A Combination of Waste Biomass Activated Carbon and Nylon Nanofiber for Removal of Triclosan from Aqueous Solutions

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1036-1045

J. Environ. Treat. Tech.

ISSN: 2309-1185

Journal web link: http://www.jett.dormaj.com

https://doi.org/10.47277/jett-8(3)1

A Combination of Waste Biomass Activated Carbon

and Nylon Nanofiber for Removal of Triclosan from

Aqueous Solutions

1,2

Nor Khoriha Eliysa Mohd Khori , Salmiati *, Tony Hadibarata , Zulkifli Yusop

Department of Water and Environmental Engineering, School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310 Skudai,

Johor, Malaysia.

Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi

Malaysia, 81310 Skudai, Johor, Malaysia.

Department of Environmental Engineering, Faculty of Engineering and Science, Curtin University, Malaysia, CDT 250, 98009 Miri Sarawak, Malaysia

Received: 25/03/2020

Accepted: 26/06/2020

Published: 20/09/2020

Abstract

Triclosan (TCS) is one of the biocide used as antibacterial and antifungal agent to kill and hinder the growth of bacteria and also it is

used in many personal care and health care products. However, TCS can cause health and environmental problems such as environmental

pollutions, acute toxicity, etc. The aim of this study is to investigate the removal of TCS from aqueous solution by combining the coconut

pulp waste (Cocos nuciefera) activated carbon (AC) with nylon 6,6 membrane. To this end, first, the effects of physico-chemical

characteristics of the membrane were studied. The nylon 6,6 membrane (14 wt.%] was prepared using electrospinning machine with injection

rate at 0.4 mL/h, tip-to-collector distance at 15 cm, rotation speed at 1000 rpm, and applied voltage at 26 kV. The parameters studied for the

membrane during the adsorption test were contact time, adsorbent dosage, agitation speed, initial TCS concentration, pH, and temperature of

the TCS solution. The filtration test was done using flat sheet membrane test machine at pressure 1.0 bar. The characteristics of the membrane

were analysed using the FESEM and FTIR tests. Based on the obtained results, the nylon 6,6 membrane can remove 90.2% of TCS within 5

minutes; the removal rate increased to 100% in less than 5 minutes after the membrane was combined with AC. This study proved that the

combination of AC and nylon 6,6 membrane is able to maximize the TCS removal from water.

Keywords: Triclosan; Activated carbon; Coconut pulp waste; Nylon 6,6 membrane

_m_e_n_w_i_t_h_c_o_n_c_e_n_t_r_a_t_i_o_n_s_f_r_o_m₀_.₄₁_t_o₂_.₉₅_n_g₍_m_g_c_r_e_a_t_i_n_i_n_e₎-1

Introduction

and it caused some adverse effects to the semen quality such as

low sperm production and poor forward mobility. Moreover, TCS

has a high bioaccumulation potential and it can enter the food web

system [4]. TCS can also cause toxicity to some aquatic life

species such as algae, planktons, fishes, and frogs [5-10].

Therefore, several treatment methods have been implemented

to remove TCS from the water, including those using cellulose

acetate (CA) membrane [11], ammonia amendment and

bioaugmentation in nitrifying activated sludge [12], dielectric

barrier discharge plasma combined with activated carbon fibers

Triclosan (TCS) (5-chloro-2-(2,4-dichlorophenoxy) phenol) is

a chlorinated aromatic compound with the molecular formula

Cl and molecular weight of 289.54 g/mol. This organic

3 2

compound, in the form of white powders, has functional groups

of both ethers and phenols. Triclosan is one of the antibacterial

and antifungal agents that are normally used in medical and

consumer products, such as surgical scrubs, toothpastes, hand

wash soaps, mouthwash, shampoos, plastics, toys, textiles, and

deodorants [1]. It has the ability to hinder the growth of

microorganisms, and due to its presence in many consumer

products, it has been detected in most of the sediments, biosolids,

surface water, soil, and aquatic species [2].

[13], structure-directing agent modified mesoporous MIL-53 (Al)

[14], dissolved organic matter on soybean peroxidase-mediated

[15], ozonation [16], and microalgal species [17]. However, these

Though TCS is an antibacterial agent, it also poses a potential

risk to the human health and the environment. Zhu et al. [3]

reported that TCS was detected in 97% of urine samples of 471

treatments involved complex procedures, high costs of treatments

and maintenance, large volumes of chemicals, and long

Corresponding author: Salmiati, (a) Department of Water and Environmental Engineering, School of Civil Engineering, Faculty of

Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. (b) Centre for Environmental Sustainability and Water Security

(

IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia.

Department of Environmental Engineering, Faculty of Engineering and Science, Curtin University, Malaysia, CDT 250, 98009 Miri

Sarawak, Malaysia. Email: salmiati@utm.my.

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1036-1045

processing times [18].

Materials and Methods

In recent years, the adsorption process has been one of the

popular methods applied to remove chemicals and dyes in water

and wastewater treatments due to its advantages of having less

processing procedures with less sludge being produced. Several

adsorption studies to remove TCS were done using rice straw-

derived activated carbon [19], charcoal-based activated carbon

.1 Chemical

In this study, the following chemicals were used: TCS and

acetic acid that were supplied by Merck KGaA (Darmstadt,

Germany), Tween 80 supplied by Sigma-Aldrich, ethanol 96%

obtained from Qrecᵀᴹ (Malaysia), Nylon 6,6 (polyamide 6,6)

pellets supplied by DSM Co. (Netherlands), and formic acid

supplied by HmbG Chemicals (Barcelona, Spain). The coconut

pulp waste activated carbon was prepared during the preliminary

study [45]. The physical and chemical characteristics of TCS and

nylon 6,6 are shown in Table 1.

[20], conventional activated carbon [21], civilian protective gas

mask activated carbon [22], magnetic carbon composites from

hydrochar [23], and wastewater biosolids-derived biochar [24].

High surface areas, micro-porous structures, and high degrees of

surface reactivity cause activated carbons to become versatile

adsorbents, particularly effective for the adsorption of organic and

inorganic pollutants from aqueous solutions [25].

Table 1: Physico-chemical characteristics of TCS and nylon 6,6

TCS

Nylon 6,6

However, the preparation of commercial activated carbons is a

costly activity, which has encouraged researchers to search for

low-cost materials as alternatives [26]. There are many types of

natural wastes used as low-cost adsorbents such as human hair,

sheep wool, cane bagasse, and many more [27, 28]. Among all,

agricultural wastes are one of the promising sources as they are

inexpensive, easy to collect, and environmentally friendly [29].

Furthermore, they have a high efficiency in trapping and

removing chemicals and dyes from water due to possessing many

functional groups such as alcohols, phenolic, amido, amino,

carboxyl, carbonyl, and ester [30]. The agricultural wastes from

coconut trees have become one of the promising materials to be

used as adsorbents due to their abundance in nature, cheaper price,

high porous structures, and high absorption capability. The

coconut tree parts commonly used as adsorbents are the bunch

Chemical

structure

Poly[imino(1,6-

dioxohexamethylene)

iminohexamethylene]

White pellets

-chloro-2-(2,4-

IUPAC name

dichlorophenoxy)phenol

Appearance

Physical state

Molecular weight

Chemical

White solid

Solid

262.3458 g mol

-1

289.54 g·mol⁻¹

12 22 2 2

C H N O

formula

ethanol, methanol,

diethyl ether, strongly

basic solutions, and

Soluble in acid, slightly

soluble in boiling water

Solubility

slightly soluble in water

(10mg/L at 20˚C)

[29], frond [31], pulp waste [32], husk [33], coir [34], leaves [35],

Melting point

55-57 °C

255-265 °C

and shell [36].

In addition, membrane is one of the technologies used for

removal of various chemicals and pollutants from water. This

advanced, well-known treatment technology has become one of

the most preferred options for water and wastewater treatments in

food industries, chemical industries, and pharmaceutical

industries [37-39]. Such popularity of membrane treatment is

because of many advantages such as no addition of chemicals

required, no secondary pollutants produced, low energy

consumption, easy to handle, low operating and maintenance

costs, easy to scale-up, high porous structure, and high recovery

and reusability [40, 41]. Most of the membranes are made from

polymeric materials. Nylon 6,6 is one of the polyamide group that

is excellent in mechanical strength, toughness, rigidity, and

stability with self-lubricating properties and cost effectiveness in

nature [42, 43]. It is also hydrophilic, thin enough, highly porous,

highly permeant, acceptable in fouling resistant, and low

complicated in structures [44]. These advantages have promoted

nylon as a functional polymer for many biomedical and

environmental applications [43].

However, finding the best and the most affordable treatments

for TCS (because of its long-term negative effects on the aquatic

life, wild life, and human health) has remained a concern for

researchers working in this field. Therefore, the aim of this

research is to study the efficiency of combining both adsorption

and filtration methods to remove TCS from water. The objectives

of this study are to investigate the physico-chemical

characteristics of nylon 6,6 membrane and to examine their effect

on the TCS removal from water.

A 500 mg/L of TCS stock solution was prepared in 500 mL

volumetric flask by dissolving 250 mg TCS powder into 500 mL

ethanol with 0.1% Tween 80. Tween 80 is a surfactant that can

solubilize hydrophobic organic compound and increase the

treatment process efficiency to remove hydrophobic particles in

water and soil. As stated by Cheng et al. [46], Tween 80 has many

advantages such as cheap, low toxicity to environment, low

polarity, and also has high solubilization capacity. As followed by

Behera et al. [20], the stock solution was stored in refrigerator at

temperature ± 4 ˚C and was used within one month from its

preparation date. The standard solutions for adsorption process

were prepared by diluting stock solution with distilled water.

.2 Preparation of the nylon 6,6 membrane

Nylon 6,6 membrane was fabricated in an electrospinning

machine (FNM Ltd., Iran). The preparation of one membrane

sheet was done within three days. Firstly, 5 ml of acetic acid and

ml of formic acid were poured in a 30 ml glass bottle. Then,

.40 g of Nylon 6,6 pellets were weighed using analytical

weighing scale. The Nylon 6,6 pellets were dissolved with acetic

acid-formic acid solution using magnetic stirrer for 12 hours. This

procedure was done in order to get a homogenous solution.

For the electrospinning process, several parameters were set up

for fabrication of Nylon 6,6 membrane. 5 ml syringe and 0.6 x 32

mm needles supplied by Terumo® (Canada) were used in this

process. Firstly, the collector drum was covered with aluminum

net as a membrane base support. This step was carried out so that

the membrane sheet can be removed easily. The Nylon 6,6

solution prepared was sucked into the syringe and placed at the

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2020, Volume 8, Issue 3, Pages: 1036-1045

syringe pump holder. A high voltage was supplied by clipping a

small crocodile clipper at the middle of the needle used. As

performed by Jasni et al. [43], the jetting flow rate, supplied

voltage, drum collector speed, and tip-to-collector distance were

set to 0.4 mL/h, 26 kV, 1000 rpm, and 15 cm, respectively. Then,

the membrane sheet produced was removed from the drum

collector and was dried in a clean cupboard at room temperature

for 24 hours. Then, it was stored in a clean container for further

research.

membrane pores to be filled and be in contact with water. The

compaction test was done using 4000 mL distilled water with 1.5

bar pressure for one hour or until a stable permeation rate was

achieved. The volume of permeate water from the membrane test

cell outlet was recorded every 5 minutes to check the permeation

rate pattern. After the permeation volume became stable, the

pressure was reduced to 1.0 bar.

Then, the water flux test proceeded using distilled water. The

volume of permeate water were recorded every 5 minutes. After

that, the distilled water was removed and replaced with 4000 mL

of 5 mg/L TCS solution for filtration process and TCS flux

analysis. For TCS flux experiment, the volume of TCS solution

permeated from the permeation cell was recorded every 5

minutes. Besides that, the TCS samples were taken from

permeation cell and feed tank for TCS removal analysis. The

entire membrane filtration tests were done at room temperature.

The flux value was calculated using Equation (1) as follows:

.3 Adsorption studies

The adsorption studies of TCS adsorption using Nylon 6,6

membrane were conducted by means of 100 mL conical flask.

Based on Jasni et al. [43], the batch studies were conducted in

order to analyse the effect of various parameters on the uptake of

TCS onto Nylon 6,6 membrane. As suggested by Muhamad et al.

[47], for adsorption performance experiment, the membrane sheet

was cut to smaller pieces (5 mm x 5 mm) before being weighed

using analytical weighing scale. The adsorption tests were

conducted using a conical flask and a shaker [43, 48]. The effects

parameters analysed in this experiment were contact time,

adsorbent dosage, agitation speed, initial TCS concentration,

initial pH of TCS solution, and temperature.

Flux, J (L/m h) = (V/t) / A

(1)

where V/t (L/h) is volume permeation rate and A (m ) is

membrane area (A=0.002124 m ).

The effects of contact time were studied from 10 minutes until

hours. Next, the effects of membrane dosage were investigated

2.5 Combination of activated carbon and nylon 6,6 membrane

The coconut pulp waste activated carbon and nylon 6,6

membrane were combined in order to maximize the TCS removal

in water. All the optimum parameters conditions were obtained

from the batch adsorption and membrane experiments. The

combination test was done using flat sheet membrane test and a

stand stirrer. A piece of fabric was installed at the inlet pipe in

order to prevent the activated carbon from entrance to the

membrane machine. The nylon 6,6 membrane was put in the

permeation cell. After the compaction test, 4000 mL of the TCS

solution with initial concentration at 5 mg/L was poured into the

feed tank together with coconut pulp activated carbon. A stand

stirrer was setup beside the feed tank with its stirrer pointed in the

tank. Then, the TCS solution was stirred with activated carbon for

20 minutes. After that, the inlet valve was opened and TCS

solution was filtered with nylon 6,6 membrane. The concentration

of TCS permeated from the membrane was collected and

analysed.

using 0.01 g, 0.05 g, 0.10 g, 0.15 g, and 0.20 g of nylon 6,6

membrane. For agitation speed, the speeds of orbital shaker were

tested from 50 rpm to 250 rpm with 50 rpm interval. Then, the

effects of TCS initial concentration were analysed at 5 mg/L, 10

mg/L, 30 mg/L, 50 mg/L, 70 mg/L, and 90 mg/L, and the effect

of pH was investigated by varying the value from 3.0 to 9.0.

Lastly, the effect of temperature was studied using incubator

shaker at temperature 25 ˚C to 60 ˚C. A summary of design

parameters for TCS adsorption using nylon 6,6 membrane is

tabulated in Table 2. The remaining of the TCS concentration in

water after adsorption treatment was determined using

Ultraviolet-Visible

NANOCOLOR® UV/Vis Macherey-Nagel) at maximum

wavelength of 279 nm.

(UV-Vis)

Spectrophotometer

(

Table 2: The design parameters for TCS adsorption using nylon

,6 membrane

Parameters Contact Membrane speed TCS conc.

pH Temperature

2.6 Characterizations of nylon 6,6 membrane

time (hr) mass (g) (rpm)

(mg/L)

5.0

(˚C)

In this research, the surface structure and morphology of the

nylon 6,6 membrane were analysed using Field Emission

Scanning Electron Microscopy (FESEM) (FESEM, JEOL 6335f-

SEM, Japan) test. The test was done for the membrane before and

after treatments of TCS solution. As recommended by Jasni et al.

Contact time 0.17-6.00

0.01

0.01-0.15

150

5.6

Adsorbent

dosage

Agitation

TCS conc.

4.00

0.01

50-250

150

5.0

5.0-90.0

5.0

5.6

3.0-9.0

5.6

[43], before conducting the FESEM test, the samples were coated

Temperature

150

5.0

25-60

using a gold sputter of a Bio Rad Polaron Division SEM coating

system machine at 10 Mbar in order to reduce charging. Then,

they were inserted in FESEM instrument to analyse their surface

structures and morphologies. The magnifications scales were

used from 5000x to 10000x.

.4 Filtration

Filtration experiments were done using the flat sheet

membrane test. The filtration test was done to analyse the water

flux, TCS flux, and permeate concentration of TCS solution after

filtering with nylon 6,6 membrane. The membrane sheet was cut

to an oval shape with 57 mm diameter to fit in the permeation cell.

Then, the cell was tightened with screws. Afterward, the distilled

water was poured in the feed tank for further tests. Next, after

setting the permeation cell and tightening all screws, the

membrane compaction test was conducted to allow all the

In addition, the functional groups existed on the membrane

were analyzed using Fourier Transform Infrared Spectroscopy

(FTIR) (Perkin-Elmer spectrum ONE). The FTIR test was

recorded in the spectral range of 4000 to 400 cm⁻¹ at resolution 4

cm . For the nylon 6,6 membrane, the FTIR analysis was

conducted using the Attenuated Total Reflectance (ATR)

technique. ATR mode was used because the membrane was

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1036-1045

already in solid form and not in powder form. The ATR technique

allows the solid or liquid samples to be examined directly without

any preparation in advance.

membrane.

100

Results and Discussion

.1 Characteristics of the nylon 6,6 membrane

.1.1 Surface morphologies

The FESEM test was done to analyze the surface morphologies

2934

298

of the nylon 6,6 membrane. Figures 1 (a) and (b) show the

FESEM images of this membrane before and after the TCS

adsorption, respectively. As can be seen in Figure 1 (a), the

morphology of nylon 6,6 fiber threads appear to be thin, smooth,

free from beads, and continuous. These results show that, the

optimum electrospinning parameters used during the production

of nylon 6,6 membrane can produce a quality nanofiber. Based on

Figure 1 (b), on the other hand, can be used to analyse the

activated carbon after adsorption of TCS. The image shows that

the nylon 6,6 nanofiber threads were filled up by a lot of particles

until most of the nanofiber threads were covered. This showed

that the nylon 6,6 membrane can adsorb and trap TCS particles in

aqueous solutions.

535

1636

000 3600 3200 2800 2400 2000 1600 1200 800

400

Wavenumber (cm¯ ¹)

Figure 2: The FTIR spectra of the nylon 6,6 membrane

3.2 Adsorption studies

3.2.1 Contact time

The contact time was measured to determine the maximum

time taken for adsorbate removal and adsorption capacity of the

adsorbent until it reaches the equilibrium condition. The effect of

contact time was examined through applying 0.1 g nylon 6,6

membrane to treating 50 ml of 5 mg/L TCS solution.

In Figure 3, it shows the effect of contact time on TCS removal

by the nylon 6,6 membrane. The graph shows that the TCS

removal and adsorption capacity increased with an increase of

contact time. The TCS removal increased from 40.2% to 86.3%

by the 4 hour before reaching its equilibrium conditions. Then,

the TCS removal started to slightly decrease during the 5 and the

Figure 1: FESEM image of the nylon 6,6 membrane (a) before adsorption

(magnification x10000) and (b) after TCS adsorption (magnification

hours from 85.3% to 83.3%. Meanwhile, the adsorption

x5000)

capacity also increased from 1.01 mg/g to 2.16 mg/g for 10

minutes during 4 hours of contact time before it decreased from

2.13 mg/g to 2.08 mg/g during the 5 to 6 hours of contact time.

Therefore, the optimum time taken for TCS removal using nylon

6,6 membrane to reach equilibrium was achieved with 4 hours of

contact time.

.1.2 Functional groups

FTIR is one of the important methods to identify and determine

the functional groups of adsorbent samples and it influences the

occurrence of the adsorption process. Figure 2 shows the FTIR

spectra of the nylon 6,6 membrane. According to the obtained

results, the nylon 6,6 has a medium band at peak 3298cm that

was attributed to the N-H stretch from amino groups [41].

Following this, a C-H stretching vibration due to alkanes group

was observed with a medium peak at 2934cm . At peaks 1636cm

-1

and 1535cm , two strong peaks were detected, and after

-1

500cm , all the peaks weakened in intensity. The strong peaks

-1 -1

formed at peaks range from 1500cm to 1700cm , due to amide

I and II bands [42]. At peak 1636cm , C=O stretching from the

carbonyl group can bind with the amino group to form intra

molecular hydrogen bonding, causing the C=O stretching that

-1

normally forms at peak 1760cm to 1665cm to be shifted to

636 cm [43]. Meanwhile, the amide II band at peak 1535cm^-¹

-1

appeared due to C-N stretching and N-H bonding.

Xu et al. [40] stated that “the hydrogen bonding interactions

might play an important role in the sorption processes, because

hydrogen bonds could be formed between phenolic hydroxyl

group of TCS acting as hydrogen-bonding donors and carbonyl

groups of electrospun fibrous membranes”. This FTIR test

showed that the nylon 6,6 membrane has a carbonyl group and it

can produce hydrogen bonding with the hydroxyl group of TCS

molecules [43]. Therefore, it can be proven that the chemisorption

process happened during the TCS removal using nylon 6,6

Figure 3: The effect of contact time on the TCS removal using nylon 6,6

membrane

According to the results, the higher and rapid adsorption rates

at the initial period were due to the number of vacant sites

available at the initial stage on the external surface of nanofibrous

adsorbents [49]. On the other hand, the slow adsorption rate from

hours to 4 hours of contact time was due to the availability of

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2020, Volume 8, Issue 3, Pages: 1036-1045

decreased membrane pores and the fact that TCS had to move into

deeper sites [26,49]. The decrease in removal percentage after

equilibrium might also be due to some adsorbate particles which

started being released from the adsorbent surface into the solution

adsorption capacity [53]. A similar trend for effect of membrane

dosage was also reported by Li et al. [15] in their study into

methylene blue dye removal using calcium algitate membrane.

The study achieved the optimum dye removal of 96.0% using 20

mg of membrane.

[30]. The same pattern for adsorption capacity was also achieved

in [50] for chitosan/PVA nanofibers to remove nickel and cobalt

where it reached equilibrium at 120 min. Razzaz et al. [49] also

3.2.3 Agitation

reported the same trends for adsorption capacity of chitosan/TiO

nanofibrous for Pb(II) and Cu(II) ions removal, reaching

equilibrium at 30 min of contact time.

Agitation was performed to ensure the maximum contact of

fiber surface with the TCS in the solution [48]. The effect of

agitation was investigated by varying the agitation speed of the

shaker from 50 rpm to 250 rpm. Figure 5 shows the effect of

agitation speed on TCS removal using the nylon 6,6 membrane.

According to the graph, the optimum TCS removal and

absorption capacity of 86.3% and 2.16 mg/g, respectively, were

achieved at 150 rpm. A slower speed will reduce mobility and

transfer force between TCS and the adsorbent, while a higher

speed will lead to weakening of the bonding strength between the

TCS and the membrane surface area. It results in low removal

percentage and adsorption capacity using activated carbon.

Therefore, the best agitation speed for TCS adsorption using the

nylon 6,6 membrane was achieved at 150 rpm, and it was used for

all the other parameters during this study.

.2.2 Adsorbent dosage

Adsorbent dosage is a parameter that affects the availability of

the adsorption sites. The effect of adsorbent dosage was examined

by varying the amount of nylon 6,6 membrane from 0.01 g to 0.20

g. The experiments were conducted at room temperature to treat

0 ml of 5 mg/L TCS solution, at 150 rpm. Figure 4 shows the

effect of adsorbent dosage on TCS removal using the nylon 6,6

membrane. As depicted by the graph, the removal of TCS

increased from 56.9% to 86.3% with an increase of membrane

mass from 0.01 g to 0.10 g. However, when the mass of the nylon

,6 was added in the range of 0.15 g to 0.20 g, the TCS removal

also decreased from 82.4% to 70.6%. On the other hand, the

adsorption capacity of nylon 6,6 membrane was found to decrease

by increasing the membrane mass. The adsorption capacity

decreased from 14.22 mg/g to 0.88 mg/g when the membrane was

increased from 0.01 g to 0.20 g. Thus, the optimum membrane

dosage to remove 5 mg/L TCS solution was achieved with 0.10 g

of the adsorbent.

Figure 5: The effect of agitation speed on the TCS removal using nylon

,6 membrane

Figure 4: The effect of adsorbent dosage on the TCS removal using

nylon 6,6 membrane

The increase in removal percentage from 0.01 g to 0.10 g was

due to the high surface area and the availability of binding sites

for adsorption [51]. As for the decrease in the removal after the

optimum dosage was given, it was attributed to the overlapping

of adsorption sites due to crowded membranes that would reduce

the active sites for adsorption [15]. Moreover, the decrease of

adsorption capacity with an increase in the adsorbent dosage was

due to the fact that the adsorbent sites available were not fully

utilized at a higher adsorbent dosage. When the adsorbents

increased, there were more sites available in number which finally

reduced the amount of TCS adsorbed for each unit weight of

membranes [52]. Additionally, at a high adsorbent dosage, the

interfacial tension between two phases increased, which reduced

the driving force for the mass transfer, hence reducing the

Figure 6: The effect of initial TCS concentration on the TCS removal by

using nylon 6,6 membrane

3.2.4 Initial TCS concentration

The effects of initial TCS concentrations were tested from 5

mg/L to 90 mg/L, while the other parameters were kept constant.

Figure 6 shows the effect of initial TCS concentration on its

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2020, Volume 8, Issue 3, Pages: 1036-1045

removal using nylon 6,6 membrane. From the graph plotted, when

the initial concentration of TCS was increased from 5 mg/L to 50

mg/L, the TCS removal also increased from 86.3% to 93.5%. This

was due to the many active sites available for the adsorption

process at low concentrations [54]. However, when the TCS

concentration was increased to 70 mg/L and 90 mg/L, the removal

percentage almost remained constant with a slight decrease to

forces between the positively charge TCS and the negatively

charge membrane. At pH values higher than 7.90, TCS particles

will be deprotonated and become negatively charged. Thus, the

electrostatic repulsion between the deprotonated TCS and

nanofibers caused a reduction for both TCS removal and

adsorption capacity [40]. Xu et al. [40] also reported a similar

trend for the adsorption of TCS using electrospun fibrous

membranes and achieved the best TCS removal at pH 6 compared

to those fixed at pH 4, 8, and 10.

3.5% and 93.4%, respectively. According to Feng et al. [55], this

could be due to the decrease and the saturation of active sites on

the adsorbent surfaces. While the membrane adsorption capacity

increased with an increase in the TCS initial concentration. The

nylon 6,6 membrane adsorption capacity increased from 2.16

mg/g to 42.01 mg/g in 5 mg/L to 90 mg/L TCS concentrations.

Increase of the concentration will increase the electrostatic

interactions between the adsorbate and adsorbent, hence

improving the adsorption capacity of the adsorbent [56].

Literature consists of a number of studies reporting similar

trends on the effect of the initial concentration using various

nanofibers. Li et al. [15] reported that the adsorption capacity of

calcium alginate membrane increased from 520 mg/g to 1680

mg/g when methylene blue initial concentration was increased

from 30 mg/L to 170 mg/L.

3.2.6 Temperature

The surrounding temperature influences the bonding strength

between TCS particles and the surface of the membrane. The

temperature was varied from 25 ˚C to 60 ˚C to treat 50 mL of the

5 mg/L TCS solution. The experiments were conducted in an

incubator shaker. Figure 8 shows the effect of temperature on the

TCS removal using the nylon 6,6 membrane. The results show

that the TCS removal and adsorption capacity decreased with an

increase in temperature. The TCS removal and adsorption

capacities both decreased from 86.3% to 55.9% and from 2.16

mg/g to 1.40 mg/g, respectively, when the temperature was

increased from 25 ˚C to 60 ˚C. The melting point of TCS is 57 ˚C;

therefore, TCS solubility in water increases when the temperature

increases, hence causing the adsorption process to recede [57].

Furthermore, increasing the temperature weakens the electrostatic

interactions between the adsorption surface and adsorbate

particles and this will reduce the adsorption capacity and TCS

removal [15]. The adsorption of TCS using the nylon 6,6

membrane was an exothermic process since its removal rate and

adsorption capacity lowered with the increase of temperature

.2.5 The pH effect

The effect of pH value was tested through fixing it at 3.0-9.0.

The pH values selected were in range of TCS pkₐ value and

isoelectric point of the nylon 6,6 membrane. Figure 7 shows the

effect of pH on the TCS removal using the nylon 6,6 membrane.

[53].

Aluigi et al. [53] also reported a similar trend for the removal

of methylene blue using keratin nanofibrous membrane where the

adsorption capacity and the methylene blue removal both

decreased from 175 mg/g to 128 mg/g and from 68% to 51%,

respectively, when the temperature was increased from 20 ˚C to

0 ˚C.

Figure 7: The effect of pH on the TCS removal using nylon 6,6

membrane

As shown by the graph, the highest removal percentage and

adsorption capacity of 86.3% and 2.16 mg/g, respectively, were

achieved at pH 5.6. The other pH values resulted in lower TCS

removal percentages and adsorption capacities. At a pH lower

than TCS pkₐ= 7.90, the TCS molecules are available in a

protonated form [40]. Based on Jasni et al. [43], the isoelectric

point of the nylon 6,6 membrane is at pH 5, where the nylon 6,6

membrane is in positive charge at pH 5 and below, but it turns to

negative charge with pH values higher than 5. Therefore, the TCS

removal and adsorption capacity were low at pH 5 and below due

to the electrostatic repulsions between the positive charge of TCS

and the positive charge of the nylon 6,6 membrane. On the

contrary, for pH higher than 5, the nylon 6,6 membrane was

turned to the negative charge nanofiber. As a result, it increases

both TCS adsorption and adsorption capacity due to attraction

Figure 8: The effect of temperature on the TCS removal using nylon 6,6

membrane

3.3 Filtration studies

3.3.1 Compaction

For the filtration method, the pre-compaction test was

necessary before the compound filtration process can be done.

This procedure was done in order to reduce the interference of

compaction with other factors such as fouling, and the test was

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1036-1045

conducted until a steady flux was achieved [58]. The pre-

compaction test was done in order to maximize the water contact

in all membrane pores before the filtration test can be done. The

time taken to achieve a steady flux can vary based on the types

and material of membrane. Hussain and Al-Saleh [58] also stated

that the steady flux for ultrafiltration membranes can be reached

within minutes, but it will take more time for reverse osmosis

membranes. For the compaction test, a volume of 4000 mL

distilled water was used and poured into the feed tank. The test

was conducted for 90 minutes while the pressure was set to 1.5

bar.

The water flux achieved during the pre-compaction test using

the nylon 6,6 membrane is shown in Figure 9. Based on the

results, the water flux decreased from 2028 L/m h to 1570 L/m h

and reached a steady flux in 75 minutes. The compaction process

caused the membrane structure porosity to be reduced and a flux

reduction occurred [58]. After a steady flux was achieved, the

compaction test was stopped and the pressure was reduced to 1.0

bar before continuing further experiments.

Figure 10: The results of distilled water flux, TCS solution flux, and

percentage TCS removal obtained using nylon 6,6 membrane through

filtration process

.4 The effect of combined activated carbon and membrane on

TCS removal

The combination method was done in order to find the best

setting for TCS removal from aqueous solutions. The experiments

on the combination method using coconut pulp waste activated

carbon and nylon 6,6 membrane were conducted using a flat sheet

membrane test machine. The optimal parameters values obtained

from previous experiments were used in this process where 4 L of

mg/L TCS solution was poured into the feed tank with 8.0 g

coconut pulp waste activated carbon and was stirred with a stand

stirrer. After 20 minutes of the adsorption process, the TCS

solution was filtered using the nylon 6,6 membrane by

unfastening the inlet valve from the feed tank. The TCS solution

pH at 5.6, room temperature, and inlet pressure 1.0 bar were set

up for this test. Figure 11 shows the TCS removal after combining

both the adsorption and filtration methods.

Figure 9: The water flux during pre-compaction test

.3.2 Water flux and TCS solution flux analysis

After the compaction process, the pressure was decreased to

.0 bar. Subsequently, the flux analysis using distilled water was

conducted for 30 minutes at pressure 1.0 bar. Figure 10 shows the

distilled water flux, TCS solution flux, and TCS removal within

0 minutes. As can be observed in the figure, the distilled water

flux is higher than the TCS solution flux. The water flux was

recorded with 1655 L/m h during the first 5 minutes before it

decreased to 1491 L/m h at 30 minutes. As for the TCS solution,

the flux also decreased from 1209 L/m h to 1062 L/m h, from 5

to 30 minutes. The reduction of flux when using TCS solution

might be due to the presence of TCS particles trapped into the

membrane pores, causing their porosity to be reduced for water

permeation.

The removal of TCS by filtration method decreased

with the increase in time. The TCS removal decreased from

Figure 11: The TCS removal through combining the adsorption method

using coconut pulp waste activated carbon and filtration method using

nylon 6,6 membrane

0.2% to 17.7% from 5 minutes to 30 minutes. The same results

were also reported by Muhamad et al. [47] in their experiment for

the removal of BPA using PES-SiO membrane, where the BPA

According to the obtained results, TCS was removed 100% in

minutes of the filtration process where it already reached its

removal decreased from 81% to 52% from 10 minutes to 170

minutes during the filtration test. This occurred due to the

reduction of adsorption sites available for TCS after its saturation

equilibrium. During the adsorption process, most of the TCS

particles in the solution were already removed. As such, the nylon

,6 membrane only filtered the leftover of TCS particles that

[47]. According to the obtained results, the TCS achieved its

escaped during the adsorption process. According to Skouteris et

al. [59] and Wang et al. [60], the activated carbon can be used as

maximum removal within 5 minutes of the filtration process.

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 1036-1045

a pre-treatment for membrane by removing the majority of

dissolved organic matters and inorganic particles in the water,

thereby reducing the membrane fouling. Therefore, it shows that

this combination method can increase the TCS removal in

aqueous solutions within a shorter time.

Similar results were reported by Wang et al. [60], using the

combination of coconut shell activated carbon and polyamide NF

membrane to remove dimethyl phthalate, di-(2-ethylhexyl)

phthalate and dioctyl phthalate where more than 99% of removal

rate was achieved for all the three chemicals.

paraben, and triclosan in rats. Environmental health perspectives.

015 Jun 5;124(1):39-45.

Montaseri H, Forbes PB. A review of monitoring methods for

triclosan and its occurrence in aquatic environments. TrAC Trends in

Analytical Chemistry. 2016 Dec 1;85:221-231.

Zhu W, Zhang H, Tong C, Xie C, Fan G, Zhao S, Yu X, Tian Y,

Zhang J. Environmental exposure to triclosan and semen quality.

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Dhillon GS, Kaur S, Pulicharla R, Brar SK, Cledón M, Verma M,

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Conclusion

684.

Based on this study, 90.2% of the TCS removal was achieved

Shanmugam G, Ramasamy K, Selvaraj KK, Sampath S, Ramaswamy

BR. Triclosan in fresh water fish gibelion catla from the Kaveri River,

India, and its consumption risk assessment. Environmental Forensics.

using the nylon 6,6 membrane through filtration method within 5

minutes. Then, after combining both coconut pulp waste activated

carbon and nylon 6,6 membrane, the TCS removal was increased

up to 100% within less than 5 minutes. Therefore, this

combination method can help to increase the TCS removal from

the water and reduce the fouling probabilities. Based on the

FESEM images, the results showed that the nylon 6,6 membrane

had thin, smooth, beads-free, and continuous fibers. While the

results of the FTIR test showed that the nylon 6,6 membrane had

carbonyl group and it was able to produce hydrogen bonding with

hydroxyl group of TCS molecules. Thus, it proved that the

chemisorption process happened during the TCS removal using

the nylon 6,6 membrane. As a conclusion, combining activated

carbon and nylon 6,6 membrane is one of the promising methods

that can help to increase the TCS removal from the aqueous

solutions.

014 Jul 3;15(3):207-212.

Eriksson KM, Johansson CH, Fihlman V, Grehn A, Sanli K,

Andersson MX, Blanck H, Arrhenius Å, Sircar T, Backhaus T. Long‐

term effects of the antibacterial agent triclosan on marine periphyton

communities. Environmental toxicology and chemistry. 2015

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Martins D, Monteiro MS, Soares AM, Quintaneiro C. Effects of 4-

MBC and triclosan in embryos of the frog Pelophylax perezi.

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Chen J, Meng T, Li Y, Gao K, Qin Z. Effects of triclosan on gonadal

differentiation and development in the frog Pelophylax

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Wang S, Poon K, Cai Z. Removal and metabolism of triclosan by

three different microalgal species in aquatic environment. Journal of

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Nag SK, Das Sarkar S, Manna SK. Triclosan–an antibacterial

compound in water, sediment and fish of River Gomti, India.

International journal of environmental health research. 2018 Sep

Aknowledgment

The authors would like to acknowledge the Ministry of High

Education of Malaysia for providing LRGS Grant on Water

Security entitled Protection of Drinking Water: Source

Abstraction and Treatment (203/PKT/6720006) and Universiti

;28(5):461-470.

Zhang G, Sun M, Liu Y, Liu H, Qu J, Li J. Ionic liquid assisted

electrospun cellulose acetate fibers for aqueous removal of triclosan.

Langmuir. 2015 Jan 26;31(5):1820-1827.

Teknologi

Malaysia

(R.J130000.7809.4L810,

12 Lee DG, Cho KC, Chu KH. 945201. Removal of triclosan in

nitrifying activated sludge: Effects of ammonia amendment and

bioaugmentation. Chemosphere. 2015;125:9-15.

Q.J130000.2522.19H06 and Q.J130000.2422.04G06) as financial

support of this project.

Xin L, Sun Y, Feng J, Wang J, He D. Degradation of triclosan in

aqueous solution by dielectric barrier discharge plasma combined

with activated carbon fibers. Chemosphere. 2016 Feb 1;144:855-863.

Ethical issue

Authors are aware of, and comply with, best practice in

publication ethics specifically with regard to authorship

14 Dou R, Zhang J, Chen Y, Feng S. High efficiency removal of

triclosan by structure-directing agent modified mesoporous MIL-53

(Al). Environmental Science and Pollution Research. 2017 Mar

(avoidance of guest authorship), dual submission, manipulation

;24(9):8778-8789.

of figures, competing interests and compliance with policies on

research ethics. Authors adhere to publication requirements that

submitted work is original and has not been published elsewhere

in any language.

Li J, Zhang Y, Peng J, Wu X, Gao S, Mao L. The effect of dissolved

organic matter on soybean peroxidase-mediated removal of triclosan

in water. Chemosphere. 2017 Apr 1;172:399-407.

Orhon KB, Orhon AK, Dilek FB, Yetis U. Triclosan removal from

surface water by ozonation-Kinetics and by-products formation.

Journal of environmental management. 2017 Dec 15;204:327-336.

Wang F, Liu F, Chen W, Xu R, Wang W. Effects of triclosan (TCS)

on hormonal balance and genes of hypothalamus-pituitary-gonad axis

of juvenile male Yellow River carp (Cyprinus carpio). Chemosphere.

Competing interests

The authors declare that there is no conflict of interest that

would prejudice the impartiality of this scientific work.

017 Feb 1;193:695-701.

Authors’ contribution

Wang Y, Li P, Liu Y, Chen B, Li J, Wang X. Determination of

triclocarban, triclosan and methyl-triclosan in environmental water

by silicon dioxide/polystyrene composite microspheres solid-phase

extraction combined with HPLC-ESI-MS. Journal of Geoscience

and Environment Protection, 2013 Jan 1;1(02):13-17.

Liu Y, Zhu X, Qian F, Zhang S, Chen J. Magnetic activated carbon

prepared from rice straw-derived hydrochar for triclosan removal.

RSC Advances. 2014;4(109):63620-63626.

All authors of this study have a complete contribution for data

collection, data analyses and manuscript writing

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