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