Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18

Research Article, Issue 4

Analytical Methods in Environmental Chemi s try Journal

Journal home page: www.amecj.com/ir

AMECJ

Surface-engineered TiO2 nanoparticles incorporated Chitosan

polymer membrane for seawater desalination: Fabrication,

characterization, and performance evaluation

Muhammad Nurdin a,*, Mike Delvinasari a, La Ode Ahmad a, Maulidiyah Maulidiyah a, Dwiprayogo Wibowob,c,

Faizal Mus tapa d, Amir Mahmud e, Muhammad Idris f, and Muh. Ramli h

a Department of Chemis try, Faculty of Mathematics and Natural Sciences, Universitas Halu Oleo,

Kendari 93231, Southeas t Sulawesi, Indonesia.

b Department of Environmental Science, School of Environmental Science, Universitas Indonesia, Jakarta 10430, Indonesia.

c Department of Environmental Engineering, Faculty of Engineering, Universitas Muhammadiyah Kendari,

Kendari 93231, Southeas t Sulawesi, Indonesia.

d Department of Marine Sciences, Ins titut Teknologi dan Bisnis Muhammadiyah Kolaka, Kolaka 93511, Southeas t Sulawesi, Indonesia.

e Department of Fishery Resources, Faculty of Marine, Universitas Muhammadiyah Kendari,

Kendari 93231, Southeas t Sulawesi, Indonesia.

f Department of Agriculture Sciences, Faculty of Agriculture, Universitas Halu Oleo, Kendari 93231, Southeas t Sulawesi, Indonesia.

h Department of Marine Sciences, Faculty of Marine, Universitas Halu Oleo, Kendari 93231,Southeas t Sulawesi, Indonesia.

ABS TRACT

The eect of surface coating over titanium dioxide nanoparticles

(TiO2-NPs) incorporated with chitosan (TiO2-NPs/chitosan) was

evaluated as a reverse osmosis membrane (RO) for enhanced

performance on seawater desalination. The impact of surface coating

on the chitosan membrane performance in seawater reverse osmosis

(SWRO) was inves tigated by altering the mass of TiO2-NPs (0.25

g and 0.5 g) used for the surface coating RO membrane. TiO2-NPs

were applied to the membranes using a surface coating technique

and dried to create a s turdy polymer s tructure. The characteris tic of

fabricated membranes shows the function group reects on organic

compounds from /chitosan membranes polymer (–OH, -CH, C=O,

C-O-C, -CH3, C-O, and NH2). In addition, TiO2-NPs are expressed

in the wavenumber range of 850-500 cm-1, which characterizes the

presence of Ti-O-Ti bonds. Morphological and crys tal analyses of

TiO2-NPs incorporated in chitosan membrane show signicantly

smaller pores formed because TiO2-NPs are essential in the high

permeability performance under the amorphous phase s tructure.

Also, the high performance of fabricated membranes was evaluated

agains t water ux and salt. Adding TiO2-NPs can decrease the water

ux value by 23 L m-2 h-1 and increase salt rejection by 52.94%. In

optimized pH, the seawater desalination had ecient recovery.

Keywords:

Desalination,

Membrane,

TiO2,

Polymer s tructure,

Reverse Osmosis,

Seawater,

ARTICLE INFO:

Received 17 Jul 2023

Revised form 23 Sep 2023

Accepted 10 Nov 2023

Available online 28 Dec 2023

*Corresponding Author: Muhammad Nurdin

Email: mnurdin06@gmail.com

https://doi.org/10.24200/amecj.v6.i04.246

1. Introduction

Indonesia’s marine waters cover 70% of its total

land area, making it an excellent opportunity to

increase the utilization of seawater as raw water as

a source of clean water that can be used to meet the

needs of the people in Indonesia [1, 2]. Therefore,

seawater treatment is needed to remove or reduce

its salt content using RO desalination techniques to

become clean water. Pure water is a vital element

------------------------

6Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18

within the ecosys tem, playing a crucial role in the

advancement and well-being of humans and various

other forms of life [3,4]. The increase in population

has led to a situation where not every segment of

society can access uncontaminated water. [5]. As a

result, many people utilize groundwater and river

water for domes tic purposes, even though the water

is not necessarily suitable for consumption [6].

However, even though the potential availability of

water is relatively abundant, people often experience

diculties accessing and fullling their water

needs for daily life. These problems have led to a

lot of research on seawater purication processes.

One of the mos t widely used methods is using

semipermeable membranes in RO desalination,

which separates low molecular weight solutes

such as inorganic salts or small organic molecules

such as glucose and sucrose from the solution

[7]. RO membranes are widely utilized in various

ltration processes, such as groundwater ltration,

seawater, and brackish water desalination [8]. The

RO process requires membranes to lter out salt

molecules to produce ready-to-use fresh water [9].

Transporting specic ions and removing dierent

ions use porous media or membranes. These semi-

porous membranes serve as barriers that divide

molecules by their respective sizes in a solution.

Among the various methods involving membranes

for separation, there’s the ultraltration technique,

which relies on pressure dierentials for the

separation process. The elements isolated within a

liquid are contingent on the size and composition

of the dissolved subs tances. [10,11]. Ultraltration

membranes are principally used to retain colloids

and macromolecules but pass salt particles.

Separation using membranes was chosen due to

its simple, energy-ecient, and environmentally

friendly process. Ultraltration membranes are

usually made of polymeric materials; one of the

mos t commonly used is cellulose acetate (CA)

compound [12,13]. RO membranes can be made

from various materials; one uses CA compound,

which has advantages as an easy-to-produce and

renewable raw material source. The disadvantages

of the CA membrane are that it is susceptible to

acidic and base solutions and is easy for natural

microbes [14,15]. The selection of polymers as

membrane materials is based on s tructural factors

that will aect the intrinsic properties of the

polymer, namely perm selectivity [16]. However, it

seems that the CA compound has a full role in the

basic ingredients of polymer membrane formation.

It dissolves easily with acetone solution and has

high capabilities in the ultraltration process and

high selectivity to lter small materials [17]. The

CA compound cannot s tand alone as a polymer

membrane component; it requires a reinforcing

additive compound to improve the membrane’s

resis tant characteris tics under s tressed conditions.

In addition, the function of additive compounds has

a role in inuencing the formation of membrane

morphology, both physicochemical to produce

high-performance material properties. PEG is one

of the organic compound additives that can reliably

improve polymer membrane properties such as

surface porosity and membrane pore dis tribution

[18,19]. In some s tudies, adding PEG as an additive

improves membrane performance, like enlarging

membrane pores while maintaining membrane

resis tance to external factors. Besides, the basic

membrane organic using CA and PEG is a potential

material when combined with chitosan [20]. It has

an excellent ability as a coagulant material because

it contains many amine groups (-NH2) that are

benecial in the polymetric sys tem of membrane

manufacturing. The presence of amine and hydroxyl

groups in chitosan makes it have polycationic

properties to increase the coagulant in membrane

formation, thus s trengthening membrane s tiness

and high durability in water treatment [21]. These

groups can be evaluated with ins truments such as

Fourier-transform infrared spectroscopy (FTIR) to

identify the infrared spectrum of the absorption or

emission of the synthesized RO membrane. This

characterizes the chemical groups that play a role in

membrane formation and inuence the adsorption

performance. Amine groups in the membrane play

a role in various adsorption reaction mechanisms

with metal ions. In addition, the amine groups

on chitosan are easily modied to improve the

Chitosan polymer membrane for seawater desalination Muhammad Nurdin et al

adsorption ability and sorbent to handle metal ions in

was tewater. In addition, the synthesized membrane

observed the crys tallinity and morphology to

describe the properties of the membranes analyzed

using XRD and SEM ins trumentation. They are

commonly used in material analysis to observe the

porosity and s tiness of the membrane.

In this s tudy, we varied the addition of TiO2

material as a photocatalys t and antifouling agent

because it is believed to be a bioceramic material

that is resis tant in various conditions with non-

toxic, antimicrobial, and environmentally friendly

properties, making it safe to use as a base material

for making membranes with high s trength [22,23].

Amazingly, it is widely used as a water purier

under photocatalys t performance for demineralizing

organic, inorganic, and microorganisms dissolved

in was tewater. In some of our recent research, TiO2

is applied as an antibacterial material in inhibiting

bacterial growth [24], a photocatalys t material

for treating organic pollutants in was tewater, and

an electrochemical sensor for detecting organic

pollution in was tewater because it has high

photoactivity and chemical s tability, making it

resis tant to photo corrosion under neutral solution

conditions [25,26]. In addition, it also has redox

properties that can oxidize organic pollutants and

reduce the number of metal ions in water. This

s tudy discovered the unique eect of chitosan

semipermeable membrane incorporating TiO2-

NPs. The mass variation of TiO2 was shown to

signicantly inuence the characterization and

performance tes t of the fabricated membranes under

RO desalination. The seawater observed comes

from the Southeas t Sulawesi Province, Indonesia,

which has a good sea salt level, and the surrounding

community s till has diculty obtaining clean water

for daily use.

2. Material and Methods

2.1. Chemicals and materials

Cellulose acetate (CA, purity, 99%), Polyethylene

glycol (PEG 400, purity, 99%), TiO2 Degussa P25

(Purity: 99%), and 2-Amino-2-deoxy-(1,4)-β-D-

glucopyranose, Poly-(1,4-β-D-glucopyranosamine)

(chitosan, purity: 70%) were purchased from

Sigma-Aldrich. The acetone solution (Purity: 99%)

was purchased from Merck & Co., Inc.

2.2. Feed water collection

Seawater samples for tes ting were collected from

Toronipa Beach in Konawe Regency, Southeas t

Sulawesi Province, Indonesia. This location was

chosen due to its popularity as a touris t des tination

and the ongoing challenges coas tal communities

face in accessing freshwater [27]. The sampling

process was conducted approximately 10 meters

from the shoreline. We collected 5 gallons of

seawater (equivalent to 5 × 3.78 Liters) and passed

it through a lter cloth to eliminate impurities,

such as seagrass and sand. The ltered samples

were then s tored in a sample container at room

temperature to maintain their integrity for further

laboratory analysis.

2.3. Synthesis of TiO2-NPs–incorporated

Chitosan membranes

In this s tudy, 2 grams of CA and 0.5 grams of PEG

were mixed in a 50 mL beaker and followed by

adding 2 mL of chitosan and 17 mL of an acetone

solvent. The media was s tirred cons tantly at 130°C

until homogeneous for 24 h. After obtaining a

homogeneous solution, it was printed on a at glass

plate for 15 minutes. The membrane layer dries

slightly, followed by TiO2-NPs colloidal coating

according to the coating variation by coating evenly

on the membrane surface. The media was allowed

to dry for 64 hours in a s terile room. After that, to

release the membrane that has dried on the surface

of the glass plate, the method is to soak the media

in cold water for 15 minutes. The membrane is

ready for use in the reverse osmosis method design

tool with UV light emission.

2.4. Membrane material characterization

The TiO2 incorporated in chitosan membranes was

characterized to conrm the presence of TiO2 in chitosan

membranes. The functional group was conrmed

using FTIR spectra (Shimadzu, IR Pres tige 21) to

identify inorganic materials (Ti-O-Ti). Morphological

analysis was also conducted using Scanning Electron

Microscopy (SEM) (FEI, Inspect-S50) to observe the

porosity of synthesized membranes, and crys tallinity

was inves tigated using X-ray diraction (XRD, PAN

anlytical X’Pert PRO) to determine the crys tallinity of

a material.

2.5. Reverse osmosis tes t

The synthesized membranes were assessed for their

performance in a desalination process utilizing the

reverse osmosis (RO) technique. The portable design

of the reverse osmosis pilot ins trument (Fig. 1)

involves introducing feed water into a s torage tank,

which is then pumped into a pretreatment sys tem

incorporating ltering materials such as sand, palm

bre, s tone, and charcoal. Subsequently, seawater is

directed into a horizontal tank equipped with vertically

positioned synthetic membranes and subjected to

UV light exposure. Excess water is returned to the

pretreatment process, while the remainder passes

through the membranes and is collected in a permeate

container. The permeate was subsequently tes ted

to evaluate membrane performance parameters,

including salt rejection, water ux, pH, and salinity.

3. Results and Discussion

This s tudy aims to overview the eect of the surface

coating method on TiO2-NPs incorporated chitosan

membrane. In Figure 1, we modelled desalination

technology engineering to observe the performance

of TiO2-NPs-chitosan membrane in reverse osmosis

(RO) sys tem. Schematically, the feed water is

owed and passed through a pretreatment material

consis ting of activated carbon. A pressurized pump

passes the feed water from the pretreatment through

the membrane with UV light to see the photocatalys t

performance of the membrane containing TiO2-

NPs. The membrane fabrication, characterization,

and performance tes ts were identied to determine

the well-oriented performance membrane, such as

identifying ux and salinity values.

The synthesized membrane has been fabricated with

a coating process using TiO2-NPs of 0.25 g and 0.50

g. The simple membrane fabrication was conducted

by inverse technique, in which the mixed solution

was evaporated on a glass plate for 64 h. The organic

solution also plays an essential role in accelerating

the evaporation process to obtain a high permeability

and resis tance to hydrophilic properties, making it

easily soluble in water [27]. The organic solvent

(acetone) was chosen in this s tudy because it is

environmentally friendly for plas tic, pharmaceutical,

and paper fabrication. Moreover, acetone can reduce

the boiling point so the membranes can quickly be

dried. In this s tudy, the fabricated membranes have

been printed with a diameter size of 8 cm, which

Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18

Fig. 1. Schematic of reverse osmosis desalination

helps determine the membrane’s performance for

water ux. Several s tudies have also reported that the

addition of TiO2-NPs to organic membranes that have

been developed can improve the hydrophilicity and

selectivity properties expected for high membrane

permeability ux. Herein, we present the fabrication

of the chitosan membrane by showing the unique

characterization membranes incorporated into TiO2-

NPs using FTIR, SEM, and XRD. They are the basics

for material characterization for an overview of a

functional group of Ti-O-Ti bonds, morphological

analysis of fabricated membranes incorporated TiO2-

NPs and crys tallinity. Besides that, performance

tes ts over fabricated membranes were also reported,

including salt rejection, water ux, pH, and salinity.

All tes ts will be explained in detail below.

3.1. Membranes characterization

3.1.1.Fourier transform infrared spectroscopy

(FTIR)

The identication of functional groups has been

applied using FTIR analysis to identify the chemical

compound groups presented in the fabricated

membranes. Raw material based on CA, PEG, as

basic membranes, and chitosan contains organic

compounds that are easily identied using FTIR.

Meanwhile, the TiO2-NPs are also placed in

ngerprint regions under 750-400 nm [28]. The

organic functional group is bonded with -OH

s tretching aected by water, alcohol specimens, and

acidic conditions or organic oxidation. The presence

of the -OH group in membranes characterizes

the hydrophilicity value over membranes. The

polarization functional group from OH attracts the

attention of polar groups that bind together in several

chemical positions [29]. The hydrophilicity value can

be calculated using the peak area from -OH groups

in the FTIR graph using the origin application.

Based on Figure 2, the FTIR spectra for each

fabricated membrane are shown by varying

composition and without adding TiO2-NPs. The

specic absorption on wavenumber of 3479-3549

cm-1 is presented of -OH groups from cellulose

acetate that have -OH bonds outside the aromatic

ring. The C=O (es ter) group was presented under

the wavenumber of 1755-1757 cm-1, and the -CH

group was marked on 2887-2889 cm-1. In addition,

the -CH3 group is also shown on 1433-1436 cm-1

and the -NH2 group on wavenumber of 1527-

1544 cm-1. The Ti-O-Ti group was identied in

the specic wavenumber range of 850-500 cm-1,

identied with widened absorption.

Chitosan polymer membrane for seawater desalination Muhammad Nurdin et al

Fig. 2. FTIR spectra of the fabricated membranes, (a) Chitosan polymer membrane,

(b) Chitosan–TiO2-NPs (I: 0.25 g), and (c) Chitosan–TiO2-NPs (II: 0.50 g)

Meanwhile, 871-877 cm-1 wavenumber indicated

a pyranose ring (CA), and 1250-1257 cm-1

presented C-O-C s tretching from cellulose acetate.

Referring to Figure 2, the fabricated membranes

have chemically shown -OH, C=O, C-O, -CH

-CH3, NH2, and C-O-C groups. The functional

groups -OH, C-O, C=O, and C-O-C are the

main functional groups of CA. Particularly, the

wavenumber characteris tics could be identied,

such that the peak area of the -OH group was

increased along with the addition of TiO2-

NPs. This condition indicates an increase in

hydrophilicity in the fabricated membrane. The

highly increased number of hydroxyl groups also

plays a role in photocatalys t and hydrophilicity

performances. Based on Figure 1, the principle of

RO performance agains t the fabricated membrane

is irradiating under UV light for 30 minutes to

activate the performance of TiO2-NPs attached to

the membrane surface. In addition, the atomic mass

eect of TiO2-NPs is expressed using Hooke’s

law equation, where the more signicant the

mass of interacting atoms indicates, the lower the

vibrational frequency to a smaller wavenumber.

3.1.2.Scanning Electron Microscopy (SEM)

SEM identication is frequently used as an

analytical method to determine the morphological

s tructure of fabricated membranes. The typical

s tructure on the membrane area illus trates

the dierence of membrane surface agains t

incorporated TiO2-NPs. Based on SEM analysis,

Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18

Fig. 3. Morphological analysis of fabricated membranes;

(a) Chitosan polymer membrane [27], (b) Chitosan-TiO2 (I) (0.25 g), and (c) Chitosan-TiO2 (II) (0.5 g)

40 µm

5 µm

40 µm

2 µm

40 µm

indentations and protrusions of the fracture surface

were also generated, and the enlargement of the

pores in the fabricated membrane was observed.

Figure 3 shows a typical morphological analysis of

the fabricated membrane; it shows the dierence

in morphological s tructure between without and

the addition of TiO2-NPs. Figure 3a shows that

the variable chitosan polymer membrane without

TiO2-NPs has irregular pores compared to Figures

3b and 3c. The inclusion of TiO2-NPs is reected

in a reduction in pore size, particularly at higher

TiO2 concentrations. The solvent exchange process

inuences the formation of membrane pores

during membrane synthesis, which facilitates the

entry of TiO2-NPs into the lattice of membrane

pores. Additionally, the incorporation of TiO2-NPs

results in a decrease in pore size due to the small

particle size of TiO2, which attracts particles into

the membrane pores. PEG also plays a crucial

role in s tandardizing and increasing the number

of membrane pores. Using acetone as a solvent

leads to a delayed demixing mechanism, creating

tighter pores. To assess the pore size dis tribution

of the fabricated membranes, Figure 4 presents our

calculations. In Figure 4a, the average pore size is

approximately 800 nm; in Figure 4b, it is around

500 nm, and in Figure 4c, it is roughly 200 nm.

These peaks represent the average pore size of

each membrane. The larges t peaks are observed

when TiO2-NPs are not added, while the smalles t

pore size is seen when 0.5 grams of TiO2-NPs

are added. This aligns with the morphological

Particle size (nm)

Counts

Average Particle Size 200 nm

Particle size (nm)

Counts

aAverage Particle Size 800 nm

Particle size (nm)

Counts

bAverage Particle Size 500 nm

Chitosan polymer membrane for seawater desalination Muhammad Nurdin et al

Fig. 4. His togram of the particle size dis tribution of fabricated membranes,

(a) Chitosan polymer membrane, (b) Chitosan–TiO2-NPs (I), (c) Chitosan–TiO2-NPs (II).

analysis, indicating that adding TiO2 further

reduces membrane pore size. As per Dietz et al., the

typical range of membrane pore sizes formed falls

within 100 nm to 10,000 nm, categorizing them as

microltration membranes [30].

3.1.3. X-ray diffraction (XRD)

The crys tallinity phase is also identied to analyze

the fabricated membrane, including the composition

or type of crys tals formed, such as amorphous,

semicrys talline, or crys talline. Generally, the TiO2

phase has three crys tals formed: anatase, rutile, and

brookite types. In Figure 5, the fabricated membrane

includes an amorphous phase with no sharp peaks.

High absorption peaks at two theta 25.49° (type

I: 0.25 g TiO2) and 25.84° (type II: 0.50 g TiO2)

correspond to the peaks belonging to the anatase

phase based on JCPDS No. 21-1276. The same peak

was also shown without adding TiO2 at two theta of

22.95°. This was identied from the crys tallinity

of the chitosan polymer membrane. Based on

particle size analysis, the average particle size of

TiO2 in chitosan-TiO2-NPs (I) and chitosan-TiO2-

NPs (II) were 2.92 nm and 2.97 nm, respectively

These conditions were expressed that the TiO2 was

quickly inserted into the membrane pore lattice to

s trengthen the s tructure and reduce the membrane

pores. In addition, a lower crys talline nature or

higher amorphous s tructure coincides with the

decrease of polymer chain packing and will result

in higher permeability performance.

3.2. Reverse osmosis tes t

3.2.1.Determination of water flux and salt

rejection

Before the analysis of water ux, the water

compaction in the RO sys tem was conducted to

achieve a uniform s tructure with s teady water ux.

This condition has been performed using a high-

pressure pump in the RO sys tem to remove the air

trapped inside the ins tallation. The compaction of

water pressure results in changes in the membrane

position. However, the water pressure in this

s tudy was 68 bar above an osmosis pressure for

Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18

Chitosan-TiO2-NPs (II)

Chitosan-TiO2-NPs (I)

Chitosan polymer

membrane

Intensity (a.u.)

2 theta

Fig. 5. XRD pattern of fabricated membranes

60 minutes. The fabricated membrane showed an

almos t cons tant decrease with the addition of TiO2-

NPs, and RO tes ting for 60 min of operation has

conrmed that the permeate production is very

minimal due to the tiny membrane pores (Fig. 6a).

The TiO2 plays an essential role in the porosity

and selectivity of the fabricated membranes, this

condition makes the membrane pores tighter.

The slow ux reduction can be associated with

the porosity and s trength of the membrane. The

compaction results in a denser membrane s tructure,

which minimizes the water ux.

Salt rejection was also identied to determine the

salt content in the permeate. A desalination tes t was

carried out with the RO sys tem by comparing salt

concentration results to permeate water with feed

water whose units refer to the percentage of salt

rejected. Based on the analytical results in Figure

6b, salt rejection increases with the addition of TiO2-

NPs. This graph is inversely proportional to the water

ux. It has been discovered that such ne-regulation

of the polymer microporous s tructure leads to a

crucial increase in the salt rejection of the chitosan-

TiO2 (II) membrane towards high-performance RO

desalination [16]. Based on the salt rejection results,

adding 0.5 grams of TiO2 can increase salt rejection

with a value of 52.94% following the morphological

analysis that the membrane pore size aects salt

rejection in RO desalination.

3.2.2. Determination of pH and salt contents

Water quality (pH) based on chemical properties

is also analyzed using a pH meter to determine

acidity or alkaline salt content. In general, the pH

of seawater varies depending on the location of

the collection area, with a range of pH conditions

between 6.0 and 8.5. The feed water comes from

Southeas t Sulawesi Province, Indonesia, with a pH

of 7.7. We determined the pH level to observe if

the RO desalination process of seawater inuences

changes in pH value. Fluctuations also aect the

high and low pH of the feed water in terms of the

levels of O2 and CO2 dissolved in the feed water.

Based on the analysis results (Figure 7a), the pH

measurement results decrease along with the

increase in TiO2 addition to the membrane; although

this condition is not too signicant, it shows there

is little change.

Furthermore, the surface potentials of the

membranes produced exhibit negativity when

the pH is above 7 and 6. This negativity signies

a subs tantial electros tatic repulsion between the

negatively charged membrane surface and the

Cl¯ ions at higher pH levels [31]. As a result,

the desalination process led to a reduction in salt

Chitosan polymer membrane for seawater desalination Muhammad Nurdin et al

Fig. 6. Membranes performance tes ts, (a) water ux and (b) salt rejection

Fabricated membranes

Flux (L/m

Pretreatment Chitosan

polymer

membrane

Chitosan-

TiO

(I)

Chitosan-

TiO

(II)

Fabricated membranes

% Salt rejection

Pretreatment Chitosan

polymer

membrane

Chitosan-

TiO2(I)

Chitosan-

TiO2(II)

levels of over 53%. These ndings are consis tent

with earlier s tudies that have reported similar data

regarding the incorporation of TiO2 into CA-PEG

membranes [31]. The results of salt content by three

RO membranes at dierent TiO2-NP concentrations

are shown in Figure 7b. The experiment was

conducted using a refractometer ins trument to

identify the measured salt concentration of the feed

water. This was calculated based on the percentage

of salt content before and after the RO desalination

process. Generally, salinity is dened as the salt

content at which the salt level in aqueous solutions

and some seawater have unequal salinity values. In

this case, the salinity of pure seawater on Southeas t

Sulawesi beach ranges from 34 ppt. Based on

Figure 7b, there is a decrease in salt content in

permeate water that passes through each fabricated

membrane. The feed water passed the pretreatment

process and decreased the salt content to 27 ppt.

This indicates that the pretreatment process

containing sand, palm bre, activated charcoal, and

lter paper contributes to a decrease in salt content

by 20.5%. This was followed by a membrane

without TiO2 addition, which reduced 26% (20 ppt)

from the pretreatment process. Furthermore, the

performance comparison of the membrane with the

addition of TiO2 0.25 g and 0.5 g showed a decrease

in the percentage of salt content by 37% (17 ppt)

and 41% (16 ppt), respectively. From the results of

this s tudy, it can be concluded that increasing the

composition of TiO2 as an agent of permeability

and selectivity of chitosan membrane has a high

eect in changing the salt content in seawater.

Numerous research s tudies imply that TiO2-NPs

alter water ux and rejection performance, as shown

in Table 1[27,32-35]. All s tudies using the phase

inversion method (NIPS) and solution cas ting to

fabricate RO membranes incorporated with TiO2-

NPs have produced dierent ux and salt rejection

results. The addition of TiO2 resulted in an increase

in total salt rejection followed by ux values. This

condition implies that the TiO2-modied membrane

aects the porosity of the membrane, which also

acts the performance. When the average pore size

increases, the CA-TiO2 membrane becomes more

porous.

4. Conclusion

The proposed method introduced TiO2-NPs into

chitosan membranes to enhance permeability

and selectivity performance for reverse osmosis

(RO) desalination. It was incorporated into

Fig. 7. Membranes performance tes ts, (a) pH and (b) salt content

Fabricated membranes

Pretreat

ment Chitosan

polymer

membrane

Chitosan-

TiO

(I)

Chitosan-

TiO

(II)

Seawater

7.85 7.77 7.68 7.66 7.65

Fabricated membranes

Salt Content (ppt)

Pretreat

ment

Chitosan

polymer

membrane

Chitosan-

TiO

(I)

Chitosan-

TiO

(II)

Seawater

Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18

chitosan membranes using the surface coating

method, with varying TiO2 mass fractions

of 0.25 grams and 0.50 grams. The physical

characterization of the fabricated membranes

revealed functional groups representing organic

and inorganic compounds. Additionally, TiO2-

NPs were identied within the wavenumber

range of 850-500 cm-1, indicating the presence of

Ti-O-Ti bonds. Morphological analysis exhibits

the TiO2-NPs led to signicantly smaller pores

in chitosan membranes due to their contribution

to the amorphous phase s tructure. During the

RO desalination process, the performance of

the fabricated membranes was assessed in terms

of water ux and salt rejection. The addition of

TiO2-NPs resulted in a 23 Lm-2 h-1 decrease in

water ux and a 52.94% increase in salt rejection.

Furthermore, the pH and salt content values

were measured, indicating a reduction under

favourable conditions. TiO2 played a crucial role

as a permeability and selectivity enhancer within

the TiO2-chitosan membranes, signicantly

reducing salt content in seawater.

5. Acknowledgments

Financial support from the Minis try of Education,

Culture, Research, and Technology, Republic of

Indonesia, is gratefully acknowledged for basic

research grant no. 51/UN29.20/PG/2023 and

World Class Professor research grant no. 3252/E4/

DT.04.03/2023. Department of Chemis try, Faculty

of Mathematics and Natural Sciences, Halu Oleo

University, and Photocatalysis Laboratory for

facilitating this research.

6. References

[1] P.H. Nienhuis, J. Coosen, W. Kiswara,

Community s tructure and biomass

dis tribution of seagrasses and macrofauna

in the Flores Sea, Indonesia, Netherlands

J. Sea Res., 23 (1989) 197–214. https://doi.

org/10.1016/0077-7579(89)90014-8.

[2] E. Has tuti, M.W. Wardiha, A s tudy of

brackish water membrane with ultraltration

pretreatment in indonesia’s coas tal area, J.

Urban Environ. Eng., 6 (2012) 10–17. https://

doi.org/10.4090/juee.2012.v6n1.010017.

Table 1. Comparison between previous and current s tudies

Polymer composition NPs Methods Flux

(LMH) Pollutant Rejection % Ref.

Cellulose acetate / polyethylene-

glycol / chitosan TiO2

Phase inversion method

(NIPS) and cas ting

solution

50.00 Salt 61.76 [27]

Polyvinyl alcohol /

cellulose acetate TiO2

Phase inversion method

(NIPS) and cas ting

solution

15.50 Salt 92 [32]

Cellulose acetate TiO2

Phase inversion method

(NIPS) and cas ting

solution

58.21 Salt 92.6 [33]

Polyvinylpyrrolidone

/ N-methyl pyrrolidone TiO2

Phase inversion method

(NIPS) and cas ting

solution

34.3 Salt - [34]

Polyamide/carbon dots TiO2

Phase inversion method

(NIPS) and cas ting

solution

54.6 Salt 99.2 [35]

Chitosan/cellulose acetate /

polyethylene-glycol TiO2

Phase inversion method

(NIPS) and cas ting

solution

23 Salt 52.94 This

work

Chitosan polymer membrane for seawater desalination Muhammad Nurdin et al

[3] S. Han, Y.-W. Rhee, S.-P. Kang, Inves tigation

of salt removal using cyclopentane hydrate

formation and washing treatment for

seawater desalination, Desalination, 404

(2017) 132–137. https://doi.org/10.1016/j.

desal.2016.11.016.

[4] S. Timoori, Environmental Health: Evaluation

of heavy metals pollution in Isfahan indus trial

zone from soils, well/eluent waters and was te

water by microwave-electro-thermal atomic

absorption spectrometry, Anal. Methods

Environ. Chem. J., 2 (2019) 55–62. https://

doi.org/10.24200/amecj.v2.i01.44.

[5] B. Suhartawan, J. Haurissa, S.A. Rumawak,

Lake Sentani water quality index based on

NSF-WQI as raw water for drinking water

for Lake Sentani Coas tal communities,

Jayapura Regency, J. Syntax Admiration, 3

(2022) 1189–1204. https://doi.org/10.46799/

jsa.v3i9.481.

[6] K. Katsanou, H.K. Karapanagioti, Surface

water and groundwater sources for drinking

water, Appl. Adv. Oxid. Process. Drink.

Water Treat., (2019) 1–19. https://doi.

org/10.1007/698_2017_140.

[7] S.H. Mutasher, H.S. Al-Lami, Preparation

of chitosan lms plas ticized by lauric and

maleic acids, Anal. Methods Environ. Chem.

J., 5 (2022) 43–54. https://doi.org/10.24200/

amecj.v5.i04.209.

[8] Y. Cai, J. Wu, S.Q. Shi, J. Li, K.-H. Kim,

Advances in desalination technology and its

environmental and economic assessment, J.

Clean. Prod., 397 (2023) 136498. https://doi.

org/10.1016/j.jclepro.2023.136498.

[9] A.M. Ghaithan, A. Mohammed, L. Hadidi,

Assessment of integrating solar energy with

reverse osmosis desalination, Sus tain. Energy

Technol. Assessments, 53 (2022) 102740.

https://doi.org/10.1016/j.seta.2022.102740.

[10] A. Hassanzadeh, B. Amirheidari, A. Salarifar,

A. Asadipour, Y. Pourshojaei, Synthesis and

identication of meta-(4-bromobenzyloxy)

benzaldehyde thiosemicarbazone (MBBOTSC)

as novel ligand for cadmium extraction by

ultrasound assis ted-dispersive-ionic liquid-

liquid micro extraction method, Anal.

Methods Environ. Chem. J., 4 (2021) 92–106.

https://doi.org/10.24200/amecj.v4.i04.161.

[11] A.B.D.N. Kurnia, R. Ismiati, A. Annisa,

F. Finandia, N.N.A. Nissa, R.C. Dewi,

Economic evaluation analysis of nano-silica

ultraltration membrane production from

sand, Int. J. Energ., 3 (2018) 6–9. https://doi.

org/10.47238/ijeca.v3i1.59.

[12] A. Knebel, J. Caro, Metal–organic

frameworks and covalent organic frameworks

as disruptive membrane materials for energy-

ecient gas separation, Nat. Nanotechnol.,

17 (2022) 911–923. https://doi.org/10.1038/

s41565-022-01168-3.

[13] V. Vatanpour, M.E. Pasaoglu, H. Barzegar,

O.O. Teber, R. Kaya, M. Bas tug, A. Khataee,

I. Koyuncu, Cellulose acetate in fabrication

of polymeric membranes: A review,

Chemosphere, 295 (2022) 133914. https://doi.

org/10.1016/j.chemosphere.2022.133914.

[14] I. Ouni, Y. Guesmi, C. Ursino, R. Cas tro-

Muñoz, H. Agougui, M. Jabli, A. Haane,

A. Figoli, E. Ferjani, Synthesis and

characterization of a thin-lm composite

nanoltration membrane based on polyamide-

cellulose acetate: application for water

purication, J. Polym. Environ., 30 (2022)

707–718. https://doi.org/10.1007/s10924-021-

02233-z

[15] Y. Yamashita, T. Endo, Deterioration behavior

of cellulose acetate lms in acidic or basic

aqueous solutions, J. Appl. Polym. Sci., 91

(2004) 3354–3361. https://doi.org/10.1002/

app.13547.

[16] Y. Yang, Z. Wang, Z. Song, D. Liu, J.

Zhang, L. Guo, W. Fang, J. Jin, Thermal

treated amidoxime modied polymer

of intrinsic microporosity (AOPIM-1)

membranes for high permselectivity reverse

osmosis desalination, Desalination, 551

(2023) 116413. https://doi.org/10.1016/j.

desal.2023.116413.

[17] S. Yang, R. Tang, Y. Dai, T. Wang, Z. Zeng,

Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18

L. Zhang, Fabrication of cellulose acetate

membrane with advanced ultraltration

performances and antibacterial properties

by blending with HKUS t-1@ LCNFs, Sep.

Purif. Technol., 279 (2021) 119524. https://

doi.org/10.1016/j.seppur.2021.119524.

[18] S. Hasheminasab, J. Barzin, R. Dehghan, High-

performance hemodialysis membrane: Inuence

of polyethylene glycol and polyvinylpyrrolidone

in the polyethersulfone membrane, J. Membr.

Sci. Res., 6 (2020) 438–448. https://doi.

org/10.22079/JMSR.2020.128323.1391.

[19] L. Qi, R. Liang, T. Jiang, W. Qin, Anti-

fouling polymeric membrane ion-selective

electrodes, TrAC Trends Anal. Chem., 150

(2022) 116572. https://doi.org/10.1016/j.

trac.2022.116572.

[20] M. Chaudhary, A. Maiti, Fe–Al–Mn@

chitosan based metal oxides blended cellulose

acetate mixed matrix membrane for uoride

decontamination from water: removal

mechanisms and antibacterial behavior, J.

Memb. Sci., 611 (2020) 118372. https://doi.

org/10.1016/j.memsci.2020.118372.

[21] P.S. Bakshi, D. Selvakumar, K. Kadirvelu,

N.S. Kumar, Chitosan as an environment

friendly biomaterial–a review on recent

modications and applications, Int. J. Biol.

Macromol., 150 (2020) 1072–1083. https://

doi.org/10.1016/j.ijbiomac.2019.10.113.

[22] M. Nurdin, D. Wibowo, T. Azis, R.A.

Satri, M. Maulidiyah, A. Mahmud, F.

Mus tapa, R. Ruslan, A. Salim, L. Ode,

Photoelectrocatalysis response with synthetic

Mn–N–TiO2/Ti electrode for removal

of rhodamine B dye, Surf. Eng. Appl.

Electrochem., 58 (2022) 125–134. https://

doi.org/10.3103/S1068375522020077.

[23] D. Wibowo, M.Z. Muzakkar, M. Maulidiyah,

M. Nurdin, S.K.M. Saad, A.A. Umar,

Morphological analysis of Ag doped on

TiO2/Ti prepared via anodizing and thermal

oxidation methods, Biointerface Res. Appl.

Chem., 12 (2022) 1421–1437. https://doi.

org/10.33263/BRIAC122.14211427.

[24] M. Natsir, M. Maulidiyah, A. Ansharullah,

Z. Arham, D. Wibowo, M. Nurdin, Natural

biopeicide preparation as antimicrobial

material based on lignin photodegradation

using mineral ilmenite (FeoTio2), Int. Res.

J. Pharm., 9 (2018) 170–174. https://doi.

org/10.7897/2230-8407.096111.

[25] M. Nurdin, N. Dali, I. Irwan, M. Maulidiyah,

Z. Arham, R. Ruslan, B. Hamzah, S. Sarjuna,

D. Wibowo, Selectivity determination of

Pb2+ Ion based on TiO2-Ionophores BEK6

as carbon pae electrode composite, Anal.

Bioanal. Electrochem., 10 (2018) 1538–

1547. https://doi.org/-.

[26] D. Wibowo, M.Z. Muzakkar, S.K.M. Saad,

F. Mus tapa, M. Maulidiyah, M. Nurdin,

A.A. Umar, Enhanced visible light-driven

photocatalytic degradation supported by Au-

TiO<inf>2</inf> coral-needle nanoparticles,

J. Photochem. Photobiol. A Chem., 398

(2020) 112589. https://doi.org/10.1016/j.

jphotochem.2020.112589.

[27] D. Wibowo, F. Mus tapa, S. Selviantori, M.

Idris, A. Mahmud, M. Maulidiyah, M.Z.

Muzakkar, A.A. Umar, M. Nurdin, CA/

PEG/Chitosan membrane incorporated

with TiO2 nanoparticles for s trengthening

and permselectivity membrane for reverse

osmosis desalination, Environ. Nanotechnol.

Monit. Manag., 20 (2023) 100848. https://

doi.org/10.1016/j.enmm.2023.100848.

[28] S. Chelbi, D. Djouadi, A. Chelouche, L.

Hammiche, T. Touam, A. Doghmane, Eects

of Ti-precursor concentration and annealing

temperature on s tructural and morphological

properties of TiO 2 nano-aerogels synthesized

in supercritical ethanol, SN Appl. Sci., 2

(2020) 1–10. https://doi.org/10.1007/s42452-

020-2633-3.

[29] Y.-H. Chiao, A. Sengupta, S.-T. Chen, S.-

H. Huang, C.-C. Hu, W.-S. Hung, Y. Chang,

X. Qian, S.R. Wickramasinghe, K.-R. Lee,

Zwitterion augmented polyamide membrane

for improved forward osmosis performance

with signicant antifouling characteris tics,

Chitosan polymer membrane for seawater desalination Muhammad Nurdin et al

Sep. Purif. Technol., 212 (2019) 316–325.

https://doi.org/10.1016/j.seppur.2018.09.079.

[30] P. Dietz, P.K. Hansma, O. Inacker, H.-

D. Lehmann, K.-H. Herrmann, Surface

pore s tructures of micro-and ultraltration

membranes imaged with the atomic force

microscope, J. Memb. Sci., 65 (1992)

101–111. https://doi.org/10.1016/0376-

7388(92)87057-5.

[31] M.H. Oo, L. Song, Eect of pH and ionic

s trength on boron removal by RO membranes,

Desalination, 246 (2009) 605–612. https://

doi.org/10.1016/j.desal.2008.06.025.

[32] E.S. Mansor, H. Abdallah, A.M. Shaban,

Development of TiO2/polyvinyl alcohol-

cellulose acetate nanocomposite reverse

osmosis membrane for groundwater-surface

water interfaces purication, Mater. Sci.

Eng. B, 289 (2023) 116222. https://doi.

org/10.1016/j.mseb.2022.116222.

[33] H. Jain, A.K. Verma, R. Dhupper, S.

Wadhwa, M.C. Garg, Development of CA-

TiO2-incorporated thin-lm nanocomposite

forward osmosis membrane for enhanced

water ux and salt rejection, Int. J. Environ.

Sci. Technol., 19 (2022) 5387–5400. https://

doi.org/10.1007/s13762-021-03415-x.

[34] A.H. Konsowa, H.Z. AbdAllah, S. Nosier,

M.G. Eloy, Thin-lm nanocomposite

forward osmosis membrane for water

desalination: synthesis, characterization and

performance improvement, Water Qual. Res.

J., 57 (2022) 72–90. https://doi.org/10.2166/

wqrj.2022.034.

[35] V. Vatanpour, S. Paziresh, S.A.N. Mehrabani,

S. Feizpoor, A. Habibi-Yangjeh, I. Koyuncu,

TiO2/CDs modied thin-lm nanocomposite

polyamide membrane for simultaneous

enhancement of antifouling and chlorine-

resis tance performance, Desalination, 525

(2022) 115506. https://doi.org/10.1016/j.

desal.2021.115506.

Anal. Methods Environ. Chem. J. 6 (4) (2023) 5-18