Piezo- photo- and piezophotocatalytic activity of electrospun fibrous PVDF/CTAB membrane published by Ural Federal University eISSN 2411-1414; chimicatechnoacta.ru ARTICLE 2022, vol. 9(4), No. 20229420 DOI: 10.15826/chimtech.2022.9.4.20 1 of 8 Piezo-, photo- and piezophotocatalytic activity of electrospun fibrous PVDF/CTAB membrane Alina Rabadanova a , Magomed Abdurakhmanov a , Rashid Gulakhmedov a , Abdulatip Shuaibov a , Daud Selimov a , Dinara Sobola a,b , Klára Částková c , Shikhgasan Ramazanov d , Farid Orudzhev a,d,e * a: Smart Materials laboratory, Dagestan State University, Makhachkala 367015, Russia b: Department of Physics, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno 61600, Czech Republic c: CEITEC BUT – Brno University of Technology, Brno 61200, Czech Republic d: Amirkhanov Institute of Physics of Dagestan Federal Research Center, Russian Academy of Sciences, Makhachkala 367003, Russia e: REC Smart Materials and Biomedical Applications, Immanuel Kant Baltic Federal University, Kaliningrad 236041, Russia * Corresponding author: farid-stkha@mail.ru This paper belongs to a Regular Issue. © 2022, the Authors. This article is published in open access under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Abstract A composite material based on polyvinylidene fluoride (PVDF) nano- fibers modified with cetyltrimethylammonium bromide (CTAB) was synthesized by coaxial electrospinning. The morphology and structure of the material were studied by SEM, FTIR spectroscopy, X-ray diffrac- tion analysis, XPS, and the piezo-, photo- and piezophotocatalytic activ- ity during the decomposition of the organic dye Methylene blue (MB) was studied. It was shown that the addition of CTAB promotes addi- tional polarization of the PVDF structure due to the ion-dipole interac- tion. It was shown for the first time that the addition of CTAB promotes the photosensitivity of the wide-gap dielectric polymer PVDF (the band gap is more than 6 eV). It was demonstrated that the photocatalytic de- composition efficiency is 91% in 60 minutes. The material exhibits pie- zocatalytic activity – 73% in 60 minutes. The experiments on trapping active oxidizing forms established that OH hydroxyl radicals play the main role in the photocatalytic process. Keywords PVDF photocatalysis piezocatalysis piezophotocatalysis nanofibers coaxial electrospinning CTAB methylene blue Received: 18.10.22 Revised: 07.11.22 Accepted: 10.11.22 Available online: 17.11.22 1. Introduction Water pollution caused by persistent organic dyes is a seri- ous environmental problem. Various effective methods have been developed to eliminate pollution, such as absorption, electrochemical treatment, photocatalysis, piezocatalysis, pi- ezophotocatalysis [1]. However, inappropriate band gap structure, low mobility rate, fast recombination of the gen- erated charge carriers often limit the photocatalytic applica- tions [2]. Recently, the internal electric field of piezoelectric materials that can be used to overcome the above limitations in the photocatalytic process has generated a lot of interest [3]. The piezoelectric effect is used to enhance photocatalysis by an internal electric field, which promotes the separation and migration of photogenerated electron-hole pairs, thereby realizing higher piezophotocatalytic efficiency for the simultaneous use of these two types of natural energy. Compared to the relatively mature research on photocatalysis, piezocatalysis is seen as a new strategy for tackling environmental pollution and energy shortages [4]. So far, the research on piezocatalytic applications is still in its infancy. However, it is already clear from the available studies that the wide spread practical application of hetero- geneous photo-, piezo- and piezophotocatalysts in the sus- pension mode is difficult due to their uneven dispersion and the difficulty of extracting and reusing the catalysts. The so- lution to these problems can be the immobilization of the cat- alyst on a polymer matrix. A recent review [5] summarized significant progress in the preparation of various photocata- lytic materials based on hybrid polymers. In recent years, polymer composites based on PVDF and semiconductor na- noparticles, the so-called heterophase doping, have been in- tensively studied for the purposes of piezocatalysis and pie- zophotocatalysis [6–9]. Moreover, poly(vinylidene fluoride) (PVDF) can crystallize into at least four polymorphs (α, β, γ and δ), which leads to different ferroelectric properties. http://chimicatechnoacta.ru/ https://doi.org/10.15826/chimtech.2022.9.4.20 mailto:farid-stkha@mail.ru http://creativecommons.org/licenses/by/4.0/ https://orcid.org/0000-0003-2254-2161 https://orcid.org/0000-0002-0805-2089 https://orcid.org/0000-0001-6856-5954 https://orcid.org/0000-0002-5015-8274 https://orcid.org/0000-0002-4911-4282 https://orcid.org/0000-0002-0008-5265 https://orcid.org/0000-0002-6343-6659 https://orcid.org/0000-0003-2190-7704 https://orcid.org/0000-0002-2966-8931 https://crossmark.crossref.org/dialog/?doi=https://doi.org/10.15826/chimtech.2022.9.4.20&domain=pdf&date_stamp=2022-11-17 Chimica Techno Acta 2022, vol. 9(4), No. 20229420 ARTICLE 2 of 8 Compared to the α-phase, the polar β- and γ-phases have attracted a lot of attention due to their unique physical properties and potential applications [10]. For example, the polar phases, β and γ, cause pyroelectricity, piezoelectric- ity, and ferroelectricity. Meanwhile, the γ-phase increases transparency, which makes it suitable for optical devices. To obtain the maximum content of the β phase in PVDF membranes, various approaches are used, among which the most effective are the choice of a synthesis method and the addition of various fillers [11]. One of the most effective methods for the synthesis of PVDF with the maximum con- tent of the β phase is considered to be electrospinning, in which high voltages contribute to the repolarization of the structure due to the alignment of electric dipoles. A recent review [12] summarized the generalized approaches to the fabrication of hybrid piezoelectric materials based on PVDF and its copolymer, poly-(vinylidene fluoride)-trifluoroeth- ylene PVDF-TrFE with fillers of inorganic and metal nano- particles, conductive rGO nanosheets and others to improve the piezoelectric characteristics of composites and their practical application as mechanical energy converters. However, for photocatalytic applications, composite poly- mer-inorganic structures have their own specific require- ments [13]. In most studies, composites are synthesized by phase inversion, in which most of the nanoparticles are in the bulk of the polymer membrane, which limits the access of light and solution to the surface of the nanoparticles. Pro- ceeding from this, the actual task of materials science is to find a method for homophase doping of PVDF to give it new functional properties. The previous reports have demon- strated that the addition of a low concentration of the cati- onic surfactant cetyltrimethylammonium bromide (CTAB) can effectively induce a pure γ-phase by introducing a strong ion-dipole interaction between the CTAB and PVDF dipoles [14, 15]. In [16] the authors reported the piezocatalytic activ- ity of pure PVDF and its copolymer with hexafluoropropylene (HFP) to produce hydrogen under ultrasonic irradiation. In this study, we synthesized a composite PVDF/CTAB nanofiber membrane by electrospinning. It was shown that doping with CTAB leads to photosensitization of the poly- mer. It was also shown for the first time that a PVDF poly- mer membrane exhibits high piezocatalytic and photocata- lytic activity towards the decomposition of methylene blue. It was demonstrated for the first time that irradiation with UV-visible light leads to the suppression of piezocata- lytic properties during piezophotocatalysis. Figure 1 Contipro 4SPIN LAB electrospinning device and the im- age of the resulting sample. 2. Methodology 2.1. Synthesis of PVDF/CTAB nanofibers For electrospinning, PVDF with a molecular weight of 275,000 g mol–1 (Sigma Aldrich, St. Louis, MO, USA) was used. Dimethyl sulfoxide (DMSO, Sigma Aldrich, St. Louis, MO, USA) and acetone (Ac, Sigma Aldrich, St. Louis, MO, USA) were used as solvents. CTAB (Sigma Aldrich, St. Louis, MO, USA) was added as a surfactant. PVDF with a concentration of 20 wt.% was dissolved in the binary solvent dimethyl sulfoxide/acetone in a volume ratio of 7/3 at 50 °C for 24 h until a visually homogeneous solution was formed. A PVDF/CTAB solution was prepared by modification of the neat PVDF solution with 1 wt.% CTAB (by weight of solution). PVDF nanofibers were produced by coaxial electrospinning on a Contipro 4SPIN LAB facility (Contipro as, Dolni Dobrouc, Czech Republic). A coaxial setup included two syringes to feed PVDF and PVDF/CTAB solutions independently to a coaxial tip consisting of two concentric needles. The interior needle had an inner diameter of 0.514 mm and was set 0.5 mm longer than the exterior one at the end of the tip. The outer needle had an inner diameter of 1.372 mm. The coaxial electrospinning was performed with feeding rates of 9 μl/min at a constant voltage of 50 kV and a collector rotation speed of 2000 rpm. The distance between the tip of the needle and the collector (a rotating metal drum covered with aluminium foil) was 20 cm. The processing time was 30 minutes. Visually, the pro- cess is shown in Figure 1. 2.2. Characterization and analysis of nanofibers The morphology of the samples was studied using a scan- ning electron microscope (SEM) LYRA3 (Tescan, Brno, Czech Republic). The samples were coated with a 15 nm car- bon layer using a Leica EM ACE600 coater (Leica Microsys- tems, Wetzlar, Germany). Mean fiber diameters were calcu- lated from the SEM images using ImageJ software. The XRD analysis was performed with an X-ray powder diffractometer Rigaku SmartLab 3 kW (Rigaku Corporation, Tokyo, Japan) in the Bragg-Brentano configuration. Diffrac- tion patterns were obtained between 10 ° and 50 ° (2θ) with Cu Kα radiation. XPS spectra were recorded on an AXIS SupraTM X-ray photoelectron spectrometer (Kratos Analytical Ltd., Man- chester, UK) with an emission current of about 15 mA. The spectra were adjusted using CasaXPS v.2.3.23 program. The measurement of FT-IR spectroscopy was carried out in transmission mode using a Bruker spectrometer (Biller- ica, Massachusetts, USA) with a resolution of 1 cm–1 and 512 iterations. 2.3. Piezophotocatalytic experiment The piezocatalytic/piezophotocatalytic decomposition test was carried out using UV-visible irradiation. A 250 W high- pressure mercury lamp (Philips) was used as a source of UV-visible light. The distance from the light source to the Chimica Techno Acta 2022, vol. 9(4), No. 20229420 ARTICLE 3 of 8 reactor was 10 cm. Piezophotocatalytic decomposition was carried out in an ultrasonic (US) bath with a power of 250 W at a frequency of 18 kHz. To eliminate the effect of temper- ature on the decomposition efficiency, the reactor was kept at a constant temperature of 26 °C. Before testing, a film (3x1 cm2, thickness 25 μm, weight 0.7 mg) was immersed in a beaker with a solution of methylene blue (MB) (1 mg L–1, 20 mL) and kept in a dark place for 1 h to establish the ad- sorption–desorption balance. During the test, 3 ml of the sample solution was taken every 15 min and analyzed using a UV-visible spectrometer. The dye concentration was measured from the maximum absorption peak λ = 663 nm. The percentage of degradation was indicated as C/C0 (C and C0 are the measured and initial concentrations of the dye solution, respectively). 3. Results and Discussions The morphology of the samples was characterized using a scanning electron microscope (SEM). Figure 2 shows the SEM images of the films of PVDF/CTAB nanocomposite fi- bers obtained by electrospinning. To determine the parti- cle size distribution, the SEM image was examined using ImageJ. It can be seen that the surface and structure are smooth, uniform, without visible defects. The PVDF/CTAB fibers are formed as elongated nanofibers with different diameters. From the distribution histogram obtained us- ing ImageJ program, it can be seen that the average diam- eter of the nanofibers is about 450 nm. To determine the phase composition, the samples were characterized using FTIR spectroscopy and XRD. The data are presented in Figure 3. The XRD measurements of the PVDF/CTAB nanofibers show that the predominant phase is the β-phase. The peaks at 20.6 ° (110/200) and 36.6 ° (101) testify to this [17, 18] (Figure 2a). The diffraction bands of the monoclinic α phase peaks are located at 18.4 ° (020) and 41.1 ° (111). Since the diffraction bands of the γ and α phases overlap and it is not possible to accurately determine the phase distribution, FTIR analysis was used to quantify the phase distribution in PVDF. From the FTIR spectra, the relative abundance of all three α-, β- and γ-phases in the samples were calculated. First, the fraction of the electroactive phase (FEA) was cal- culated, according to equation 1: 𝐹EA = 𝐼EA ( 𝐾840∗ 𝐾763 ) 𝐼763 + 𝐼EA ∙ 100% (1) where IEA and I763 are the absorbances at 840 and 763 cm–1, respectively; K840* and K763 are the absorption coefficients at the respective wave numbers, whose values are 7.7·104 and 6.1·104 cm2 mol–1, respectively. Then, using equations 2 and 3, the distribution of β- and γ-phases in the electroactive phase was calculated: 𝐹(β) = 𝐹𝐸𝐴 ∆𝐻β′ ∆𝐻β′ + ∆𝐻γ′ ∙ 100% (2) and 𝐹(γ) = 𝐹𝐸𝐴 ∆𝐻𝛾′ ∆𝐻β′ + ∆𝐻γ′ ∙ 100%, (3) where ΔHβ′ and ΔHγ′ are the height differences (absorbance differences) between the peak around at 1275 cm–1 and the nearest valley around at 1260 cm–1, and the peak around at 1234 cm–1 and the nearest valley around at 1225 cm–1, respectively [18]. The calculations showed that in pure PVDF the fraction of the α phase was 9.74%, the fraction of the γ phase was 4.71%, and the fraction of the β phase was 85.55%, respec- tively. After the modification of CTAB, the proportion of the β-phase increased to 90.34%, the proportion of the α-phase was 9.51%, and the proportion of the γ-phase was 0.15%. The effect of CTAB addition on the formation of pure PVDF γ-phase due to the ion-dipole interaction was previously re- ported for membranes prepared by thermally induced phase inversion (TIPS). At the same time, it was reported that in the presence of CTAB, the charges in CTAB molecules attract the PVDF chains due to ion-dipole interactions, and the PVDF chains tend to form a trans conformation that is favorable for the nucleation of the γ-phase, which leads to the suppression of the growth rate of the α-phase. However, our results show that the addition of CTAB leads to suppres- sion of the growth of the γ-phase and an increase in the proportion of the β phase. This discrepancy is apparently explained by the contribution of electric polarization during electrospinning. The chemical state of the surface was examined using XPS. The wide spectrum (see Figure 4a) shows peaks in the main levels of carbon (C1s), fluorine (F1s) and oxygen (O1s). The F1s ground level spectra can be well decomposed into two peak components associated with CF (686.5 eV) and CF2 (687.4 eV), respectively [19]. Figure 2 SEM images of PVDF/CTAB nanofibers at various magni- fications (a, b) and the histogram of the distribution of nanofibers by diameter (c). Chimica Techno Acta 2022, vol. 9(4), No. 20229420 ARTICLE 4 of 8 Figure 3 X-ray diffraction analysis of PVDF/CTAB nanofibers (a); IR Fourier spectrum of PVDF/CTAB nanofibers and pure PVDF (b). These components can be attributed to the presence of covalent and semi-ionic fluorinated bonds. The previous work showed that pure PVDF has a high content of semi- ionic bonds [20, 21]. As is known, semi-ionic bonds are more oriented than covalent bonds, and a decrease in the proportion of semi-ionic bonds may indicate a decrease in the concentration of the more oriented β-phase. This result confirms the conclusions drawn from the FTIR spectra, where it was shown that the addition of CTAB leads to a change in the proportion of the β-phase by more than 5%. The changes in the concentration suggest that CTAB mole- cules bind to the PVDF structure and change the orientation of the polymer chain, rather than simply being located be- tween individual fibers. The XPS spectra of C1s (Figure 4c) show the presence of the standard bands expected for PVDF [22]. Deconvolution of the C1s spectrum identifies 6 peaks: C-C/C-H, CH2, C-O, FC-OH, CF2 and CF3, among which the CH2 peak is the most prominent. Deconvolution of the O1s peaks shows that the samples prepared with CTAB are enriched in oxygen-con- taining functional groups (Figure 4d), associated with re- sidual oxygen from solvents and possible oxidative pro- cesses during the synthesis in open air. Figure 5 shows the results of catalytic experiments in the decomposition of MS using a PVDF/CTAB membrane as a catalyst. Two blank experiments were carried out in order to elu- cidate the contribution of MB self-decomposition under di- rect light (photolysis) and ultrasonic treatment (sonolysis). Blank experiments showed that MB degraded under the ac- tion of US treatment and UV-visible light, while the degree of degradation was 51.3% and 62.0% after 60 minutes. The results of the piezocatalytic experiment, where the degree of dye decomposition was 73.0%, clearly in- dicate the generation of a piezopotential. When a sample is deformed by an external force from ultrasonic treat- ment, a polarization phenomenon occurs inside it, which generates positive and negative charges present on two relative surfaces. Thus, an effective conversion of the ex- ternal force into electrical energy occurs and a polariza- tion electric field is generated, which contributes to the occurrence of redox chemical reactions, leading to the generation of highly active oxygen species, which oxidize the MB. It can also be seen that the sample exhibits high pho- tocatalytic activity – 93% of the dye decomposed in 60 minutes. The presence of PC activity under UV-visible irradiation in a polymer material whose band gap (BG), according to the literature data, is more than 6 eV, is an unexpected result and requires a deeper study of the electronic structure of the material. For example, in [23] using ultraviolet photoelectron and inverse photoemis- sion spectroscopy, it was demonstrated that a change in the polarization state from positive to negative in the P(VDF-TrFE) ferroelectric caused a distinct shift of the valence band towards the Fermi level by 2.1 eV and the conduction band by 0.4 eV, as a result of which the BG decreased by 2.5 eV. It is likely that the addition of CTAB and the electrical polarization of the material during electrospinning facilitate the rearrangement of the elec- tronic structure of PVDF, leading to a narrowing of the BG. It is well known that photocatalytically active piezoelec- tric materials are widely used for photocatalytic wastewater treatment from organic pollutants, due to the because they are able to generate more free radicals with stronger oxidizing properties with the synergy of mechani- cal force and light [24]. Taking this into account, we studied the piezophotocata- lytic oxidation of MB under the simultaneous action of ul- trasonic and UV-visible irradiation. The degree of MB decomposition in this case was 91%, which practically corresponds to the photocatalytic activity. This may probably indicate that, upon photoexcitation of PVDF/CTAB, a large number of photogenerated charge car- riers suppress the piezoelectric properties. Chimica Techno Acta 2022, vol. 9(4), No. 20229420 ARTICLE 5 of 8 Figure 4 XPS spectra of PVDF/CTAB nanofibers: Wide XPS and high-resolution (a) F1s (b); C1s (c) and O1s spectra (d). To the best of our knowledge, this effect has not been previ- ously mentioned in the literature, and the explanation requires ad- ditional research. The rate constants (k) were calculated from the kinetic curves according to the pseudo-first order equa- tion and are presented in Figure 5b: ln(C0/C) = k t. (4) The k values were 0.011, 0.018, 0.021, 0.043, and 0.046 min–1 for sonolysis, photolysis, piezocatalysis, photoca- talysis, and piezophotocatalysis, respectively. During piezoca- talysis, the reaction rate increased by a factor of 1.91 compared to sonolysis, indicating the generation of the PVDF/CTAB pie- zopotential under ultrasonic treatment. During photocatalysis, the reaction rate increased by a factor of 2.4 compared with photolysis, indicating the photogeneration of electron-hole pairs upon irradiation with UV-visible light. These data indicate that the as-synthesized PVDF/CTAB composite membranes have a certain photocatalytic activ- ity, and the comparable values reported in the literature are shown in Table 1. 3.1. Mechanism According to the classical concepts, the photocatalytic reac- tion can be generally divided into three stages: (1) after the absorption of photons by a semiconductor, electron-hole pairs are formed in the volume; Figure 5 MB degradation curves (1 mg L–1, 20 mL) (a); time de- pendence of ln(C/C0) for PVDF/CTAB nanofibers (b). (2) the photogenerated electrons and holes, meanwhile, separate and migrate to the surface of the photocatalyst; (3) the photogenerated charge carriers participate in the redox reaction on the surface of the photocatalyst lead- ing to the generation of reactive oxygen species. To find out by what mechanism the photocatalytic reac- tion proceeds, the experiments were carried out with traps for reactive oxygen species. Generally, superoxide radicals (·O2–), holes (h+), electrons (e–) and hydroxyl radicals (·OH) are considered to be the potential dominant active species in the photocatalytic decomposition process. We used iso- propanol (IP) for fixing hydroxyl radicals (·OH), ethylene- diaminetetraacetic acid (EDTA) for holes (h+), benzoqui- none (BZQ) for superoxide radicals (·O2–) and silver nitrate (AgNO3) for electrons (e–) respectively. The data are pre- sented in Figure 6. When irradiated with light, PVDF/CTAB is excited, pro- ducing electrons and holes. The holes, migrating to the sur- face, enter into chemical reactions, oxidizing OH- with the formation of ·OH. Thus, MB decomposes at the expense of h+ and ·OH in the reaction system. PVDF/CTAB + ℎ𝑣 → ℎ+ + 𝑒 − (5) ℎ+ + OH – →∙ OH + H+ (6) Chimica Techno Acta 2022, vol. 9(4), No. 20229420 ARTICLE 6 of 8 Table 1 Comparison of photocatalytic contaminant removal rates by immobilized catalyst on PVDF substrates. Photocatalyst Pollutant Light source Efficiency Ref PVDF/GO/ZnO MB, 60 mL, 10 mg L–1 Xenon, 300W 86.8% (100 min) [25] PVDF/ZIF-8/ZnO MB, 100 mL, 10 mg L–1 Xenon, 300W 95% (4.5 h) [26] PVDF/TiO2 RhB, 10 ppm LED, 18 W 80% (6 h) [27] PVDF/TiO2/g-C3N4 RhB, 50 mL, 5 mg L –1 Xenon, 800 W 78% (180 min) [28] SnO2/TiO2/PVDF RhB, 100 mL, 10 mg L –1 Xenon, 250W 92% (270 min) [29] TiO2/PVDF MB, 300 mL, 10 ppm High-pressure mercury lamp 95% (60 min) [30] PVDF/GO MB, 150 mL, 10 µmol L–1 Xenon, 150W 83% (360 min) [31] PVDF-GO/NB-TiO2 MB, 50 mL, 5 mg L –1 Halogen lamp, 500W 39% (30 min) [32] PVDF-B4C MB, 50 mL, 50 mg L –1 UV lamp 96% (20 min) [33] PVDF/ZnO/Ag2O MB, 30 mL, 10 mg L –1 UV light, 6 W 97.2% (210 min) [34] PVDF/CTAB MB, 20 mL, 1 mg L–1 High-pressure mercury lamp, 250W 91% (60 min) This work Since electrons have little effect on the MB degradation, they will accumulate in the conduction band. Probably, the accumulation of excess negative charge acts as an inhibitor for the piezopotential, or as a depolarizer of the piezo field. It should be noted that a clear deactivation of the cata- lytic activity manifests itself when IP is added to the re- action system, at which the efficiency of MB decomposi- tion decreased from 91% to 12.0%. This indicates the dominant role of hydroxyl radicals ·OH. Holes also play an important role in the course of the reaction, because with the addition of EDTA, the decomposition efficiency was 60%. With the addition of AgNO3 and benzoquinone, the decomposition efficiency was 86 and 82%, which in- dicates a small contribution of e– and ·О2– to the reaction. Based on this, the proposed mechanism of photocata- lytic decomposition of MB is shown in Figure 7. 4. Conclusions Thus, it was shown that the modification of PVDF with the cationic surfactant CTAB leads to an increase in the elec- troactive phase due to the ion-dipole interaction. It was also shown for the first time that the addition of CTAB promotes the photosensitivity of the wide-gap dielectric polymer PVDF (the band gap is more than 6 eV). It was demonstrated that the photocatalytic decomposition effi- ciency is 91% in 60 minutes. The material exhibits piezo- catalytic activity – 73% in 60 minutes. The experiments on trapping active oxidizing forms established that ·OH hydroxyl radicals play the main role in the photocatalytic process. Supplementary materials No supplementary materials are available. Funding This work was supported by the Russian Science Founda- tion (grant no. 22-73-10091), https://www.rscf.ru/en. Figure 6 Photocatalytic under Uv-Vis light performance of PVDF/CTAB nanofibers for degradation of MB after adding various scavengers. Figure 7 Schematic illustration of the photocatalytic mechanism for PVDF/CTAB. Acknowledgments Part of the work was carried out with the support of CEITEC Nano Research Infrastructure supported by MEYS CR (LM2018110) and the Grant Agency of the Czech Republic under project No. 19-17457S. https://www.rscf.ru/en Chimica Techno Acta 2022, vol. 9(4), No. 20229420 ARTICLE 7 of 8 Author contributions Conceptualization: F.O., D.So. Data curation: A.Sh., R.G. Formal Analysis: Sh.R., D.So., F.O. Funding acquisition: F.O., D.So. Investigation: D.Se., K.C., A.R., M.A., R.G., A.Sh. Methodology: D.Se., K.C., F.O. Project administration: F.O. Resources: D.So., K.C., F.O. Software: Sh.R., Supervision: F.O. Validation: D.So., Sh.R. Visualization: D.Se. Writing – original draft: F.O. Writing – review & editing: F.O., D.So. Conflict of interest The authors declare no conflict of interest Additional information Author IDs: Alina Rabadanova, Scopus ID 57429741000, Colab Magomed Abdurakhmanov, Scopus ID 57291263400, Colab Rashid Gulakhmedov, Scopus ID 57291948600, Colab Abdulatip Shuaibov, Scopus ID 57291948700, Colab Daud Selimov, Scopus ID 57292170300, Colab Dinara Sobola, Scopus ID 57189064262 Klára Částková, Scopus ID 6508308746 Shikgasan Ramazanov, Scopus ID 23100974400 Farid Orudzhev Scopus ID 57201133063, Colab Websites: Dagestan State University, https://dgu.ru; Brno University of Technology, https://www.vut.cz/en; Amirkhanov Institute of Physics of Dagestan Federal Re- search Center, Russian Academy of Sciences, http://www.dagphys.ru; Immanuel Kant Baltic Federal University, https://eng.kantiana.ru. https://smart-mat.ru/, https://colab.ws/labs/282, References 1. Ma D, Yi H, Lai C, Liu X, Huo X, An Z, Yang L. Critical review of advanced oxidation processes in organic wastewater treat- ment. 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