HUNGARIAN JOURNAL OF INDUSTRY AND CHEMISTRY Vol. 49(1) pp. 9–16 (2021) hjic.mk.uni-pannon.hu DOI: 10.33927/hjic-2021-02 PHOTOCATALYTIC DEGRADATION OF RHODAMINE B IN HETEROGE- NEOUS AND HOMOGENEOUS SYSTEMS ASFANDYAR KHAN1,2 , ZSOLT VALICSEK1 , AND OTTÓ HORVÁTH*1 1Department of General and Inorganic Chemistry, Center for Natural Sciences, Faculty of Engineering, University of Pannonia, Veszprém, HUNGARY 2Department of Textile Engineering, National Textile University Faisalabad, PAKISTAN This study focuses on the photocatalytic degradation of Rhodamine B (RhB) in heterogeneous and homogeneous photo- Fenton reactions. In the heterogeneous system, iron(II) doped copper ferrite CuII (x) FeII (1−x)Fe III 2 O4 nanoparticles (NPs) prepared in our previous work were employed as potential catalysts. The photodegradation of RhB was carried out in a quartz cuvette located in a diode array spectrometer. The experimental conditions such as pH, NPs dosage and H2O2 dosage with regard to the photocatalytic degradation of RhB were optimized to be 7.5, 500 mg/L and 8.9 × 10−2 mol/L, respectively. In addition, visible light-induced photodegradation of RhB was also carried out by using H2O2 over a wide pH range in the absence of heterogeneous photocatalysts. It was observed that the reaction rate significantly increased above pH 10, resulting in a faster rate of degradation of RhB, which may be attributed to the deprotonation of hydrogen peroxide. Furthermore, the potential antibacterial property of such catalysts against the Gram-negative bacterium Vibrio fischeri in a bioluminescence assay yielded inhibition activities of more than 60% in all cases. Keywords: heterogeneous photo-Fenton system, iron(II) doped copper ferrites, deprotonation effect, photodegradation 1. Introduction Synthetic dyes have numerous applications in several in- dustries, e.g., paper, textile, leather and paint. Besides these applications, some dyes are toxic organic com- pounds and their discharge into the environment causes eutrophication, aesthetic pollution and distress for ma- rine organisms [1, 2]. Some synthetic dyes are recalci- trant, that is, resistant to biological degradation and di- rect photolysis. In addition, many dyes contain nitrogen which produces carcinogenic as well as mutagenic aro- matic amines as a result of natural anaerobic reductive degradation [3, 4]. These toxic organic dyes can be mineralized into wa- ter and carbon dioxide via photocatalytic reactions us- ing catalysts under ultraviolet or visible light irradiation [5, 6]. Only a handful of research groups have devel- oped and applied ferrite nanoparticles (NPs) as catalysts which can utilize larger bandwidths of the visible light spectrum. Manganese ferrite [7], zinc ferrite [8–10], alu- minium doped zinc ferrite [11], manganese doped cobalt ferrite [12], barium ferrite [13], copper ferrite [14], and nickel ferrites [15, 16] have been investigated with regard to the degradation of certain dyes and other toxic com- pounds. *Correspondence: horvath.otto@mk.uni-pannon.hu Our research group prepared and applied iron(II) doped copper ferrites CuII (x) FeII (1−x)Fe III 2 O4 (where x = 0, 0.2, 0.4, 0.6, 0.8, 1) for the photo-induced degradation of Methylene Blue (MB) [17]. Here, a detailed photocat- alytic study on the degradation of Rhodamine B is pre- sented by using heterogeneous photo-Fenton systems and compared to homogeneous photocatalytic procedures. In addition, the antibacterial property of iron(II) doped cop- per ferrites in the Vibrio scheri bioluminescence inhibi- tion assay was investigated. 2. Experimental 2.1 Materials Rhodamine B (molecular formula: C28H31ClN2O3) was used as a model dye for visible light-induced photocat- alytic degradation. Anhydrous copper(II) sulfate, ferric chloride hexahydrate, ammonium iron(II) sulfate hexahy- drate and sodium hydroxide were used to prepare the cat- alysts. Sodium hydroxide or hydrochloric acid was added to adjust the pH during photocatalysis. Hydrogen per- oxide (30%w/w) was employed as Fenton’s reagent and double distilled water used as a solvent throughout the study. All the laboratory-grade chemicals were obtained from Sigma-Aldrich (Budapest, Hungary) and used with- out further purification. https://doi.org/10.33927/hjic-2021-02 mailto:horvath.otto@mk.uni-pannon.hu 10 KHAN, VALICSEK, HORVÁTH 2.2 Applied catalysts The catalysts applied in this study were iron(II) doped copper ferrite CuII (x) FeII (1−x)Fe III 2 O4 NPs (where x = 0 (NP-1), 0.2 (NP-2), 0.4 (NP-3), 0.6 (NP-4), 0.8 (NP- 5), 1.0 (NP-6)), which were prepared by a simple co- precipitation-calcination technique. The detailed meth- ods for the synthesis of these catalysts and their struc- tural elucidation have been reported in our earlier studies [17, 18]. 2.3 RhB photocatalytic reactions For photocatalysis, a stock solution of 0.5 g/L RhB was prepared. In order to perform the photocatalysis, a small cuvette used as a reactor was adjusted to a S600 UV/Vis diode array spectrophotometer. The concentration of RhB (approximately 1.8×10−5 mol/L) in the cuvette was cal- culated by using the Beer-Lambert law [17]. Control experiments for the self-degradation of RhB were carried out without ferrite nanoparticles in the ab- sence and presence of both light and hydrogen perox- ide (for the oxidant effect). Then the NP catalyst of a given concentration was added to the RhB solution and stirred for 30 mins to ensure a good degree of dispersion and reach an adsorption equilibrium before photodegra- dation. The temperature of the photoreactor (25±2 ◦C), concentration of RhB (1.8 × 10−5 mol/L) and duration (140 mins.) of photocatalytic experiments were kept con- stant. The process variables investigated were the catalyst dosage (80 to 800 mg/L), hydrogen peroxide concentra- tion (2.2 × 10−2 to 3.0 × 10−1 mol/L) and pH (2 to 12). Meanwhile, the original pH of the total aqueous solution was approximately 7.5. The pH was adjusted by adding HCl or NaOH before starting the photocatalytic experi- ment. 2.4 Determination of reaction rate The Beer-Lambert law was used to determine the reac- tion rate of each experiment. The spectral changes ob- served in the visible range of the absorption spectrum (Fig. 1) indicate that the intermediates and end prod- ucts formed during the photocatalytic degradation of RhB did not produce any remarkable peaks. Therefore, the re- action rate of RhB photodegradation can be determined from the reduction in absorbance at the maximum wave- length (λmax = 554 nm). The addition of heterogeneous photocatalysts caused the baseline in the recorded spectra to change as a consequence of scattering. This problem was resolved during the evaluation of the reaction rate by applying baseline corrections. 2.5 Assessment of antibacterial property A Luminoskan Ascent microplate luminometer (Thermo Scientific) was used to measure the antibacterial prop- erty of the ferrite NPs in a Vibrio scheri bioluminescence Figure 1: Spectral changes during Rhodamine B pho- todegradation in the presence of NP-3. The inset shows the absorbance vs. time plot at 554 nm. Experimental con- ditions: concentration of RhB is 1.8 × 10−5 mol/L, con- centration of H2O2 is 1.8 × 10 −1 mol/L, concentration of NP-3 is 400 mg/L, initial pH is = 7.5, and irradiation time is 140 mins. inhibition assay. According to the manufacturer’s (Hach Lange GmbH, Germany) recommendations, a test speci- men of a Gram-negative Vibrio fischeri (NRRL-B-11177) suspension was prepared with a lifespan of 4 hours after being reconstituted. The same test protocol was followed as reported in the literature [19]. During the evaluation, the results obtained from 2 par- allel measurements were averaged before the relative in- hibition (%) was calculated using Relative inhibition (t) = Ic(t) − Is(t) Ic(t) × 100 % (1) where Ic(t) denotes the emission intensity of the control sample at time t and Is(t) represents the emission inten- sity of the test specimen at the same time. 3. Results and discussion A detailed explanation regarding the control experiments concerning the photodegradation of RhB was reported in one of our previous studies [18]. The experiment used as a basis for comparisons (RhB + H2O2 + Light) is shown in Fig. 2. After the control experiments, the photocatalytic effi- ciency of six doped ferrite nanoparticles was investigated. Fig. 1 shows the spectral changes obtained during the photocatalytic experiment using NP-3 and the decrease in the absorbance of RhB at λmax = 554 nm (inset of Fig. 1). The degradation reaction of RhB follows apparent rst- order kinetics (Fig. 3), which is also consistent with ear- lier observations regarding other catalysts [20, 21]. The slight deviation from the straight line is due to the com- plex nature of this heterogeneous system. Fig. 4 reveals that all doped ferrite NPs in the series of CuII (x) FeII (1−x)Fe III 2 O4 (x = 0 − 1) delivered higher apparent rate constants for the degradation of RhB com- pared to the control experiment. Doped copper ferrites Hungarian Journal of Industry and Chemistry PHOTOCATALYTIC DEGRADATION OF RHODAMINE B 11 Figure 2: Spectral changes during the photodegradation of Rhodamine B in the absence of NPs. The inset shows the absorbance vs. time plot at λmax = 554 nm. Experimental conditions: concentration of H2O2 is 1.8 × 10 −1 mol/L, concentration of RhB is 1.8×10−5 mol/L, and irradiation time is 140 mins. Figure 3: A plot of the logarithm of the absorbance at 554 nm vs. time for the photodegradation of RhB (see the inset of Fig. 1) NP-2 and NP-3 exhibited outstanding photocatalytic per- formances in the series studied. Nickel doped cobalt fer- rite NPs revealed a very similar trend with regard to the photo-oxidative degradation of RhB [22]. The higher ap- parent rate constants for the degradation of RhB using NP-2 and NP-3 may be attributed to their special needle- like crystalline structure [17]. On the basis of the first ex- perimental series, NP-3 was chosen to further investigate three important determinants, namely the catalyst dosage, hydrogen peroxide concentration and pH of the heteroge- neous photo-Fenton system. 3.1 The effect of catalyst dosage Fig. 5 shows the effect of the NP-3 dosage (0−800 mg/L) on the apparent rate constant. The increase in dosage from 0−500 mg/L yielded a significant increase in the ap- parent rate constant. This phenomenon can be attributed to the higher number of available active sites in heteroge- neous photo-Fenton processes [23]. However, increasing the dosage of NPs above 500 mg/L caused a moderate Figure 4: Photocatalytic efficiency in terms of apparent rate constants (compared to the control experiment) for NP-1 to 6. Experimental conditions: concentration of NPs is 400 mg/L, concentration of RhB is 1.8 × 10−5 mol/L, concentration of H2O2 is 1.8 × 10 −1 mol/L, initial pH is 7.5, and irradiation time is 140 mins. Figure 5: Effect of the concentration of NP-3 on the appar- ent rate constant of RhB photodegradation. Experimental conditions: concentration of RhB is 1.8 × 10−5 mol/L, concentration of H2O2 is 1.8 × 10 −1 mol/L, initial pH is 7.5, and irradiation time is 140 mins. decrease in the apparent rate constant, which may be at- tributed to the fact that higher concentrations of NPs can increase the turbidity of the reaction system, thereby hin- dering the absorption of light [4]. Therefore, for the pho- tocatalytic experiments that followed, an optimum NP-3 dosage of 500 mg/L was used. 3.2 The effect of the hydrogen peroxide con- centration At first, the effect of H2O2 on the photodegradation of RhB in the absence of NPs was investigated (Fig. 6). The concentration of H2O2 was increased from 4.5 × 10−2 to 6.7 × 10−1 mol/L. The reaction rate was enhanced by increasing the concentration of H2O2 up to 3.5 × 10−1 mol/L. However, beyond this value, a slight decrease in the apparent rate constant was observed. The second experimental series focused on checking the effect of increasing the concentration of H2O2 from 2.2 × 10−2 to 3 × 10−1 mol/L in the presence of NPs 49(1) pp. 9–16 (2021) 12 KHAN, VALICSEK, HORVÁTH Figure 6: Effect of the concentration of H2O2 on the appar- ent rate constant of RhB photodegradation in the absence of NPs. Experimental conditions: concentration of RhB is 1.8 × 10−5 mol/L, initial pH is 7.5, and irradiation time is 140 mins. Figure 7: Effect of the concentration of H2O2 on the appar- ent rate constant of RhB photodegradation in the presence of NP-3 in a heterogeneous photo-Fenton system. Exper- imental conditions: concentration of RhB is 1.8 × 10−5 mol/L, concentration of NP-3 is 500 mg/L, initial pH is 7.5, and irradiation time is 140 mins. in a heterogeneous photo-Fenton system (Fig. 7). The re- action rate was remarkably improved by increasing the concentration of H2O2 up to 8.9 × 10−2 mol/L. A further increase in the concentration of H2O2 did not enhance the reaction rate significantly, moreover, similar results have been published in the literature [24, 25]. The excess H2O2 could act as a •OH scavenger, producing the less reactive HO•2 species instead of the highly potent •OH [4, 23, 25]. Hence 8.9 × 10−2 mol/L as an optimum concentration of H2O2 was used in experiments on the photocatalytic degradation of RhB that followed. 3.3 The effect of pH The surface charge properties of the photocatalyst and the ionic species present in the photocatalytic reactor are greatly influenced by the pH. Furthermore, the pho- todegradation efficiency of the dye is affected by the ionic Figure 8: Effect of the initial pH on the apparent rate con- stant of RhB photodegradation in the absence of NPs. Ex- perimental conditions: concentration of RhB is 1.8×10−5 mol/L, concentration of H2O2 is 8.9×10 −2 mol/L, and ir- radiation time is 140 mins. species and surface charge of the photocatalyst in the re- action mixture. Two experimental series were designed to study the effect of pH on the visible light-induced degra- dation of RhB. In the first series, the pH was varied from 3.8 to 12.1 while the concentrations of RhB and H2O2 were kept constant in the absence of NPs. Remarkably, neutral and alkaline pHs were found to be more effective in this system concerning RhB photodegradation (Fig. 8). In addition, the presence and absence of H2O2 were also investigated at higher pH values (approximately pH 12), which can be seen from the last two data points in Fig. 8. It was observed that significantly enhancing the fraction of the more reactive deprotonated form of hydrogen per- oxide (HO –2 ) at higher pH values ( pKa = 11.75 [26]) noticeably accelerated the rate of RhB degradation. On the basis of Fig. 8, it was possible to determine the indi- vidual (apparent) rate constants (under these conditions) for the differently protonated forms of peroxide, namely 1.9 × 10−5 s−1 for H2O2 and 6.2 × 10−4 s−1 for HO – 2 . Deprotonation resulted in increasing the degradation ef- fect by 32 times. Moreover, the effect of the pH in the presence of NPs (Fig. 9) revealed that a neutral or near alkaline pH could be optimal during this type of reaction. Although the best apparent rate constant was observed at pH ≈ 8, further increasing the pH resulted in a slight decrease in the re- action rate. By comparing Figs. 8 and 9, it can be ob- served that the partly hydroxylated forms of the metal ions ([FeIII(OH)2] +, [CuII(OH)]+) could also be identi- fied at the local maximum of approximately pH = 8 presented in Fig. 9. Therefore, the partly hydroxylated metal ions can react with H2O2, resulting in a ≈ 14- times increase in the individual (apparent) rate constant (2.7×10−4 s−1 compared to 1.9×10−5 s−1 for H2O2 in the absence of NPs). The pH can also alter the charge state of RhB in the re- action mixture. Furthermore, at high pH values, RhB ag- gregates are produced as a result of the excessive concen- Hungarian Journal of Industry and Chemistry PHOTOCATALYTIC DEGRADATION OF RHODAMINE B 13 Figure 9: Effect of the pH on the apparent rate constant of RhB photodegradation in the presence of NP-3 in a hetero- geneous system. Experimental conditions: concentration of NP-3 is 500 mg/L, concentration of RhB is 1.8 × 10−5 mol/L, concentration of H2O2 is 8.9 × 10 −2 mol/L, and irradiation time is 140 mins. tration of OH– ions, which compete with COO– to bind with N+. In addition, since the surface of the solid cat- alyst is negatively charged, it repels the RhB due to the presence of ionic COO– groups under basic conditions. Therefore, the degradation efficiency on the surface of the photocatalyst is decreased. The same phenomenon in the case of bismuth ferrite nanoparticles has been reported in the literature [4, 27]. However, an increase in the pH above 11 significantly enhanced the reaction rate (Fig. 9) in a very similar manner to the reaction in the absence of NPs. As a result, the presence of NPs does not further increase the reactivity of HO –2 . In addition, the effect of light, hydrogen peroxide and NPs at an approximately constant pH is illustrated in Ta- ble 1. The light-induced degradation of RhB at pH 12 in the absence of both hydrogen peroxide and NP-3 yielded a very low reaction rate (Step 1). In Step 2, the addition of hydrogen peroxide in the absence of both light and NP-3 at pH 11.9 yielded a faster reaction rate. Step 3, which represents a heterogeneous Fenton system, yielded a much faster reaction rate. The heterogeneous photo- Fenton system shown in Step 4 yielded the best reaction rate as far as the degradation of RhB is concerned. The catalyst NP-3 (CuII (0.4) FeII (0.6) FeIII2 O4) was able to overcome the disadvantage of the narrow pH range of conventional photo-Fenton processes. Based on this ex- perimental series, the catalyst CuII (0.4) FeII (0.6) FeIII2 O4 is a promising candidate for the degradation of various recal- citrant dyes. 3.4 Generalized RhB degradation mecha- nism A very simple schematic mechanism is proposed for the purpose of RhB degradation since the reactive species produced during irradiation, namely •OH, H+ and •O−2 , oxidize RhB molecules to intermediates of lower molec- ular weights. Generally speaking, the active species react Figure 10: Visual and spectrometric comparison of RhB before and after its degradation; experimental conditions: concentration of NPs is 500 mg/L, concentration of RhB is 1.8×10−5 mol/L, concentration of H2O2 is 8.9×10 −2 mol/L, and irradiation time is 140 mins. with the central carbon atom in the chemical structure of RhB. Then the oxidizing agents attack the intermediates produced in the previous step, yielding smaller open-ring compounds. Subsequently, the latter compounds are min- eralized to water and carbon dioxide [28]. As is displayed in Fig. 10, the UV/visible absorption spectrum of RhB degradation yields prominent peaks at 262, 358 and 554 nm. However, no significant peaks were observed follow- ing photodegradation (Fig. 10) in neither the visible nor UV region, which confirmed the complete mineralization of RhB. The images obtained from the photoreactor (cuvette) before and after photocatalysis also confirmed the com- plete degradation of RhB, namely a clear, colorless solu- tion was obtained after the removal of solid catalysts (Fig. 10) by centrifugal filtration. 3.5 Photocatalytic efficiencies under opti- mized conditions Finally, the photocatalytic efficiencies of all six NPs (NP- 1 to 6) were determined under optimized conditions for the degradation of RhB (Fig. 11). It was observed that all of the NPs were active photocatalysts, the application of NP-3 yielded the highest reaction rate. These results are quite comparable to those presented in Fig. 4 obtained from the first series of experiments. However, the concen- tration of hydrogen peroxide under the optimized condi- tions (8.9 × 10−2 mol/L) is considerably lower than in the first series (1.8×10−1 mol/L) and is, therefore, much more economical. Although the concentration of the pho- tocatalyst is higher under the optimized conditions (500 vs. 400 mg/L), the NPs can be reused over several cy- cles. According to our results, all NPs in the series can potentially be applied for the purpose of environmental remediation. 49(1) pp. 9–16 (2021) 14 KHAN, VALICSEK, HORVÁTH Table 1: Comparison of the reaction rate and apparent rate constant at pH ≈ 12 in homogeneous (Steps 1 & 2) and heteroge- neous (Steps 3 & 4) systems. Step No. Light Hydrogen peroxide NP-3 (mg/L) Initial pH Final pH Apparent Comparison (mol/L) by adding 15 rate constant (1/s) with basic µ L 1M NaOH) reaction (%) 1 visible 0 0 12.1 11.7 2.6 × 10−6 12 2 no 8.9 × 10−2 0 11.9 11 1.6 × 10−4 749 3 no 8.9 × 10−2 500 11.9 11.3 2.7 × 10−4 1256 4 visible 8.9 × 10−2 500 11.9 11.2 3.6 × 10−4 1642 Figure 11: Photocatalytic efficiency in terms of apparent rate constants (compared to the control experiment) for NP-1 to 6. Experimental conditions: concentration of NPs is 500 mg/L, concentration of RhB is 1.8 × 10−5 mol/L, concentration of H2O2 is 8.9 × 10 −2 mol/L, initial pH is 7.5, and irradiation time is 140 mins. 3.6 Assessment of the antibacterial activity of doped copper ferrites The inhibition effect (%) of doped copper ferrites against Gram-negative Vibrio scheri in bioluminescence assays is illustrated in Fig. 12. The inhibition (%) of bacteria in the presence of doped nanoparticles containing varying ratios of copper (CuII) and iron (FeII) revealed that all doped copper ferrites yielded sufficient antibacterial ac- tivities. In our research, higher ratios of CuII proved to be useful in improving antibacterial activity. The same trend in terms of bacterial inhibition against Gram-negative Es- cherichia coli was observed using cobalt ferrite nanopar- ticles synthesized by co-precipitation [29]. Generally speaking, CuII can disrupt the functions of cells in several ways, hence the ability of microorganisms to develop resistance to CuII is remarkably reduced. The attachment of CuII ions to the surface of microorganisms plays a key role in their antibacterial activity [30]. The ions from the surface of doped copper ferrites, especially CuII, are adsorbed onto bacterial cell walls, damaging the cell membrane in two possible ways, namely by alter- ing the functions of enzymes or solidifying the structures of proteins. Therefore, the presence of copper ferrites in the bacterial growth medium immobilizes and inactivates bacteria, inhibiting their ability to replicate and ultimately leading to cell death [31]. Figure 12: Comparison of the degree of bacterial inhi- bition using doped copper ferrites against Gram-negative Vibrio scheri. In our study, a mechanism is proposed (Fig. 13) in which doped copper ferrites are attached to the cell wall of the bacterium Vibrio fischeri, reducing its ability to replicate. The degree of bacterial inhibition in all cases is approximately 60%, which confirms the potential appli- cation of doped copper ferrites in terms of antibacterial developments. 4. Conclusion Iron(II) doped copper ferrites CuII (x) FeII (1−x)Fe III 2 O4 have been proven to be efficient catalysts for the degradation of organic pollutants under visible-light irradiation in the presence of hydrogen peroxide. The performances of NPs with copper(II) ratios of x = 0.2 and 0.4 were especially promising under optimized conditions. Contrary to con- ventional homogeneous photo-Fenton systems, our cat- alysts exhibit higher efficiencies under neutral and near alkaline conditions. Besides their advantageous photo- catalytic ability, these NPs also show a sufficient de- gree of antibacterial activity, due to their copper(II) con- stituents. By taking both properties into consideration, CuII (0.4) FeII (0.6) FeIII2 O4 yields the optimum combination of these features. Therefore, from the series of NPs studied in this work, NP-3 is the most promising candidate for the combined photocatalytic purification and disinfection of water. Hungarian Journal of Industry and Chemistry PHOTOCATALYTIC DEGRADATION OF RHODAMINE B 15 Figure 13: Proposed mechanism for the attachment of nanoparticles to Vibrio fischeri: bacterium and nanoparticles before (A) and after (B) attachment. Acknowledgments The proficient support of Prof. Dr. Éva Kristóf-Makó, Prof. Dr. Kristóf Kovács and Dr. Balázs Zsirka in terms of the structural elucidation of nanoparticle catalysts is gratefully acknowledged. This work was supported by the National Research, Development and Innovation Office of Hungary in the framework of the bilateral Hungarian-French science and technology (S&T) coop- eration project 2019-2.1.11-TÉT-2019-00033). Declaration of interest The authors declare that they have no known competing financial interests or personal relationships that may have appeared to influence the work reported in this paper. REFERENCES [1] Bao, N.; Feng, X.; Yang, Z.; Shen, L.; Lu, X.: Highly efficient liquid-phase photooxidation of an azo dye methyl orange over novel nanostructured porous titanate-based fiber of self-supported radi- ally aligned H2Ti8O17 • 1.5 H2O Nanorods. Env- iron. Sci. Technol., 2004, 38(9), 2729–2736 DOI: 10.1021/es034388k [2] Abdi, J.; Yahyanezhad, M.; Sakhaie, S.; Vossoughi, M.; Alemzadeh, I.: Synthesis of porous TiO2/ZrO2 photocatalyst derived from zirconium metal organic framework for degradation of organic pollutants un- der visible light irradiation. J. Environ. 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Clay Sci., 2006, 31(3-4), 180–184 DOI: 10.1016/j.clay.2005.10.010 Hungarian Journal of Industry and Chemistry https://doi.org/10.1016/j.jmrt.2020.10.080 https://doi.org/10.1016/j.jmrt.2020.10.080 https://doi.org/10.1016/j.jphotochem.2014.01.010 https://doi.org/10.1016/j.matchemphys.2019.122181 https://doi.org/10.1016/j.jece.2017.07.035 https://doi.org/10.1016/j.jece.2017.07.035 https://doi.org/10.1016/j.jece.2016.02.014 https://doi.org/10.1016/j.jece.2016.02.014 https://doi.org/10.1016/j.ijhydene.2014.01.050 https://doi.org/10.1016/j.ijhydene.2014.01.050 https://doi.org/10.1016/j.cej.2012.07.071 https://doi.org/10.1016/j.cej.2012.07.071 https://doi.org/10.3390/nano10050921 https://doi.org/10.3390/nano11010225 https://doi.org/10.1002/bio.3745 https://doi.org/10.1021/cs2006668 https://doi.org/10.1016/j.matlet.2012.09.044 https://doi.org/10.1039/C4NR01730G https://doi.org/10.1039/C4NR01730G https://doi.org/0.1016/j.chemosphere.2014.09.055 https://doi.org/0.1016/j.chemosphere.2014.09.055 https://doi.org/10.1016/j.apcatb.2012.06.015 https://doi.org/10.1016/j.chemosphere.2009.04.033 https://doi.org/10.1016/j.chemosphere.2009.04.033 https://doi.org/10.1155/2010/643120 https://doi.org/10.1016/j.jclepro.2018.06.122 https://doi.org/10.1016/j.jclepro.2018.06.122 https://doi.org/10.1016/j.apsusc.2018.08.133 https://doi.org/10.1016/j.partic.2016.06.003 https://doi.org/10.1046/j.1365-2672.2000.00800.x https://doi.org/10.1046/j.1365-2672.2000.00800.x https://doi.org/10.1016/j.clay.2005.10.010 Introduction Experimental Materials Applied catalysts RhB photocatalytic reactions Determination of reaction rate Assessment of antibacterial property Results and discussion The effect of catalyst dosage The effect of the hydrogen peroxide concentration The effect of pH Generalized RhB degradation mechanism Photocatalytic efficiencies under optimized conditions Assessment of the antibacterial activity of doped copper ferrites Conclusion