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Article

Tribocatalytic Degradation of Organic Dyes by Disk-Shaped PTFE and Titanium: A Powder-Free Catalytic Technology for Wastewater Treatment

by
Hanze Zhu
,
Zeren Zhou
,
Senhua Ke
,
Chenyue Mao
,
Jiannan Song
and
Wanping Chen
*
School of Physics and Technology, Wuhan University, Wuhan 430072, China
*
Author to whom correspondence should be addressed.
Catalysts 2025, 15(8), 754; https://doi.org/10.3390/catal15080754
Submission received: 28 June 2025 / Revised: 16 July 2025 / Accepted: 4 August 2025 / Published: 7 August 2025
(This article belongs to the Special Issue Environmentally Friendly Catalysis for Green Future)
Browse Figures
Versions Notes

Abstract

Tribocatalysis is receiving more and more attention for its great potential in environmental remediation. In this study, a special tribocatalysis was explored as a powder-free catalytic technology for the degradation of organic dyes. Polytetrafluoroethylene (PTFE) and titanium (Ti) disks were first assembled as magnetic rotary disks and then driven to rotate through magnetic stirring in dye solutions in beakers with PTFE, Ti, and Al2O3 disks coated on bottoms separately. PTFE and Ti generated dynamic friction with the disks on the beaker bottoms in the course of magnetic stirring, from which some interesting dye degradations resulted. Among those dynamic frictions generated, 40 mg/L rhodamine b (RhB), 30 mg/L methyl orange (MO), and 20 mg/L methylene blue (MB) were effectively degraded by the one between PTFE and PTFE, the one between Ti and Ti, and the one between PTFE and Ti, respectively. Hydroxyl radicals and superoxide radicals were detected for two frictions, one between PTFE and PTFE and the other between Ti and Ti. It is proposed that Ti in friction increases the pressure in blocked areas through deformation and then catalyzes reactions under high pressure. Mechano-radicals are formed by PTFE through deformation, and are responsible for dye degradation. This work demonstrates a powder-free tribocatalysis for organic pollutant degradation and suggests an especially eco-friendly catalytic technology to wastewater treatment.

1. Introduction

With various invaluable merits, many organic chemicals are used in huge amounts in industry, agriculture, and our daily life [1,2,3]. Unfortunately, many of them appear as major harmful organic pollutants in wastewater, such as organic dyes [4], pharmaceuticals [5], phenols [6], biphenyls [7], pesticides [8], fertilizers [9], plasticizers [10], detergents [11], and carbohydrates [12]. They inflict serious harms to human health and environmental ecosystems if not treated properly [1,13,14]. For instance, organic dyes can alter the physical properties of water bodies [15], produce toxicity [16], and affect photosynthesis in aquatic plants [17], thus destroying the ecological balance and stability of water bodies. They also affect soil fertility [18] and nutrient cycling [19] through irrigation or run-off. Many organic pollutants are known as persistent organic pollutants (POPs), whose molecules need to be destroyed through chemical oxidation [20]. Currently, some oxidizing chemicals, such as Fenton [21] and hydrogen peroxide [22], are used in large amounts in wastewater treatment to eliminate these POPs completely from the environment [23]. The application of these chemicals in wastewater treatment not only increases costs but also results in secondary pollution [24]. Alternative green oxidation methods are highly desirable for wastewater treatment.
A well-known green technology in wastewater treatment is photocatalysis, in which solar light induces redox reactions in wastewater via semiconductor nanoparticles suspended in water [25,26,27]. Another newly emerging appealing technology in wastewater treatment is tribocatalysis, in which mechanical energy is absorbed by powder in water through friction and is converted into chemical energy [28,29,30,31]. For photocatalysis, wastewater should be relatively transparent for light to reach the semiconductor nanoparticles suspended in it. While for tribocatalysis, there is no such limitation, and it is more attractive for treating wastewater of low transparency than photocatalysis [32]. A mechanism based on the excitation of electron–hole pairs in semiconductor particles by mechanical energy has been proposed for tribocatalysis, which is quite similar to that for photocatalysis [33,34,35,36]. Though photocatalysis and tribocatalysis both make good use of clean energies in wastewater treatment, their dependence on particles suspended in water to absorb these clean energies actually faces some challenges for practical large-scale wastewater treatment, including catalyst recovery and secondary pollution.
With particles like TiO2 [37], ZnO [38], NiO [39], and Co3O4 [40] as catalysts, tribocatalysis has been successfully applied to the degradation of organic dyes and to the conversion of H2O and CO2. It is worth noting that, besides this typical tribocatalysis with particles as catalysts, another novel form of powder-free tribocatalysis has emerged for the conversion of H2O and CO2 into flammable gases [41,42]. Specifically, Cui et al. assembled copper (Cu) disks as Cu magnetic rotary disks, which were driven to rotate through magnetic stirring in reactors enclosed with H2O and CO2. Without any powders, the dynamic friction between Cu magnetic rotary disks and reactor bottoms catalyzed the conversion of H2O and CO2 into flammable gases [41]. Similarly, nickel (Ni) disks were employed to catalyze the conversion from H2O and CO2 into chemical fuels through friction [42]. It was shown that Ni exhibited significant catalytic effects during friction, and its chemical stability was maintained. Thus, these findings demonstrated the great potential of disk-shaped metals to catalyze important chemical reactions through friction without powders. In this study, a powder-free tribocatalytic degradation of organic dyes was successfully explored for disk-shaped polytetrafluoroethylene (PTFE) and titanium (Ti). Mounted as parts of magnetic rotary disks, disk-shaped PTFE and Ti were driven through magnetic stirring to generate friction with beaker bottoms in solutions of rhodamine b (RhB), methylene blue (MB), and methyl orange (MO) separately, which are widely studied as model organic pollutants in photocatalysis [43,44,45]. To our great surprise, all three kinds of organic dyes degraded through magnetic stirring without the participation of any powders. It has thus clearly extended powder-free tribocatalysis from the conversion of H2O and CO2 to the degradation of organic pollutants, which is especially attractive for wastewater treatment prospects regarding powder-related secondary pollution. To our knowledge, this is the first report of a powder-free catalytic technology for the degradation of organic pollutants, which is especially attractive for wastewater treatment in view of powder-related secondary pollution.

2. Results and Discussion

2.1. Organic Dyes Degradation

Figure 1 shows the results obtained for the PTFE magnetic rotary disk, which was driven to rotate through magnetic stirring in solutions of 40 mg/L RhB, 20 mg/L MB, and 30 mg/L MO contained in glass beakers with Ti, aluminum oxide (Al2O3), and PTFE coatings separately. PTFE from the magnetic rotary disk generated dynamic friction with the bottoms of beakers in the course of magnetic stirring and the friction pairs are termed as PTFE@Ti, PTFE@Al2O3, and PTFE@PTFE, respectively. As shown in Figure 1a, for 40 mg/L RhB in a Ti-coated beaker, the characteristic peak at 554 nm decreased significantly while remaining observable after 180 min of magnetic stirring. It can also be seen from the inset that the dye color faded from red to pink rather than to colorless. As shown in Figure 1b, for 40 mg/L RhB in an Al2O3-coated beaker, the characteristic peak decreased with magnetic stirring time much slower than that in Figure 1a, and after 180 min of magnetic stirring, the peak was still rather high, and the solution was still rather bright in color. Encouragingly, for 40 mg/L RhB in a PTFE-coated beaker, the characteristic peak completely disappeared and the solution became colorless after 180 min of magnetic stirring, as shown in Figure 1c, which form sharp contrasts with those in Figure 1a,b. Obviously, the frictions between PTFE and the coatings of the beakers in the course of magnetic stirring resulted in the observed RhB degradations, and the best result was obtained for the beaker with PTFE coating. Namely, the friction between PTFE and PTFE was most effective for RhB degradation.
The results for the degradation of 20 mg/L MB are shown in Figure 1d–f. At the initial stage of magnetic stirring, the characteristic peak at 665 nm decreased readily with magnetic stirring time for all three kinds of coatings. After 180 min of magnetic stirring, however, the decreasing speed of the peak began to slow down for Al2O3 and PTFE coatings. After 300 min of magnetic stirring, a complete degradation was only obtained for the Ti coating. Namely, the peak completely disappeared, and the solution almost became colorless, as shown in Figure 1d. It is clear that the friction between PTFE and Ti is most effective for the degradation of MB.
For 30 mg/L MO, the peak at 464 nm decreased rather slowly with magnetic stirring time for all three kinds of coatings. Even after 540 min of magnetic stirring, the peak did not disappear and the solution was not colorless for all the three coatings, as shown in Figure 1g–i. It seems that the PTFE magnetic rotary disk was less effective for the degradation of MO than for those of RhB and MB.
The results obtained for the Ti magnetic rotary disk are shown in Figure 2. In sharp contrast with the PTFE magnetic rotary disk, the Ti disk was found especially effective in degrading MO. For both Ti and Al2O3 coatings, the characteristic peak of MO at 464 nm completely disappeared and the solution also became colorless after 120 min of magnetic stirring, as shown in Figure 2a,b. It should be pointed out that a new peak appeared at 247 nm, which has been observed in previous studies and suggests that MO molecules have been broken into some less harmful small molecules [46,47]. However, for PTFE coating, the characteristic peak and the bright orange color were still observed even after 540 min of magnetic stirring, as shown in Figure 2c. Together with the results shown in Figure 1g–i, it is clear that PTFE is not effective for degrading MO through friction either as a magnetic rotary disk or as a coating.
The results obtained for the degradation of 20 mg/L MB solution by the Ti disk are shown in Figure 2d–f. As shown in Figure 2d, the degradation in the Ti-coated beaker was relatively slow. The characteristic peak at 665 nm was decreased by 70% and the solution color was changed from dark blue to light blue after 540 min of magnetic stirring. As for 20 mg/L MB in the Al2O3-coated beaker, the Ti disk induced a nearly 100% degradation and the solution became colorless after 540 min of magnetic stirring, as shown in Figure 2e. A dynamic friction between PTFE and Ti occurred for the PTFE rotary disk in the Ti-coated beaker, and also for the Ti rotary disk in the PTFE-coated beaker. In both cases, 20 mg/L MB was effectively degraded, as shown in Figure 1d and Figure 2f. In short, both the PTFE and Ti magnetic rotary disks were very successful in degrading 20 mg/L MB through friction.
Although the Ti magnetic rotary disk was very successful for the degradation of MO and MB, it was found quite incompetent for the degradation of RhB through friction. As shown in Figure 2g–i, even after 360 min of magnetic stirring, the peak at 554 nm did not disappear and the solution was still rather red for all three coatings. It is worth noting that though the friction between PTFE and PTFE was very effective for degrading RhB, as shown in Figure 1c, the friction between PTFE and Ti was far less effective for the degradation of RhB, as shown in both Figure 1a and Figure 2i.
Figure 3 shows the relationship between C/C0 and magnetic stirring time for the three dye solutions in this study. As shown in Figure 3a, for 40 mg/L RhB, the fastest degradation was observed for PTFE@PTFE, while the slowest one was observed for Ti@Ti, which roughly suggests that PTFE is much more effective than Ti in degrading RhB through friction.
For the 20 mg/L MB shown in Figure 3b, almost 100% degradation was observed for three friction pairs, namely PTFE@Ti, Ti @PTFE, and Ti@Al2O3. It seems that the friction between PTFE and Ti is especially useful for the degradation of MB.
Among the results obtained for the 30 mg/L MO shown in Figure 3c, two friction pairs, namely Ti@Ti and Ti@Al2O3, were much better than all the others in degrading MO. As two hard materials happened to appear only in these two friction pairs, it seems that for Ti, friction with a hard material is necessary for the degradation of MO. On the other hand, as PTFE is present in all the other friction pairs that are not effective for the degradation of MO, in view of the efficiency of PTFE in degrading RhB, this suggests that PTFE is less effective in degrading MO than RhB through friction.
Though only three kinds of disk-shaped materials (PTFE, Ti, and Al2O3) were employed to take part in the friction pairing in this study, the results obtained are highly surprising in several ways. Firstly, all the model dye solutions in this study, namely 40 mg/L RhB, 20 mg/L MB, and 30 mg/L MO, were successfully degraded in a relatively short period of time by these materials stimulated through magnetic stirring. As a matter of fact, the concentrations of these solutions were actually so high that they were challenging to be degraded by photocatalysts under solar light irradiation. Secondly, for the same organic dye, different materials showed highly different capabilities to degrade through friction. For example, PTFE was much more competent than Ti at degrading RhB, while Ti was much more competent than PTFE at degrading MO. It is thus expected that many other organic pollutants can be degraded in this way after many more kinds of materials have been investigated and chosen to take part in friction pairing. Therefore, it can be expected that many other organic pollutants can be degraded in this way once a wider range of materials for use in friction pairs is investigated and selected. Thirdly, the power of magnetic stirring in this study was below 10 W, which indicates that this powder-free technology is scalable for large-scale wastewater treatment. While this powder-free tribocatalysis first appeared for the conversion of H2O and CO2 [41,42], it should be especially appealing for large-scale wastewater treatment in which powder-related secondary pollution has long been a major concern.

2.2. Mechanism Analysis

There are two special friction pairs in this study, namely PTFE@PTFE and Ti@Ti, whose two materials in friction are of the same kind. Since some highly surprising results have been observed for them, the radicals that were generated by their dynamic frictions have been investigated in depth. Terephthalic acid (TA) and nitrotetrazolium blue chloride (NBT) have been used as molecule probes, as the reaction of TA with ·OH produced 2-hydroxyterephthalic acid (TAOH) with a fluorescence response at 425 nm [48], and the reaction of NBT with · O 2 − caused the absorption peak of NBT at 259 nm to gradually decrease [49]. For a PTFE magnetic rotary disk rotated in 0.5 mM TA and 2 mM NaOH contained in a PFTE-coated beaker, as shown in Figure 4a, the fluorescence intensity of TAOH gradually increased with magnetic stirring time, which indicates that ·OH was continuously generated through the friction of PTFE@PTFE. On the other hand, the characteristic peak of NBT at 259 nm gradually decreased with magnetic stirring time and finally disappeared within 120 min, as shown in Figure 4b, indicating that superoxide radicals ( · O 2 − ) were continuously generated through the friction of PTFE@PTFE. For a Ti magnetic rotary disk rotating in a Ti-coated beaker, both radicals were generated in much greater amounts through the friction of Ti@Ti than their counterparts through the friction of PTFE@PTFE separately, as shown in Figure 4c,d.
As a matter of fact, a mechanism has been proposed for the tribocatalytic conversion from H2O and CO2 to chemical fuels by Cu and Ni, in which hydroxyl radicals have been detected as intermediate products [41,42]. These metals first increase the pressure in blocked holes in friction surface through elastic deformation and then exert their catalytic role under elevated pressures. Similarly, this mechanism can be adopted to explain the dye degradation induced by the Ti magnetic rotary disk. When Ti forms dynamic friction with another hard material, including Ti, small holes in the friction surface can be blocked and squeezed by Ti through elastic deformation, and Ti catalyzes dye degradation under high pressures. As catalytic reactions, it is common for hydroxyl and super oxygen radials to be detected as intermediate products.
As for the dye degradations induced by the PTFE magnetic rotary disk, quite similar results were reported by Grzybowski et al. in 2012 [50]. As they observed that some polymers are able to induce redox reactions in surrounding solutions merely through mechanical deformation, they proposed that mechano-radicals created by mechanically stressed polymers are responsible for the reactions. Though the nature of mechano-radicals needs further investigations, we would like to tentatively explain the degradations induced by PTFE in this study in the same way. Specifically for the friction between PTFE and PTFE, PTFE is deformed in some local areas under friction, as shown in Figure 5. Mechano-radials are created by deformed PTFE and subsequently induce dye degradation.
Many interesting results obtained in this study deserve further in-depth exploration. For instance, the friction between PTFE and PTFE was especially effective for degrading RhB, while the friction between Ti and Ti was especially effective for degrading MO. The mechanisms behind them are important not only for wastewater treatment but also for the development of tribocatalysis as a whole.

3. Materials and Methods

3.1. PTFE and Ti Disks Assembled as Magnetic Rotary Disks

A PTFE disk, ϕ 35 mm × 5 mm, was assembled as a PTFE magnetic rotary disk by mounting 18 magnets, ϕ 5 mm × 5 mm, on its back, which were then encapsulated with epoxy. The fabrication of PTFE magnetic rotary disks was described in detail in a previous paper [39].
Four Ti disks, ϕ 10 mm × 3 mm, were mounted symmetrically on a PTFE disk, ϕ 35 mm × 5 mm, as shown in Figure 6a. A total of 18 magnets, ϕ 5 mm × 5 mm, were placed into the recess of a PFTE disk, ϕ 35 mm × 8 mm. These two PTFE disks were bound together with strong glue, as shown in Figure 6b. Driven through magnetic stirring, this Ti magnetic rotary disk will rotate, and its Ti disks will form dynamic friction with the beaker bottom.

3.2. Modifying Glass Beakers with PTFE, Ti, and Al2O3 Disks on Their Bottoms

Commercially available flat-bottomed quartz glass beakers (ϕ 50 mm × 75 mm, 150 mL) were modified through coating disks of PTFE, Ti, and Al2O3 on their bottoms separately. This approach resulted in beakers with bottoms of PTFE, Ti, and Al2O3, prepared separately for further investigation.

3.3. Degradation of Organic Dyes Through Magnetic Stirring

As in a typical experiment, a PTFE or a Ti magnetic rotary disk was placed in a beaker that contained 20 mL of 20 mg/L MB, 30 mg/L MO, or 40 mg/L RhB solution. The magnetic rotary disk was driven to rotate at 400 rpm in the solution through a magnetic stirrer (HO3-A, Shanghai Meiyingpu Instrument manufacturing Co., Shanghai, China), as shown by an example in Figure 7, the room temperature was kept at 25 °C, and the beaker was kept in dark environment. Samples of 2 mL were collected at specified intervals. The absorbance spectra for MB, MO, and RhB were recorded with a UV–Vis spectrophotometer (UV-2550; Shimadzu, Kyoto, Japan). The efficiency of organic dye degradation was typically calculated using the equation D  =  1  −  A/A0, with A0 and A denoting the initial and remaining absorbance at the dye’s characteristic peak (RhB: 554 nm; MO: 464 nm; MB: 665 nm), respectively.

3.4. Detection for Hydroxyl Radicals and Superoxide Radicals

A PTFE magnetic rotary disk was first placed in a PTFE-coated beaker, and a Ti magnetic rotary disk was first placed in a Ti-coated beaker. For the detection of hydroxyl radicals (·OH), 20 mL of a mixture of 0.5 mM terephthalic acid (TA) and 2 mM NaOH was added to the PTFE-coated beaker and the Ti-coated beaker separately. The magnetic rotary disks in the beakers were driven to rotate at 400 rpm in darkness and 2 mL of samples was collected at certain time intervals, and their fluorescence spectra were measured on a fluorescence luminescence spectrophotometer (FL-F4600, Hitachi, Tokyo Japan) using 315 nm excitation light. For the detection of superoxide radicals ( · O 2 − ), 20 mL of 10 mg/L NBT solution was added to the PTFE-coated beaker and 20 mL of 40 mg/L NBT solution was added to the Ti-coated beaker. Magnetic stirring was conducted similarly, and 2 mL of samples was also collected at certain time intervals, whose absorption spectra were determined through a UV–Vis spectrophotometer (UV-2550; Shimadzu, Kyoto, Japan).

4. Conclusions

PTFE and Ti magnetic rotary disks were separately assembled from their disks with magnets, and were placed in dye solutions contained in separate beakers with PTFE, Ti, and Al2O3 disks coated on their bottoms. The magnetic rotary disks were driven to rotate in the dye solutions through magnetic stirring, which resulted in some highly surprising dye degradations. Among them, 99.7% of 40 mg/L RhB was degraded after 3 h of magnetic stirring for PTFE@PTFE, 100% of 30 mg/L MO was degraded after 2 h of magnetic stirring for Ti@Ti, and 95% of 20 mg/L MB was degraded after 5 h of magnetic stirring for PTFE@Ti. The tribocatalytic performance of Ti is explained in terms of its catalytic role under high pressures, and that of PTFE is explained in terms of the formation of mechano-radicals by deformed polymers. These findings clearly demonstrate an appealing powder-free technology to utilize mechanical energy for wastewater treatment.

Author Contributions

Conceptualization, H.Z. and W.C.; methodology, H.Z. and C.M.; formal analysis, H.Z.; investigation, H.Z., S.K. and J.S.; data curation, H.Z. and Z.Z.; writing—original draft preparation, H.Z.; writing—review and editing, W.C.; visualization, H.Z., Z.Z. and C.M.; supervision, W.C.; project administration, W.C.; funding acquisition, W.C. All authors have read and agreed to the published version of the manuscript.

Funding

This research was partially supported by Jiangsu Engineering Research Center of New Materials for Adsorptive Separation in Chemical Industry and Environmental Treatment, Suzhou, 215123, China (Grant No. SDGC2424).

Data Availability Statement

Data are contained within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

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Catalysts 15 00754 g001
Figure 1. UV–Vis absorption spectra of organic dye solutions contained in glass beakers with Ti, Al2O3, and PTFE coatings separately and stimulated through a PTFE magnetic rotary disk that was driven to rotate by magnetic stirring (inset: solution color change): (a) RhB (40 mg/L) in a Ti-coated beaker; (b) RhB (40 mg/L) in an Al2O3-coated beaker; (c) RhB (40 mg/L) in an PTFE-coated beaker; (d) MB (20 mg/L) in a Ti-coated beaker; (e) MB (20 mg/L) in an Al2O3-coated beaker; (f) MB (20 mg/L) in a PTFE–coated beaker; (g) MO (30 mg/L) in a Ti-coated beaker; (h) MO (30 mg/L) in an Al2O3-coated beaker; (i) MO (30 mg/L) in a PTFE-coated beaker.
Figure 1. UV–Vis absorption spectra of organic dye solutions contained in glass beakers with Ti, Al2O3, and PTFE coatings separately and stimulated through a PTFE magnetic rotary disk that was driven to rotate by magnetic stirring (inset: solution color change): (a) RhB (40 mg/L) in a Ti-coated beaker; (b) RhB (40 mg/L) in an Al2O3-coated beaker; (c) RhB (40 mg/L) in an PTFE-coated beaker; (d) MB (20 mg/L) in a Ti-coated beaker; (e) MB (20 mg/L) in an Al2O3-coated beaker; (f) MB (20 mg/L) in a PTFE–coated beaker; (g) MO (30 mg/L) in a Ti-coated beaker; (h) MO (30 mg/L) in an Al2O3-coated beaker; (i) MO (30 mg/L) in a PTFE-coated beaker.
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Figure 2. UV–Vis absorption spectra of organic dye solutions contained in glass beakers with Ti, Al2O3, and PTFE coatings separately and stimulated through a Ti magnetic rotary disk that was driven to rotate by magnetic stirring (inset: solution color change): (a) MO (30 mg/L) in a Ti-coated beaker; (b) MO (30 mg/L) in an Al2O3-coated beaker; (c) MO (30 mg/L) in a PTFE-coated beaker; (d) MB (20 mg/L) in a Ti-coated beaker; (e) MB (20 mg/L) in an Al2O3-coated beaker; (f) MB (20 mg/L) in a PTFE-coated beaker; (g) RhB (40 mg/L) in a Ti-coated beaker; (h) RhB (40 mg/L) in an Al2O3-coated beaker; (i) RhB (40 mg/L) in a PTFE-coated beaker.
Figure 2. UV–Vis absorption spectra of organic dye solutions contained in glass beakers with Ti, Al2O3, and PTFE coatings separately and stimulated through a Ti magnetic rotary disk that was driven to rotate by magnetic stirring (inset: solution color change): (a) MO (30 mg/L) in a Ti-coated beaker; (b) MO (30 mg/L) in an Al2O3-coated beaker; (c) MO (30 mg/L) in a PTFE-coated beaker; (d) MB (20 mg/L) in a Ti-coated beaker; (e) MB (20 mg/L) in an Al2O3-coated beaker; (f) MB (20 mg/L) in a PTFE-coated beaker; (g) RhB (40 mg/L) in a Ti-coated beaker; (h) RhB (40 mg/L) in an Al2O3-coated beaker; (i) RhB (40 mg/L) in a PTFE-coated beaker.
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Figure 3. Relationship between C/C0 and stirring time for the degradation of three kinds of dye solutions in this study: (a) 40 mg/L RhB; (b) 20 mg/L MB; (c) 30 mg/L MO.
Figure 3. Relationship between C/C0 and stirring time for the degradation of three kinds of dye solutions in this study: (a) 40 mg/L RhB; (b) 20 mg/L MB; (c) 30 mg/L MO.
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Figure 4. A PTFE magnetic rotary disk rotating in a PTFE-coated beaker: (a) fluorescence intensity spectra for 0.5 mM TA and 2 mM NaOH; (b) UV–Vis absorption spectra for 10 mg/L NBT. A Ti magnetic rotary disk rotating in a Ti-coated beaker: (c) fluorescence intensity spectra for 0.5 mM TA and 2 mM NaOH; (d) UV–Vis absorption spectra for 40 mg/L NBT.
Figure 4. A PTFE magnetic rotary disk rotating in a PTFE-coated beaker: (a) fluorescence intensity spectra for 0.5 mM TA and 2 mM NaOH; (b) UV–Vis absorption spectra for 10 mg/L NBT. A Ti magnetic rotary disk rotating in a Ti-coated beaker: (c) fluorescence intensity spectra for 0.5 mM TA and 2 mM NaOH; (d) UV–Vis absorption spectra for 40 mg/L NBT.
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Figure 5. A schematic drawing for PTFE deformation in friction between PTFE and PTFE disks, and the creation of mechano-radicals from deformed PTFE.
Figure 5. A schematic drawing for PTFE deformation in friction between PTFE and PTFE disks, and the creation of mechano-radicals from deformed PTFE.
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Figure 6. Images of a Ti magnetic rotary disk: (a) front surface; (b) side surface.
Figure 6. Images of a Ti magnetic rotary disk: (a) front surface; (b) side surface.
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Figure 7. Image of the experimental setup for tribocatalytic degradation of organic dyes in this study: a Ti magnetic rotary disk was placed in MB solution contained in a PTFE-coated beaker.
Figure 7. Image of the experimental setup for tribocatalytic degradation of organic dyes in this study: a Ti magnetic rotary disk was placed in MB solution contained in a PTFE-coated beaker.
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MDPI and ACS Style

Zhu, H.; Zhou, Z.; Ke, S.; Mao, C.; Song, J.; Chen, W. Tribocatalytic Degradation of Organic Dyes by Disk-Shaped PTFE and Titanium: A Powder-Free Catalytic Technology for Wastewater Treatment. Catalysts 2025, 15, 754. https://doi.org/10.3390/catal15080754

AMA Style

Zhu H, Zhou Z, Ke S, Mao C, Song J, Chen W. Tribocatalytic Degradation of Organic Dyes by Disk-Shaped PTFE and Titanium: A Powder-Free Catalytic Technology for Wastewater Treatment. Catalysts. 2025; 15(8):754. https://doi.org/10.3390/catal15080754

Chicago/Turabian Style

Zhu, Hanze, Zeren Zhou, Senhua Ke, Chenyue Mao, Jiannan Song, and Wanping Chen. 2025. "Tribocatalytic Degradation of Organic Dyes by Disk-Shaped PTFE and Titanium: A Powder-Free Catalytic Technology for Wastewater Treatment" Catalysts 15, no. 8: 754. https://doi.org/10.3390/catal15080754

APA Style

Zhu, H., Zhou, Z., Ke, S., Mao, C., Song, J., & Chen, W. (2025). Tribocatalytic Degradation of Organic Dyes by Disk-Shaped PTFE and Titanium: A Powder-Free Catalytic Technology for Wastewater Treatment. Catalysts, 15(8), 754. https://doi.org/10.3390/catal15080754

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