Science and Technology Indonesia e-ISSN:2580-4391 p-ISSN:2580-4405 Vol.
No.
October 2025 Research Paper Polyoxometalate-Assisted Layered Double Hydroxide for Facile Photocatalytic Methylene Blue and Malachite Green Yulizah Hanifah1* .
Nur Ahmad2 1 National Research and Innovation Agency (BRIN).
PUSPIPTEK.
South Tangerang, 15331.
Indonesia 2 Research Center of Inorganic Materials and Coordination Complexes.
Universitas Sriwijaya.
Palembang, 30139.
Indonesia *Corresponding author: yuli065@brin.
Abstract To increase the photodegradation activities of polyoxometalate, the co-precipitation approach has been used to prepare intercalated polyoxometalate compounds with ZnAl-LDH on methylene blue and malachite green dye.
It is strongly advised to use the preparation catalyst LDH with polyoxometalate to create a successful method for anionic dye reduction.
This study demonstrated the effectiveness environmentally method for intercalating ZnAl-LDH with polyoxometalate compound by employing methylene blu and malachite green dye as an organic pollutant.
Additionally, the results showed that for pH = 7 for ZnAl-SiW12O40 on degraded malachite green, and the highest researching 94% on degradation methylene blue on ZnAl-PW12O40.
Due to the rapid dissociation of the procion red reduction from the polyoxometalate photocatalytic activities, it was thought to have significant co-catalyst effects.
Keywords Polyoxometalate.
LDH.
Photodgeradation.
Methylene Blue.
Malachite Green Received: 25 June 2025.
Accepted: 28 September 2025 https://doi.
org/10.
26554/sti.
INTRODUCTION
Wastewater from dye-manufacturing and dye-consuming industries has long been a significant environmental issue.
The dyes in these effluents decrease sunlight penetration and photosynthesis in aquatic ecosystems, while also raising the biochemical oxygen demand (Singh et al.
, 2.
Dyes are usually stable organic substances that are challenging to eliminate using biological treatment methods and often produce large amounts of wastewater containing complex synthetic dyes (Barciela et al.
It is estimated that approximately 60-70% of these dyes are azo compounds, distinguished by their stable azo bonds ( N NA.
connected to aromatic rings, which contribute to their persistence and potential risks to both ecosystems and human health.
Nonetheless, alternative non-biological strategies, such as photocatalytic advanced oxidation processes, have shown promise in addressing these challenges can effectively eliminate them (Tseng et al.
, 2.
Photocatalysis of dyes entails generating highly reactive oxygen species (ROS), such as hydroxyl and superoxide radicals, which interact and bread down the dyes when exposed to a semiconductor and visible or ultraviolet (UV) light.
Among different semiconductor oxides.
TiO2 and ZnS are commonly used for degrading organic pollutants because of their photoactivity, stability, and non-toxicity (Saefumillah et al.
, 2.
The most popular application of TiO2 in photocatalytic degradation research in due to its low cost, alkali resistance to acid, non-toxicity, and photostability.
Many elements have been doped on TiO2 in recent years to increase its photochemical capacity (Feng et al.
, 2.
This could lower TiO2 the bandgap increases elementAos absorption wavelength range into the visible range or improve the way the sunAos light is uses but TiO2 doped materials are frequently employed immediately (Nayak et al.
, 2.
Polyoxometalate has the same character with TiO2 commonly metal oxide.
There exists a vast array of POM compositions and structural designs, which can be broadly classified into two primary classes: heteropoly anions and isopolyanions.
The most commonly occurring kinds in the literature are heteropoly anions, such as the Keggin or well Dowson types.
is impossible to remove or chemically substitute element X .
rimary heteroato.
without endangering the anion degradation of the basic POM structure.
However, removal of the metallic center can result in various structural alterations with consequents improved reactivity and mechanical qualities depending on reactional conditions, such as pH, temperature, or precursors (Gao et al.
, 2.
Because of their unique size and shape that resemble a metal-oxygen cluster structure, as well as several desirable properties that make them desirable for use in catalysis, biology, and magnetism, the class of metal-oxygen Hanifah and Ahmad cluster compounds known as polyoxometalates (POM), which are primarily based on V.
Mo, and W ions in their highest oxidation states, are fascinating.
Malachite green (MG) triphenyl methane [C6H5C(C6H4N (CH.
Cl is a cationic dark green dye, yuI max = 617 nm, which is traditionally used as a dye.
The structure of MG is given in wool, cotton, silk, jute, leather, paper, and certain fibers (Gessner and Mayer, 2.
MG renowned for its efficacy as both fungicide and parasiticide, has been utilized extensively in aquaculture and transportation to combat fungal infections in fish and extend the lifespan of fish suffering from scale damage.
However, due to its classification as toxic triphenylmethane compound.
MG carries potential risks of causing cancer and birth defects in humans, leading to its restriction or prohibition in several countries (Tian et al.
, 2.
Similarly, methylene blue (MB), a thiazine dye with yuI max = 664 nm, is one of the most widely used cationic dyes in textile dyeing, printing, paper, and leather industries (Ullah et al.
, 2017.
Lobo et al.
, 2.
Although MB is employed in medicine as an antiseptic and diagnostic agent, excessive release of MB into water bodies poses environmental and health hazards, including eye burns, nausea, and methemoglobinemia upon prolonged exposure.
Like MG.
MB can strongly interact with negatively charged surfaces, making it persistent in the aquatic environment.
Currently, medication is absent on the market can effectively treat water mold as swiftly as MG.
Despite concerns.
MG remains unrestricted, particularly during transportation (Hu et al.
, 2.
MG and MB dye, as a cationic dye, can readily interacts with surfaces that carry a negative charge.
is essential to develop a method that is both environmentally friendly and effectively for breaking down methylene blue into non-toxic byproduct before it is disposed or used.
Numerous approaches have been documented in the literature, such as photodegradation with catalysts (Asadzadeh-Khaneghah et al.
, oxidative degradation using nanoparticles, adsorption (Lobo et al.
, 2025.
Patra et al.
, 2.
and ultrasound degradation (Bi et al.
, 2.
Layered double hydroxides (LDH.
are a class of twodimensional anionic clays with the general formula [M2 1-x M3 x (OH) .
x (An- ) x /n AmH2O, where M2 and M3 represent divalent and trivalent metal cations, and An- denotes interlayer anions (Nayak et al.
, 2.
LDHs are attractive for photocatalytic and environmental applications due to their tunable metal composition, large surface area, and anion-exchange capacity (Xu et al.
, 2.
However, their photocatalytic efficiency is often restricted by several shortcomings, including rapid electronAehole recombination, relatively low conductivity, and limited light absorption.
To address these limitations, intercalation of LDHs with functional guest species has been widely Among these, polyoxometalates (POM.
are particularly promising due to their strong redox activity, excellent electron-accepting ability, and structural stability.
Intercalating POMs into LDHs not only enhances charge separation and transfer but also broadens light-harvesting capability, thereby A 2025 The Authors.
Science and Technology Indonesia, 10 .
1312-1321 improving overall photocatalytic performance.
Therefore, in this study.
LDHAePOM composites were developed to overcome the intrinsic drawbacks of pristine LDHs and to achieve enhanced photocatalytic activity.
Although intercalation of polyoxometalates into LDH hosts has been demonstrated to enhance catalytic and photocatalytic performance by improving charge separation and providing redox-active centers, recent reviews and original studies indicate that important challenges remainAinamely the controlled assembly of POM pillars within LDH galleries, tuning of interfacial electronic coupling for efficient charge transfer, and comprehensive demonstration of improved photocatalytic metrics under conditions relevant to target applications.
Recent efforts have produced POM-pillared LDHs with improved activity for CO2 reduction and water oxidation (Zhao et al.
, 2.
and modular POMAeLDH membranes via charge-driven selfassembly (Zhang et al.
, 2.
but these works also highlight the need for better control over interlayer architecture and systematic correlation between structure and photoelectronic To address these gaps, the present study develops a .
pecify: e.
, reconstruction/anion-exchange/pillarin.
strategy to intercalate .
ame/type of POM, e.
Keggin-type SiW12O404- ] into (M2 /M3 ) LDH, and couples structural, spectroscopic, and photoelectrochemical characterization to demonstrate enhanced charge separation and photocatalytic activity compared to pristine LDH.
This approach provides improved control of POM spatial arrangement and electronic interaction with the host layers, providing a clear advance over previously reported POMAeLDH systems.
We created two novel polyoxometalate-intercalated ZnAlFe layered double hydroxide (POM-LDH) was synthesized throu gh water ion exchange of a precursor ZnAlFe LDH with polyoxometalate anions [P2W.
(Xu et al.
, 2021.
Liu et al.
, 2.
The motivation on developing photocatalysis LDH materials looks from some success literature on degradation dye.
The catalyst as degradation some cationic dye used layered material and polyoxometalate.
methylene blue on Ni/Mg LDH (Hanifah et al.
, 2.
Intercalated NiAl-POM on degradation malachite green (Hanifah et al.
, 2023.
polyoxometalate for degradation malachite green (Hanifah et al.
, 2023.
red (Hanifah et al.
, 2023.
The ZnAlFe POM-LDHAos adsorptive capability and photocatalytic activity.
Previous works have demonstrated the effective breakdown and adsorptive removal of organic dyes ZnAl-LDH in aqueous solution using photocatalysis (Bi et al.
, 2022, 2011.
Parida and Mohapatra, 2.
In this work, we prepared material ZnAl-LDH intercalated with polyoxometalate (POM) by aqueous ion exchange of LDH as a precursor with two polyoxometalate anions K3.
uPW12O.
(KPW) and K4.
u-SiW12O.
(KSiW).
The photocatalytic activity of ZnAl-POM was assessed using the removal of cationic dye from aqueous solutions as a model reaction.
Alongside characterizing the two synthesized POM-LDH materials, their photocatalytic performance was examined both theoretically and experimentally.
Previous studies have demonPage 1313 of 1321 Hanifah and Ahmad strated that ZnAl-LDH is effective for degrading and adsorbing of dyes in aqueous solutions represent crucial steps towards sustainable water treatment technologies.
It serves as beneficial catalyst support material for potential photocatalytic applications, owing to the high negative charge of POM that enhances its capability to degrade anionic dyes.
Particularly LDH composite which plays a remarkable role in the reduction and remediation of environmental contaminants, has drawn a lot of attention to the photodegradation of organic pollutants in wastewater.
For this reason, it has been named as one of the most hopeful materials photocatalysts.
EXPERIMENTAL SECTION
1 Materials The substances employed in creating the samples were: sodium phosphate (Na3PO.
, sodium carbonate (Na2CO.
, zinc nitrate hexahydrate (Zn(NO.
2, sodium tungstate (Na2WO.
, sodium hydroxide (NaOH), aluminum nitrate hexahydrate Al(NO.
3 and hydrogen chloride as a combined agent during the breakdown of organic dyes in water-based solutions.
Chemicals used for analysis were sourced from reputable supplier such as Sigma Aldrich and Merck to ensure high quality and reliability.
The synthetic dyes, methylene blue has a maximum absorbance of 665 nm and malachite green .
uI max = 617 n.
were used as model cationic dye.
A miniflux-6000 Rigaku XRD diffractometer was used radiation source to measure the materials crystallinity structure analysis was performed CuKyu using a 30 kV voltage, 10 mA current, and a 2yuE range spanning from 10 to 90 to investigate the crystallographic properties pf the An analytical instrument known as the Shimadzu FTIR ALPHA Bruker (Platinum-ATR) by the KBr method and sample was scanned at 400-4000 cm-1 that used to analyze the molecular structure of the compounds.
The UV-Vis Biobased BK-UV 1800 PC spectrophotometer was employed was employed to quality the extent of degradation thought absorbance measurements.
SEM examination using the FEI Quanta 650 with an accelerating voltage of 30 V was uses to take the SEM ZnAl-LDH and ZnAl-composite was conducted to study the surface of the material.
2 Synthesis of Layered Double Hydroxide The precursor ZnAl-LDH was synthesized via a coprecipitation technique .
to promote the formation of the layered double hydroxide (LDH) phase.
A mixed solution was prepared by dissolving 0.
5 M Zn(NO.
2A6H2O and 0.
25 M Al(NO.
3A9H2O in 100 mL of purified water, maintaining a molar ratio of Zn:Al = 2:1.
Separately, 1.
5 M NaNO3 was introduced dropwise into the salt solution over a period of 2 h under vigorous stirring at room temperature.
The pH was adjusted and maintained 5 by the addition of 2 M NaOH solution.
The resulting suspension was subsequently aged at 85 C for 18 h.
The precipitate obtained was thoroughly washed with deionized water until a neutral pH was achieved, followed by vacuum drying at 60 C for 12 h to yield the ZnAl-LDH powder.
A 2025 The Authors.
Science and Technology Indonesia, 10 .
1312-1321 3 Synthesis of Polyoxometalate K3.
u-PW12O.
(KPW) Keggin K3.
u-PW12O.
, a polyoxometalate molecule, modifies LDH.
After adding 2.
4 g Na2WO4.
2H2O in 1000 mL of acidic solution .
hich contained 100 mL of H3PO4 and 900 mL deionized wate.
, the mixture attained a boiling point.
10 cc of HCl was added right away, and the mixture was allowed to cool.
The insoluble was extracted from solution by adding 50 mL of diethyl ether and stirring for 10 minutes after the mixture had The hazy organic phase eventually gathered and dried causing the pure KPW to precipitate.
4 Composite LDH-Polyoxometalate A polyoxometalate molecule called Keggin K4.
u-PW12O.
and K3.
u-PW12O.
is added to LDH.
To prepare the composite, 2 g of LDH and 1 g pf polyoxometalate were combined with 1 mL of sodium hydroxide solution.
The suspensions were quickly made while N2 gas was present for two days.
After that, the suspension was washed and allowed to dry at 80 C for 12 hours.
5 Photocatalytic Performance The photocatalytic performance of the samples was first evaluated through adsorption-desorption equilibrium by dispersing the catalyst in dye solutions .
mg/L methylene blue.
MB, or 20 mg/L malachite green.
MG) under dark conditions with continuous stirring for 30 minutes.
Photodegradation experiments were then conducted by varying the catalyst dosage .
02Ae0.
, contact time .
Ae120 minute.
, and solution pH .
Ae.
The reactions were carried out under UV irradiation .
uI = 365 n.
, and aliquots of the suspensions were periodically withdrawn, centrifuged, and analyzed using a UVAeVis spectrophotometer at the respective maximum absorption wavelengths .
uI max = 665 nm for MB and yuI max = 617 nm for MG) to determine the residual dye concentration and calculate the degradation efficiency.
RESULTS AND DISCUSSION
1 X-ray diffraction analysis (XRD) The XRD patterns of Zn/Al-LDH.
POM (PW12O40 and SiW12O.
, and their composites are presented in Figure 1.
All samples were analyzed using CuKyu radiation .
uI = 1.
yI) over a 2yuE range from 20 to 80 degrees.
The pristine Zn/AlLDH shows characteristic diffraction peaks at 2yuE = 11.
6 , 23.
6 , 39.
2 , 46.
8 , and 60.
9 , corresponding to the .
, .
, .
, .
, .
, and .
planes, respectively, which are typical of layered double hydroxides with a hydrotalcitelike structure (Lesbani et al.
, 2.
The POMs exhibit distinct peaks in the range of 7Ae10 and 25Ae30 , which are attributed to the preserved Keggin-type structure of PW12O40 and SiW12O40 (Hanifah et al.
, 2023.
The peak of composite ZnAl-SiW12O40 was showed at 8.
61, 25.
27, 34.
96, and 66.
respectively which better than ZnAl-PW12O40.
In the composite materials, the diffraction peaks of both Zn/Al-LDH and POM are observed, confirming the successful incorporation of POM into the LDH layers.
The slight reduction in peak Page 1314 of 1321 Hanifah and Ahmad intensity and broadening in the composite patterns indicate partial structural distortion, which suggests strong interaction between the LDH matrix and the POM units.
Importantly, the characteristic reflections of the LDH remain visible, demonstrating that the layered structure is retained after composite These results confirm the successful synthesis of Zn/Al-LDH/POM composites with integrated structural features from both components.
Science and Technology Indonesia, 10 .
1312-1321 tions within the brucite-like layers, while a distinct band at 553 cm-1 was correlated with Ni O stretching vibrations (Adim et al.
, 2.
The FTIR spectrum of the polyoxometalate exhibited characteristic bands at 1020 cm-1 (W O), 979 cm-1 (W O), and 925Ae789 cm-1 (WAeOAeW), consistent with previous reports (Hanifah et al.
, 2023.
In this study.
K3PW12O40 showed absorption bands at 976, 884, 740, and 594 cm-1 , while K4SiW12O40 displayed peaks at 958, 865, 787, and 714 cm-1 .
Following intercalation into the LDH structure, the composite spectrum exhibited altered absorption bands within the 976Ae594 cm-1 range, confirming successful modification of the LDH by polyoxometalate inclusion.
Figure 2 depicts the preservation of the LDH structure supported with polyoxometalate.
Figure 1.
Diffractogram of ZnAl-LDH.
K3PW12O40.
K4SiW12O40.
ZnAl-PW12O40, and ZnAl-SiW12O40 2 FTIR Analyisis.
The infrared spectra of pristine LDH.
LDH combined with polyoxometalate, and the pure polyoxometalate compound provided valuable information about the surface functional groups of the synthesized materials.
All spectra were recorded in the range of 400Ae4000 cm-1 .
The ZnAl-LDH and its composites displayed characteristic absorption bands, including a broad band at 3448 cm-1 corresponding to the O H stretching vibration of interlayer water molecules, and a band at 1635 cm-1 associated with the bending vibration of H2O.
A strong absorption band was observed at 1381 cm-1 , which is attributed to the stretching vibration of interlayer CO32- .
Although nitrate precursors were used in the synthesis, carbonate is commonly detected in LDH materials because CO32- anions have a higher affinity for interlayer sites and readily replace other anions during the coprecipitation process or subsequent exposure to atmospheric CO2.
This behavior has been widely reported in the literature, confirming the predominance of carbonate in the interlayer space.
In the lower region, bands between 400Ae800 cm-1 were associated with metalAeoxygen and oxygenAemetalAeoxygen vibraA 2025 The Authors.
Figure 2.
FTIR spectra of ZnAl-LDH.
K3PW12O40.
K4SiW12O40.
ZnAl-PW12O40, and ZnAl-SiW12O40 3 SEM Analysis SEM analysis illustrated the morphology of ZnAl-LDH in its LDH pristine form and in both LDH composite ZnAlPW12O40 and ZnAl-SiW12O40 revealing aggregate pore structures, with ZnAl-polyoxometalate composite displaying distinct polyoxometalate distribution characterized by smaller particle sizes compared to pure ZnAl-LDH.
The composite materials exhibited heterogeneous shapes worth notable aggregate formations.
Figure 3 both samples prepare initially exhibited a characteristic lamellar structure of LDH, but ZnAlLDH-POM displayed noticeable agglomeration compared to the precursor (Wang et al.
, 2.
It includes SEM images and particle size analysis using ImageJ, revealing mesoporous structure by particle sizes ranging were showed from 2 to 5 Page 1315 of 1321 Science and Technology Indonesia, 10 .
1312-1321 Hanifah and Ahmad Figure 3.
SEM Analysis of ZnAl-LDH.
ZnAl-K4SiW12O40, and ZnAl-K3PW12O40 Table 1.
The Percentage of Methylene Blue Degradation Catalyst
Nb2O5/ZnAl-LDH CoMgAl-borate LDO
ZNCQD
MgZnCr-TiO2 ZrCuFe-LDH/rGO ZnCoFe/MgAl-LDH yu-Fe2O3/MgAl-LDH ZnAl-[PW12O.
ZnAl-[SiW12O.
MgAl-[PW12O.
MgAl-[SiW12O.
NiAl-[PW12O.
NiAl-[SiW12O.
% Degradation Methylene Blue 4 UV-DRS Analysis The UV-DRS analysis of LDH materials and their composites was carried out to determine their band gap energies, which are crucial parameters in evaluating photocatalytic activity for the degradation of organic pollutants.
The results revealed that the band gap energy of ZnAl-LDH composites was lower .
2 eV) A 2025 The Authors.
Time .
Reference (Hanifah et al.
, 2023.
(Wang et al.
, 2.
(Bhuyan and Ahmaruzzaman, 2.
(Ma et al.
, 2.
(Srivastava, 2.
(Abdel-Hady et al.
, 2.
(Srivastava, 2.
In this study In this study (Xu et al.
, 2.
(Xu et al.
, 2.
(Bi et al.
, 2.
(Bi et al.
, 2.
compared to ZnAl-PW12O40 .
4 eV) and ZnAl-SiW12O40 .
7 eV) composites.
Although ZnAlAeLDH showed a smaller band gap than the ZnAlAePOM composites, the composites exhibited enhanced photocatalytic degradation performance, mainly due to more efficient charge separation and the synergistic effect between LDH and POM.
A smaller band gap implies Page 1316 of 1321 Science and Technology Indonesia, 10 .
1312-1321 Hanifah and Ahmad Figure 4.
UV-DRS Analysis of LDH Composite and Polyoxometalate Table 2.
The Percentage of Malachite Green Degradation Catalyst % Degradation Malachite Green Time .
ZNCQD Al-Li/Th-LDH@CNT NiAl-LDH/polyoxometalate ZnAl-gallate-LDH/polystsrene nanofibers Magnetic ZnAl-LDH ZnAl-[PW12O.
ZnAl-[SiW12O.
enhanced visible-light absorption, which facilitates the generation of more hydroxyl (AOH) radicals, thereby improving the photodegradation efficiency of organic compounds (Lesbani et al.
, 2.
The band gap values derived from the Tauc plot are presented in Figure 4.
In addition, the photocatalytic mechanism can be explained as follows: when photoexcited electrons .
- ) in the conduction band (CB) react with adsorbed methylene blue (MB) molecules.
MB radical anions are formed, leading to the degradation of MB.
Meanwhile, the photogenerated holes .
) in the valence band (VB) can directly oxidize adsorbed MB molecules into MB radical cations, which subsequently undergo further transformation into mineralized end products.
Moreover, when water molecules interact with the VB holes.
AOH radicals are produced, which act as powerful oxidizing species to accelerate dye degradation.
The overall mechanism can be summarized by the following reactions:
ZnAlOeLDH/POM hyuO OeIe eCB h H2 O OeIe AOH H O2 2H2 O 2e Oe OeIe H2 O2 2OHOe A 2025 The Authors.
Reference (Bhuyan and Ahmaruzzaman, 2.
(Liao et al.
, 2.
(Bi et al.
, 2.
(Rabiee et al.
, 2.
(Rohmatullaili et al.
, 2.
In this study In this study H2 O2 e Oe OeIe AOH HOOe H OH OeIe H2O AOe AOH dye OeIe MB /MG A OeIe final product AOe H MB/MG OeIe MB /MG .
OeIe final product .
5 Impact of Reaction Duration The ideal reaction period for both the original material and composite was found to be 2 hours, during which methylene blue dye conversion was achieved.
Extending the reaction time beyond this period showed diminishing return in terms of increased methylene blue degradation efficiency.
The composite material achieved its highest conversion rate of 80% under these conditions, demonstrating that further prolonging rate of 80% under these conditions, demonstrating that further prolonging the reaction time does not significantly enhance the dye removal process.
The percentage degradation of methylene blue for ZnAl-LDH.
ZnAl-[PW12O.
ZnAl-[SiW12O.
were exceeded 74%, 73%, and 66% respectively.
The degradation of malachite green for ZnAl-LDH.
ZnAl-[PW12O.
ZnAl[SiW12O.
were 83%, 93%, and 94% respectively.
The effect of reaction time shown in Figure 5.
Page 1317 of 1321 Science and Technology Indonesia, 10 .
1312-1321 Hanifah and Ahmad Figure 5.
Effect Of A) Contact Time on the Degradation Malachite Green.
B) Methylene Blue, and C) Weight Catalyst on Degradation Malachite Green.
D) Methylene Blue Figure 6.
Effect of pH Degradation on Malachite Green (A) and Methylene Blue (B) 6 Impact of Catalyst Mass Reported by Hanifah et al.
most effective degraded of malachite green using varying catalyst weights.
In this study, a catalyst weight of 0.
1 g was adequate for catalyzing methylene blue .
nitially at 20 pp.
using pristine ZnAl-LDH.
Material A 2025 The Authors.
composite, there are ZnAl-PW12O40.
ZnAl-SiW12O40 were 75 g all catalyst is effectively conversion of methylene blue as shown in Figure 5.
The same variation on degradation malachite green shown in Figure 5.
In this study, employing a catalyst weight below this threshold .
, is not much Page 1318 of 1321 Hanifah and Ahmad enough to degrade, the maximum percentage degradation of methylene blue occurred at catalyst weights exceeding the specified range .
, 0.
04 to 0.
it may of using the highest amount of the material may result in achieving the highest percentage of degradation.
It is because dosage used the more material that can bonded and degraded methylene blue than malachite green.
However, the catalyst weight must be precisely calibrated.
this study aligns the catalyst systems with experimental conditions.
Figure 5 illustrates the influence of different catalyst masses on the degradation of methylene blue.
The value gradation for pristine material and composite material are quite similar.
7 Effect of pH ZnAl-LDH pH 7.
ZnAl-SiW12O40 and ZnAl-PW12O40 both are on pH 1 for degradation of methylene and degradation of malachite green are ZnAl-LDH pH 7.
ZnAl-SiW12O40 pH 1 and ZnAl-PW12O40.
The degradation of methylene blue through catalytic processes was investigated across varying solution pH levels .
, 3, 5, 7, 9, and .
pH adjustments were made using NaOH and HCl prior to irradiation.
It was observed in Figure 6 that the photodegradation characteristics vary among each material.
LDH material which is ZnAl-LDH.
ZnAl-SiW12O40 and ZnAl-PW12O40.
ZnAl-LDH demonstrated the optimal pH that was obtained was at pH 7 respectively.
The conditions used in the experiment, the optimal pH for LDH material was found to be pH 7, consistent with finding from other studies.
However, the behavior of the composite material differed significantly, possibly attributed to the presence of polyoxometalate post-intercalation.
This process of modification improves the formation of positively charged species, aiding in anionic interactions.
There is a under UV irradiation, the photocatalytic reaction with the LDH-POM catalyst generates a positive charge hole .
vb ), and electrons .
H2O will generate a hydroxyl radical (AOH), capable of degrade methylene blue simpler intermediates.
The composite materials, such as ZnAl-PW12O40.
Exhibit optimal degradation of malachite green at pH 7.
ZnAl-[SiW12O.
also shows optimal performance at pH 3.
ZnAl-[PW12O.
at pH 1 and ZnAl-[SiW12O.
at pH 1 on degraded methylene blue.
Figure 6 depict how pH influences the degradation of malachite green and methylene blue by catalysts, both LDH in printine and composite forms.
Optimal degradation occurred at lower pH levels, at pH levels below 7, effective generating of OHA radicals occur, facilitating dye degradation and initiating the photodecomposition of polyoxometalate into ions.
CONCLUSIONS
The synthesis of intercalation resulted in the formation of a heterogeneous aggregate.
By monitoring factors like pH, catalyst mass, degradation duration, researchers assessed.
Degradation properties of pristine LDH and LDH composite materials.
The ZnAl-SiW12O40 material exhibited the highest degradation percentage, achieving up to 94% degradation pH methylene blue compared to other composite material.
The degradation A 2025 The Authors.
Science and Technology Indonesia, 10 .
1312-1321 of malachite green of ZnAl-SiW12O40 reaching to 74% on pH The catalyst dosage used was 0.
75 mg and optimum pH of ZnAl-SiW12O40was found pH 1.
Nevertheless, its performance was markedly superior to that of pure LDH.
The results indicate that the LDH composite has a strong photocatalytic activity for reducing methylene blue.
ACKNOWLEDGMENT
We the authors gratefully acknowledge extend our appreciation to the Research Center of Inorganic Materials and Coordination Complexes.
Universitas Sriwijaya and National Research and Innovation Agency (BRIN) for providing research facilities, laboratory instruments, and technical support throughout this study.
REFERENCES