CHEMICAL ENGINEERING TRANSACTIONS

VOL. 56, 2017

A publication of

The Italian Association
of Chemical Engineering
Online at www.aidic.it/cet

Guest Editors: Jiří Jaromír Klemeš, Peng Yen Liew, Wai Shin Ho, Jeng Shiun Lim
Copyright © 2017, AIDIC Servizi S.r.l.,

ISBN 978-88-95608-47-1; ISSN 2283-9216

Performance of Polysulfone/PANI Membrane for Humic Acid
Separation

Azlinnorazia Ahmad*,a,b, Muhamad Zaini Yunosa,b, Zawati Haruna,b, Mohd Fahrul
Hassana, Sharifah Adzilaa, Ahmad Mubarak Tajul Arifina, Mohd Nasrull Abdol
Rahmana, Reazul Haq Abdul Haqa, Norfhairna Baharulrazic,
aIntegrated Materials & Process, Advanced Manufacturing and Materials Centre, Universiti Tun Hussein Onn Malaysia, Parit
Raja, Batu Pahat 86400, Johor Darul Takzim, Malaysia
bFaculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, Parit Raja, Batu Pahat
86400, Johor Darul Takzim, Malaysia
cFaculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia.
azlinnorazia@yahoo.com

The effect of polymer mixed matrix membrane was investigated by mixing Polyaniline (PANI) in Polysulfone
(PSf) membrane for humic acid separation. The purpose addition of PANI in PSf was to improve the membrane
hydrophilicity and increase membrane permeability The membrane preparation was undergo phase inversion
method at high concentration of PANI (0-15 wt.%). The characterization and performance of the membrane
were evaluated in respect to membrane hydrophilicity, pure water flux and rejection properties against humic
acid. The result showed that by blending PANI in PSf membrane, the contact angle decreased up to 17 %. This
result indicate that addition of PANI improve surface hydrophilicity of membrane. Meanwhile, the addition of
PANI increased membrane permeability up to 84 %. The rejection properties also improved up to 25 %.
According to the membrane hydrophilicity and the performance against humic substance, PANI has a strong
potential to be used as an additive in membrane fabrication.

1. Introduction
Humic acid is one of many substances which are available in river water. It is generally displays macromolecular
characteristics from a subclass of humic substances. It contains both hydrophobic and hydrophilic moieties and
numerous substance capacities, for example, carboxylic, phenolic, carbonyl, and hydroxyl gatherings
associated with the aliphatic or fragrant carbons in the macromolecules. Yunos et al. (2013a) reported that the
properties of humic substances are depending on the sources of humic acid which is degradation product from
plants, creature residue and microorganism’s activities. The presence of humic acid in water will discolour the

water to brown or black.
Nowadays, membranes can be used for many different types of water filtration applications. It acts as a physical
barrier that permits certain compounds to pass through (Harun et al., 2013a). It is depending upon their physical
and chemical properties. It regularly comprises of a porous support layer with a dainty thick layer on top that
forms the actual membrane (Saini, 2014). According to Yunos et al. (2013b), membrane process only need a
low space and its separation process will not change the water phase. Membranes are used on large scale
industrial effluents and recover valuable constituents, to concentrate, purify, or fractionate macromolecular
mixtures in the food and drug industries, and to separate gases and vapors in petrochemical processes. They
are also key components in energy conversion and storage system, in chemical reactors, in artificial organs, an
in drug delivery devices.
It is strongly agreed that water treatment using membrane filtration is one of the best method in order to reduce
carbon footprint in our surrounding. Furthermore, Mehrparvar et al. (2014) reported that the ultrafiltration (UF)
method is commonly used by researcher because it can removed all humic substances and some viruses. UF
is the separation process of very small particles and dissolve molecules from liquids. The important factor for

DOI: 10.3303/CET1756118

Please cite this article as: Ahmad A., Yunos M.Z., Harun Z., Hassan M.F., Adzila S., Arifin A.M.T., Rahman M.N.A., Haq R.H.A., Baharulrazi N.,
2017, Performance of polysulfone/ pani membrane for humic acid separation, Chemical Engineering Transactions, 56, 703-708
DOI:10.3303/CET1756118

703

separation is molecular size. Moreover, the permeability of a filter medium will be affected by the chemical,
molecular or electrostatic properties of the sample in all filtration applications (Kumar et al., 2015). Jamalludin
et al. (2013) also reported that However, high concentration of inorganic additives will lead to increase surface
roughness and reduce water permeability due to pore blockage.
In recent decades, there are a lot of researches on improving membrane surface to improve membrane
hydrophilicity. The membrane surface modifications utilizing grafting, plasma, and blending technique with
hydrophilic polymer or nanoparticle were produced with excellent result. Among those techniques, polymer
blend is less complicate method to improve membrane separation. The design of polymer blends constitutes an
interesting alternative to improve membrane hydrophilicity. According to Jaymand (2013), it is reported that the
cost of membrane blending is quite reasonable and it is free from time-consuming procedures.
In this study, PSf membrane surface will be improved by blending hydrophilic PANI in PSf dope solution. PSf
need to be modified to reduce membrane fouling with the hydrophilicity properties of PANI (Harun et al., 2013b).
However, there are limit number of studies that investigate the behaviour of PANI in PSf membrane. Thus, the
influence of PANI concentration in PSf membrane were investigated in respects to its chemical properties,
permeability and rejection against humic acid.

2. Details Experimental
2.1 Materials and Procedures

In this study, Polysulfone (PSf) has been used as the base polymer in the membrane casting solution and N-
methyl-2-pyrrolidone (NMP) acts as the solvent. Polyaniline (PANI) has been chosen as an additive and
Polyethylene glycol (PEG) act as pore former agent. The concentrations of PANI used are as follows: 0 wt. %,
5 wt. %, 10 wt. % and 15 wt. %. The flat sheet membranes were prepared via phase inversion method. The
solution was poured on a glass plate and the casting process occurs on the glass plate using a casting steel
knife. In order to get wet thin films on average 0.10 μm to 0.14 μm thickness, the membrane was exposed to air
for 30 s, and immersed in a coagulation bath of distilled water for a few seconds. All of the membranes were
prepared under environmental humidity of 60 % at room temperature of 25 °C.

2.2. Membrane Evaluation

The performance of PANI membrane was conducted by using three different tests on the samples. At this stage,
the sample of membrane went through each test and the performance of it was clearly seen after the result
came out. Each test has shown variety of different features at each sample. Below are some general
explanations about the test for this membrane evaluation.
The characteristics of hydrophilic and hydrophobic of membrane were investigated by using contact angle
measurement. This test was conducted using VCA Optima contact angle machine. The measurement of contact
angle as a primary data, which indicated the degree of wetting when the solid and liquid interact is call as a wet
ability studies. Small contact angle which is less than 90 is in a hydrophilic property while more than 90 degree
is in the hydrophobic properties. The membrane was cut into 5 cm x 2 cm. 2 μL of water were injected onto the
membrane surface to measure the degree of contact angle. After the water drop to the tip of the needle, the
position of the moving plate was adjusted to fit with the scale in the screen monitor. Image was captured and
the measurement of angle was recorded. This testing had been repeated for 5 times to minimize the
experimental error. Average values were calculated to take the result.
The water permeability test of the membrane was measured by using UF/NF Membrane Permeation Testing
Unit. The test was conducted to examine permeation flux and rejection. The sample will be cut into disk-like
shapes and then will be placed in the glass between two rubber rings. The distilled water were use during pure
water flux testing while the rejection test were conduct using humic acid. This permeation test has been done
with constant hydrostatic pressure. At the beginning of the testing, the pressure used is about 0.3 MPa until the
flow of distilled water in a steady state condition. Then, slowly drop the pressure to 0.1 MPa to determine the
value of pure water flux and rejection process. Record the result in every 10 minutes. The permeation water flux
was calculated using the Eq(1) and to calculate the rejection flux, the formula used as in Eq(2):

PWF =
Q

A × ∆T
(1)

Where PWF is the permeation water flux, (Lm-2h-1), Q is the permeate volume (L), A is membrane areas (m2)
and Δt is the time interval (s).

R = (1-
Cp

Cf
) ×100 % (2)

Where Cp and Cf are retentive of permeate and feed.

704

3. Results and Discussion
3.1 Contact Angle Analysis

Figure 1 shows the result of contact angle result for the four membrane samples with different content of PANI.
The result shows that contact angle of membrane is reduced as concentration PANI increases. This is due to
the presence of PANI that enhances the hydrophilicity of the PSf membrane. This result is in line with Razali et
al. (2014) where the hydrophilicity increases with the addition of PANI. Yunos et. al. (2014) also reported that
the mechanisms and causes of fouling that strongly depend on the membrane surface characteristic which is
the hydrophilicity, charge and roughness that have been well reported.

Figure 1: Contact Angle result

3.2 Water Permeability Analysis

Figure 2 demonstrates the increment of membrane permeability properties with addition of PANI from 5 to 10 g
(sample 2 and 3). This increment of membrane permeability is led by the improvement of hydrophillicity on
membrane with addition of PANI which was discussed in previous section.
The hydrophilicity membrane increases with addition of PANI gradually reduces surface tension between water
and membrane. This reduction increases absorption rate of water molecule on membrane. This result is in line
with Zhu et al. (2015) where the increased membrane roughness with the presence of PANI will increase
membrane surface area which allowed more way for water molecule to permeate trough membrane. According
to Fan et al. (2008), PS/PANI nanofibers blended membranes had higher influence on pure water flux result.
The increased of porosity allowed more water to be transported inside the membrane. The result is in line with
where blended membranes had better hydrophilicity, thus increase water permeability.

1 2 3 4

C
o

n
ta

ct
A

n
g

le
(

o
)

Sample

705

However, addition of PANI at 15 g (sample 4) reduced water permeability. This result might be due to pore
blocking of membrane surface due to the presence of PANI. Although the hydrophilicity and membrane
roughness increases, membrane pore blocking limited the number of channel for water to be transported in a
membrane. Hence, it reduces membrane permeability. Costa et al. (2005) also reported that in the more
permeable membranes was fabricated, the convection fluxes overcome in several orders of magnitude. Thus,
the back diffusion fluxes and this together with the decrease of membrane/humic solutes interactions results in
humic acid deposition and leads to flux decline.

Figure 2: Water Permeation Result

3.3 Rejection Analysis

The rejection test was carried out using 100 mg/L humic acid as a waste water to be filtered by membrane. The
influence of PANI concentration in PSf membrane is shown in Figure 3. As shown in the figure, membrane
rejection increases up to 25 % at 15 g PANI in PSf membrane as compared to pristine PSf membrane. This
result shows that the porosity of the membrane was reduced as increasing the amount of PANI. This result is in
line with Shohur et al. (2013) which the membrane with smallest mean pore size will provide better rejection
properties. Apart from that, the flux decline, rejections, flux recovery ratio, and anti-fouling properties of the
membranes were significantly enhanced by the membrane modification after blending with PANI (Tokala et. al.,
2015).

100

200

300

400

500

600

1 2 3 4

P
e

rm
e

a
b

il
it

y
(

L
m

-2
h

-1
)

Sample

706

Figure 3: Rejection test result

4. Conclusions
In this study, the fabrication of PSf membranes containing different concentration of Polyaniline (PANI) was
successfully prepared through polymer blending method. Difference concentration of PANI does affect the
membrane performance and characteristics. The membrane hydrophilicity had been observed via contact angle
measurement. It is found that membrane contact angle reduced significantly with PANI addition. The
performance test was evaluated by permeability and rejection test. The result showed that PANI concentration
had highly influenced the membrane properties and performance. Membrane permeability and rejection was
increased by 84 % and 25 %. Statistical data allow a better and more precise evaluation of the permeation data
obtained. From this study, the result strongly suggested that PANI is suitable to be an additive in membrane
modification process for water treatment application.

Acknowledgement

The authors would like to thank the Department of Materials and Design Engineering, Faculty of Mechanical
and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia for funding this research under IGSP and
STG grant Vot no. U244 and U125 and also Ministry of Higher Education (MOHE), Malaysia.

References

Costa A.R., De Pinho M.N., 2005, Effect of membrane pore size and solution chemistry on the ultrafiltration of
humic substances solutions, Journal of Membrane Science 255 (1–2), 49–56.

Fan Z., Wang Z., Sun N., Wang J., Wang S., 2008, Performance improvement of polysulfone ultrafiltration
membrane by blending with polyaniline nanofibers, Journal of Membrane Science 320 (1–2), 363–371.

Harun Z., Jamalludin M.R., Basri H., Shohur M.F., Rosman N., Yunos M.Z., 2013a, The effect of synthetic silica
on ultrafiltration PSf membrane, Jurnal Teknologi (Sciences and Engineering) 65 (4), 121--125.

100

1 2 3 4

R
e

je
ct

io
n

P
e

rc
e

n
ta

g
e

(
%

)

Sample

707

Harun Z., Shohur M.F., Yunos M.Z., Jamalludin M.R., Ismail A.F., 2013b, The Effect of Crystalline Rice Husk
Silica on Polysulfone Membrane for Wastewater Treatment, Applied Mechanics and Materials 328, 798–
801.

Jamalludin M.R., Harun Z., Basri H., Yunos M.Z., Shohur M.F., 2013, Performance studies of polysulfone-based
membrane: Effect of silica morphology, Applied Mechanics and Materials 372, 8-12.

Jaymand M., 2013, Recent progress in chemical modification of polyaniline, Progress in Polymer Science 38
(9), 1287–1306.

Kumar S., Guria C., Mandal A., 2015, Synthesis, characterization and performance studies of
polysulfone/bentonite nanoparticles mixed-matrix ultra-filtration membranes using oil field produced water,
Separation and Purification Technology 150, 145–158.

Mehrparvar A., Rahimpour A., Jahanshahi M., 2014, Modified ultrafiltration membranes for humic acid removal,
Journal of the Taiwan Institute of Chemical Engineers 45 (1), 275–282.

Razali N.F., Mohammad A.W., Hilal N., 2014, Effects of polyaniline nanoparticles in polyethersulfone
ultrafiltration membranes: Fouling behaviours by different types of foulant, Journal of Industrial and
Engineering Chemistry 20 (5), 3134–3140.

Saini P., 2014, Pre-Treatment of Textile Industry Wastewater Using Ceramic Membranes, PhD Thesis, Thapar
Institute of Engineering and Technology University, Patiala, India.

Shohur M.F., Harun Z., Lau W.J., Yunos M.Z., Jamalludin M.R., 2013, Performance of PSf ultrafiltration
membrane: Effect of different nonsolvent on coagulation medium, Jurnal Teknologi (Sciences and
Engineering) 65 (4), 59–63.

Tokala M.R., Padya B., Jain P.K., Shilpa Chakra C.H., 2015, Preparation and characterization of graphene
nano-platelets integrated polyaniline based conducting nanocomposites, Superlattices and Microstructures
82, 287–292

Yunos M.Z., Harun Z., Basri H., Ismail A.F., 2014, Studies on fouling by natural organic matter (NOM) on
polysulfone membranes: Effect of polyethylene glycol (PEG), Desalination 333 (1), 36–44.

Yunos M.Z., Harun Z., Basri H., Shohur M.F., Jamalludin M.R., Hassan S., 2013a, Effect of zinc oxide on
performance of ultrafiltration membrane for humic acid separation, Jurnal Teknologi (Sciences and
Engineering) 65 (4), 117–120.

Yunos M.Z., Harun Z., Basri H., Shohur M.F., Jamalludin M.R., Hassan S., Ismail A.F., 2013b, Influence of
inorganic additives on the performance of polysulfone ultrafiltration membrane. Jurnal Teknologi (Sciences
and Engineering) 65 (4), 111–115 .

Zhu S., Zhao S., Wang Z., Tian X., Shi M., Wang J., Wang S., 2015, Improved performance of polyamide thin-
film composite nanofiltration membrane by using polyetersulfone/polyaniline membrane as the substrate.
Journal of Membrane Science 493, 263–274.

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