Available online at website: https://journal.
id/index.
php/bcrec Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
2026, 262-273 Original Research Article Synthesis of Cu-PTC (Perylene 3,4,9,10-tetracarboxylat.
MetalOrganic Framework (MOF) for Methylene Blue Photodegradation Farhah Syahidatul Mala1.
Nanda Saridewi2,3*.
Siti Nurbayti1.
Adawiah1.
Agustino Zulys3 1Department of Chemistry.
Faculty of Science and Technology.
UIN Syarif Hidayatullah Jakarta.
Jl.
Ir.
Juanda No.
95 Ciputat Tangerang Selatan 15412.
Indonesia.
2Department of Chemistry Education.
Faculty of Tarbiya and Teaching Sciences.
UIN Syarif Hidayatullah.
Jl.
Ir.
Juanda No.
Ciputat Tangerang Selatan 15412.
Indonesia.
3Department of Chemistry.
Faculty of Mathematics and Natural Sciences.
University of Indonesia.
Jl.
Lingkar Kampus Raya.
Pondok Cina.
Beji.
Depok.
Jawa Barat 16424.
Indonesia.
Received: 31th October 2025.
Revised: 20th January 2026.
Accepted: 21st January 2026 Available online: 30th January 2026.
Published regularly: August 2026 Abstract Disposal of synthetic dye waste, including methylene blue, has been increasing in recent years.
The photocatalytic method is an effective approach for degrading dyes, using MetalAeOrganic Frameworks (MOF.
as catalysts and light as the energy source.
This study aims to synthesize Cu-PTC MOF as a photocatalyst and evaluate its performance in degrading methylene blue dye.
Cu-PTC was synthesized using Cu(NO.
3H2O and perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) via a solvothermal method.
The resulting MOF was characterized using X-ray Diffraction (XRD).
UltravioletAeVisible Diffuse Reflectance Spectroscopy (UV-Vis DRS).
Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM).
Cu-PTC exhibits a bandgap energy of 1.
72 eV and characteristic functional groups at wavenumbers 1689 cm-1 (C=O), 1590 cm-1 and 1360 cm-1 (-COO), 3450 cm-1 (O-H), and 738 cm-1 and 654 cm-1 (Cu-O).
The Cu-PTC MOF has a crystallinity degree of 85.
35%, a crystal size of 35.
33 nm, and a rod-like surface Under visible light irradiation, it achieves an optimum degradation efficiency of 71.
45%, with an adsorption capacity of 73.
28 mg/g for methylene blue dye at a concentration of 50 ppm, using 25 mg of Cu-PTC MOF at pH of 7 over a period of 60 minutes.
Copyright A 2026 by Authors.
Published by BCREC Publishing Group.
This is an open access article under the CC BY-SA License .
ttps://creativecommons.
org/licenses/by-sa/4.
Keywords: Cu-PTC.
methylene blue.
Metal-Organic Framework.
MOF
How to Cite: Mala.
Saridewi.
Nurbayti.
Adawiah.
Zulys.
Synthesis of Cu-PTC (Perylene 3,4,9,10-tetracarboxylat.
Metal-Organic Framework (MOF) for Methylene Blue Photodegradation.
Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 262-273.
(DOI: 10.
9767/bcrec.
Permalink/DOI: https://doi.
org/10.
9767/bcrec.
Supporting Information (SI): https://journal.
id/index.
php/bcrec/article/downloadSuppFile/20525/5939 Introduction Discharge of synthetic dye waste into water bodies has been increasing in recent years.
This waste originates from various industries, including textiles, cosmetics, paper, and pharmaceuticals .
Numerous efforts have been made to remove organic dye pollutants from aqueous environments due to their harmful effects on aquatic life and human health.
Their high stability, stemming from a high content of * Corresponding Author.
Email: nanda.
saridewi@uinjkt.
id (N.
Saridew.
aromatic compounds, makes these dyes resistant to biological degradation .
Methylene blue is one such dye that is persistent in the environment and exhibits toxic, carcinogenic, and mutagenic properties .
Several methods have been developed to remove dye pollutants from water, such as electrochemical processes, biological technologies, membrane filtration, and reverse osmosis .
However, these methods have several limitations, including low removal efficiency, high cost, long processing times, high sludge production, suitability only for small-scale remediation, and bcrec_20525_2025 Copyright A 2026.
ISSN 1978-2993.
CODEN: BCRECO
Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 263 the generation of toxic by-products .
Advanced Oxidation Processes (AOP.
have been identified as a promising approach for degrading organic pollutants in water .
The key feature of AOPs is the in-situ generation of highly reactive oxidizing free radicals, particularly hydroxyl radicals (AOH).
These reactive radicals can oxidize organic pollutants into COCC.
HCCO, or specific inorganic ions, thereby avoiding the formation of byproducts that might hinder complete degradation of the target pollutants .
The photocatalytic system is a part of AOPs that is highly effective, cost-efficient, and environmentally friendly, making it a promising remediation approach.
The photocatalytic process occurs in three main steps.
First, when the photon energy matches the bandgap of the semiconductor photocatalyst, electronAehole pairs are generated .
AAehA).
These charge carriers are then separated and transported to the surface of the Finally, the light-induced charge carriers participate in redox reactions at the active sites on the photocatalyst surface .
MetalAeOrganic Frameworks (MOF.
Photocatalysis is typically carried out using semiconductor-based catalysts because they possess a relatively small bandgap energy.
When illuminated by light .
with energy equal to or greater than this bandgap, the material can absorb the energy and excite electrons from the valence band to the conduction band.
This electron transfer creates electron holes in the valence band, which play a key role in generating hydroxyl radicals that degrade dyes .
The use of MOFs as materials in photochemical reactions has been widely developed and represents a promising option for removing dye contaminants from wastewater .
MOFs possess characteristics well-suited for wastewater treatment, including a unique porous structure, tunable pore size, abundant adsorption sites, and high specific surface area and porosity .
MOFs are also promising materials for photocatalysis due to their tunable bandgap, which enables them to absorb light and generate the electronAehole pairs required for photocatalytic reactions .
One of the most used methods for synthesizing MOFs is the solvothermal method.
This approach is widely employed because it is straightforward to carry out and can produce materials with high crystallinity .
The solvothermal method offers several advantages, morphology by varying the starting materials and reaction conditions, as well as producing MOFs with high reactivity .
Saridewi and her team studied Cr-PTC synthesized from chromium ions and perylene3,4,9,10-tetracarboxylate ligand using the solvothermal method.
The resulting material exhibited a bandgap energy of 2.
01 eV.
Cr-PTC effectively removed methylene blue pollutant .
with an adsorption capacity of 87.
22 mg/g within 180 minutes under visible light irradiation .
Perylene-3,4,9,10-tetracarboxylate reduce the bandgap energy of MOFs due to the conjugated aromatic ring bonds, making it responsive to visible light .
Zhang and his team synthesized two 3D MOFs [Cu.
,4A-bip.
n (MOF .
and [Co.
,4Abip.
(HCOO).
n (MOF .
MOF 1 achieved 93.
degradation of methylene blue after 150 minutes under visible light, whereas MOF 2 reached only 70% degradation at the same time .
Copper-based MOFs exhibit high stability, abundant elemental availability, and high surface area and porosity .
, making copper a promising candidate for photocatalyst development.
Based on a literature review, no studies have been found on the combination of copper metal ions and PTC ligands in a MOF used as a photocatalyst for methylene blue degradation.
The main objective of this study is to synthesize Cu-PTC MOF via the solvothermal method and evaluate its photocatalytic performance in degrading methylene blue under visible light Additionally, the effects of methylene blue concentration.
MOF dosage, and pH were also investigated.
Materials and Method Materials The materials used in this study included perylene 3,4,9,10-tetracarboxylic dianhydride (PTCDA) (Sigma Aldrich, 97%), copper (II) nitrate trihydrate (Cu(NO.
3H2O) (Merc.
, distilled water, sodium hydroxide (NaOH), ethanol .
%).
N-dimethylformamide (DMF) (Palla.
, and methylene blue (Merc.
Conversion of PTCDA to Na4PTC A total of 500 mg .
27 mmo.
of PTCDA was dissolved in 50 mL of distilled water, followed by the addition of 356 mg of NaOH .
9 mmo.
The mixture was stirred at room temperature using a magnetic stirrer at 300 rpm for 1 hour.
Excess ethanol was then added to the mixture to precipitate yellow NaCEPTC.
The solid NaCEPTC was collected by filtration and washed repeatedly with ethanol until neutral pH was reached.
The product was dried overnight at room temperature .
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 264 Synthesis of Cu-PTC MOF Cu-PTC MOF was synthesized by dissolving Cu (NO.
3H2O .
and Na4PTC .
,5 mmo.
in a mixture of 5 mL DMF and 25 mL deionized The solution was stirred thoroughly and then transferred into a Teflon-lined autoclave The sealed autoclave was heated in an oven at 170 AC for 24 hours.
After heating, the autoclave was allowed to cool naturally to room temperature over 24 hours.
The resulting Cu-PTC solid was collected by filtration and washed repeatedly with deionized water until the filtrate became clear.
The product was then dried overnight in an oven at 70 AC .
Characterizations Analysis of diffraction patterns and crystal size using the Debye-Scherrer equation was performed using XRD (Rigaku Minifle.
with CuK radiation ( = 1.
5418 yI).
Band gap energy analysis was performed using UV-Vis DRS (Agilent Carry .
at 200-800 nm wavelengths with BaSO4 powder as a blank.
The Kubelka Munk equation and the Tauc Plot determined band gap energy values.
Functional group analysis was performed using FTIR (Bruker Alph.
in the wavenumber range of 400-4000 cmOe1, with a spectral resolution of 4 cmOe1 and samples prepared in the form of pellets with KBr.
Surface morphology was determined using SEMEDX (JSM 6.
with a voltage of 20 kV.
Photocatalytic Activity Test of Cu-PTC MOF A preliminary test was carried out by dispersing 25 mg of Cu-PTC MOF into 50 mL of methylene blue .
The mixture was stirred at 300 rpm for 1 hour at room temperature under a visible light source .
-watt mercury lam.
and in the dark .
ithout a light sourc.
Then, 2 mL of the suspension was taken every 15 minutes for 1 hour and centrifuged for 10 minutes at 6000 rpm.
The methylene blue concentration was then measured using a UV-Vis spectrophotometer and a standard calibration curve of methylene blue solution at a wavelength of 665 nm.
The degradation efficiency and adsorption capacity of methylene blue were calculated using the following equations:
yaya Oe yayaycyc Degradation Efficiency (%) = 0 yaya0 y 100 yaya Oe yayaycyc Adsorption Capacity .
= 0 ycoyco yV This experiment also determined the optimum conditions for methylene blue degradation by Cu-PTC.
The variables studied were methylene blue concentration .
, 50, 75, and 100 pp.
, photocatalyst mass .
, 25, 35, and 45 m.
, and solution pH .
, 7, and .
Photocatalytic Degradation Kinetics Studies The optimum condition data were used to study the degradation kinetics using the pseudofirst order and pseudo-second order models, along with the corresponding kinetic equations shown in the following Equations .
Ae.
ln (C0/C.
= kt 1/Ct = .
/C.
C0 is the initial dye concentration .
g/L).
Ct is the dye concentration at a given reaction time .
, k is the pseudo-first-order rate constant .
inOe.
, and k2 is the pseudo second-order rate constant (L/mg.
Results and Discussion Cu-PTC Metal Organic Framework (MOF) In this study, the MOF was synthesized using Cu2 from (Cu(NO.
3H2O) as the metal center and PTCDA in its salt form (NaCEPTC) as the organic ligand.
Perylene is a carboxylate-type organic ligand that can reduce the bandgap energy of the MOF due to its conjugated aromatic ring system.
As a result, incorporating perylene as the ligand enables the resulting MOF to act as a visible-light-responsive photocatalyst .
Figure 1 shows the physical appearance of Cu-PTC MOF, which has a dark brown color.
The solvothermal method was chosen for synthesizing Cu-PTC MOF because it is straightforward to carry out and capable of producing materials with high crystallinity.
The elevated temperature and pressure conditions in this method are particularly suitable for growing crystals with sizes ranging from micrometers to nanometers .
C0 is the initial dye concentration .
g/L).
Ct is the dye concentration at a given reaction time .
g/L), m is the mass of the catalyst .
, and V is the volume of the solution (L).
Figure 1.
Physical appearance of Cu-PTC MOF Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 265 Characteristic of Cu-PTC MOF Functional group Figure 2 shows the wavenumber absorption peaks of each functional group in Cu-PTC MOF.
When compared with the absorption peaks of NaCEPTC, a shift in wavenumber is observed between the NaCEPTC and Cu-PTC MOF spectra.
Table 1 shows that in the FTIR spectrum of NaCEPTC, asymmetric and symmetric stretching vibrations of the carboxylate ion (AeCOO) appear at wavenumbers 1631 cm-1 and 1426 cm-1, respectively, whereas in Cu-PTC MOF, these peaks shift to 1590 cm-1 and 1360 cm-1.
This shift in wavenumber occurs because the Na-COO bond, which is an ionic bond, being broken and then forming a Cu-COO bond, which is a coordination The coordination bond energy is weaker than the ionic bond energy, causing a shift in the wavenumber towards a smaller value .
The FTIR spectrum of Cu-PTC MOF shows an absorption peak at 3450 cm-1, which corresponds to the stretching vibration of the OAeH group, likely originating from water molecules or carboxylic acid groups.
This absorption peak has also been observed in other copper-based MOFs .
The FTIR spectrum of Cu-PTC MOF shows absorption bands at wavenumbers 738 cm-1 and 654 cm-1, assigned to the stretching vibrations of the CuAeO group.
This is consistent with the findings of Varughese and colleagues, who reported CuAeO stretching vibrations at 784 cm-1 and 624 cm-1 .
MetalAeoxygen vibrations typically appear in the wavenumber range of 400Ae800 cm-1 .
In addition, an absorption peak at 1689 cmAA is observed, corresponding to the C=O stretching vibration.
This may indicate that the carboxylate groups in the PTC ligand coordinate with the metal center in a manner resembling anhydride-like functionality .
The FTIR results confirm that Cu-PTC MOF has been successfully synthesized.
Crystallinity and crystal size of Cu-PTC Based on the diffraction pattern of Cu-PTC (Figure .
, seven distinct peaks with the highest intensities appear at 2 values of 11.
705A, 25.
22A, 43.
266A, 50.
443A, 74.
12A, and 89.
The crystallinity degree of Cu-PTC MOF is 85.
which is significantly higher than that reported by Fathurrahman and colleagues, who obtained a crystallinity degree of 46.
56% for Fe-PTC MOF .
The crystal size was determined using the DebyeAeScherrer equation based on the peak with the highest intensity, yielding a nanoscale crystal size of 35.
33 nm for Cu-PTC MOF (Table .
The choice of metal can influence the crystal size of MOFs .
The crystal size and crystallinity of a MOF photocatalyst can significantly influence its photocatalytic activity.
Higher crystallinity generally results in fewer crystal defects.
These defects often act as traps for photogenerated electrons and holes.
Figure 2.
FTIR Spectrum of Na4PTC and Cu-PTC.
Figure 3.
Diffraction pattern of Cu-PTC MOF.
Table 1.
Absorption peaks of Na4PTC and Cu-PTC functional groups.
Na4PTC Wavenumber .
Cu-PTC
738, 654
Reference 1770 .
721, 624 .
Description OeC=O stretching OeCOO asymmetric stretching OeCOO symmetric stretching OeOH stretching CuOeO stretching Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 266 promoting their recombination and thereby reducing photocatalytic efficiency.
Conversely, smaller crystal size shortens the migration distance between photogenerated holes .
A) and electrons .
A), which decreases the likelihood of recombination and enhances photocatalytic activity .
Smaller crystal size leads to a larger specific surface area, which can enhance photocatalytic activity.
Conversely, larger crystal size results in a smaller surface area, as a results reducing photocatalytic activity .
Band gap energy of Cu-PTC Figure 4 shows the bandgap energy of CuPTC MOF obtained from UV-Vis DRS measurements, which is 1.
72 eV.
This indicates that Cu-PTC MOF has a narrow bandgap, enabling it to effectively act as a photocatalyst capable of absorbing light in the visible region.
The bandgap energy of a material can be influenced by ligands containing conjugated Abonds and the metal atoms, as reflected in the size of the Secondary Building Unit (SBU).
The larger the SBU size of the metal in the framework, the smaller the bandgap energy becomes .
The band gap energy value of Cu-PTC is smaller than that of Cu-BTC, wich is based on Cu2 ions and benzene-1,3,5-tricarboxylic acid (H3BTC) ligands and has a band gap energy of 68 eV .
The band gap energy of Cu-PTC is smaller than that of Cu-BTC because the PTC ligand possesses a more extended conjugated bond compared to BTC.
Additionally, the metal ion also influences the MOFAos bandgap energy.
For instance, a chromium-based MOF (Cr-PTC) using the same PTC organic ligand has been successfully synthesized and exhibits a higher bandgap energy of 2.
01 eV .
Fe-PTC MOF has a band gap energy of 1.
93 eV .
Morphology of Cu-PTC The surface morphology analysis of Cu-PTC at magnifications of 1,000x and 10,000x (Figures 5a and 5.
reveals that the particles exhibit a rodlike morphology.
Table 3 shows that the elemental composition of Cu-PTC MOF consists of carbon (C), oxygen (O), copper (C.
, and trace impurities, with concentrations of 74.
26%, 17.
51%, 8.
08%, respectively.
Photocatalytic Activity of Cu-PTC Cu-PTC MOF exhibited a methylene blue adsorption percentage of 43.
88% under dark conditions after 60 minutes, and a degradation percentage of 71.
45% under visible light irradiation .
sing a mercury lam.
within the same time (Figure .
The significantly higher degradation percentage under illumination indicates that Cu-PTC possesses photocatalytic activity for the degradation of methylene blue dye.
The photocatalytic process requires the absorption of light at a specific wavelength by a semiconductor material .
, which excites electrons from the valence band (VB) to the conduction band (CB).
This transition generates positively charged holes .
) in the valence band .
The photogenerated electrons and positive holes can then migrate to the surface of the photocatalyst and participate in redox reactions Table 3.
Elemental composition of Cu-PTC MOF.
Figure 4.
Band gap energy of Cu-PTC.
Element Impurities Concentration (%w/.
Table 2.
Comparison of diffraction pattern angle and crystal size of Cu-PTC with reference data.
MOF
Fe-PTC .
Cr-PTC .
Cu-PTC .
his stud.
2 (A) 9, 12.
66, 24.
12, 24.
88, 25.
34, 27.
68, 31.
74, 33.
16, 35.
88, 45.
52, 49.
48, 54.
06, 57.
52, 62.
42, 64.
02, 71.
17, 12.
865, 25.
621, 27.
Crystal size .
705, 25.
17, 27.
22, 43.
266, 50.
443, 74.
12, 89.
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 267 with adsorbed species, producing superoxide radicals (AO2O.
and hydroxyl radicals (AOH) .
The mechanism for the formation of hydroxyl and superoxide radicals are shown in the following Equations .
MOFs hv Ie MOFs .
OeCB h VB ) eOe O2 Ie AO2Oe h H2O Ie AOH H Dye AOH Ie degradation products .
The photocatalytic degradation of methylene blue dye involves hydroxyl radicals (AOH), which attack the NAeS heterocyclic group in methylene blue, leading to its cleavage into 2-amino-5dimethylamino-benzenesulfonic acid anion and N.
N-dimethyl-p-phenylenediamine.
A series of stepwise oxidations by AOH radicals lead to the formation of simpler aromatic fragments, such as benzenesulfonate derivatives and hydroquinone.
This progressive oxidation continues until the carbon backbone is completely decomposed, ultimately yielding COCC and HCCO as final products (Figure .
Effect of Methylene Blue Concentration The degradation efficiencies at methylene blue concentrations of 25, 50, 75, and 100 ppm 53%, 71.
45%, 44.
55%, and 33.
The optimal methylene blue concentration was determined to be 50 ppm, which corresponded to an adsorption capacity of 28 mg/g (Figure 8.
These findings are consistent with the results reported by Saridewi and colleagues, who also identified 50 ppm as the optimal methylene blue concentration for photocatalytic degradation using Cr-PTC .
The adsorption capacity at 25 ppm was 38.
mg/g, which is lower than that at 50 ppm.
This is because, at the lower concentration of 25 ppm, fewer methylene blue molecules are available to interact with the active sites of the catalyst, resulting in a lower adsorption capacity compared to the higher concentration.
The adsorption capacities at 75 ppm and 100 ppm decreased to 62 mg/g and 64.
84 mg/g, respectively.
This reduction is attributed to the photocatalyst reaching saturation due to the high dye concentration, which leads to excessive coverage of the photocatalyst surface by methylene blue Once saturated, the photocatalyst experiences reduced photon efficiency and partial deactivation .
In general, degradation efficiency decreases as the dye concentration increases.
The higher methylene blue concentration leads to greater Figure 5.
SEM morphology of Cu-PTC MOF .
1,000x magnification.
10,000x magnification.
Figure 6.
Degradation efficiency, and .
adsorption capacity of methylene blue in the preliminary test of Cu-PTC.
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 268 adsorption of dye molecules onto the photocatalyst surface.
This causes the incident light energy to be absorbed or blocked by the excess dye molecules in solution, preventing it from reaching the photocatalyst surface.
As a result, the photocatalyst is not effectively irradiated, and electron excitation does not occur.
This inhibits the generation of hydroxyl radicals (AOH) and superoxide radicals (AO2-), which are essential for the degradation of methylene blue .
The adsorption capacity of methylene blue using Cu-PTC at a concentration of 50 ppm over 60 minutes is higher than that of Cr-PTC under the same conditions, which yielded approximately 60 mg/g .
The degradation efficiency of methylene blue using Cu-PTC at a concentration of 50 ppm within 15 minutes was 44.
63%, which is higher than that of Cu-BTC, which achieved 4% degradation efficiency at a lower MB concentration of 30 ppm under the same irradiation time .
Effect of Cu-PTC Mass The results show that increasing the mass of Cu-PTC MOF leads to higher degradation Figure 7.
Degradation mechanism of methylene blue dye.
percentages (Figure 9.
Specifically.
Cu-PTC masses of 15, 25, 35, and 45 mg yielded degradation efficiencies of 42.
38%, 71.
35%, and 88.
03%, respectively.
This trend is consistent with the study by Lubis and colleagues, who reported that higher photocatalyst loading results in greater degradation efficiency .
The increase in photocatalyst amount is associated with a greater number of active surface sites, which enhances the generation of hydroxyl radicals that play a key role in degrading the dye .
A Cu-PTC mass of 25 mg was identified as the optimal dosage, yielding the highest adsorption capacity of 73.
28 mg/g.
In comparison.
MOF masses of 15, 35, and 45 mg resulted in adsorption capacities of 71.
24, 51.
63, and 47.
67 mg/g, respectively (Figure 9.
The decrease in adsorption capacity at 35 mg and 45 mg is attributed to increased turbidity in the solution caused by the excessive amount of photocatalyst.
This high catalyst loading enhances light scattering and reduces light penetration depth, thereby limiting photon availability for photocatalytic activation and ultimately lowering adsorption performance .
Figure 8.
Degradation efficiency, and .
adsorption capacity at varying concentrations of methylene blue.
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 269 Effect of pH The results of the pH variation test in the methylene blue degradation process by Cu-PTC MOF are shown in Figures 10a and 10b.
The degradation efficiency of Cu-PTC MOF at pH of 5 yielded a degradation percentage of 9.
The degradation efficiency of Cu-PTC MOF at pH of 7 gave the highest degradation efficiency of 71.
while at pH of 9, its degradation efficiency was At pH of 5, there was no photocatalytic activity due to the absence of a significant increase in degradation efficiency.
At pH of 7 and 9, high degradation efficiencies were observed, indicating the presence of photocatalytic activity under these conditions.
pH of 7 exhibited the highest adsorption capacity, at 73.
28 mg/g, while pH of 5 and pH of 9 showed adsorption capacities 48 mg/g and 66.
68 mg/g, respectively.
Based on these results, pH of 7 represents the optimal condition for the photocatalytic activity of CuPTC.
The pH condition can influence the photocatalytic activity of a photocatalyst.
Under acidic conditions.
H ions interact with carboxylate groups, resulting in a positively charged catalyst surface.
In contrast, under basic conditions.
OH- ions interact with hydrogen atoms on the organic ligand, leading to a negatively charged surface .
For that reason, under acidic conditions, the positively charged surface of CuPTC experiences repulsion with the cationic methylene blue dye molecules, reducing dye adsorption onto the MOF surface and consequently decreasing degradation efficiency.
similar result was reported by Saridewi and colleagues, who used Cr-PTC for methylene blue photodegradation and observed no significant increase in degradation efficiency at pH of 5 .
Under basic conditions, the surface of Cu-PTC MOF becomes negatively charged, causing attractive forces with the cationic methylene blue dye molecules.
This leads to increased adsorption of the dye onto the MOF surface, and degradation efficiency also increases under basic conditions compared to acidic conditions.
However, at pH of 9, the degradation efficiency was lower than that at pH of 7.
This is consistent with the study by Suprihatin and colleagues, who found that the Figure 9.
Degradation efficiency, and .
adsorption capacity of methylene blue at varying masses of Cu-PTC.
Figure 10.
Degradation efficiency, and .
adsorption capacity of methylene blue at varying solution pH Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 270 more basic the solution, the lower the degradation This is likely due to excess OHA ions covering the photocatalyst surface, causing strong adsorption of positively charged methylene blue molecules onto the photocatalyst.
As a result, the photocatalyst surface becomes blocked by methylene blue molecules, leading to suboptimal light absorption and reduced generation of free radicals available for degrading methylene blue .
Figure 10a shows that the degradation efficiency of methylene blue with the addition of Cu-PTC is significantly higher than that without a photocatalyst.
This demonstrates that the addition of Cu-PTC photocatalyst substantially enhances the degradation rate.
The presence of the photocatalyst increases the degradation rate due to the generation of free radical species, which play a crucial role in the degradation process.
Degradation Kinetics of Cu-PTC towards Methylene Blue A degradation kinetics plot was constructed to determine the kinetic parameters of Cu-PTC in degrading methylene blue.
Figure 11 shows presents the degradation kinetics of methylene blue fitted to both pseudo first-order and pseudo second- order models.
The correlation coefficient (R.
for the pseudo second-order model .
is higher than of the pseudo first-order model .
This indicates that the degradation rate follows pseudo second-order kinetics.
Conclusions The synthesis of Cu-PTC MOFs yielded a narrow bandgap energy of 1.
72 eV.
The FTIR spectrum of Cu-PTC MOF shows characteristic functional groups at wavenumbers 1689 cm-1 (C=O), 1590 and 1360 cm-1 (-COO), 3450 cm-1 (OH), 738 and 654 cm-1 (Cu-O).
The diffraction patterns of Cu-PTC MOFs with 2 angles of 705A, 25.
17A, 27.
22A, 43.
266A, 50.
443A, 74.
933A, with a crystallinity degree of 85.
and a crystallite size of 35.
33 nm, and a rod-like surface morphology.
Cu-PTC MOF demonstrates photocatalytic activity in degrading methylene blue dye under visible light irradiation, achieving a degradation efficiency of 71.
45% and an adsorption capacity of 73.
28 mg/g under optimal conditions: 50 mL of 50 ppm methylene blue solution, 25 mg of Cu-PTC MOF, and pH of 7.
Reusability testing and radical trapping experiments are required to evaluate the stability of Cu-PTC MOF and to identify the reactive species involved in the photocatalytic degradation mechanism of methylene blue.
Acknowledgment The authors would like to express their gratitude to Integrated Laboratory Centre (PLT) UIN Syarif Hidayatullah Jakarta for facilitating this work.
CRedit Author Statement Author Contributions: F.
Mala: formal analysis, investigation, data gathering, writing an original draft.
Saridewi: conceptualization, validation, resources, review.
Nurbayti:
Supervision.
Adawiah:
Supervision, data curation, reviewing.
Zulys:
Supervision, resources.
All authors have read and agreed to the published version of the manuscript.
Figure 11.
Plots of pseudo first-order model .
= 0.
02 minOe1.
R2 = 0.
, and .
pseudo second-order model .
2 = 0.
0008 L/mg.
R2 = 0.
for methylene blue degradation.
Copyright A 2026.
ISSN 1978-2993
Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 271
References