A system for the synthesis of a cost-effective photocatalyst for the degradation of rhodamine B and tetracycline hydrochloride

Abstract

A system for the synthesis of a cost-effective photocatalyst based on the FeOOH / CuBi2O4 heterostructure, consisting of: a) a CuBi2O4 synthesis plant for the production of CuBi2O4 (CBO) microspheres from Bi(NO3)3·6H2O and Cu(NO3)2.3H2O precursors; b) a heterostructure formation unit is configured to deposit FeOOH nanoparticles onto an outer surface of the CBO microspheres to form an FeOOH / CBO heterostructure; and c) a processing unit configured to wash and dry the FeOOH / CBO heterostructure to obtain the photocatalyst.

Description

AREA OF INVENTION

[0001] The present disclosure relates to a system for the synthesis of a cost-effective photocatalyst based on FeOOH / CuBi2O4 heterostructure for the degradation of rhodamine B and tetracycline hydrochloride. BACKGROUND OF THE INVENTION

[0002] The growing global concern about water pollution from dyes, pharmaceuticals, and other hazardous organic pollutants has significantly increased interest in the development of advanced wastewater treatment technologies. Among these, advanced oxidation processes (AOPs), particularly those with persulfate activation, have emerged due to their ability to remove SO4• -Generating high-oxidation potential α- and OH• radicals has proven to be a promising approach. This enables the mineralization of persistent pollutants into non-toxic end products. However, the practical application of persulfate-based photocatalysis is hampered by the lack of efficient, stable, and visible-light-active photocatalysts.

[0003] Several previous studies have highlighted the potential of heterostructure development to overcome the inherent limitations of single-component photocatalysts. The integration of iron oxides into semiconductors has been shown to accelerate electron transfer and increase radical formation during persulfate activation. FeOOH is considered particularly promising due to its Fe content. 2+ / Fe 3+Its redox cycling ability, which effectively promotes the formation of reactive oxygen species (ROS), makes it a promising co-catalyst. However, its independent activity remains limited due to low charge carrier mobility.

[0004] Bismuth-based semiconductors such as Bi₂O₃, BiVO₄, and CuBi₂O₄ (CBO) are frequently used for visible-light-driven photocatalysis due to their strong absorption in the visible range and their suitable band structure. The combination of bismuth oxides with transition metal oxides can significantly reduce electron-hole recombination and broaden light absorption, thereby increasing photocatalytic performance. CBO-based heterostructures with Fe₂O₃ and Co₃O₄ have been reported to enable efficient degradation of organic dyes, antibiotics, and pharmaceutical impurities via persulfate activation. FeOOH-based heterojunctions exhibit superior charge separation efficiency and improved radical-mediated oxidation pathways compared to pure FeOOH.

[0005] The preceding discussion clearly shows that the combination of FeOOH and CBO results in a synergistic heterostructure. This influences both the strong oxidizing power of Fe. 2+ / Fe 3+ The redox cycle as well as the light absorption of CBO in the visible range. This accelerates the activation of persulfate and reactive oxygen species (ROS) such as SO4• - and OH• are generated with high efficiency. The FeOOH / CBO heterostructure offers numerous active centers, an increased surface area, and improved charge transfer pathways, thus overcoming the disadvantages of the individual components.

[0006] For the production of the FeOOH / CBO heterostructure photocatalyst, the present invention provides a system configured for the synthesis of a cost-effective photocatalyst based on the FeOOH / CuBi2O4 heterostructure for the decomposition of Rhodamine B and Tetracycline Hydrochloride. SUMMARY OF THE INVENTION

[0007] The present disclosure relates to a system for the synthesis of a cost-effective photocatalyst based on an FeOOH / CuBi2O4 heterostructure for the degradation of rhodamine B and tetracycline hydrochloride. The heterostructure enables a synergistic interaction between the Fe 2+ / Fe 3+ -Redox cycle capability of FeOOH and the ability of CBO to absorb visible light, leading to improved charge separation and generation of reactive oxygen species including SO4• - , OH•, O2• - -radicals and 1 O2 leads to the activation of peroxymonosulfate under irradiation with visible light.

[0008] The present disclosure relates to a system for the synthesis of a cost-effective photocatalyst based on an FeOOH / CuBi2O4 heterostructure. The system comprises: a) a CuBi2O4 synthesis unit for the production of CuBi2O4 (CBO) microspheres from the precursors Bi(NO3)3·6H2O and Cu(NO3)2·3H2O; b) a heterostructure formation unit for the deposition of FeOOH nanoparticles on the outer surface of the CBO microspheres, thereby forming an FeOOH / CBO heterostructure; and c) a processing unit for washing and drying the FeOOH / CBO heterostructure to obtain the photocatalyst.

[0009] The subject of the present disclosure is the provision of a system for the synthesis of a cost-effective photocatalyst based on FeOOH / CuBi2O4 heterostructure for the decomposition of rhodamine B and tetracycline hydrochloride.

[0010] Another objective of the present disclosure is the synthesis of a photocatalyst based on the FeOOH / CuBi2O4 heterostructure, which, compared to single-component photocatalysts, exhibits increased charge separation efficiency and improved absorption of visible light.

[0011] Another objective of the present disclosure is to provide a cost-effective and scalable synthesis system capable of producing FeOOH / CBO heterostructures in controlled mass ratios for optimized photocatalytic performance in persulfate activation.

[0012] Another objective of the present disclosure is to provide a heterostructure photocatalyst that acts via a dual mechanism involving both free radicals and non-radical species for efficient oxidative degradation processes in wastewater treatment.

[0013] To further clarify the advantages and features of the present disclosure, the invention is described in more detail with reference to specific embodiments illustrated in the accompanying drawings. It is understood that these drawings merely show typical embodiments of the invention and are therefore not to be understood as limiting its scope of protection. The invention is described and explained in more detail and with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE IMAGES

[0014] These and other features, aspects and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which identical symbols represent identical parts, wherein: Fig. Figure 1 shows a block diagram of a system for the synthesis of a cost-effective photocatalyst based on FeOOH / CuBi2O4 heterostructure according to an embodiment of the present disclosure; Fig. Figure 2 shows a block diagram of a wastewater treatment system using the prepared photocatalyst according to an embodiment of the present disclosure; and Fig. Figure 3 shows a diagram illustrating the photocatalytic mechanism on the surface of the FeOOH / CBO heterostructure according to an embodiment of the present disclosure.

[0015] Furthermore, those skilled in the art will recognize that the elements in the drawings are simplified and not necessarily drawn to scale. For example, the flowcharts illustrate the process by highlighting the main steps to facilitate understanding of this disclosure. With regard to the construction of the device, one or more components may be represented in the drawings by conventional symbols. The drawings may show only those specific details relevant to understanding the embodiments of this disclosure, so as not to clutter the drawings with details that are already apparent to those skilled in the art from the description contained herein. DETAILED DESCRIPTION:

[0016] To facilitate understanding of the principles of the invention, reference is made below to the embodiment illustrated in the drawings, which is described using specific terms. It is understood, however, that this does not limit the scope of protection of the invention. Rather, modifications and further developments of the illustrated system, as well as further applications of the inventive principles depicted therein, are conceivable, insofar as they would typically occur to a person skilled in the art in the field of the invention.

[0017] It will be clear to those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not to be understood as a limitation of it.

[0018] References to “an aspect”, “another aspect”, or similar phrases in this description mean that a particular feature, structure, or property described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, phrases such as “in one embodiment”, “in another embodiment”, and similar expressions in this description may, but do not necessarily, all refer to the same embodiment.

[0019] The terms "includes," "comprehensive," or similar expressions denote non-exclusive inclusion. Thus, a procedure or method containing a list of steps does not only include those steps but may also include further steps not explicitly listed or inherent in the procedure or method. Likewise, the statement "includes..." for one or more devices, subsystems, elements, structures, or components, without further limitations, does not preclude the existence of other devices, subsystems, elements, structures, or components.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meanings generally known to those skilled in the art in the field to which this invention belongs. The systems, methods, and examples described herein serve only for illustration and are not to be understood as limiting.

[0021] Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0022] Fig. Figure 1 shows a block diagram of a system (100) for the synthesis of a cost-effective photocatalyst based on the FeOOH / CuBi2O4 heterostructure according to an embodiment of the present disclosure.

[0023] According to Fig. 1 The system comprises: a) a CuBi2O4 synthesis unit (102) for the production of CuBi2O4 (CBO) microspheres from the precursors Bi(NO3)3·6H2O and Cu(NO3)2.3H2O; b) a heterostructure formation unit (104) for the deposition of FeOOH nanoparticles on the outer surface of the CBO microspheres to form an FeOOH / CBO heterostructure; and c) a processing unit (106) for washing and drying the FeOOH / CBO heterostructure to obtain the photocatalyst.

[0024] In one embodiment, the heterostructure formation unit (104) is configured to produce the FeOOH / CBO heterostructure with mass ratios of FeOOH to CBO of 1:1, 1:2 and 2:1.

[0025] In one embodiment, the heterostructure formation unit (104) is configured to produce an FeOOH / CBO heterostructure in a mass ratio of 1:1.

[0026] In one embodiment, the CuBi2O4 synthesis unit (102) comprises: a dissolution chamber (102a) configured to dissolve Bi(NO3)3·6H2O in water with nitric acid and Cu(NO3)2·3H2O in an aqueous solution; a mixing chamber (102b) configured to combine the dissolved solutions with NaOH solution; and a hydrothermal reactor (102c) configured to process the mixture at 100 °C for 24 hours.

[0027] In one embodiment, the heterostructure formation unit (104) comprises: a dispersion chamber (104a) configured to disperse the CBO microspheres in water and supply NaOH solution to generate a negative charge on the surface of the CBO; a deposition chamber (104b) configured to supply an aqueous solution of Fe precursor and H2O2 for rapid oxidation; and a pH adjustment mechanism (104c) configured to adjust the pH to 12 using NaOH solution.

[0028] In one embodiment, the CuBi2O4 synthesis unit (102) is configured to produce CBO microspheres by dropwise adding a 2.4 M NaOH solution to the combined metal salt solutions.

[0029] In one embodiment, the heterostructure formation unit (104) is configured to supply the Fe precursor solution with H2O2 for rapid oxidation and stirs continuously for 15 minutes.

[0030] In one embodiment, the processing unit (106) is configured to wash the heterostructure with deionized water and ethanol to remove impurities.

[0031] In one embodiment, the processing unit (106) is configured to dry the heterostructure for 12 hours at 60°C.

[0032] In one embodiment, the system (100) is configured to synthesize a photocatalyst capable of activating peroxymonosulfate upon irradiation with visible light.

[0033] The invention aims to provide a cost-effective photocatalyst based on an FeOOH / CuBi2O4 heterostructure. This overcomes the limitations of single-component photocatalysts, particularly the low charge carrier mobility of FeOOH and the electron-hole recombination in CBO. The system enables the controlled deposition of FeOOH nanoparticles onto CBO microspheres via hydrothermal synthesis and surface modification. The resulting heterostructure offers numerous active sites, an increased surface area, and improved charge transfer pathways, thus enabling the efficient activation of peroxymonosulfate under visible light irradiation. The invention represents a scalable, energy-efficient material platform for applications in environmental remediation, especially for the degradation of persistent organic pollutants such as dyes and pharmaceuticals in wastewater treatment.

[0034] In one implementation, the system is configured to utilize a controlled hydrothermal synthesis technique for the fabrication of FeOOH / CBO heterostructures with optimized morphology and interface architecture. The coupling of FeOOH with CBO enhances electron-hole separation and promotes the Fe 2+ / Fe 3+ - redox cycle and facilitates the formation of reactive oxygen species (ROS, OH). - and SO4 2-) during persulfate activation. These reactive species enable the rapid degradation of dyes and antibiotic residues. The synergy between FeOOH and CBO ensures improved photocatalytic efficiency under visible light irradiation compared to the pure components. The FeOOH / CBO heterostructure exhibits superior catalytic activity during persulfate activation, leading to efficient degradation of RhB and TC. The material displays improved stability, higher mineralization rates, and greater resistance to charge recombination. These improvements result from synergistic heterostructure engineering, enhanced visible light absorption, and the effective use of persulfate oxidants. The photocatalyst remains reusable over multiple cycles, highlighting its robustness for practical applications.The present invention provides a scalable and cost-effective system for the production of heterostructured photocatalysts for environmental remediation. By combining readily available, non-toxic components with a simple synthesis, the invention aims to treat industrial wastewater, pharmaceutical residues, and dye wastewater under sunlight. The FeOOH / CBO heterostructure represents an innovative photocatalyst platform that contributes to sustainable wastewater management, clean water technology, and the further development of environmentally friendly solutions.

[0035] In one embodiment, the present disclosure relates to a system for the synthesis of a cost-effective photocatalyst based on the FeOOH / CuBi2O4 (CBO) heterostructure. The system comprises a CuBi2O4 synthesis unit, a heterostructure formation unit, and a processing unit, which work together in a coordinated manner to produce the FeOOH / CBO heterostructure photocatalyst.

[0036] In one embodiment, the CuBi₂O₄ synthesis apparatus is configured for the production of CuBi₂O₄ (CBO) microspheres using Bi(NO₃)₃·6H₂O and Cu(NO₃)₂·3H₂O as metal precursors. During operation, 1.358 g of Bi(NO₃)₃·6H₂O, along with a small amount of nitric acid to facilitate dissolution of the bismuth metal, are added to a solution chamber containing 20 mL of deionized water. The bismuth solution is stirred for 0.5 hours to ensure complete dissolution. Separately, 0.338 g of Cu(NO₃)₂·3H₂O are dissolved in 20 mL of aqueous solution. The resulting copper solution is then added dropwise to the bismuth solution with continuous stirring to achieve a homogeneous mixture. Subsequently, a 2.4 M NaOH solution is added dropwise to the combined metal salt solution with continuous stirring for 0.5 hours to promote the formation of precursor complexes. The resulting mixture is then transferred to a hydrothermal reactor (e.g.The mixture is transferred to a 100 ml Teflon-lined autoclave and hydrothermally treated in a temperature-controlled chamber at 100 °C for 24 hours. After completion of the reaction, the mixture is cooled to room temperature. The resulting product is washed four times in the washing module of the process unit with Milli-Q water and anhydrous alcohol to remove residual impurities. The washed, dark brown to blackish CuBi₂O₄ product is then transferred to a drying chamber and dried there for 8 hours at 70 °C to obtain the final CuBi₂O₄ (CBO) microspheres.

[0037] In one embodiment, the heterostructure formation unit is configured to deposit FeOOH nanoparticles onto the surface of CBO microspheres to form the FeOOH / CBO heterostructure. First, a specific amount of the synthesized CBO is added to a dispersion chamber containing 50 ml of deionized water and treated with ultrasound for 0.5 hours to achieve a homogeneous dispersion. Next, 5 ml of a 2 M NaOH solution is added to the chamber to impart a negative surface charge to the CBO microspheres, thus facilitating the subsequent deposition of the FeOOH nanoparticles. Then, 50 ml of an aqueous Fe precursor solution is added to the dispersion under magnetic stirring for 0.5 hours. To promote rapid oxidation and FeOOH formation, 2 ml of H₂O₂ is added under continuous stirring for 15 minutes. The pH of the solution is then adjusted to 12 using a 0.1 M NaOH solution.The precipitate obtained after the reaction is washed with deionized water and ethanol to remove residual reactants and impurities. The washed product is then transferred to a drying chamber and dried for 12 hours at 60 °C to obtain the FeOOH / CBO heterostructure. Catalysts with different mass ratios of FeOOH to CBO (1:1, 1:2, and 2:1) are synthesized and designated as 1:1 FeOOH / CBO, 1:2 FeOOH / CBO, and 2:1 FeOOH / CBO, respectively. For comparison, pure FeOOH is synthesized in the heterostructure formation apparatus using a similar procedure, but without the addition of CBO microspheres.

[0038] The crystal structure of the synthesized materials was confirmed by XRD analysis. Characteristic peaks for CuBi₂O₄ (CBO), corresponding to the tetragonal phase, were observed. The results indicated that the crystallinity of CBO was not affected by the formation of FeOOH. The absence of FeOOH diffraction peaks confirmed its amorphous nature, as it was synthesized at room temperature. In the composite materials, the intensity of the CBO diffraction peaks decreased with increasing proportion of amorphous FeOOH, confirming the high dispersion of the FeOOH nanoparticles on the CBO surface. FTIR spectroscopy confirmed the chemical structure and the interaction between CBO and FeOOH. The spectra showed characteristic Bi-O and Cu-O stretching vibrations in CBO, while FeOOH exhibited hydroxyl group vibrations as well as Fe-O and Fe-OH stretching vibrations.The presence of all characteristic IR bands of both FeOOH and CBO in the composite material confirmed the successful formation of the FeOOH / CBO heterostructure without structural alteration of either component.

[0039] XPS analysis confirmed the elemental composition and oxidation states of the CBO and the FeOOH / CBO composite. Overview spectra showed the presence of Cu, Bi, O, and Fe, thus confirming composite formation. The OLS spectrum exhibited peaks attributable to the lattice oxygen of Cu-O / Bi-O / Fe-O, Fe-OH, and chemisorbed OH groups. The Fe 2p spectra indicated the presence of Fe. 2+ - and Fe 3+ -ions with satellite peaks, while the Cu 2p peaks indicate the existence of Cu 2+- and Cu(OH)2 species were confirmed. Bi was identified in the +3 oxidation state. A shift to higher bond energies in the FeOOH / CBO spectra indicated a reduced electron density in the CBO and the formation of a heterojunction that facilitates charge transfer between CBO and FeOOH.

[0040] SEM analysis revealed that CBO exhibited uniform, hierarchically structured 3D microspheres with smooth surfaces, while FeOOH displayed a needle-like morphology. The FeOOH / CBO composite exhibited a rough surface due to the spindle-shaped FeOOH structures, confirming the successful deposition of FeOOH onto CBO. EDX elemental analysis demonstrated the homogeneous distribution of Cu, Bi, Fe, and O on the composite surface, thus confirming the formation of a uniform heterostructure.

[0041] The photocatalytic activity of FeOOH / CBO composites was investigated for the degradation of rhodamine B (RhB) and tetracycline (TC) under visible light in the presence of peroxymonosulfate (PMS). Pure CBO and FeOOH showed degradation rates of 34.15% and 68%, respectively, for RhB after 100 minutes, while the FeOOH / CBO composites with mass ratios of 1:1, 1:2, and 2:1 achieved degradation rates of 97.56%, 94.16%, and 80%, respectively. An excess of FeOOH or CBO led to lower activity due to light shielding and a reduced number of active sites. The addition of PMS significantly increased the degradation rate, confirming a photo-Fenton mechanism. The FeOOH / CBO 1:1 + PMS + visible light system achieved a RhB degradation rate of 98.83% within 30 minutes with a rate constant of 0.136 min⁻¹. -1The absorption of visible light was 5.8 times higher than that of FeOOH + PMS + visible light and 3.6 times higher than that of the CBO + PMS + visible light and FeOOH / CBO 1:1 + visible light systems. The results show that the FeOOH / CBO 1:1 heterostructure enhances the absorption of visible light, extends the lifetime of the charge carriers, and improves photocatalytic efficiency. The synergy factor of 9.1 indicates efficient PMS activation under visible light.

[0042] In TC degradation studies, FeOOH / CBO (1:1) achieved a degradation rate of 92.8% within 30 minutes, compared to 55% for CBO and 58.7% for FeOOH. The FeOOH / CBO (1:1) + PMS + visible light system showed a rate constant of 0.082 min⁻¹. -1, which was 3.6 times higher than that of CBO + PMS and 2.8 times higher than that of FeOOH + PMS, corresponding to quasi-first-order kinetics. These results confirm the superior catalytic performance of the FeOOH / CBO composite (1:1) in the degradation of both organic dyes and pharmaceutical contaminants and underscore its efficiency as a visible-light-sensitive photocatalyst for peroxymonosulfate activation.

[0043] In one embodiment, the synthesized FeOOG / CBO photocatalyst is used to degrade organic pollutants in water. The photocatalyst composition is provided in an aqueous solution containing persulfate and organic pollutants and subsequently irradiated with visible light. This activates the persulfate, generating reactive oxygen species that degrade the organic pollutants into harmless products. The organic pollutants include at least one substance from the group consisting of RhB, TC, pharmaceutical residues, dye wastewater, and other persistent organic pollutants.

[0044] Fig. Figure 2 shows a block diagram of a wastewater treatment system using the prepared photocatalyst according to an embodiment of the present disclosure.

[0045] Fig. Figure 2 shows a wastewater treatment system with a reaction chamber containing the photocatalyst composition, an oxidizing agent source (persulfate), and a visible light source. The system is configured to degrade organic pollutants in contaminated water streams through photocatalytic persulfate activation. The purified water is collected in a holding tank.

[0046] Fig. Figure 3 shows a diagram illustrating the photocatalytic mechanism on the surface of the FeOOH / CBO heterostructure according to an embodiment of the present disclosure.

[0047] To understand the charge transfer mechanism during the photocatalytic decomposition of pollutants by the FeOOH / CBO composite under visible light, two possible degradation pathways were proposed based on the band structure of FeOOH and CBO in the FeOOH / CBO composite. According to the type II heterostructure, photogenerated electrons (e) migrate when light strikes the catalytic surface. - ) from the conduction band (CB) of the CBO to the conduction band of the FeOOH, while holes (h + Charges are transferred from the valence band (VB) of FeOOH to the valence band of CBO. However, this charge transfer mechanism proves to be energetically unfavorable for an effective photocatalytic system. The reduction potential of the conduction band of FeOOH is insufficient to transfer O2. -· to generate from molecular oxygen, and the oxidation potential of the valence band of CBO is insufficient to generate OH·. A Z-scheme charge transfer pathway is proposed for a more favorable charge transfer mechanism ( Fig. 3) In this mechanism, electrons (e - ) from the conduction band (CB) of FeOOH to the valence band (VB) of CBO, leading to a spatial separation of the high-energy charge carriers. Consequently, the electrons remaining in the CB of CBO (e - ) and the holes accumulated in the VB of FeOOH (h + ) exhibit a strong redox potential and significantly enhance the activation of PMS to form reactive species such as OH·, O2 - and SO4 - • for the photocatalytic degradation of pollutants. Furthermore, the Cu 2+ - and Fe 2+ -Species on the catalyst surface involved in the redox cycle reaction with PMS, thereby producing SO4 -· is formed and the continuous production of Cu 2+ / Cu + - and Fe 2+ / Fe 3+ -Redox couples are promoted. Additionally, the OH present on the Fe-based FeOOH structure increase - -Groups, PMS adsorption and ROS formation. As already known from the prior art, a non-radical degradation pathway also occurs. O2 - · can be converted into singlet oxygen ( 1 O2), a highly reactive, non-radical species, are converted. In CBO-based systems, partially oxidized Fe species (Fe) react 3+ ) on the catalyst surface with O2 - · to singlet oxygen. Furthermore, singlet oxygen can also be produced by the self-reaction of O2. - or are formed through its interaction with OH·, as shown in the following equations. In the FeOOH / CBO + PMS + Vis system, these pathways jointly contribute to the formation of 1O2 is involved. Consequently, this photocatalytic system operates via a dual mechanism that involves both free radicals and non-radical species, thus leading to enhanced oxidative degradation of pollutants. The simultaneous occurrence of radical and non-radical reaction pathways enables a more versatile and efficient degradation process, making the FeOOH / CBO + PMS + Vis system highly effective for environmental remediation. The photodegradation mechanism is illustrated in equations (4) to (15) below. Catalyst+vis→e−+h+ O2+e−→O2−. HSO5−+e−→SO4−.+OH. SO4− + OH− → SO42− + OH− Fe3++HSO5−→Fe2++SO5−.+H+ Fe2++HSO5−→Fe3++SO4−.+OH− Cu2++HSO5−→Cu++SO5−.+H+ Cu++HSO5−→Cu2++SO4−.+H− O2−.+Cu2+→Singlet oxygen+Cu+ O2−.+O2−.→Singlet oxygen+H2O2 O2−.+OH.→Singlet oxygen+OH− h++O2−.+SO4−.+OH.+Pollutant→CO2+H2O+products

[0048] Various compositions of FeOOH and CBO, including FeOOH / CBO 1:1, FeOOH / CBO 1:2, and FeOOH / CBO 2:1, exhibit high degradation rates of 98.83%, 91.3%, and 86.36%, respectively, within 30 minutes. The rate constant for FeOOH / CBO 1:1 / PMS / Vis is 0.136 min⁻¹. -1 , which is 5.8 times higher than for FeOOH / PMS / Vis (0.023 min -1 ), 3.6 times higher than for the CBO + PMS + Vis system (0.038 min -1 ) and 3.6 times higher than for FeOOH / CBO 1:1 + Vis (0.038 min -1 ) in the photocatalytic decomposition of RhB. The catalyst was also used in the degradation of tetracycline (TC). The results show that FeOOH / CBO (1:1) successfully degraded TC compared to the single catalysts CBO and FeOOH, with a degradation rate of 92.8% within 30 minutes. Thus, this photocatalytic system operates via a dual mechanism that catalyzes both free radicals (such as SO4) and tetracycline (CBO). - , OH - and O2- ) as well as non-radical species ( 1 O2) is involved, leading to enhanced oxidative degradation of pollutants. The presence of both radical and non-radical reaction pathways enables a more versatile and efficient degradation process, making the FeOOH / CBO + PMS + Vis system highly effective for environmental remediation.

[0049] The synthesized catalyst exhibits significant photocatalytic activity under visible light and is therefore ideally suited for environmental remediation. In addition to its light sensitivity, the catalyst plays a crucial role in activating PMS, a powerful oxidizing agent that further enhances the degradation performance of organic pollutants. This dual functionality enables a synergistic effect in which photocatalysis is coupled with PMS-driven, advanced oxidation processes. A hybrid system is proposed that combines photocatalysis with other oxidation processes, leading to faster pollutant degradation and improved mineralization rates. All developed multi-component heterostructures of the photocatalysts demonstrated effective photocatalytic activity and each exhibited distinct and advantageous properties.

[0050] The drawings and the preceding description illustrate embodiments. Those skilled in the art will recognize that one or more of the described elements can be combined to form a single functional element. Alternatively, certain elements can be divided into several functional elements. Elements of one embodiment can be added to another. For example, the process flows described here can be modified and are not limited to the manner described herein. Furthermore, the actions of a flowchart need not be performed in the sequence shown; nor do all actions necessarily need to be carried out. Actions that do not depend on other actions can be performed in parallel with the other actions. The scope of protection of the embodiments is in no way limited by these specific examples. Numerous variations, whether explicitly stated in the description or not, such as...Differences in structure, dimensions, and materials are possible. The scope of protection of the embodiments is at least as comprehensive as described by the following claims.

[0051] The advantages, other benefits, and problem solutions have been described above with reference to specific embodiments. However, the advantages, benefits, problem solutions, and any components that can effect or enhance an advantage, benefit, or solution are not to be construed as critical, necessary, or essential features or components of the claims. REFERENCES 100 A system for the synthesis of a cost-effective photocatalyst based on an FeOOH / CuBi2O4 heterostructure. 102 Cubi2O4 synthesis unit 102a Dissolution Chamber 102b Mixing chamber 102c Hydrothermal Reactor 104 Heterostructure formation unit 104a Dispersion chamber 104b Deposit chamber 104c pH regulatory mechanism 106 processing units 202 A reaction chamber 204 The Photocatalyst as an Oxidizing Agent Source 206 A visible light radiation source 208 collection containers

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