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Article

Catalytic Ozonation of Diclofenac Using CuO/Al2O3- and MnO2/Al2O3-Supported Catalysts

by
Wenli Zhou
1,
Xiaoxia Wang
2,
Yanghong Xu
1,
Qingsong Xu
3,
Zheng Shen
2 and
Junlian Qiao
1,*
1
College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
2
School of Electronics and Information Engineering, Institute of New Rural Development, Tongji University, Shanghai 201804, China
3
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, China
*
Author to whom correspondence should be addressed.
Chemistry 2025, 7(4), 107; https://doi.org/10.3390/chemistry7040107
Submission received: 24 May 2025 / Revised: 18 June 2025 / Accepted: 20 June 2025 / Published: 25 June 2025
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Abstract

Pharmaceuticals such as diclofenac (DCF), a widely used anti-inflammatory drug, are frequently detected in water bodies and pose serious environmental and health risks due to their persistence and low biodegradability. Although ozonation is an effective method for pollutant removal, its efficiency is often limited by low ozone utilization and incomplete mineralization. In this work, CuO/Al2O3- and MnO2/Al2O3-supported catalysts were prepared via an impregnation method and evaluated for their performance in catalytic ozonation of diclofenac (DCF) in an aqueous solution. The catalysts were characterized by TEM, N2 adsorption–desorption, FTIR, and XPS analyses. The effects of catalyst type, dosage, initial pH, and ozone flow rate on degradation efficiency were systematically investigated. Under optimal conditions, the DCF removal efficiencies reached 73.99% and 76.33% using CuO/Al2O3 and MnO2/Al2O3, respectively, while COD removal efficiencies were 77.6% and 89.3%. Quenching experiments indicated that hydroxyl radicals (•OH) were the predominant reactive species involved in the catalytic ozonation process. The results demonstrate that supported CuO and MnO2 catalysts can effectively enhance diclofenac degradation by ozone, offering potential for advanced water treatment applications.

1. Introduction

Pharmaceuticals and personal care products (PPCPs) have emerged as a group of persistent organic pollutants widely found in aquatic environments [1,2]. Their widespread use and poor removal by conventional water treatment systems have raised growing environmental and health concerns [3,4,5]. Among them, diclofenac (DCF), a widely used non-steroidal anti-inflammatory drug (NSAID), is frequently detected in surface water, groundwater, and even drinking water due to its high chemical stability and resistance to biodegradation [6]. Long-term exposure to DCF and its metabolites has been linked to ecological toxicity [7] and adverse effects on human health [8].
Ozonation is considered a promising advanced oxidation process (AOP) for the degradation of refractory organic contaminants due to its strong oxidizing potential and clean reaction profile [9]. However, direct ozonation often suffers from low ozone utilization efficiency and limited mineralization capacity. To address these limitations, catalytic ozonation has been developed to enhance the decomposition of ozone into highly reactive hydroxyl radicals (•OH), thereby improving pollutant removal efficiency.
Among heterogeneous catalysts, metal oxides supported on alumina (Al2O3) have shown great promise. Al2O3 is widely used as a catalyst support due to its high surface area, thermal stability, and inherent Lewis acidity. Transition metal oxides such as CuO and MnO2 are capable of activating ozone to generate reactive oxygen species and have been applied in various pollutant degradation systems. Previous studies have demonstrated that supported catalysts such as Fe/Cu, MnO2/Al2O3, and Ce/Mn can significantly enhance the degradation of organic pollutants including phenol, toluene, and p-nitrophenol [10,11,12]. Among these, CuO and MnO2 supported on Al2O3 exhibit unique redox properties and catalytic activity, making them attractive candidates for catalytic ozonation. Despite existing work on supported CuO and MnO2 catalysts, direct comparative studies on their catalytic performance for DCF degradation under varying operating conditions are still limited. Moreover, the underlying reaction mechanisms and the role of different reactive oxygen species in the catalytic process remain to be clarified.
In this work, CuO/Al2O3 and MnO2/Al2O3 catalysts were synthesized by an impregnation method and evaluated for their catalytic ozonation performance in DCF degradation. The physicochemical properties of the catalysts were characterized using techniques such as TEM, BET, FTIR, and XPS. The effects of catalyst dosage, initial pH, and ozone flow rate on degradation efficiency were systematically investigated. In addition, quenching experiments were conducted to identify the dominant reactive species involved in the oxidation process. This study aims to provide insight into the catalytic behavior and reaction mechanisms of CuO/Al2O3 and MnO2/Al2O3 catalysts in advanced water treatment.

2. Materials and Methods

2.1. Preparation of Catalyst

Cu(NO3)2·3H2O (Analytical Reagent, AR) and Al2O3 (AR) were purchased from National Pharmaceutical Group Chemical Reagents Co., Ltd., Beijing, China. CHClNNaO (98%) and Mn(NO3)2·4H2O (98%) were purchased from Shanghai Wokai Pharmaceutical Co., Ltd., Shanghai, China.
The bimetallic catalyst was prepared by incipient wetness impregnation. Taking the preparation of CuO/Al2O3 as an example, the specific operation steps were as follows: First, Al2O3 was placed in a drying oven and dried at 110 °C for 2 h; then, a certain amount of dry Al2O3 powder was weighed, and the mass was donated as m1. Distilled water was added dropwise to the beaker until the carrier was submerged, and the mass was denoted as m2. The saturated water absorption rate was calculated according to Equation (1). The quasi-loading rate of CuO was 10%. The Cu(NO3)2·3H2O solution required for the impregnation method was calculated by the water absorption rate of Al2O3 and the quasi-loading rate of CuO. Finally, the corresponding mass of Al2O3 was added to the corresponding volume of Cu(NO3)2·3H2O and stirred. After standing for 24 h, it was placed in a drying oven at 110 °C for 10 h to obtain a bulk solid. It was calcined at 450 °C for 5 h in a muffle furnace and ground into powder. The preparation method of MnO2/Al2O3 is the same as above.
Water absorption of carrier = [(m2 − m1)/m1] × 100%

2.2. Characterization of Catalyst

The BET specific surface area was measured at −196 °C, and the sample was degassed at 120 °C for 7 h under vacuum before testing (BET, Mac ASAP 2460, Micromeritics, Norcross, GA, USA). The surface morphology of the catalyst was observed by SEM, and the surface content of the elements was detected by OXFORD Xplore (SEM, Gemini 300, ZEISS, Jena, Germany). XPS uses Al Kα ray as the emission source and C1s = 284.80 eV binding energy as the energy standard for charge correction (XPS, K-Alpha, Thermo Scientific, Waltham, MA, USA). FTIR was detected by Nicolet (FTIR, iS20, Thermo Scientific, USA). The catalyst was dried and tested by KBr tableting.

2.3. Ozone Catalytic Degradation of DCF

Catalytic ozonation studies with or without catalysts were carried out in a glass reactor constructed from a flat-bottom flask in a batch mode at ambient temperature. The solution and catalyst are mixed by a magnetic stirrer. The ozone is produced by the laboratory ozone generator (YJF-004, Zhongshan Yijiafu Co., Ltd., Zhongshan, China, CHN). After the generator reaches a steady state, the DCF solution and catalyst are immediately introduced, and the magnetic stirrer is opened to start the timing. The sample is collected from the reactor every 10 min until the reaction is 60 min. After the sample was collected, it was immediately filtered to clarify, and the supernatant was taken to detect the content of DCF. DCF was detected by HPLC. The chromatographic column (5 μm, 4.6 mm × 250 mm) was used. The mobile phase was methanol-4% glacial acetic acid solution (70:30). The flow rate was 1.0 mL/min, the column temperature was 35 °C, and the detection wavelength was 276 nm.
COD detection was performed using the potassium dichromate method (GB11914-89), and was determined by the COD constant temperature heater. The DCF removal rate calculation method is as shown in Equation (2).
η = [(C0 − Ct)/C0] × 100%
In the equation, η represents the removal rate of DCF at time t, %; C0 represents the initial concentration of diclofenac in the reaction solution, mg/L; and Ct represents the concentration of diclofenac in the reaction solution at time t, mg/L.

3. Results

3.1. Characterization of Bimetallic Catalysts CuO/Al2O3 and MnO2/Al2O3

Table 1 shows the basic physicochemical property characteristic parameters of different metal-modified materials and raw materials. Compared with the carrier, the specific surface area of the loaded catalyst has increased, which is beneficial for improving the catalytic activity of the catalyst. The total pore volume has slightly decreased, with almost no change in the average pore size. The reason for the decrease in total pore volume is that the active components CuO and MnO2 are loaded on the surface of the carrier and enter the pores. This indicates that both the active components, CuO and MnO2, are well loaded on the carrier, Al2O3.
The changes in specific surface area, pore volume, and pore size before and after Al2O3 modification were analyzed using N2-adsorption/desorption experiments, and the results are shown in Figure 1. The curves of the three catalysts all belong to typical type IV isotherms, and the hysteresis loop belongs to H3 type, indicating that the pore size distribution of the three catalysts is uniform and belongs to mesoporous structure, but there are narrow cracks and pores present [13]. Figure 1 shows that the hysteresis loop of the Al2O3 catalyst is the largest, the hysteresis loop of CuO/Al2O3 catalyst is smaller, and the hysteresis loop of MnO2/Al2O3 catalyst is the smallest. In the BET adsorption/desorption isotherm, when the hysteresis loop is at a relative pressure of 0.2–0.8, the adsorption type is mesoporous adsorption [14]. When the relative pressure of the hysteresis loop is greater than 0.8, the adsorption type is macroporous adsorption. The hysteresis loops of the three catalysts in Figure 1 all occur between relative pressures of 0.5 and 1.0, indicating that Al2O3, CuO/Al2O3, and MnO2/Al2O3 catalysts belong to mesoporous and macroporous adsorption. The hysteresis of MnO2/Al2O3 is smaller than that of CuO/Al2O3, indicating that MnO2/Al2O3 and CuO/Al2O3 have smaller adsorption pore sizes, while Al2O3 has the largest adsorption pore size. Bimetallic catalysts have stronger catalytic ability than single-metal catalysts.
Figure 2 shows the surface SEM images of three catalysts. From Figure 2a, it can be seen that the grain shape of the Al2O3 catalyst before loading is regular, neat, and clear, presenting cubic and spherical particles with a tight surface and compact particles, showing a good crystal structure. The loaded catalyst, as shown in Figure 2c, has sparse and loose surface particles, irregular particles, and an uneven surface. After zooming in, it can be seen from Figure 2b that the surface of the carrier has a relatively smooth crystal plane and some slight metallic luster. By comparing Figure 2d,f, it can be seen that there are rod-shaped small grains loaded on the carrier, which have a regular appearance, uniform distribution, and good dispersion. CuO and MnO2 are highly dispersed on the surface of the carrier.
The elemental composition of the catalyst can be analyzed by XPS, and the valence states of each element were determined based on their electronic binding energy. The results are shown in Figure 3a,b. From Figure 3a, four different characteristic peaks of Cu 2p, O 1s, C 1s, and Al 2p can be seen, indicating that the CuO/Al2O3 catalyst surface contains Cu, O, C, and Al elements, with surface atomic concentrations of Cu, 1.76%; C, 37.23%; and Al, 60.36%, respectively. In addition, as shown in Figure 3, the characteristic peak of Cu 2p is composed of two peaks with electron binding energies of 932.81 eV and 953.08 eV after peak fitting. It is known that 932.81 eV is the electron binding energy of CuO. Based on another electron binding energy of 953.08 eV, it is speculated that Al-O-Cu bonds may form in the CuO/Al2O3 catalyst. Similarly, from Figure 3b, four different characteristic peaks of Mn 2p, O 1s, C 1s, and Al 2p can be seen, indicating that the catalyst surface contains four elements: Mn, O, C, and Al, with surface atomic concentrations are Mn, 1.33%; C, 47.38%; and Al, 50.99%, respectively. From the illustration in Figure 4, it can be seen that the characteristic peak of Mn 2p, after peak fitting, consists of two peaks with electron binding energies of 642.1 eV and 657.1 eV, respectively. Moreover, 642.1 eV is the electron binding energy of MnO2. Based on another electron binding energy of 657.1 eV, it is speculated that Al-O-Mn bonds will form in the MnO2/Al2O3 catalyst.
In summary, the main substances in the catalyst CuO/Al2O3 are CuO, Al2O3, and some substances formed by a small amount of Al-O-Cu bonds; the main substances in the catalyst MnO2/Al2O3 are MnO2, Al2O3, and a small amount of Al-O-Mn bonds.
The surface functional groups of the compounds were identified by FTIR, and the results are shown in Figure 4. The strong broad peak around 3452 cm−1 in the three spectra is the stretching vibration absorption peak of the H-O bond in the water molecule. The two absorption peaks at 1396 cm−1 and 1630 cm−1 are the hydroxyl bending vibration absorption peaks of water molecules, which may be due to the adsorption of water molecules during the preparation of the sample. The 750 cm−1 in the figure are the characteristic peaks of the carrier Al2O3. It is known that the characteristic absorption peak of CuO and MnO2 appears at about 500 cm−1 and 610 cm−1 [15,16,17]. However, the catalysts loaded with CuO and MnO2 have obvious changes at this place, indicating that the catalysts do load CuO and MnO2.

3.2. Bimetallic Catalyst Catalyzed Ozone Degradation of DCF

Figure 5 shows the performance of O3, CuO, MnO2, and Al2O3 single-metal catalytic O3, and CuO/Al2O3 and MnO2/Al2O3 bimetallic catalytic O3 on DCF degradation and COD removal.
One can see that the presence of a catalyst significantly improved DCF degradation. Specifically, only 25% of DCF could be degraded by O3 alone within 60 min, while the removal efficiency of DCF in the reaction system with the catalyst can be increased by more than 40%. Among them, the removal efficiencies of DCF by Al2O3, CuO, and MnO2 single-metal catalytic ozonation were 67.1%, 64.89%, and 68.9%, respectively. CuO/Al2O3 and MnO2/Al2O3 bimetallic catalysts have the best performance toward the degradation of DCF by O3, and the removal efficiencies can reach 73.99% and 76.33%, respectively. At the same time, the mineralization degree of DCF in the system using a catalyst has also been significantly improved. The COD removal efficiency in the CuO/Al2O3 catalytic system reaches 77.6%, and the COD removal efficiency in the MnO2/Al2O3 catalytic system reaches 89.3%. The COD removal efficiency under the action of a bimetallic catalyst is much higher than that of other systems. The above analysis shows that the catalytic activity of the catalysts follows the order MnO2/Al2O3 > CuO/Al2O3 > MnO2 > Al2O3> CuO.
In addition, compared with previous studies, this study took into account both shorter reaction time and higher degradation efficiency [18,19].
In addition, MnO2 (E0 = 0.7 V) itself is more oxidizing than CuO (E0 = 0.2 V), and the adsorption pore size is smaller, but the degradation effect is not as good as CuO in the early stage of the catalytic reaction. According to Zhu et al.’s research [20], this may be due to the oxygen vacancies on the surface of MnO2 being competed against by water molecules. When the reaction is carried out in the middle and late stages, the oxygen vacancies on the surface of MnO2 are released again, and the catalytic performance is improved.
In the process of heterogeneous catalytic ozonation, the initial pH of the solution is always an important factor. Therefore, the effects of CuO/Al2O3 and MnO2/Al2O3 catalytic ozonation on DCF degradation at five different pH levels were explored. The results are shown in Figure 6. Figure 6a shows that both catalysts have the best degradation effect on DCF when pH0 is 5. At this time, the degradation efficiency of CuO/Al2O3 and MnO2/Al2O3 on DCF reached 81% and 79.48%, respectively. When the reaction solution is alkaline, the removal effect of DCF does not change significantly. Figure 6b,c show that the pH value of the solution decreased after 1 h of reaction under all conditions, regardless of the pH0.
Although it is reasonable to say that OH− and O3 should form O2− in the system to promote the catalytic reaction, in fact, the degradation efficiency of DCF is reduced under the action of either catalyst, which indicates that O2− is not dominant in the catalytic reaction. In addition, intriguingly, the catalytic performance of CuO/Al2O3 and MnO2/Al2O3 catalysts decreased with the increase of pH, but the decrease of MnO2/Al2O3 was less than that of CuO/Al2O3. This may be because MnO2 is used as an OER reaction catalyst under the condition [21,22].
Catalyst and ozone are two main participants in the ozone catalytic process. Their dosage will not only have a certain impact on the degradation effect but also determine the treatment efficiency and treatment cost in the practical application of wastewater treatment. Therefore, the effects of four different catalyst dosages of 0.5, 1.0, 2.0, and 4.0 g/L on catalytic ozonation of DCF and the effects of four ozone flow rates of 0.1, 0.2, 0.3, and 0.4 m3/h on catalytic ozonation of DCF were also investigated in this work. The results are shown in Figure 7.
Figure 7a,c show that the difference in the dosage of CuO/Al2O3 and MnO2/Al2O3 catalysts in the catalytic process has little effect on the degradation of DCF. When the dosage of CuO/Al2O3 catalyst increased from 0.5 g/L to 2.0 g/L, the reaction rate constant increased from 0.019 min–1 to 0.034 min–1, and the removal efficiency of DCF also increased from 74% to 86%. When the catalyst dosage was further increased to 4.0 g/L, the DCF removal efficiency only increased slightly to 87.7%, and the reaction rate constant decreased to 0.03. When the dosage of MnO2/Al2O3 catalyst gradually increased from 0.5 g/L to 2.0 g/L, the reaction rate constant of the solution increased from 0.02 to 0.036, and the removal efficiency of diclofenac increased from 70.01% to 84.22%. When the catalyst dosage was further increased to 4.0 g/L, the removal rate of diclofenac only slightly increased to 88.95%, and the reaction rate constant decreased to 0.033. On the one hand, it may be because the amount of bimetallic catalyst in the solution has reached saturation, and the dose of ozone needs to be increased to improve the DCF removal efficiency. On the other hand, due to the continuous supply of ozone, ozone itself can also oxidize DCF, so the amount of catalyst has little effect on the degradation of DCF. When the dosage of catalyst is more than 2.0 g/L, the removal efficiency of DCF is no longer increased. Therefore, the optimal dosage of catalyst in the reaction solution is 2.0 g/L.
As shown in Figure 7b,d, in the CuO/Al2O3 catalytic ozonation system, when the ozone flow rate increased from 0.1 m3/h to 0.3 m3/h, the degradation efficiency of DCF increased from 68.4% to 92.1%. At this time, the reaction rate constant increased from 0.021 to 0.041, and the reaction rate constant only increased slightly when the ozone flow rate continued to increase to 0.4 m3/h. In the MnO2/Al2O3 catalytic ozonation system, when the ozone flow rate increased from 0.1 m3/h to 0.2 m3/h, the reaction rate constant increased by about two times, and the degradation efficiency of DCF also increased by nearly 22%. When the ozone flow rate continued to increase to 0.4 m3/h, the reaction rate constant increased to 0.053, and the increase rate slowed down. At this time, the removal efficiency of DCF was 93.69%. It shows that the amount of O3 injected into the solution before is insufficient to meet the degradation requirements of DCF; when the O3 flow rate is large, the O3 in the water reaches the dissolution equilibrium, and the O3 in the water is sufficient and reacts rapidly with DCF. However, when the O3 flow rate is further increased, the removal efficiency of DCF is not significantly increased; therefore, in the study of bimetallic catalytic degradation of DCF, the optimal flow rate of O3 is 0.3 m3/h.
The reaction mechanism of catalytic ozone degradation of DCF was investigated by quenching experiments. TBA is a typical ·OH capture agent. The addition of TBA in the ozonation experiment can inhibit the indirect reaction of ·OH in the reaction process, and kHO•,TBA = 6.0 × 108 M−1s−1, kTBA,O3 =1.3 × 10−3 M−1s−1. Chloroform can capture O2−, and kchloroform,O3 <0.1 M−1s−1 and kchloroform,HO • = 5.0 × 107 M−1s−1 [23,24].
Figure 8 shows that the addition of tert-butanol and chloroform in the reaction solution has different effects on the catalytic ozonation of DCF by bimetallic catalyst. Figure 8b,d show that the process of catalytic ozonation of DCF by bimetallic catalyst conforms to first-order kinetics. The results show that the catalytic oxidation process mainly occurs on the surface of the catalyst, and the generation of ·OH is the main reason for the catalyst to improve the catalytic ozonation efficiency, but ·OH is not the only free radical involved in the degradation of DCF. Figure 8d shows that when the concentration of chloroform in the reaction solution increases from 0.00 mol/L to 1.00 mol/L, there is no significant difference in the degradation kinetic constant of DCF, indicating that the presence of chloroform has little effect on the degradation process, which proves that there is little O2− generated in the process of catalytic ozonation degradation of DCF; in contrast, the addition of tert-butanol has a significant inhibitory effect on the reaction process. It can be seen from Figure 8a,c that when the concentrations of tert-butanol were 0.00 mol/L, 0.25 mol/L, 0.50 mol/L, and 1.00 mol/L, the degradation efficiencies of DCF were 70.91%, 59.89%, 50.28%, and 28.76%, respectively. At the beginning of the reaction, the degradation efficiencies of DCF decreased with the increase of tert-butanol concentration, indicating that ·OH was indeed generated during the reaction. The contribution of ·OH to the degradation efficiencies of DCF was 70.91–28.76% = 42.15%; the contribution of O2− to the degradation efficiencies of DCF was 70.91–66.85% = 4.06%.

4. Conclusions

In this study, CuO/Al2O3- and MnO2/Al2O3-supported bimetallic catalysts were prepared by the impregnation method to catalyze the degradation of DCF by O3. The active components of the catalyst CuO and MnO2 are well loaded and have a smaller adsorption pore size than the Al2O3 single-metal catalyst. The Cu-O-Al and Mn-O-Al chemical bonds may be formed in the catalyst. CuO/Al2O3 and MnO2/Al2O3 bimetallic catalysts were superior to CuO and MnO2 alone in the catalytic degradation of DCF and COD by O3, and the removal rates of DCF are 73.99% and 76.33%, respectively. The COD removal rates were 77.6% and 89.3%, respectively. The optimal degradation conditions for DCF degradation by O3 catalyzed by bimetallic catalysts are as follows: pH0 is 5, catalyst dosage is 2.0 g/L, and ozone flow rate is 0.3 m3/h. The results of quenching experiments showed that ·OH was the dominant reactive oxidative species responsible for DCF degradation.

Author Contributions

X.W. and Q.X. conceived and designed the experiments and performed the experiments; W.Z., X.W., Y.X. and Q.X. interpreted and analyzed the data; and W.Z. wrote the manuscript. Z.S. and J.Q. provide financial support. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (Nos. 52270047), the Science and Technology Commission of Shanghai Municipality (23dz1203700, 20dz1203600), and the National Natural Science Foundation of China (U21A20322).

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

References

  1. Xue, Y.E.; Sun, W.J.; Shao, P.H.; Yuan, Y.X.; Cui, F.Y.; Shi, W.X. Degradation of contaminants of PPCPs by photocatalysis for water purification: Kinetics, mechanisms, and cytotoxicity analysis. Chem. Eng. J. 2023, 454, 140505. [Google Scholar] [CrossRef]
  2. Li, S.; Lin, F.X.; Zheng, H.S.; Zheng, Y.J.; Zhang, B.G.; Ma, J.; Nan, J. Efficient PPCPs degradation by self-assembly Ag/Ti3C2@BiPO4 activated peroxydisulfate with microwave irradiation: Enhanced adsorptive binding and radical generation. Chem. Eng. J. 2023, 452, 139298. [Google Scholar] [CrossRef]
  3. Krishnan, R.Y.; Manikandan, S.; Subbaiya, R.; Biruntha, M.; Govarthanan, M.; Karmegam, N. Removal of emerging micropollutants originating from pharmaceuticals and personal care products (PPCPs) in water and wastewater by advanced oxidation processes: A review. Environ. Technol. Innov. 2021, 23, 101757. [Google Scholar] [CrossRef]
  4. Jiang, L.; Li, Y.X.; Chen, Y.X.; Yao, B.; Chen, X.; Yu, Y.E.; Yang, J.; Zhou, Y.Y. Pharmaceuticals and personal care products (PPCPs) in the aquatic environment: Biotoxicity, determination and electrochemical treatment. J. Clean. Prod. 2023, 388, 135923. [Google Scholar] [CrossRef]
  5. Yang, R.M.; Zeng, G.L.; Xu, Z.Q.; Zhou, Z.Y.; Huang, J.Y.; Fu, R.B.; Lyu, S.G. Comparison of naphthalene removal performance using H2O2, sodium percarbonate and calcium peroxide oxidants activated by ferrous ions and degradation mechanism. Chemosphere 2021, 283, 131209. [Google Scholar] [CrossRef]
  6. Peghin, M.; Vena, A.; Graziano, E.; Giacobbe, D.R.; Tascini, C.; Bassetti, M. Improving management and antimicrobial stewardship for bacterial and fungal infections in hospitalized patients with COVID-19. Ther. Adv. Infect. Dis. 2022, 9, 20499361221095732. [Google Scholar] [CrossRef]
  7. Avetta, P.; Fabbri, D.; Minella, M.; Brigante, M.; Maurino, V.; Minero, C.; Pazzi, M.; Vione, D. Assessing the phototransformation of diclofenac, clofibric acid and naproxen in surface waters: Model predictions and comparison with field data. Water Res. 2016, 105, 383–394. [Google Scholar] [CrossRef]
  8. Lonappan, L.; Brar, S.K.; Das, R.K.; Verma, M.; Surampalli, R.Y. Diclofenac and its transformation products: Environmental occurrence and toxicity—A review. Environ. Int. 2016, 96, 127–138. [Google Scholar] [CrossRef]
  9. Tian, Y.Y.; Liu, M.X.; Sang, Y.X.; Kang, C.Y.; Wang, X.H. Degradation of prometryn in Ruditapes philippinarum using ozonation: Influencing factors, degradation mechanism, pathway and toxicity assessment. Chemosphere 2020, 248, 126018. [Google Scholar] [CrossRef]
  10. Xiong, Z.K.; Lai, B.; Yang, P. Quantitative analysis the role of reactive oxygen species (ROS) in a Fe/Cu/O3 process for p-nitrophenol treatment. In Proceedings of the 8th International Conference on Environment Science and Engineering (ICESE), Barcelona, Spain, 11–13 March 2018. [Google Scholar]
  11. Qi, W.C.; Wang, J.; Quan, X.; Chen, S.; Yu, H.T. Catalytic Ozonation by Manganese, Iron and Cerium Oxides on γ-Al2O3 Pellets for the Degradation of Organic Pollutants in Continuous Fixed-Bed Reactor. Ozone Sci. Eng. 2020, 42, 136–145. [Google Scholar] [CrossRef]
  12. Liu, L.; Wu, N.; Ouyang, M.; Fu, M.L. Enhancement Effect Induced by the Second Metal to Promote Ozone Catalytic Oxidation of VOCs. Environ. Sci. Technol. 2024, 58, 6725–6735. [Google Scholar] [CrossRef] [PubMed]
  13. Ambroz, F.; Macdonald, T.J.; Martis, V.; Parkin, I.P. Evaluation of the BET Theory for the Characterization of Meso and Microporous MOFs. Small Methods 2018, 2, 1800173. [Google Scholar] [CrossRef]
  14. Dong, L.H.; Liu, W.J.; Jiang, R.F.; Wang, Z.S. Physicochemical and porosity characteristics of thermally regenerated activated carbon polluted with biological activated carbon process. Bioresour. Technol. 2014, 171, 260–264. [Google Scholar] [CrossRef] [PubMed]
  15. Gandhi, S.; Subramani, R.H.H.; Ramakrishnan, T.; Sivabalan, A.; Dhanalakshmi, V.; Nair, M.R.G.; Anbarasan, R. Ultrasound assisted one pot synthesis of nano-sized CuO and its nanocomposite with poly(vinyl alcohol). J. Mater. Sci. 2010, 45, 1688–1694. [Google Scholar] [CrossRef]
  16. Sivakumar, S.; Prabu, L.N. Synthesis and Characterization of α-MnO2 nanoparticles for Supercapacitor application. In Proceedings of the 12th National Web Conference on Recent Advancements in Biomedical Engineering (NCRABE), Electrical Network, Chennai, India, 3 December 2020; pp. 52–55. [Google Scholar]
  17. Ma, D.; Xue, Q.; Liu, Y.; Liang, F.; Li, W.; Liu, T.; Zhuang, C.; Zhao, Z.; Li, S. Manipulating interfacial charge redistribution in Mn0.5Cd0.5S/N-rich C3N5 S-scheme heterojunction for high-performance photocatalytic removal of emerging contaminants. J. Mater. Sci. Technol. 2025, 243, 265–274. [Google Scholar] [CrossRef]
  18. Chen, W.R.; Li, X.K.; Tang, Y.M.; Zhou, J.L.; Wu, D.; Wu, Y.; Li, L.S. Mechanism insight of pollutant degradation and bromate inhibition by Fe-Cu-MCM-41 catalyzed ozonation. J. Hazard. Mater. 2018, 346, 226–233. [Google Scholar] [CrossRef]
  19. Tong, X.Y.; Li, Z.D.; Chen, W.R.; Wang, J.; Li, X.K.; Mu, J.X.; Tang, Y.M.; Li, L.S. Efficient catalytic ozonation of diclofenac by three-dimensional iron (Fe)-doped SBA-16 mesoporous structures. J. Colloid Interface Sci. 2020, 578, 461–470. [Google Scholar] [CrossRef]
  20. Zhu, G.X.; Zhu, J.G.; Jiang, W.J.; Zhang, Z.J.; Wang, J.; Zhu, Y.F.; Zhang, Q.F. Surface oxygen vacancy induced α-MnO2 nanofiber for highly efficient ozone elimination. Appl. Catal. B Environ. 2017, 209, 729–737. [Google Scholar] [CrossRef]
  21. Meng, Y.T.; Song, W.Q.; Huang, H.; Ren, Z.; Chen, S.Y.; Suib, S.L. Structure-Property Relationship of Bifunctional MnO2 Nanostructures: Highly Efficient, Ultra-Stable Electrochemical Water Oxidation and Oxygen Reduction Reaction Catalysts Identified in Alkaline Media. J. Am. Chem. Soc. 2014, 136, 11452–11464. [Google Scholar] [CrossRef]
  22. Yin, M.M.; Miao, H.; Hu, R.G.; Sun, Z.X.; Li, H. Manganese dioxides for oxygen electrocatalysis in energy conversion and storage systems over full pH range. J. Power Sources 2021, 494, 229779. [Google Scholar] [CrossRef]
  23. Buxton, G.V.; Greenstock, C.L.; Helman, W.P.; Ross, A.B. Critical-Review of Rate Constants for Reactions of Hydrated Electrons, Hydrogen-Atoms and Hydroxyl Radicals (.OH/.O-) in Aqueous-Solution. J. Phys. Chem. Ref. Data 1988, 17, 513–886. [Google Scholar] [CrossRef]
  24. Neta, P.; Huie, R.E.; Ross, A.B. Rate Constants for Reactions of Inorganic Radicals in Aqueous-Solution. J. Phys. Chem. Ref. Data 1988, 17, 1027–1284. [Google Scholar] [CrossRef]
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Figure 1. N2-adsorption/desorption isotherms of catalysts Al2O3, CuO/Al2O3, and MnO2/Al2O3.
Figure 1. N2-adsorption/desorption isotherms of catalysts Al2O3, CuO/Al2O3, and MnO2/Al2O3.
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Figure 2. SEM images of Al2O3 ((a): 5 μm, (b): 500 nm), CuO/Al2O3 ((c): 5 μm, (d): 500nm), and MnO2/Al2O3 ((e): 5 μm, (f): 500nm) at different magnifications.
Figure 2. SEM images of Al2O3 ((a): 5 μm, (b): 500 nm), CuO/Al2O3 ((c): 5 μm, (d): 500nm), and MnO2/Al2O3 ((e): 5 μm, (f): 500nm) at different magnifications.
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Figure 3. XPS spectra of CuO/Al2O3 (a) and MnO2/Al2O3 (b) catalysts (illustrated as peak separation spectra of Cu 2p and Mn 2p).
Figure 3. XPS spectra of CuO/Al2O3 (a) and MnO2/Al2O3 (b) catalysts (illustrated as peak separation spectra of Cu 2p and Mn 2p).
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Figure 4. FTIR spectra of Al2O3, CuO/Al2O3, and MnO2/Al2O3 catalysts.
Figure 4. FTIR spectra of Al2O3, CuO/Al2O3, and MnO2/Al2O3 catalysts.
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Figure 5. The degradation of DCF (a) and the corresponding COD removal (b) by different catalytic ozonation systems. Reaction conditions: [DCF]0 = 100 mg/L, O3: 0.2 m3/h; catalyst dosage: 1.0 g/L, [pH]0 = 7.35; catalyst active component loading: 10%.
Figure 5. The degradation of DCF (a) and the corresponding COD removal (b) by different catalytic ozonation systems. Reaction conditions: [DCF]0 = 100 mg/L, O3: 0.2 m3/h; catalyst dosage: 1.0 g/L, [pH]0 = 7.35; catalyst active component loading: 10%.
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Figure 6. Effect of different initial pH on DCF degradation in CuO/Al2O3 and MnO2/Al2O3 catalytic ozonation systems (a) and corresponding pH variations (b,c). [DCF]0 = 100 mg/L; O3: 0.2 m3/h; catalyst dosage: 1.0 g/L; and catalyst active component loading: 10%.
Figure 6. Effect of different initial pH on DCF degradation in CuO/Al2O3 and MnO2/Al2O3 catalytic ozonation systems (a) and corresponding pH variations (b,c). [DCF]0 = 100 mg/L; O3: 0.2 m3/h; catalyst dosage: 1.0 g/L; and catalyst active component loading: 10%.
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Figure 7. Effect of catalyst dosage on catalytic ozonation of DCF (a,c). [DCF]0 = 100 mg/L; O3: 0.2 m3/h; [pH]0 = 7.35; and catalyst active component loading: 10%. The effect of O3 dosage on the degradation efficiency of DCF (b,d). [DCF]0 = 100 mg/L; catalyst dosage: 2.0 g/L.
Figure 7. Effect of catalyst dosage on catalytic ozonation of DCF (a,c). [DCF]0 = 100 mg/L; O3: 0.2 m3/h; [pH]0 = 7.35; and catalyst active component loading: 10%. The effect of O3 dosage on the degradation efficiency of DCF (b,d). [DCF]0 = 100 mg/L; catalyst dosage: 2.0 g/L.
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Figure 8. Effects of different concentrations of TBA (a) and chloroform (c) on catalytic ozonation of DCF by bimetallic catalysts; ozone degradation kinetics of DCF catalyzed by bimetallic catalysts under different concentrations of TBA (b) and chloroform (d).
Figure 8. Effects of different concentrations of TBA (a) and chloroform (c) on catalytic ozonation of DCF by bimetallic catalysts; ozone degradation kinetics of DCF catalyzed by bimetallic catalysts under different concentrations of TBA (b) and chloroform (d).
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Table 1. BET test results of carrier Al2O3 and catalysts CuO/Al2O3 and MnO2/Al2O3.
Table 1. BET test results of carrier Al2O3 and catalysts CuO/Al2O3 and MnO2/Al2O3.
CATALYSTS.BET Surface AreaAverage Pore WidthPore Volume
m2/gnmcm3/g
Al2O31565.470.22
CuO/Al2O31585.370.21
MnO2/Al2O31575.330.20
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Zhou, W.; Wang, X.; Xu, Y.; Xu, Q.; Shen, Z.; Qiao, J. Catalytic Ozonation of Diclofenac Using CuO/Al2O3- and MnO2/Al2O3-Supported Catalysts. Chemistry 2025, 7, 107. https://doi.org/10.3390/chemistry7040107

AMA Style

Zhou W, Wang X, Xu Y, Xu Q, Shen Z, Qiao J. Catalytic Ozonation of Diclofenac Using CuO/Al2O3- and MnO2/Al2O3-Supported Catalysts. Chemistry. 2025; 7(4):107. https://doi.org/10.3390/chemistry7040107

Chicago/Turabian Style

Zhou, Wenli, Xiaoxia Wang, Yanghong Xu, Qingsong Xu, Zheng Shen, and Junlian Qiao. 2025. "Catalytic Ozonation of Diclofenac Using CuO/Al2O3- and MnO2/Al2O3-Supported Catalysts" Chemistry 7, no. 4: 107. https://doi.org/10.3390/chemistry7040107

APA Style

Zhou, W., Wang, X., Xu, Y., Xu, Q., Shen, Z., & Qiao, J. (2025). Catalytic Ozonation of Diclofenac Using CuO/Al2O3- and MnO2/Al2O3-Supported Catalysts. Chemistry, 7(4), 107. https://doi.org/10.3390/chemistry7040107

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