Article

Impact of magnetite on Fe₃O₄/Activated Carbon (AC)/ZnO

Nanocomposite for Photodegradation of Rhodamine B

Restina Bemis^1*, Lenny Marlinda¹, Rahmi¹, Nurul Pratiwi¹, Putu Adityo Wibimanyu¹, Lia

Anggresani^2.3

¹Department of Chemistry, Faculty of Science and Technology, Universitas Jambi, Indonesia

²Graduate School of Engineering, Gifu University, Yanagido 1-1, Gifu-Shi, Gifu, Japan

³Department of Midwifery, Syedza Saintika University, Padang City, West Sumatera, Indonesia

Abstract

Rhodamine B is an organic dye commonly used in the textile industry, but it is toxic. Therefore, a

photodegradation method using Fe₃O₄/activated carbon (AC)/ZnO nanocomposite is necessary to

address environmental issues caused by rhodamine B. The Fe₃O₄/AC/ZnO nanocomposite has been

successfully synthesized using the sonication method. Iron sand is used as a source of magnetite (Fe₃O₄),

coconut shells as a source of activated carbon, and Zinc nitrate as a source of ZnO. XRF results show that

the Fe content in iron sand is 74.10%. The ratio of Fe₃O₄addition used in Fe₃O₄/AC/ZnO nanocomposite

is 0:1:1; 1:1:1; 2:1:1; 3:1:1; 4:1:1. XRD characterization shows that the 1:1:1 ratio of Fe₃O₄/AC/ZnO

nanocomposite has the smallest crystal size of 48.17 nm. The addition ratio of Fe₃O₄does not affect the

structure of the formed Fe₃O₄/AC/ZnO nanocomposite. Fe₃O₄/AC/ZnO nanocomposite is formed at

2theta 30.23°; 35.60°; 57.11°; and 62.83° for Fe₃O₄, peak broadening at 26.72° and ~44.71 for AC, and

31.82°; 34.47°; 36.30°; 47.59°; 56.63°; 62.89° and 67.98° for ZnO. SEM results show particle sizes of 57.95

nm for ZnO and 42.74 nm for Fe₃O₄/AC/ZnO 1:1:1 nanocomposite. VSM showed saturation magnetism

of 4.41 emu/g for Fe₃O₄/AC/ZnO 1:1:1 nanocomposite and 28.8 emu/g for Fe3O4. The photocatalytic test

showed that the Fe₃O₄/AC/ZnO 1:1:1 nanocomposite had the best % degradation of rhodamine B, at

96.1%, under sunlight.

Keywords: Magnetite: nanocomposite Fe3O4/AC/ZnO; photodegradation; rhodamine B.

*

Corresponding author

Email addresses: restina@unja.ac.id

DOI: https://doi.org/10.22437/chp.v9i2.47812

Received August 14^th2025; Accepted November 11^th2025; Available online December 25^th2025

(https://creativecommons.org/licenses/by/4.0 )

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Graphical Abstract

Introduction

achieving high removal efficiencies, their

practical application is often limited by

several drawbacks. These include high

chemical consumption, substantial electrical

Rhodamine B (C₂₈H₃₁ClN₂O₃) is a synthetic

xanthene dye widely utilized in the textile

industry due to its low cost, high color

intensity, and ease of availability. However,

rhodamine B poses serious health risks, as

exposure through skin contact, eye contact,

or ingestion can lead to toxic effects,

including irritation, organ damage, and

potential carcinogenicity [1]. In addition to its

adverse health impacts, rhodamine B is

energy

requirements,

operational

complexity, elevated maintenance costs, and

the generation of secondary pollutants such

as sludge that require further handling and

disposal [5]. Consequently, there is a

growing

need

to

develop

alternative

treatment approaches that are not only

effective but also economically feasible and

environmentally sustainable.

environmentally

contaminate

persistent

aquatic ecosystems

and

can

if

discharged untreated. Therefore, effective

treatment of textile wastewater containing

rhodamine B is essential prior to its release

into the environment.

Photodegradation is one of the most widely

chosen

technologies

today.

The

photodegradation method is based on

photocatalysts derived from semiconductor

materials because they are arranged and

have a very high potential space dimension.

Various physical and chemical treatment

methods have been investigated to address

In

photocatalyzed

oxidation,

UV

light

dye-containing

photolysis [2], electrocoagulation [3], and

photo-Fenton oxidation processes [4].

Although these techniques are capable of

wastewater,

such

as

provides energy that can be used to produce

electron-hole pairs. Electron-hole pairs will

diffuse to the surface of oxide particles that

oxidize

pollutants

[6].

In

general,

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Chempublish Journal, 9(2) 2025,272-286

photocatalysts are often used. ZnO is a

material that has a broad band gap energy

(Eg) of 3.37 eV and a binding energy of 60

MeV, so it has great potential to be used as a

photocatalyst [7].

Materials and Methods

Materials

Iron sand was used as the primary raw

material.

Sodium

hydroxide

(NaOH,

analytical grade, Merck) and hydrochloric

acid (HCl, 37 wt%, analytical grade, Merck)

were employed for chemical activation and

pH adjustment. Distilled water was used as

the solvent in all experimental procedures.

Coconut shell was utilized as the carbon

precursor for material synthesis. Zinc nitrate

ZnO in photodegradation still has some

shortcomings, so modification of the ZnO

surface is needed. Usually, modification is

done with activated carbon, which acts as a

surface area giver on ZnO, but in ZnO /

activated carbon photocatalysts, it is still

difficult to remove or recover photocatalysts

that have been used, which can cause

secondary pollution [8]. Therefore, Fe₃O₄

was added as a contributor to magnetic

tetrahydrate

(Zn(NO₃)₂·4H₂O,

analytical

grade, Merck) was used as the zinc source,

while ethanol (C₂H₅OH, analytical grade,

Merck) served as a dispersing and washing

agent. Rhodamine B (analytical grade) was

used as the model organic dye pollutant in

the adsorption experiments.

properties.

This

addition

facilitates

separation after the photocatalysis process

and increases the photocatalytic activity of

Fe₃O₄/AC/ZnO nanocomposites. Fe₃O₄has

magnetic properties with a gap energy of

2.69 eV [9]. It also has a large surface area,

good biocompatibility, low toxicity, and

efficient light absorption in the visible light

Preparation of Fe₃O₄

The iron sand used was obtained from the

Batanghari River, Jambi, located on Jl. Lintas

Sumatera, Penyengat Rendah, Aur duri,

Telanaipura District, Jambi City. Before being

used for Fe₃O₄synthesis, iron sand was

obtained using a modified procedure carried

out by [13]. Iron sand was washed and

magnetized with a permanent magnet (20 g)

dissolved in 37% HCl at 70˚C for as much as

53 ml. The solution formed was cooled and

titrated with 12M NaOH at 70˚C for 48 ml

until there was a precipitate. The precipitate

that was successfully formed was then oven-

dried at 1000˚C for 3 h. The resulting solid

powder was characterized using VSM, XRF,

and XRD.

region

[10].

Fe₃O₄

can

optimize

the

separation of electron (e-) and hole (h+)

pairs. It does so by facilitating the transfer of

excited electrons from the valence band to

the conduction band. Furthermore, the

excellent magnetic properties of Fe₃O₄will

facilitate the separation of photocatalyst

materials from their solutions using an

external magnetic field [11]. Research

conducted by Wang (2021) showed an

increase in Rhodamine B photodegradation

efficiency, from 71.13% with ZnO to 76.46%

with

Fe₃O₄/ZnO,

with

band

gap

and

saturation magnetization (Ms) values of 2.86

eV and 44.77 emu/g for Fe₃O₄/ZnO [12]. In

this study, Fe₃O₄/AC-ZnO was synthesized by

varying the ratio of Fe₃O₄addition to

AC/ZnO. The aim was to analyze the effect of

Fe₃O₄addition on the characterization of the

formed Fe₃O₄/AC-ZnO nanocomposite and

Carbon Preparation and Activation

In this study, Carbon synthesis was carried

out based on the synthesis procedure of the

previous study [14]. A total of 500 g of

coconut shell carbon was baked at 110˚C for

1 h, then mashed using a mortar and pestle.

Coconut shell carbon was sieved with a 100-

its

impact

on

rhodamine

B

photodegradation.

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Chempublish Journal, 9(2) 2025,272-286

mesh sieve to produce coconut shell carbon

powder. Then, as much as 50 g of coconut

shell carbon powder was put into a 500 mL

beaker, and 250 mL of 1M NaOH solution

was added. The solution was stirred using a

magnetic stirrer for 4 h, accompanied by

heating at 85˚C. The solution was filtered

using filter paper and washed with distilled

water until the pH was neutral (pH = 7). The

residue was oven dried at 110˚C for 1 h.

Then the dry powder was calcined at 600˚C

for 1 h to obtain activated carbon.

using FTIR, XRD, SEM-EDS, and a UV-Vis

spectrophotometer.

Synthesis of Fe₃O₄/AC/ZnO

The

synthesis

of

Fe₃O₄/AC/ZnO

nanocomposite was carried out based on

the modified procedure of [16], replacing

rGO with AC because AC has the same

structure as rGO. To prepare nanostructured

Fe₃O₄/AC/ZnO, first, 500 mg of Fe₃O₄/AC and

500 mg of ZnO were dispersed separately in

60 mL of ethanol under ultrasonic treatment

for 30 min. Then, the two solutions were

mixed with vigorous stirring at 40 °C for 1 h.

The results obtained were then collected

with a permanent magnet and washed with

distilled water. And than the Fe₃O₄/AC/ZnO

obtained was dried under vacuum at room

temperature overnight. In this study, the

synthesis variables for Fe₃O₄/AC/ZnO were

(0:1:1); (1:1:1); (2:1:1); (3:1:1); and (4:1:1).

Finally, it was characterized using XRD, FTIR,

VSM, and UV-Vis.

Preparation of Fe₃O₄/AC.

The preparation of Fe₃O₄/AC uses a modified

procedure carried out by Fini (2018) [15]. At

the initial stage, magnetite was added with a

ratio of (1,1), (2,1), (3,1) and (4,1) or as much

as 0.25; 0.5; 0.75; 1 g respectively was

dispersed into 100 ml of water and then 0.25

g activated carbon was added to the solution

and the dispersion was transferred into a

Teflon-coated stainless autoclave at 180˚C

for 6 h. The precipitate was then washed

with distilled water and ethanol. The results

obtained were then characterized by XRD.

Rhodamine B photodegradation test using

Fe₃O₄/AC/ZnO nanocomposite

50 ppm rhodamine B solution at neutral pH,

Synthesis of ZnO

and

200

mg

of

Fe₃O₄/AC/ZnO

In this study, the synthesis of ZnO was

nanocomposite was added. The beaker was

exposed to sunlight while stirring using a

magnetic stirrer at a constant speed for 90

min. Then the suspension was filtered and

the filtrate was measured for absorbance

with a UV-Vis spectrophotometer at the

maximum wavelength of rhodamine B.

carried

out

based

on

the

synthesis

procedure of [14]. Zinc nitrate, 60 g of

Zn(NO₃)₂·4H₂O, was dissolved into 250 mL of

distilled water and then stirred for 1 h at

80ºC at a constant speed. Then 1M NaOH

solution was mixed dropwise into the

solution until pH ~ 10 and stirred at 60ºC at

a constant speed for 4 h, then allowed the

solution to stand for 24 h at room

temperature. Filtered and washed the

precipitate using distilled water and ethanol

until the pH was neutral. The precipitate was

dried in an oven at 60ºC for 1 h and then

calcined at 800ºC for 2 h. The solids obtained

were then crushed and further characterized

Fe₃O₄/AC/ZnO

nanocomposite

characterization

Nanocomposite characterization was carried

out using several instruments, such as

crystal structure characterization using X-

Ray Diffraction (XRD - X'Pert PRO Panalytical

PW 30/40)), and compound composition

analysis using X-ray Fluorescence (XRF -

Panalytical Epsilon 3).

Analysis of the

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magnetic properties of nanocomposites

using Vibrating Sample Magnetometer (VSM

- OXFORD tipe 1,2H), surface morphological

before and after the magnetization process,

as presented in Table 1. The results indicate

that iron (Fe) is the dominant element, with

a concentration of 74.1 wt.%, followed by

silicon (Si) at 9.12 wt.% and titanium (Ti) at

7.82 wt.%. The high Fe content confirms that

the iron sand is rich in iron-bearing minerals.

The enrichment of Fe in the magnetic

fraction can be attributed to the magnetic

separation process, in which iron-containing

characteristics

assessed

by

Scanning

Electron Microscopy-Energy

Dispersive

Spectroscopy (SEM-EDS – Thermoscientific),

and the photodegradation adsorbance of

rhodamine

B

analyzed

using

UV-Vis

Spectrophotometer (Halo DB 30).

Result and Discussions

XRF characterization

minerals

with

strong

magnetic

or

paramagnetic properties are preferentially

attracted by the applied magnetic field.

Consequently, the magnetization process

effectively concentrates Fe within the iron

sand, making it a suitable precursor for

Fe₃O₄ synthesis in this study

X-ray

fluorescence

(XRF)

analysis

was

conducted to identify and quantify the

elemental composition of iron sand

collected from the Batanghari River, both

Table 1. Elemental composition of iron sand determined by X-ray fluorescence (XRF) analysis.

Element

Value (%)

3.18

Al

Si

9.12

P

Ca

Ti

1.14

7.82

Fe

Ag

74.1

1.152

The Ti content was observed to increase

after the magnetization process, which can

be attributed to the magnetic behavior of Ti-

containing minerals that are co-enriched

during magnetic separation. This indicates

that, in addition to iron, titanium-bearing

phases are also concentrated in the

magnetic fraction. Nevertheless, the high Fe

content in the iron sand confirms its

suitability as a reliable Fe source for Fe₃O₄

synthesis in this study.

the result of XRD characterization of the

synthesized Fe₃O₄which is known to have 4

specific peaks with the highest intensity at 2θ

angles at 30.23°; 35.60°; 57.11°; and 62.83°.

Then the Fe₃O₄peaks that appear show

similarities with the peaks of Fe3O4

reference data JCPDS Number 01-075-0033

with positions 30.12 °; 35.48 °; 57.03 °; and

62.62 °. The same finding was reported by

Researcher [13] the values for the peak of

the angle 2θ at 30.09°; 35.42°; and 62.51°.

XRD characterization (XRD)

Figure 2 presents the XRD pattern of the

activated carbon sample and its comparison

with the standard reference data (JCPDS 00-

025-0284). The diffractogram exhibits two

broad diffraction features centered at 2θ ≈

26.72° and 44.71°, corresponding to the

characterization was conducted to identify

the crystal structure, crystallinity, and crystal

size. The sample analysis utilized XRD on an

X-ray tube with Cu (λ = 1.54 Å), at a voltage of

40 kV and a current of 30.0 mA. Figure 1 is

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(002) and (100) crystallographic planes of

carbon materials. The presence of these

reflections, together with their broad and

The broadening of the (002) reflection

further implies a disordered stacking of

graphitic layers, commonly associated with

high defect density and irregular carbon

domains. Such amorphous characteristics

are consistent with the reference JCPDS

pattern and have been widely reported for

activated carbons derived from biomass

precursors.

low-intensity

profiles,

indicates

a

predominantly

amorphous

carbon

structure. The absence of sharp and well-

defined diffraction peaks suggests a lack of

long-range

crystalline

order,

which

is

characteristic of activated carbon materials.

Figure 1. X-ray diffraction (XRD) pattern of the synthesized Fe₃O₄, showing characteristic

diffraction peaks corresponding to the spinel crystal structure, in good agreement with the

standard JCPDS card No. 01-075-0033.

The predominantly amorphous nature of the

activated carbon is advantageous for

adsorption and surface-mediated processes,

as it is typically associated with high surface

area and abundant active sites. These

structural

features

are

expected

to

contribute positively to the performance of

the activated carbon when employed as a

support

material

in

the

synthesized

composite system.

Figure 2. X-ray diffraction (XRD) pattern of the synthesized activated carbon, showing a broad

diffraction peak characteristic of amorphous carbon structure, consistent with the standard

JCPDS card No. 00-025-0284.

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Figure 3. XRD diffractog of synthesized ZnO

Figure

3

shows

the

results

of

XRD

close to JCPDS data No. 00-036-1451 and the

research of [18] which showed diffraction

peaks with high intensity at 2θ angles of

31.6°; 34.3°; 36.1°; 47.5°; 56.5°; 62.8°; and

67.9°.

characterization of ZnO. There are peak

intensities located at 2θ angles with

positions 31.82°; 34.47°; 36.30°; 47.59°;

56.63°; 62.89° and 67.98°. These results are

Figure 4. X-ray diffraction (XRD) patterns of Fe₃O₄/AC/ZnO nanocomposites with composition

ratios: (a) 0:1:1, (b) 1:1:1, (c) 2:1:1, (d) 3:1:1, and (e) 4:1:1.

Table 2. Application of Strategies to Enhance the Bioavailability of Minerals

Sample

Fe₃O₄

ZnO

% Relative crystallinity

Crystal size (nm)

23.97

No

1

2

-

30.82

50.06

Fe₃O₄/AC/ZnO

0:1:1

3

4

5

6

7

8

39.32

25.50

27.84

26.67

26.78

50.06

48.17

53.94

50.07

55.34

1:1:1

2:1:1

3:1:1

4:1:1

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Chempublish Journal, 9(2) 2025,272-286

In Figure 4, the XRD characterization results

of the Fe₃O₄/AC/ZnO nanocomposite show

that ZnO peaks dominate the resulting

diffractog peak pattern. However, the peaks

that appear 2ɵ at 30.12°; 35.48°; 57.03°; and

62.62 indicate the formation of Fe3O4.

The data in Table 2 show that The greater the

mass of Fe₃O₄added, the greater the crystal

size

composite.

of

the

resulting

Furthermore,

Fe₃O₄/AC/ZnO

synthesis

conditions such as temperature and reaction

time also influence crystal growth [20]. Fe₃O₄

acts as a nucleation site or template for the

growth of ZnO on its surface. During the

synthesis process, the interaction between

the Fe₃O₄surface and Zn²⁺ ions leads to the

formation of ZnO around the Fe₃O₄.

Consequently, the resulting ZnO crystals are

generally larger than those formed from

pure ZnO [21].

Meanwhile, no peaks

from AC

were

observed because AC has an amorphous

phase. ZnO peaks were produced at 2ɵ at

31.82°; 34.47°; 36.30°; 47.59°; 56.63°; and

67.98. The resulting crystal structure shows

that the combination of Fe3O4 and AC in

ZnO does not trigger ion substitution in the

ZnO lattice, so that the wurtzite structure of

ZnO also does not experience changes [19].

Figure 6. XRD diffractog (A) Activated carbon; (B) Fe₃O₄; C) ZnO; and (D) 1:1:1 Fe₃O₄/AC/ZnO

b

a

Figure 7. SEM a) ZnO and b) 1:1:1 Fe3O4/AC/ZnO nanocomposites synthesized

The Figure 6 shows that the intensity of

activated carbon is nearly imperceptible,

contributing only an amorphous phase to

the 1:1 ratio nanocomposite. In the Fe3O4

diffractog, only a very weak intensity is

observed at 2θ angle of 35.60°; 57.11°; and

62.83°.. In contrast, the intensity of ZnO is

dominant, with peaks at the 2θ angles of

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Chempublish Journal, 9(2) 2025,272-286

by activated carbon due to the lack of an

impregnation process. It can be seen that the

ZnO nanocomposite particles spread out, which

results in a larger surface area, so that it can

affect its photocatalytic activity. According to [22],

the morphological shape of ZnO is round and

fused. The particle size of ZnO and 1:1:1

Fe₃O₄/AC/ZnO nanocomposite was calculated

using ImageJ standard software. It was found that

ZnO nanoparticles and 1:1:1 Fe₃O₄/AC/ZnO

nanocomposite had particle sizes of 57.95 nm

and 42.74 nm, respectively. The particle size

decreased in line with the crystal size, with a

decrease in particle size being able to increase

photocatalytic activity. According to [23], the

smaller and more uniform particle size can

increase photocatalytic activity due to the larger

surface area.

31.76°; 34.42°; 36.24°; 47.59°; 56.63°; 62.89°

and 67.98°. These observed intensities

indicate that the nanocomposite has been

successfully synthesized.

Scanning Electron Microscopy (SEM)

To observe the morphological shape and

distribution

of

particle

dispersion,

characterization was carried out using SEM.

Morphological characterization of ZnO and

1:1:1 Fe3O4/AC/ZnO nanocomposite was

carried out using SEM under the condition of

voltage acceleration measurement of 20kV

with 15000x magnification.

Figure 7 a is the SEM result of the ZnO

nanocomposite, it is observed that the ZnO is

irregularly round and spreads and accumulates

between particles causing agglomeration on the

entire surface while Figure 7 b shows the 1:1:1

Fe₃O₄/AC/ZnO nanocomposite formed showing

that the ZnO particles stick and spread to the

surface of the Fe₃O₄-AC which is cubic and hollow

given by the activated carbon. It can be seen that

there is still some Fe₃O₄that has not been coated

Vibrating Sample Magnetometer (VSM)

To determine the magnetic strength of a sample,

the VSM instrument also known as Vibrating

Sample Magnetic is used. The following is the

curve of Fe₃O₄and 1:1:1 Fe₃O₄/AC/ZnO

nanocomposite.

Figure 8. Hysteresis curve of Fe3O4 (A), 1:1:1 Fe₃O₄/AC/ZnO nanocomposite (B)

Table 3. VSM Characterization Result

Sample

Ms (emu/gr)

28.8

Fe₃O₄

1:1:1 Fe₃O₄/AC/ZnO nanocomposite

4.41

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Figure 8 shows the hysterical curve of the

nanocomposite synthesis results showing a

decrease compared to Fe₃O₄. While in table 3 is

the result of VSM characterization of Fe₃O₄and

1:1:1 Fe₃O₄/AC/ZnO nanocomposite.

activated carbon, which can reduce the magnetic

properties of the resulting nanocomposites.

Research conducted by Astuti (2022) stated that

the effect of adding carbon to the Fe3O4@ZnO-C

nanocomposite was able to reduce the magnetic

properties of the formed nanocomposite [26].

Table 3 shows that saturation magnetization (Ms)

has decreased significantly with Fe3O4 of 28.8

emu/g with 1:1:1 Fe3O4/AC/ZnO nanocomposite

of 4.41 emu/gr. With these results, it can be

concluded that the magnetic strength the

However, the superparamagnetic properties of

the

Fe3O4/AC/ZnO

nanocomposite

enable

increased charge transfer and slow down the

occurrence of electron-hole recombination,

thereby enhancing photocatalytic activity and

facilitating the separation process for reuse [27].

Photocatalytic Studies Photocatalyst tests were

carried out with Fe3O4/AC/ZnO nanocomposite

using parameters from the research of [10].

Performed in the time range 12.00-14.00 with an

synthesis

is

superparamagnetic.

Research

conducted by [24] obtained

a

saturation

magnetization of 25.7 emu/gr; these results are

close to the results of the Fe3O4 synthesis that

has been carried out. [25] obtained a saturation

magnetization of 52.15 emu/gr, which was 2

times that of this study. According to [25], the

smaller the crystal size, the smaller the number

of magnetic domains, and the magnetic domain

boundaries are also fewer, so that the saturation

average

luxmeter

of

52350-53560,

the

photodegradation process was carried out with a

concentration of rhodamine B of 50 ppm with a

duration of sunlight irradiation for 90 min and

was constantly stirred. The following is a data

table of the % degradation of Rhodamine B used

Fe3O4/AC/ZnO nanocomposites with various

ratios.

magnetization

value

(Ms)

decreases.

In

nanocomposites, in addition to large crystal

sizes, there are components that do not have

magnetic or nonmagnetic properties, namely

Table 4. % Degradation of Rhodamine B with ratio of Fe₃O₄/AC/ZnO nanocomposite

Sample Name

Fe₃O₄/AC/ZnO

Average

Luxmeter

Average Initial

Absorbance

Average

final

absorbance

Degradation of

Rhodamine B (%)

0 : 1 : 1

1 : 1 : 1

2 : 1 : 1

3 : 1 : 1

4 : 1 :1

53560

54670

52630

53123

53340

2.795

0.463

0.109

1.033

0.479

0.712

83.4

96.1

63.0

82.8

74.5

Table 4 shows the percent degradation results

from the photodegradation of Fe3O4/AC/ZnO

nanocomposites, with the smallest percentage of

63% to 96.1%. It can be seen that the best percent

degradation is in the nanocomposite with a ratio

of 1:1:1, with a percent degradation of 96.1%. It

can be seen that with the addition of Fe3O4,

there is an increase from 83.4% to 96.1%.

However,

the

2:1:1

nanocomposite

ratio

experienced a significant decrease, then the 3,1

nanocomposite ratio increased, and the 4:1:1

nanocomposite decreased again. From the table,

it can be seen that the higher the Fe3O4 ratio, the

greater the decrease in absorbance percent is

due to clumping that covers ZnO to carry out the

photodegradation process. Because the greater

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the ratio of Fe3O4, the percentage of rhodamine

B absorbance decreases [28]. Nanocomposites

with a ratio of 1:1:1 get the highest percent

absorbance, which is comparable to the crystal

size that has been characterized using XRD of

48.17nm. With the band gap energy obtained, the

smaller the energy required for the degradation

process. The smaller the band gap energy, the

more OH● is formed and able to receive visible

light. SEM results also show that ZnO is spread

throughout the surface of Fe3O4/AC/ZnO, which

causes

more

effectiveness

in

degrading

rhodamine B substances.

100

80

60

40

20

0

0:1:1

1:1:1

2:1:1

3:1:1

4:1:1

Ratio of Fe₃O₄/AC/ZnO

Figure 9. Graph of the relationship between the Fe₃O₄/AC/ZnO ratio and the % degradation of

Rhodamine B

Where the smaller the crystal size and

crystallinity, the greater the % absorbance

to increased surface area, more defect

states, and band gap narrowing. This can

also be used for optimizing optical and

photocatalytic properties [29].

obtained.

Reducing

crystal

size

and

crystallinity enhances the % absorbance due

Figure 10. Photodegradation process of rhodamine B using Fe₃O₄/AC/ZnO nanocomposite

When the Fe₃O₄/AC/ZnO photocatalyst is

exposed to photon energy from sunlight,

Fe₃O₄and ZnO will undergo a charge

separation process that causes electron

excitation from the valence band (VB) to the

conduction band (CB) and produces holes in

the VB. When forming the Fe₃O₄/AC/ZnO

nanocomposite, Fe3O4 and ZnO are on the

AC surface

and can shift to longer

wavelengths and produce smaller band gap

energies, in accordance with the Z-scheme

heterojunction of Fe₃O₄/AC/ZnO. The CB of

ZnO is more positive than that of Fe₃O₄, but

the VB of ZnO is more negative than that of

Fe₃O₄[30]. When exposed to photon energy

from the sun, excited electrons from the CB

282

R. Bemis et al.

Chempublish Journal, 9(2) 2025,272-286

of ZnO will migrate to the VB of Fe3O4 [31].

Photogenerated electrons are captured by

the AC surface through the semiconductor-

The magnitude of the ability of the

Fe3O4/AC/ZnO nanocomposite to degrade

rhodamine B will be developed by looking at

the recycling ability of the Fe3O4/AC/ZnO

nanocomposite for reuse in the rhodamine

B photodegradation process

heterojunction,

recombination. Simultaneously, the same

number of holes is formed in the

preventing

electron-hole

semiconductor. The AC surface accepts

electrons from the semiconductor CB,

preventing electron recombination and

significantly improving the photogenerated

charge separation efficiency [32]. The

separated holes and electrons will interact

with O and OH– to produce reactive radical

species •O2– and •OH. The radical species

produced from the redox process then

Acknowledgement

The authors would like to thank the

University of Jambi for funding this research

through the DIPA PNBP Science and

Technology Applied Research Scheme with

Research

Contract

Agreement

Letter

Number:369/UN21.11/PT.01.05/SPK/2023

Date 17 April 2023.

interact with Rhodamine

B

molecules,

reducing the rhodamine B molecular chain

into a simpler, environmentally friendly

molecular chain [33].

Author Contributions

Conclusion

Conceptualization,

RB.

and

NP.;

Methodology, PAW.; Software, R.; Validation,

R., RB. and LA.; Formal Analysis, LM.;

Investigation, LA. and PAW.; Resources,

PAW.; Data Curation, RB.; Writing – Original

Draft Preparation, RB. And PAW; Writing –

Review & Editing, R. and LA.; Visualization,

Fe3O4/AC/ZnO nanocomposites have been

successfully synthesized using the ultrasonic

method. The addition of Fe3O4 variations

affects

the

characteristics

of

formed.

the

Fe3O4/AC/ZnO nanocomposites

The smallest crystal structure is produced

from the 1:1:1 composition variation of the

Fe3O4/AC/ZnO nanocomposite, specifically

48.17 nm, with a more dominant ZnO

structure. Activated carbon does not affect

NP.;

Supervision,

LM.;

Project

Administration, RB.; Funding Acquisition, RB

; LM ; R ; NP”.

Conflict of Interest

The authors declare no conflict of interest.

the

structure

of

the

Fe3O4/AC/ZnO

nanocomposite but affects the resulting

magnetic properties. SEM results show that

the 1:1:1 Fe3O4/AC/ZnO nanocomposite has

a size of 42.74 nm with a more uniform

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