD, COD, and resulting in a higher value color product
Caustic Caustic BOD, COD, Allows caustic cleaning cleaning cleaning suspended solids, solution to be recycled solutions solution caustic cleaner resulting in reduced cleaning
chemical costs
Water Softened water Hard water Potable water production. Softened water reduces scaling on equipment and heat exchange surfaces
11
2.4 Interfacial Polymerization
2.4.1 Description of Process
Most of nanofiltration membranes are thin-film composites fabricated by the
interfacial polymerization technique in purpose to overcome the limitations and
problems faced by asymmetric membrane formed by the phase inversion method
(Rao et al., 1997). The higher molecular weight polymer is produced in the
interfacial process compared to the usual polymerization. This is due to the
monomers diffusing to the interface will react only with polymer chain ends. The
reaction rates which are so high make the monomers molecules react with the
growing polymer chain ends before they can penetrate through the polymer film to
start the growth of new chains.
According to Mulder (2003), the advantage of this technique is that the
reaction is self-inhibiting through passage of limited supply of reactants through the
already form layer, resulting in an extremely thin film of thickness within 50nm
range. The thin layer produced by this technique generally will control the efficiency
of the membrane process (Abu Seman et al., 2010).
In this process, the ultra-thin selective layer with a dense property is produced
separately onto porous support having good mechanical properties (Tang et al.,
2008). A polymerization reaction between two reactive monomers will occurs at the
interface of two immiscible solvents. This is shown schematically in Figure 2.4. The
support layer is generally an ultrafiltration or microfiltration membrane. It is
12
immersed into aqueous solution containing reactive monomer which usually is
amine-type. Then, it is immersed in organic solution containing water-immiscible
solvent in which the reactive monomer is usually an acid chloride. These two
reactive monomers will react with each other to form a dense polymeric top layer
(Mulder, 2003).
Figure 2.4 Schematic drawing of the formation of a composite membrane via interfacial polymerization (Source: Mulder, 2003).
2.4.2 'fricthanolanijne (TEOA) as Monomers
In recent years, studies have been focused on choosing or synthesizing the
new monomers with special functional group to prepare the TFC membrane.
According to Tang et al., (2008), it is natural to seek an inexpensive monomer to
manufacture a new membrane whose property spectrum has the optimum cost-
performance balance for application. It is found that triethanolamine (TEOA) is an
active monomer which is environment-friendly, economical and easy to be obtained.
13
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