Introduction

One of the most environment friendly, cost-effective, and sustainable options for the efficient degradation of organic pollutants is the persulfate-based advanced oxidation processes (PS-AOPs)1,2,3. The reactive oxygen species (ROS) generated from the activation of persulfate (PS) may preferentially interact with organic pollutants via an electron transfer mechanism4,5. Peroxymonosulfate (\(\:{\text{H}\text{S}\text{O}}_{5}^{-}\), PMS)6,7,8, sodium peroxydisulfate (Na2S2O8)9, and potassium peroxydisulfate (K2S2O8)10, which are mainly PS sources, are widely used for degrading organic contaminants from wastewater. Persulfate can be activated with light, heat, transition metals, ultrasonic waves, base, carbon materials, single-atom catalysts, and organic substrates (phenols, quinones) to generate ROS1,11,12,13. In the meantime, ammonium peroxydisulfate (NH4S2O8 or NH4PDS) represents a new approach that can produce ROS to eliminate widespread pollutants efficiently. Moreover,NH4PDS is not only reasonably priced, but its decomposition byproducts can also serve as fertilizers in agriculture14. Li and co-workers discovered that NH4PDS activated by Fe-doped biochar not only degrades benzo[a]pyrene but also improves the lettuce growth due to the increase of available N in soil from NH4PDS15. Moreover, Ding et al. reported that using B-doped biochar combined with NH4PDS effectively degrades organic pollutants while enhancing soil fertility14. These active radicals exhibit elevated redox potentials and extended lifetimes across a broad pH range, resulting in the cleavage of bonds and the breakdown of organic pollutants in aquatic systems16. Although significant advancements have been achieved through the use of PS-AOPs, this technique for the effective degradation of organic contaminants still faces considerable challenges, including effective activation, low efficiencies, and relatively intricate methodologies. Recently, our research team has developed nanostructures to facilitate the degradation of dyes and antibiotics via PS-AOP technologies3,8,17,18,19. Therefore, there is a need to develop a method that is both economically viable and technically sound to effectively and safely eliminate pollutants from water substrates.

Recently, the significance and function of metal oxides in degrading contaminants have been extensively studied20,21. These metal oxide catalysts revealed exceptional features, including involvement in redox reactions, high stability, mimicking the activation of metal surfaces, as well as a broad range of chemical reactivity in the purification and treatment of wastewater22. Moreover, these metal-based oxide nanostructures have often demonstrated electrical conductivity characteristics and have participated in electron transfer/redox reactions, surface interactions, and the production of reactive oxygen species23,24. Also, these nanostructures possessed a suitable surface area, hierarchical porous structure with improved electronic, magnetic, and optical properties than those of bulk materials, which helps improve the efficacy of photo and sono-catalytic reactions and PS activation23,24. Therefore, the integration of multiple metal oxide nanostructures can enhance the aforementioned properties and produce a synergistic effect.

The current research focuses on the design and characterization of a tri-metal oxide nanocomposite, which serves as an effective NH4PDS activator for the degradation of organic pollutants in water substrate. The combination of three semiconductors is a highly efficient PS activator that enhances the generation of active radicals. Crucially, the presence of maghemite NPs in the nanocomposite, along with the straightforward separation of the catalyst from the reaction mixture using an external magnet, can effectively activate NH4PDS to generate ROS. Following the successful fabrication and characterization of the proposed tri-metal oxide, the impact of various operational parameters, including nanocomposite dosage, initial pollutant concentration, and solution pH, on the degradation of organic dyes was examined. Furthermore, density functional theory (DFT) calculations were used to evaluate the relationship between pollutants’ molecular structure and degradation rates. Recent scientific literature indicates that there has been no prior study on the activation of NH4PDS using nanostructures to produce ROSs for the degradation of wastewater contaminants. Consequently, this study represents a significant advancement in the development of PS-AOP technologies for treating water contaminated with persistent pollutants.

Experimental

Chemical

Iron (III) chloride pentahydrate, polyvinyl alcohol, sodium acetate, ethylene glycol, ethanol, ammonia, tetraethyl orthosilicate, copper (II) nitrate trihydrate, and ammonium molybdate in this study were purchased from Sigma-Aldrich and Merck, Germany. Moreover, methylene blue (MB), malachite green (MG), and indigo (IN) were used at commercial-grade quality without further purification.

Instruments

The surface morphologies and elemental distributions were examined using a ZEISS Sigma VP field emission scanning electron microscope (FESEM), as well as through transmission electron microscopy (TEM) using a Tecnai F20 model. Moreover, the crystal phases of the suggested nanocomposite were determined through PXRD patterns using a BRUKER D8 ADVANCE model. To explore the photocatalytic properties of the samples, UV-DRS analysis was conducted using a Shimadzu UV-2550 model. Saturation magnetization of the nanocomposite was assessed using an LBKFB vibrating sample magnetometer (VSM).

Fabrication of γ-Fe2O3@SiO2 core-shell structure

Initially, maghemite NPs were synthesized using our previous method25. Following this, 0.50 g of the prepared maghemite NPs were dispersed in a mixture of 20 mL of distilled water, 80 mL of EtOH, and 3.0 mL of a 25% ammonia solution for 30 min. Subsequently, 3.0 mL of TEOS was added dropwise to the dispersed solution. The reaction was then allowed to proceed under reflux conditions at 80 °C for 12 h to produce a γ-Fe2O3@SiO2 core-shell structure.

Fabrication of F@S/C-M nanocomposite

Initially, 0.03 g of the prepared γ-Fe2O3@SiO2 was mixed with 20 mL of a 20% w/w PVA solution. After 30 min of mixing, the resulting mixture was rinsed with DI-H2O to eliminate any excess PVA. Subsequently, a solution comprising 2.4 mmol of Cu(NO3)2•3H2O and 1.2 mmol of ammonium molybdate was combined and refluxed for 12 h at 100 °C. The precipitate obtained was then washed with DI-H2O and calcined at 450 °C for 3 h.

Degradation experiments

The degradation experiments for MB, MG, and IN were conducted to assess the catalytic efficiency of the F@S/C-M nanocomposite. This was achieved by introducing the catalyst and NH4PDS into a 100 mL solution of organic dyes (20 mg L− 1) contained in conical flasks, which were agitated at a temperature of 25 ℃. At specified time intervals, 1.0 mL aliquots were collected and combined with 0.5 mL of methanol to neutralize the remaining free radicals, followed by separation with an external magnet for UV-Vis spectroscopic analysis. The study of pollution degradation was conducted under various conditions: (1) the amount of catalyst used; (2) the dosage of NH4PDS; (3) pH levels ranging from acidic, neutral, and alkaline; and (4) the concentration of the initial organic dyes’ solution, which varied from 5 to 40 ppm. Additionally, research was carried out on degradation by examining two other types of organic dyes, specifically MG and IN, under optimized conditions. Three parallel experiments were conducted for each degradation process, maintaining an error margin of less than 3%.

Finally, radical scavenging assays were systematically evaluated to identify the ROS involved in the catalytic process. Specifically, isopropyl alcohol (IPA), ethanol (EtOH), p-benzoquinone (p-BQ), and furfuryl alcohol (FFA) were used for quenching ROS.

Computational methodology

DFT was used to investigate the structural and electronic properties of organic dyes comprehensively. All calculations were performed using the Gaussian 09 program package, applying the 6–311 + + G(d) basis set to ensure accurate and reliable results. To validate the optimized geometries of these molecular systems, and central focus of our analysis involved the frontier molecular orbitals, particularly the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The energy gap (Eg) between HOMO and LUMO provides valuable insights into the electronic excitation, reactivity, and potential applications of these dyes in optoelectronic and catalytic processes. Also, the molecular electrostatic potential (ESP) maps, vertical ionization potential (VIP), and electrophilic index (ω) were examined on the organic dyes (Table 2).

Results and discussion

Structural description

Our initial efforts focused on fabricating γ-Fe2O3@SiO2 core-shell to prevent agglomeration of maghemite NPs, subsequently followed by the growth of CuO and MoO3 nanostructures on the silicate surface. The incorporation of iron, copper, and molybdenum into the nanocomposite facilitates a synergistic enhancement of NH4PDS activation, leading to the production of ROS. Notably, this nanocomposite system offers distinct benefits, such as the convenience of separation using an external magnet, along with the effective activation of NH4PDS for the degradation of organic pollutants.

Following the successful synthesis of the proposed nanocomposite, FESEM and TEM spectra were performed to assess surface morphology and the distribution of nanostructures. As shown in Fig. 1a, b, the F@S/C-M nanocomposite exhibits spherical nanostructures of γ-Fe2O3@SiO2 that are deposited on the surface of CuO/MoO3 nanoplates, which can be examined in greater detail in the TEM images. Additionally, the results from EDS in Fig. 1c and SEM-mapping in Fig. 1d illustrate the purity and the distribution of elements within the nanocomposite.

FESEM images provided limited information regarding the morphology and crystal size of the nanostructures; therefore, TEM images were employed for this analysis. As depicted in Fig. 1e, the γ-Fe2O3@SiO2 revealed a nanoscale core-shell structure. We utilized silicate to prevent the aggregation of magnetic nanoparticles and to establish a functionalized surface that facilitates the effective junction of copper and molybdenum metal oxides. Figure 1f also illustrates amorphous nanoplates of copper and molybdenum oxide stacked on one another. Moreover, Fig. 1g demonstrates that copper and molybdenum metal oxide nanosheets are effectively connected to the γ-Fe2O3@SiO2 core-shell structure, resulting in the formation of a composite.

Fig. 1
figure 1

FESEM images (a, b), EDS analysis (c), and SEM-mapping of F@S/C-M (d); TEM images of γ-Fe2O3@SiO2 (e), CuO/MoO3 (f), and F@S/C-M composite (g).

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Following the evaluation of FESEM and TEM images, the PXRD pattern of the nanocomposite was measured to assess the crystal phase. As shown in Fig. 2a, the characteristic diffraction peaks at 14.9°, 30.3°, 35.4°, 43.1°, 53.5°, 57.1°, and 62.7° can be indexed using the lattice planes of maghemite (γ-Fe2O3) according to JCPDS No. 00–039-1346 with a cubic spinel crystal system26. Meanwhile, the peak appeared at 2θ about 25 degrees, reflected from the silicate coating on maghemite nanoparticles. Moreover, the other diffraction peaks in this pattern (32.6°, 35.3°, 38.5°, and 48.9°) are matched to CuO (JCPDS No. 89–2529) monoclinic crystal symmetry27 and h-MoO3 (JCPDS No. 21–0508) with a hexagonal crystal phase28,29.

Moreover, FT-IR spectra were obtained to identify the chemical groups present in the F@S/C-M composite. As illustrated in Fig. 2b, the band observed at 425 cm− 1 indicates the appearance of the Fe-O group in γ-Fe2O325,30. Meanwhile, the signals at 920 and 1150 cm− 1 correspond to Si-OH and Si-O-Si modes31, which confirms the growth of silicate on the surface of the magnetic nanoparticles. Additionally, the peak identified at 550 cm− 1 is associated with Cu-O modes27, indicating the incorporation of CuO nanostructures onto γ-Fe2O3@SiO2. Also, several absorption bands in 650 to 850 cm− 1 could be attributed to Mo-O, Mo-O-Mo, and Mo = O of the MoO3 nanostructure32.

Magnetic measurement of the nanocomposite was performed using a VSM at room temperature. Reports have shown that the saturation magnetization of γ-Fe2O3 is 74 emu g− 133,34. As illustrated in Fig.  2c, the saturation magnetization of the F@S/C-M composite was reduced to 19.8 emu g− 1, indicating a reduction in the density of maghemite NPs due to the coating with silicate, as well as metal oxides CuO and MoO3.

Furthermore, the UV–vis DRS spectra was obtained to evaluate the optical absorption capability of the nanocomposite. As shown in Fig. 2d, the absorption edge of the nanocomposite is located at 768 nm, allowing it to absorb visible light and the near-IR region. Moreover, the band gap energy (Eg) of the nanocomposite was calculated to be 2.55 eV using Tauc plots based on the Kubelka-Munk function. Consequently, the synthesized nanocomposite can be readily excited to generate ROS under visible light exposure.

Fig. 2
figure 2

The XRD pattern (a), FTIR spectra (b), VSM analysis (c), and UV–vis DRS spectra with bond gap energy (inset) of the F@S/C-M composite.

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Degradation activity

Following the characterization of the F@S/C-M composite, we investigated the potential of using the proposed composite as an NH4PDS activator for the degradation of organic dyes. Control experiments demonstrated that a single NH4PDS system is capable of directly eliminating less than 15% of MB within a 24 h period, which could be due to its self-decomposition that produces a minimal quantity of 1O2. Furthermore, the application of F@S/C-M composite in the absence of NH4PDS resulted in the adsorption of 29% of MB over a 24 h period (Fig. S1, ESI). Clearly, the suggested composite exhibits the greatest adsorption capacity for contaminants when compared to γ-Fe2O3 NPs, MoO3, and CuO, revealing a high specific surface area and various active sites. In the presence of both F@S/C-M composite and NH4PDS, complete degradation of MB is accomplished within 20 min using a minimal amount of catalyst, which is more effective than γ-Fe2O3 NPs, MoO3, and CuO. These results demonstrate the synergistic effect of copper, iron, and molybdenum species in the F@S/C-M composite for the activation of NH4PDS, leading to the generation of ROS. Importantly, the performance of the F@S/C-M/NH4PDS system was compared with various common catalysts. As depicted in the Table 1,F@S/C-M composite revealed more outstanding degradation efficiency in PS systems for the degradation of MB.

The quantity of the catalyst can be a crucial factor for the efficient degradation of pollution in AOP. It was observed in Fig. 3a that the degradation of MB increased from 39% to total removal as the concentration of the F@S/C-M composite increased from 0.10 g L− 1 to 0.50 g L− 1. The enhanced performance observed at elevated concentrations of the nanocomposite can be attributed to the increased availability of surface-active sites (copper, iron, and molybdenum) within the composite.

Furthermore, raising the MB concentration from 5.0 to 40 mg L− 1 led to a reduction in degradation efficiency (Fig. 3b). This reduction in degradation can be attributed to a limited number of reactive sites of the nanocomposite, making it challenging to handle high pollutant concentrations.

Moreover, elevating the NH4PDS concentration from 0.1 g L− 1 to 0.5 g L− 1 resulted in an increase in the degradation rate of MB from 42% to total elimination (Fig. 3c). Furthermore, an increased dosage of NH4PDS positively impacted the degradation process. After 20 min, the degradation of MB increased from 33% to total removal at NH4PDS concentrations ranging from 0.1 g L− 1 to 0.4 g L− 1, respectively. Considering the improved degradation rate of MB at room temperature and the simple operational setup, we proceeded with our research under ambient conditions.

The pH plays a crucial role in determining the surface charge properties of catalytic materials and the speciation of contaminants (Fig. 3d), which subsequently influence their effectiveness in environmental remediation. The metal oxides impart acid and alkali resistance to the nanocomposite, resulting in a high catalytic degradation. However, the degradation rate of MB by F@S/C-M composite decreases slightly under strongly acidic and alkaline conditions. In highly acidic environments, the nanocomposite surface becomes protonated and acquires a positive charge, perhaps potentially leading to an electrostatic attraction with the pollutant, which reduces the efficiency of degradation.

A series of control experiments was conducted to confirm the beneficial role of the individual components in the nanocomposite for MB degradation (Fig. 3e). Specifically, various reactions utilizing γ-Fe2O3/NH4PDS, CuO/NH4PDS, MoO3/NH4PDS, and γ-Fe2O3@SiO2/NH4PDS individually led to a slower degradation of MB compared to the use of the F@S/C-M/NH4PDS.

The efficiency of degradation for three organic pollutants was assessed in activated systems (F@S/C-M/NH4PDS). The results indicated that the efficiency of pollutant removal was suitable, primarily attributed to the generation of ROSs such as \(\:{\text{S}\text{O}}_{4}^{{\bullet\:}-}\), •OH, and •\(\:{\text{O}}_{2}^{-}\) by the F@S/C-M/PDS system. The F@S/C-M/PDS system demonstrated a degradation rate, ranked in the following order: MB (99.4%) > MG (97.1%) > IN (87.7%). The differing rates of degradation observed within the same system may be attributed to the variations in the molecular structures of organic pollutants. Therefore, the significance of DFT calculations can be crucial in elucidating this. Additionally, methods like photodegradation (30 W LED light source), sonodegradation (150 W), and degradation in the presence of H2O2 and PMS were assessed to analyze the MB degradation process (Fig. 3f). The results indicated that while the removal of MB in the presence of NH4PDS was more effective than both photodegradation and sonodegradation, it exhibited a marginally lower rate constant efficiency when compared to degradation based on PMS. Consequently, our objective is to create an innovative approach for the degradation of pollutants in the presence of NH4PDS, which offers new insight into the AOP.

Fig. 3
figure 3

Degradation efficiency of MB under different (a) dosage nanocomposite, (b) MB concentrations, (c) NH4PDS concentrations, (d) solution pH, (e) different catalysts, and (f) various AOP methods. Experimental conditions unless otherwise specified: [catalyst] = 0.5 g L− 1, [NH4PDS] = 0.5 g L− 1, MB = 20 mg L− 1). The analytical measurements demonstrate a reproducibility of less than 3% based on triplicate runs. The experimental conditions mentioned above were applied to all figures.

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Table 1 Comparison of common catalyst activities in MB degradation.
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DFT calculation simulation

DFT was employed for the calculation of molecular properties to gain a deeper insight into the connection between molecular structure and the degradation rates of proposed pollutants. The HOMO, LUMO, and ESP mapping obtained from DFT calculations can evaluate the ability of sites in pollutants to accept or lose electrons (Fig. 4). Also, VIP and ω can reflect the electron-donating ability of contaminants (Table 2)38. The colored areas within the LUMO orbital are also suitable for engaging nucleophilic radicals38. Consequently, the colored regions in the HOMO and LUMO are vulnerable to attacks from electrophiles, nucleophiles, and radicals, as evidenced by ESP mapping3. These maps serve as a powerful tool for visualizing the charge distribution within each molecule, highlighting regions susceptible to nucleophilic or electrophilic attack. The comparison of MESP surfaces for MB, MG, and IN reveals distinct differences in their charge localization patterns, which can be directly linked to their experimental photochemical and redox behaviors. Therefore, red regions indicate more negative ESP, corresponding to nucleophilic sites; meanwhile, blue regions reveal more positive ESP, representing electrophilic sites. On the other hand, the energy gap of △E (EHOMO-ELUMO) in Table 2 demonstrates the reactivity of contaminants to ROS39,40. A lower △E signifies a greater likelihood of electron transfer38,39,40.

Fig. 4
figure 4

HOMO of MB(a), MG (b), IN (c); LUMO of MB(d), MG (e), IN (f); and MESP mapping of MB(g), MG (h), IN (i).

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Table 2 Calculations of the relevant values of MB, MG, and IN at the 6–311 + + G(d) theoretical level.
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Possible catalytic mechanism

Chemical scavengers were applied to detect dominant ROS to clarify the oxidation mechanism of MB in the F@S/C-M/NH4PDS system. Radical scavengers such as EtOH, IPA, p-BQ, and FFA, at a concentration of 0.1 M, were employed to selectively quench sulfate, hydroxyl, superoxide radicals, and 1O241,42,43,44. The results in Fig. 5a revealed that adding p-BQ and FFA, the removal of MB was reduced to approximately 29% and 7% respectively, confirming the generation of radical •\(\:{\text{O}}_{2}^{-}\) and 1O2 throughout the reaction. Moreover, a concentration of IPA reduced the yield of degradation to approximately 33%, confirming the role of HO• in the degradation process. Additionally, EtOH demonstrated the most significant inhibition of about 48% due to efficiently scavenging both \(\:{\text{S}\text{O}}_{4}^{{\bullet\:}-}\) and •OH radicals. The inhibition rates after adding p-BQ, IPA, and EtOH indicate that \(\:{\text{S}\text{O}}_{4}^{{\bullet\:}-}\), •OH, and •\(\:{\text{O}}_{2}^{-}\) attack MB molecules, confirming the generation of active species during MB degradation.

According to the analyses presented above, a possible mechanism for removing contamination in the F@S/C-M/NH4PDS system was suggested. At first, NH4PDS molecules can adhere to the surface of the nanocomposite without creating new chemical bonds45. Subsequently, the interaction between NH4PDS and F@S/C-M will extend the O–O bond, allowing PDS to attain the activated state. Following this, the influence of Fe2+, Fe3+, Mo5+, Mo6+, Cu+, and Cu2+ on the nanocomposite surface will lead to the cleavage of the O–O bond in PDS, resulting in the formation of \(\:{\text{S}\text{O}}_{4}^{{\bullet\:}-}\), •OH for the degradation of MB (Eqs. 1–6). Meanwhile, in the F@S/C-M/NH4PDS system, thanks to the combination of γ-Fe2O3 and CuO, the Cu+/Cu2+ and Fe2+/Fe3+ redox cycles were accelerated (Eqs. 7 and 8)46. It demonstrated that MB and other pollutants could be decomposed into \(\:{\text{S}\text{O}}_{4}^{{\bullet\:}-}\), •OH, and •\(\:{\text{O}}_{2}^{-}\) in the F@S/C-M/NH4PDS system (Eq. 9).

$${\rm Fe^{3+}+S_{2}O^{2-}_{8}\rightarrow\:Fe^{2+}+S_{2}O^{\bullet-}_{8}}$$
(1)
$${\rm Fe^{2+}+S_{2}O^{2-}_{8}\rightarrow\:Fe^{3+}+SO_{4}^{\bullet-}+SO_{4}^{2-}}$$
(2)
$${\rm C{u^{2 +}} + {S_2}O_8^{2 -}\rightarrow\:C{u^ + } + {S_2}O_8^{\bullet- }}$$
(3)
$${\rm C{u^ + } + {S_2}O_8^{2 -}\rightarrow\:C{u^{2 +}} + SO_4^{\bullet -} + SO_4^{2 -}}$$
(4)
$${\rm M{o^{6 +}}/Mo{^{5 +}} + {S_2}O_8^{2 -}\rightarrow\:M{o^{5 +}}/Mo{^{4 +}} + {S_2}O_8^{\bullet -}}$$
(5)
$${\rm SO_4^{\bullet -} + {H_2}O\rightarrow\:O{H^\bullet} + H^{+} + SO_4^{2 -}}$$
(6)
$${\rm{C}}{{\rm{u}}^ + } + {\rm{ F}}{{\rm{e}}^{{\rm{3}} + }}/{\rm{F}}{{\rm{e}}^{{\rm{2}} + }} \to {\rm{ C}}{{\rm{u}}^{{\rm{2}} + }} + {\rm{F}}{{\rm{e}}^{{\rm{2}} + }}/{\rm{F}}{{\rm{e}}^{{\rm{3}} + }}$$
(7)
$${\rm{C}}{{\rm{u}}^{{\rm{2}} + }} + {\rm{ F}}{{\rm{e}}^{{\rm{2}} + }}/{\rm{F}}{{\rm{e}}^{{\rm{3}} + }} \to {\rm{ C}}{{\rm{u}}^ + } + {\rm{F}}{{\rm{e}}^{{\rm{3}} + }}/{\rm{F}}{{\rm{e}}^{{\rm{2}} + }}$$
(8)
$${\rm SO^{\bullet-}_{4}/OH^{\bullet-}_{2}+Pollutions\rightarrow\:CO_{2}+H_{2}O+Intermediates }$$
(9)

Reusability and stability

The catalyst’s stability and reusability are crucial for efficient practical wastewater treatment. The F@S/C-M/NH4PDS system underwent three consecutive degradation cycles with MB under optimal conditions. As depicted in Fig. 5b, the efficiency gradually decreased to approximately 95% after three cycles, indicating only a slight reduction in activity. Additionally, the TEM image in Fig. 5c and the EDX analysis in Fig. 5d illustrate the framework’s stability and the distribution of elemental components following each cycle.

Fig. 5
figure 5

Scavenger test (a), recyclability performance for MB degradation using the F@S/C-M/NH4PDS system (b), TEM image of F@S/C-M composite (b), and EDX analysis in a cycle (c). Experimental conditions for any cycle: [catalyst] = 0.5 g L− 1, [NH4PDS] = 0.5 g L− 1, MB = 20 mg L− 1, and without adjusting pH).

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Conclusion

We have strategically designed a tri-metal oxide catalyst as an NH4PDS activator for the degradation of organic dyes. The hybrid nanocomposite is comprised of CuO, MoO3 crystals, and γ-Fe2O3 NPs, which can be easily fabricated using a facile calcination method. Importantly, this material can rapidly degrade a variety of organic dyes in the presence of NH4PDS. The copper, molybdenum, and iron sites in the nanocomposite play a crucial role in activating NH4PDS for pollution degradation. Also, the presence of γ-Fe2O3 NPs in the nanocomposite enables the facile separation of the catalyst from the reaction mixtures using an external magnet. On the other hand, DFT calculations revealed the relationship between pollutants’ molecular structure and degradation rates. This study serves as an excellent illustration of designing tri-metal oxide nanocomposites based on mineral materials aimed at eliminating organic pollutants from wastewater.