Fenton-like Oxidation Process Research Articles

Degradation of Nile Blue by Photocatalytic, Ultrasonic, Fenton, and Fenton-like Oxidation Processes

The aim of this study is to investigate new catalytic systems for the degradation of a dye that has been classified as first-degree toxic pollutant. Advanced oxidation process such as photocatalytic oxidation, ultrasonic oxidation, Fenton, and Fenton-like constitute a promising technology for the treatment of wastewater containing organic compounds. Waste effluents from textile industries are a major source of water pollution. These wastewaters contain dyes, which have high toxicity and low biodegradability. In this study, degradation of Nile Blue (NB), an azo dye, was studied using the photocatalytic oxidation (TiO2 and silver-loaded TiO2 (Ag-TiO2) as catalyst), ultrasonic oxidation, Fenton (Fe(II)/H2O2), and Fenton-like (Cu(II)/H2O2, V(IV)/H2O2) processes. It was found that the photocatalytic degradation of NB increased with decreasing pH, and the degradation rate also increased in the presence of TiO2/UV compared to UV irradiation alone. In addition, Ag loading on TiO2 dramatically reduced the degradation time. The ultrasonic degradation of NB was also studied using different initial dye concentrations at different pH values and amplitudes. Concentrations of Fe(II), Cu(II), V(IV) and H2O2 on degradation ratio were investigated. It is found that Fe(II) ion is more effective than Cu(II) and V(IV) ions in the degradation of NB.

Flotation separation of ilmenite and titanaugite modified by Fe2+-assisted peroxymonosulfate oxidation: Performance and activation mechanism

Efficient separation of ilmenite and titanaugite has always been recognized challenge in modern mineral processing. The use of a heterogeneous Fenton-like oxidation process composed of peroxymonosulfate (PMS) and Fe2+ is promising to address this issue. Flotation findings indicated that effective recovery of ilmenite could be achieved under weak acidic conditions, and a TiO2 recovery of 81.56 % and a grade of 32.16 % concentrate was collected. A series of characterization analyses confirmed that the PMS-Fe2+-mediated Fenton-like reaction in the ilmenite system generated more •OH and SO4•- radicals, which oxidized Fe2+ to Fe3+ on its surface, thus improving the active sites on ilmenite surface. Moreover, PMS-Fe2+ promoted the positive shift of surface charge on ilmenite, facilitating NaOL adsorption and making the surface more hydrophobic. NaOL primarily interacted with Fe active sites on the ilmenite surface and Mg2+ and Ca2+ active sites on the titanaugite surface in the formation as chemisorption. Thus, PMS-Fe2+ activated ilmenite mainly via augmenting the quantity and reactivity of Fe active sites on the surface. In summary, these findings provide the innovative pathways to implement the advanced oxidation processes in mineral flotation.

The introduction of pyrochar boosts the generation of singlet oxygen in a ferrihydrite-based Fenton-like system to facilitate the Cr(III)-citrate decomplexation under Cr(VI) inhibition

Cr(III)-organic complexes are frequently detected in tanning effluent, but they are challenging to elimination. Ferrihydrite (Fh)/carbon materials (CMs) composites showed superior performance in Fenton-like oxidation process, but their effectiveness and mechanism in Cr(III)-organic complex treatment need to be deep explored. In this study, pyrochar (PC)/Fh compounds were successfully synthesized and the experimental results found that the 5%-PC/Fh/H2O2 system exhibited efficient elimination of Cr(III)-citrate complexes with 89% reduction in TOC and almost 100% elimination of total Cr. The cooperation of PC with Fh promoted the decomposition of H2O2 by accelerating the electron transfer between Fe(III)/Fe(II) pairs. In contrast to the traditional Fenton-like catalysts, 5%-PC/Fh equipped with Fe–O–C bond could boost the production of 1O2, resulting in decomplexation of Cr(III)-citrate rather than direct attack of the Cr(III) site in the Cr(III)-citrate complex. Consequently, Cr(VI) could not be produced in the 5%-PC/Fh/H2O2 system. Moreover, the developed 5%-PC/Fh/H2O2 system exhibited enhanced reusability and excellent stability when applied to natural water and real wastewater. Finally, the oxidation intermediates could even promote the growth of C. vulgaris, indicating the structure of Cr(III)-citrate was destroyed and their toxicity was decreased. All these phenomena suggested the great potential of the 5%-PC/Fh/H2O2 system for practical wastewater treatment. This study has provided theoretical guidance and technical support for the efficient treatment of Cr(III)-organic complexes in real wastewater.

Preparation of Perovskite-Type LaMnO3 and Its Catalytic Degradation of Formaldehyde in Wastewater.

Formaldehyde (HCHO) is identified as the most toxic chemical among 45 organic compounds found in industrial wastewater, posing significant harm to both the environment and human health. In this study, a novel approach utilizing the Lanthanum-manganese complex oxide (LaMnO3)/peroxymonosulfate (PMS) system was proposed for the effective removal of HCHO from wastewater. Perovskite-Type LaMnO3 was prepared by sol-gel method. The chemical compositions and morphology of LaMnO3 samples were analyzed through thermogravimetric analysis (TG), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The effects of LaMnO3 dosage, PMS concentration, HCHO concentration, and initial pH on the HCHO removal rate were investigated. When the concentration of HCHO is less than 1.086 mg/mL (5 mL), the dosage of LaMnO3 is 0.06 g, and n(PMS)/n(HCHO) = 2.5, the removal rate of HCHO is more than 96% in the range of pH = 5-13 at 25 °C for 10 min. Compared with single-component MnO2, the perovskite structure of LaMnO3 is beneficial to the catalytic degradation of HCHO by PMS. It is an efficient Fenton-like oxidation process for treating wastewater containing HCHO. The LaMnO3 promoted the formation of SO4•- and HO•, which sequentially oxidized HCHO to HCOOH and CO2.

Enhanced mineralization of bisphenol A by electric arc furnace slag: Fenton-like oxidation

Bisphenol A (BPA) aqueous solution was treated through a heterogeneous Fenton-like oxidation process with electric arc furnace slag (EAFS), a waste product from an Argentinian steel processing plant, as the catalyst. SEM/EDS, XRD, and Mössbauer spectroscopy characterization revealed a significant presence of Fe and minor amounts of Cu and Mn in EAFS, known to play active roles in the Fenton-like reactions. The predominant crystalline form of iron in EAFS was magnesiowüstite, accompanied by minor amounts of hematite, magnetite, maghemite, and metallic iron. Batch Fenton-like oxidation experiments were conducted under acidic conditions (pH 2.8–3), examining the effect of temperature (25, 50, and 70 °C) and catalyst load (0.1, 0.5, and 1 g/L) on BPA degradation and mineralization over 180 min. BPA was completely degraded within the first minutes, while mineralization levels improved from 40% to an outstanding 70% as the temperature increased from 25 to 70 °C. The catalyst gradually lost its activity after five cycles at 25 °C, but raising the temperature up to 70 °C allowed maintaining mineralization levels between 70 and 50% over ten cycles. The oxidation process involved a combined Fenton-like homogeneous/heterogeneous mechanism, and deactivation was linked to a lower leaching of active cations over the cycles, reduction of the Fe(II)/Fe(III) ratio in the iron phases, and blocking of active sites by adsorption of reaction intermediates. EAFS demonstrated an exceptional performance in the Fenton-like oxidation of BPA. The utilization of this type of industrial waste materials represents a promising technological alternative that could benefit both steel processing and water treatment plants.

Spatial Confinement of Co Nanoparticles in N-Doped Carbon Nanorods for Wastewater Purification via CaSO3 Activation.

Spatial confinement of organic pollutants and reactive oxygen species (e.g., SO4•- and •OH) with ultrashort lifetime inside the scale of chemical theoretical diffusion could provide a greatly promising strategy to overcome the limitation of mass transfer in the heterogeneous Fenton-like oxidation process. Herein, we first reported spatial confinement of cobalt nanoparticles in N-doped carbon nanorods (Co-NCNRs), by encapsulating Co nanoparticles into N-doped carbon nanorods, in activating CaSO3 for antibiotic degradation. Compared to Na2SO3 and NaHSO3, CaSO3 could slowly and persistently discharge SO32- due to its low solubility, thus avoiding the depletion of the generated SO3•- and •OH under the high concentration of sulfite ions. Fully physical characterizations confirmed that the 3D hydrogel was mostly transformed into the nanorod structure of Co-NCNRs at 550 °C. Co atoms were successfully nanoconfined into N-doped carbon nanorods, which contributes to mass transfer and prevents the agglomeration of Co nanoparticles, thus enhancing its catalytic activity and stability in activating CaSO3 for water decontamination. The catalytic performance, kinetic research, influences of inorganic anions, pH, and degradation mechanism of chlortetracycline degradation catalyzed by the Co-NCNRs/CaSO3 system have been studied in detail. This work not only proposed a facile method for synthesis of nanoconfined catalyst but also provided an excellent Co-NCNRs/CaSO3 system for wastewater treatment.

Enhancing Mo leaching efficiency from spent catalyst via Fenton-like oxidation process: A comprehensive investigation of leaching effects, mechanism and environmental impacts

Spent hydrodesulfurization (HDS) catalyst contains considerable amounts of Mo, Ni and V, is an important secondary resource for these valuable metals. Direct acid solution leaching method exhibits poor separation effect from catalyst carrier for Mo due to greater stability of MoS2. This study explored Mo leaching efficiencies from spent HDS catalyst by Fenton-like oxidation systems (H2O2 and K2S2O8), which were frequently employed in the wastewater treatment. To further improve Mo leaching efficiency, nano zero-valent iron (nZVFe) was used to activate H2O2/K2S2O8 and produce more free radicals (·OH and ·SO4-). Approximate 96.0 % and 93.3 % of Mo were leached from spent HDS catalyst in nZVFe + H2O2 + H2SO4 and nZVFe + K2S2O8 + H2SO4 systems under optimal experimental conditions, increased by 16.2 % and 8.2 % than normal H2O2 (79.8 %) and K2S2O8 (85.1 %) system without nZVFe. The leaching process of Mo in both nZVFe + H2O2 + H2SO4 and nZVFe + K2S2O8 + H2SO4 systems conformed to the shrinkage core model. Kinetic analysis and molecular calculation demonstrated the leaching process of Mo in nZVFe + H2O2 + H2SO4 system was driven by chemical reaction and solid film diffusion, and the leaching and oxidation reactions of MoS2 occurred simultaneously. However, the leaching process of Mo in nZVFe + K2S2O8 + H2SO4 system was driven only by chemical reaction, solid MoS2 was firstly dissolved into Mo4+ by H+, and then oxidized into Mo6+ by ·SO4-. The economic and environmental impacts evaluation indicated that the separation of Mo from spent HDS catalysts by nZVFe + H2O2 + H2SO4 was assigned as a better choice than normal H2O2 and K2S2O8 system without nZVFe due to higher leaching efficiency and lower cost.

An ultrasonic-assisted Synthesis, Characterization, and application of Nano-Fe3O4/TiO2 as nano-catalyst for the removal of organic dye by Like-Photo-Fenton reactions

In this research, Fe3O4 nanoparticles were synthesized via a simple co-precipitation method. Subsequently, these nanoparticles were used to synthesize TiO2-Fe3O4 nanocomposites via solvothermal ultrasonic-assisted method. Obtained nanomaterials Fe3O4 and TiO2-Fe3O4 were structurally characterized by UV–visible, XRD, and SEM-EDS. Synthesized nano-catalysts were tested as catalysis of organic dye degradation. Furthermore, an optimization study was conducted to evaluate selected TiO2-Fe3O4 nanocomposites to degrade Methylene Blue (MB) in an aqueous solution through Fenton-like reactions. Several experimental variables, including pH (from 2 to 8), H2O2 concentration (from 10-2 to 5.10-1M), catalyst amount (20 to 80 mg), and target organic compound concentrations, were tested in order to optimize the Fenton-like catalytic activity of the TiO2-Fe3O4 as a nano-catalyst to degrading MB under ambient light conditions (natural sunlight). The results showed that TiO2-Fe3O4 had an efficient degradation rate of up to 85% for MB at the optimal pH 3, H2O2 at 10-1M and 40 mg/L catalyst amount. Also, the results showed the good reusability of TiO2-Fe3O4 as a nanophotocatalyst. Also, based on the results of the scavenging agent experiments, hydroxyl radicals and superoxide radicals play an important role in methylene blue (MB) photodegradation. Finally, a possible mechanism for the photocatalytic degradation of MB was proposed. In this study, the synthesis and application of TiO2-Fe3O4 nanocomposite as a nano-catalyst in the Fenton-like oxidation process demonstrated a promising eco-friendly method for treating organic pollutants in water.

Degradation mechanism of Bisphenol S via hydrogen peroxide/persulfate activated by sulfidated nanoscale zero valent iron.

Fenton-like oxidation processes are widely used to degrade recalcitrant organic pollutants, but are limited by narrow application pH and low reaction efficiency. This study investigated the synchronous activation of H2O2 and persulfate (PDS) by sulfidated zero valent iron (S-nZVI) in ambient conditions for Fenton-like oxidation of bisphenol S (BPS), an estrogenic endocrine-disrupting chemical. The activation of S-nZVI induced H2O2 or PDS could be greatly enhanced with the assistance of PDS and H2O2, respectively, even across a wide range of pH value (3-11). The first-order rate constant of S-nZVI/H2O2/PDS, S-nZVI/PDS and S-nZVI/H2O2 systems was found to be 0.2766min-1, 0.0436min-1, and 0.0113min-1, respectively. A significant synergy between H2O2 and PDS was achieved when the PDS-H2O2 molar ratio was above 1:1, and where sulfidation promoted iron corrosion and decreased solution pH were observed in the S-nZVI/H2O2/PDS system. Radical scavenging experiments and electron paramagnetic resonance (EPR) investigations suggest that both SO4•- and •OH were generated and that •OH played a crucial role in BPS removal. Furthermore, four BPS degradation intermediates were detected and three degradation pathways were proposed in line with the HPLC-Q-TOF-MS analysis. This study demonstrated that compared to the traditional Fenton-like system, the S-nZVI/H2O2/PDS system could be a more efficient, advanced oxidation technology capable of being used across a broad pH range for emerging pollutants' degradation.

Competitive study of homogeneous and heterogeneous Fenton-like flow-through propoxur oxidation in ROC solution.

Reverse osmosis is used as a tertiary treatment for wastewater reclamation. However, sustainable management of the concentrate (ROC) is challenging, due to the need for treatment and/or disposal. The objective of this research was to investigate the efficiency of homogeneous and heterogeneous Fenton-like oxidation processes in removing propoxur (PR), a micro-pollutant compound, from synthetic ROC solution in a submerged ceramic membrane reactor operated in a continuous mode. A freshly prepared amorphous heterogeneous catalyst was synthesized and characterized, revealing a layered porous structure of 5-16 nm nanoparticles that formed aggregates (33-49 μm) known as ferrihydrite (Fh). The membrane exhibited a rejection of >99.6% for Fh. The homogeneous catalysis (Fe3+) exhibited better catalytic activity than the Fh in terms of PR removal efficiencies. However, by increasing the H2O2 and Fh concentrations at a constant molar ratio, the PR oxidation efficiencies were equal to those catalyzed by the Fe3+. The ionic composition of the ROC solution had an inhibitory effect on the PR oxidation, whereas increased residence time improved it up to 87% at a residence time of 88 min. Overall, the study highlights the potential of heterogeneous Fenton-like processes catalyzed by Fh in a continuous mode of operation.

Enhanced catalytic performance of CuFeS2 chalcogenides for activation of persulfate towards decolorization and disinfection of pollutant in water

This study focuses on the synthesis and properties of CuFeS2 chalcogenides, which were prepared using a heat precipitation method. The effect of synthetic temperature on the catalytic activity of CuFeS2 was also investigated. The study found that CuFeS2 prepared at 250 °C (CuFeS2–250) had higher crystallinity, a higher concentration of Fe2+ on its surface, and a higher catalytic activity in the decolorization of rhodamine B (RhB) using a Fenton-like oxidation process with Na2S2O8 (99.0% RhB decolorization efficiency within 7 min). The iron sites of CuFeS2 were found to be the catalytic active sites through density-functional theory calculations. The study also determined that •SO4− and •OH radicals were the reactive species responsible for the decolorization of RhB. In addition, the study demonstrated that CuFeS2–250 had the ability to decolorize different dyestuffs (methylene blue, methyl orange, and acridine orange) in environmental water samples (river and seawater). Furthermore, CuFeS2–250/Na2S2O8 possessed excellent antibacterial activity (>90.4% eradication rate within 120 min) against pathogen (Escherichia coli, Staphylococcus aureus, and methicillin-susceptible S. aureus). In conclusion, this study highlights the enhanced catalytic activity of CuFeS2–250 and its potential for industrial applications related to the decomposition of organics from wastewater.

High efficiency degradation of 2,4-dichlorophenol using Cu2S/Cu2O decorated nanoscale zerovalent iron via adsorption and photocatalytic performances

In this work, a novel cuprous sulfide (Cu2S) and cuprous oxide (Cu2O) decorated iron-based nanoparticles (INPs) were developed (Cu2S/Cu2O-nZVI@B, B denote bentonite) and applied for 2,4-dichlorophenol (2,4-DCP) degradation. The physicochemical properties of the as-prepared catalyst were characterized via SEM, TEM, BET, DRS, and EIS. Results of TEM images exhibited the deposition of copper species could improve the morphology and reduce the mean particles size effectively. Cu2S/Cu2O-nZVI@B exhibited excellent catalytic performance to degrade 2,4-DCP by adsorption, Fenton-like oxidation and photocatalytic processes. Under optimal conditions, the degradation percentages caused by adsorption, adsorption-Fenton like and adsorption-Fenton like-photocatalytic processes were about 27.6%, 74.58% and 99.8%, respectively. Furthermore, GC-MS served to identify the intermediates and final products, a possible mechanism and degradation pathway for 2,4-DCP were proposed based on the intermediate by-products detection and active radicals’ detection. The reusability of Cu2S/Cu2O-nZVI@B was achieved with four successive runs. Research provides a promising approach for the treatment of chlorophenols polluted water.

Improving the activation of peroxymonosulfate for highly efficient degradation of explosive 1,1-diamino-2,2-dinitroethylene through the synergetic effect of bimetallic oxides

The frequent use of explosives poses a potential threat to the ecological and human health, but regrettably, only a few researchers have attempted to adopt photocatalytic technology to remediate organic pollutants of explosives wastewater. Herein, a new g-C3N4/30%CuCo2O4-PMS photocatalytic system is rationally established and applied in 1,1-diamino-2,2-dinitroethylene (FOX-7) degradation under visible light irradiation. The effects of reaction conditions on FOX-7 degradation are explored and about 98.4% -FOX-7 can be almost completely degraded in 30 min by using 0.1 g/L catalyst and 0.1 g/L peroxymonosulfate (PMS). Quenching experiments and electron paramagnetic resonance (EPR) confirm that radical and non-radical pathways all contribute to the effective degradation of FOX-7, in which the singlet oxygen (1O2) is the dominant reactive species. Importantly, the synchronous transformations of Cu(Ⅱ)/Cu(Ⅰ) and Co(Ⅱ)/Co(Ⅲ) valence states over CuCo2O4 during PMS activation play an important role in the generation of reactive species. Additionally, the correspondent degradation pathways are proposed, and nitrate ions are the major degradation products. This work not only highlights the reaction mechanism of Cu-Co bimetallic oxide in the Fenton-like oxidation process, but also provides a new insight for the treatment of explosives wastewater.

Removal of Organics from Landfill Leachate by Heterogeneous Fenton-like Oxidation over Copper-Based Catalyst

Landfill leachates are a mixture of high concentration organic and inorganic contaminants and need to be appropriately treated due to their toxicity and severe adverse effects on the environment. Here, we studied the treatment of landfill leachate through a heterogeneous Fenton-like oxidation process using a zirconia supported copper catalyst (Cu/ZrO2). Reaction conditions such as pH, amount of catalyst, oxidant dose, temperature, and reaction time were investigated and their effects on pollutant abatement discussed. AOS (average oxidation state) and COS (carbon oxidation state) parameters were used for the evaluation of the degree of oxidation of the process, obtaining some insight into the formation of oxidized intermediates (partial oxidation) and the total oxidation (mineralization) of the leachate during the reaction. A two-step oxidation process enhanced the overall performance of the reaction with an abatement of organic compounds of 92% confirming the promising activity of a copper-based catalyst for the treatment of liquid waste. Higher catalytic activity was achieved when the following reaction conditions were applied: 70 °C, pH 5, 200 mg/L of catalyst, 30 mL/L of H2O2 dose, and 150 min. In addition, durability of the catalyst under optimized reaction conditions was verified by repeated reaction cycles.

Upcycling biomass waste into Fe single atom catalysts for pollutant control

Contaminants of heavy metals and antibiotics, which are frequently detected in water, soil and food chains with increasing prevalence in our current society, can cause potential harm to human health and disrupt human ecosystem irreversibly. Herein, we have successfully utilized biomass waste ferns contaminated by iron mines, to fabricate a first-of-its-kind high-performance class of Fe single-atom catalysts (FeSAC) by a facile pyrolysis. The optimal FeSAC-800 shows an excellent efficiency in the fast-photocatalytic degradation of six types of quinolone antibiotics (e.g., norfloxacin, levofloxacin, ciprofloxacin, enrofloxacin, lomefloxacin, flumequine) in 1 h under the simulated natural light irradiation. Based on advanced characterization, a well-defined structure of FeN4, confined in the porous carbon is elaborated for the FeSAC-800. Mechanism of the photodegradation is via a Fenton-like oxidation process whereas the reactive oxygen species play a key role. These findings open a new avenue for efficient, sustainable utilization of biomass waste in pollutant control.

Conjugated polymers templated carbonization to design N, S co-doped finely tunable carbon for enhanced synergistic catalysis

Efficient generation of 1O2 nonradical species from persulfate (PS) is demonstrated during heterogeneous catalysis systems based on the use of new Nitrogen and Sulfur doped carbons (NC, SC and NSC), as prepared by direct carbonization of polyaniline/polythiophene conjugated polymers at 800 °C. Complete organic molecules degradations were achieved with high mineralization rate (∼70%) for all systems, over a wide pH range (2.6∼9.5) in the presence of PS. Interestingly, the synergistic effect occurring between the N-Graphitic and the S-Thiophenic sites, modulates the surface electron density toward basic carbon structure (N∼4.76 at% and S∼3.87 at%, with SBET∼251 m2 g−1), leads to increases of the adsorption abilities and the reaction rate constant (from 0.076 to 0.338 min−1), and boosts the carbocatalyst' stability. Our discovery sheds new light on new systems promoting the Fenton-like oxidation process by 1O2 nonradical species, it may be a long-lasting sustainable environmentally strategy for water remediation.

Adsorption and catalytic performance of pipe growth rings from water distribution networks using 5-BSA as the target pollutant

In this study, we investigated the use of pipe growth rings from water distribution networks as a catalyst in heterogeneous Fenton-like oxidation processes. The major constituents of real pipe growth rings (α- and γ-FeOOH) were prepared and considered as a simulated growth ring (SGR). Its performance in removing 5-bromosalicylic acid (5-BSA), a novel phenolic halogenated disinfection byproduct, was examined. SGR exhibited strong catalytic ability and a certain degree of adsorption capacity. Under acidic conditions, the adsorption and oxidation efficiencies were 32.65% and 87.67%, respectively. Furthermore, 72.19% of 5-BSA could be oxidized even at pH0 of 7. Kinetic characterizations at various temperatures revealed that both the adsorption and catalytic oxidation processes followed pseudo-second-order kinetic models and were surface-controlled with high activation energies (31.26 and 23.58 kJ mol−1, respectively). Ecotoxicity analyses of the transformation products (TPs) showed that the SGR/H2O2 system could effectively reduce the toxicity of 5-BSA. Moreover, the number of iron ions leaching from SGR was below 0.1 mg L−1 in all experiments. The results of this study support further investigation of using real pipe growth rings in off-line water treatment, as well water network contamination remediation.

Heterogeneous Fenton-Like Oxidation of Methylene Blue Using Alternative Catalysts

Abstract The usage of the low-cost catalysts for methylene blue removal from wastewater was investigated. Heterogeneous Fenton-like process consists of the use of a hydrogen peroxide solution, and an iron-rich catalyst, red mud and black nickel mud were used for that purpose. The factors such as the catalyst dose and the hydrogen peroxide solution volume were monitored. The results of experiments showed that the degradation of methylene blue dye in Fenton-like oxidation process using selected catalysts can be described by a pseudo-second-order kinetic model. The highest dye removal efficiency (87.15 %) was achieved using the black nickel mud catalyst after 30 minutes of reaction.

Facile synthesis of muscovite–supported Fe3O4 nanoparticles as an adsorbent and heterogeneous catalyst for effective removal of methyl orange: Characterisation, modelling, and mechanism

The discharge of organic pollutants including dyes into the aquatic system represents a main source of environmental contamination. Decontamination of dye molecules from polluted water bodies through adsorption process is reported to be an effective and economic technology. Herein, a one-pot preparation method was used to decorate the available and low-cost layered silicate muscovite (MUS) mica by iron oxide (Fe3O4) nanoparticles. The new Fe3O4@MUS composite was characterised by XRD, FTIR, SEM, and TEM techniques and tested for the adsorption and Fenton-like degradation of hazardous methyl orange (MO). The results of experimental parameters such as reaction time, Fe3O4@MUS mass, MO concentration, solution pH, H2O2 concentration, and temperature indicated that Fenton-like oxidation process was rapid (i.e., around 98 % of MO removal was achieved after 60 min). The pseudo-first-order for kinetics and Langmuir for equilibrium models fitted the MO adsorption data. The maximum Langmuir uptake capacity of Fe3O4@MUS presented the value of 149.25 mg/g at 25°C. Fenton-like degradation data followed the first-order removal rate at varied initial concentrations (i.e., 50, 100, and 150 mg/L) of MO dye. Electrostatic interactions, hydrogen bonding, and the π-π bond (i.e., dye‒dye interaction) were involved during MO adsorption onto Fe3O4@MUS surface. Degradation of MO was mainly associated with the generation of •OH radicals through H2O2 catalytic decomposition using Fe3O4@MUS composite. The synthetic catalyst was reused up to five runs without an apparent decrease in its removal efficiency even after 5th use, reflecting the high stability of Fe3O4@MUS.

Effect of Alkaline Concentrations on the Synthesis of Volcanic Soil-Based Zeolite for Methylene Blue Removal by Fenton-Like Oxidation Process

This study demonstrates the potential use of volcanic ash soil (VAS) as raw materials for preparing zeolite without adding any templates or seeds. Here we investigated the effect of alkaline concentrations on the synthesis of VAS-based zeolite and enhanced its ability for methylene blue (MB) removal by Fenton-like process. Zeolite materials were directly synthesized by mixing the amount of VAS within alkaline concentrations of 0.5 (P1), 1.5 (P2), and 3.0 mol/L (P3), respectively, followed by a simple hydrothermal procedure at 100 oC for 24 h. The prepared sample characteristics were obtained from the Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis, which confirmed the formation of zeolite A and some mineral phases in P2 and P3 samples. The mentioned samples reached equilibrium state at MB concentration of 200 mg/L with high adsorption capacity values compared to VAS. The adsorption showed a better fit to the Langmuir isotherm model (R2]0.99), in which the maximum uptake capacities were found to be 24.03 mg/g for P2 and 14.30 mg/g for P3. Interestingly, the percentage of MB removal using P2 and P3 increased greatly from 52.81% and 32.26% to 98.92% and 98.85% by Fenton-like process, respectively.