When bimetallic oxides and their complexes meet Fenton-like process

Recent Advances Hydrogenation of Carbon Dioxide to Light Olefins over Iron-Based Catalysts via the Fischer-Tropsch Synthesis

The massive burning of fossil fuels has been important for economic and social development, but the increase in the CO2 concentration has seriously affected environmental sustainability. In industrial and agricultural production, light olefins are one of the most important feedstocks. Therefore, the preparation of light olefins by CO2 hydrogenation has been intensively studied, especially for the development of efficient catalysts and for the application in industrial production. Fe-based catalysts are widely used in Fischer-Tropsch synthesis due to their high stability and activity, and they also exhibit excellent catalytic CO2 hydrogenation to light olefins. This paper systematically summarizes and analyzes the reaction mechanism of Fe-based catalysts, alkali and transition metal modifications, interactions between active sites and carriers, the synthesis process, and the effect of the byproduct H2O on catalyst performance. Meanwhile, the challenges to the development of CO2 hydrogenation for light olefin synthesis are presented, and future development opportunities are envisioned.

Metronidazole degradation mechanism by sono-photo-Fenton processes using a spinel ferrite cobalt on activated carbon catalyst

A heterogeneous catalyst was prepared by anchoring spinel cobalt ferrite nanoparticles on porous activated carbon (SCF@AC). The catalyst was tested to activate hydrogen peroxide (HP) in the Fenton degradation of metronidazole (MTZ). SCF nanoparticles were produced through the co-precipitation of iron and cobalt metal salts in an alkaline condition. Elemental mapping, physico-chemical, morphological, structural, and magnetic properties of the as-fabricated catalyst were analyzed utilizing EDX mapping, FESEM-EDS, TEM, BET, XRD, and VSM techniques. The porous structure of AC enhanced the catalytic activity of SCF by a significant decrease in the agglomeration of SCF nanoparticles. The effectiveness of SCF@AC in Fenton degradation improved substantially when UV light and ultrasound (US) irradiations were induced, most likely due to the strong synergistic effect between the catalyst and these irradiation sources. The photo-Fenton system was more efficient than the Fenton, sono-, and sono-photo-Fenton processes eliminating both MTZ and TOC. It was found that AC not only dispersed SCF nanoparticles and improved the stability of the catalyst, but also provided a high adsorption capacity of MTZ, resulting in a faster degradation. After 60 min of the photo-Fenton reaction, the elimination efficiencies of MTZ (30 mg L-1) and TOC were 97 and 42.1% under optimum operational conditions (pH = 3.0, HP = 4.0 mM, SCF@AC = 0.3 g L-1, and UV = 6 W). SCF@AC showed excellent stability with low leaching of metal ions during the reaction. Radical and non-radical (O2•-, HO•, and 1O2 species), alongside adsorption and photocatalysis mechanisms, were responsible for MTZ decontamination over the SCF@AC/HP/UV system. A comprehensive study on the HP activation mechanism and MTZ degradation pathway was obtained through scavenging tests. The findings demonstrate that SCF@AC is an effective, reusable, and environmentally sustainable catalyst for advanced oxidation processes that can effectively remove organic pollutants from wastewater. This study offers valuable insights into the feasibility of employing SCF@AC catalysts in Fenton-based processes for the degradation of MTZ.

Cobalt based bimetallic catalysts for heterogeneous electro-Fenton adapting to vary pH for HEDP and MIT degradation

Most of the materials studied as catalysts in the electro-Fenton system are variants of iron oxide or iron hydroxide. However, iron-based catalysts often exhibit weak catalytic capabilities under neutral and alkaline conditions. In this work, we synthesized three cobalt based bimetallic oxides, Co2CuOx, Co2AlOx, and Co2NiOx, using hydrothermal method and evaluated them as catalysts for the heterogeneous electro-Fenton system to remove 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and Methylisothiazolinone [2-methyl-4-isothiazolin-3-one] (MIT). Co2NiOx has the highest catalytic degradation activity for HEDP, and Co2CuOx has the best catalytic degradation effect for MIT. Based on characterization results of the catalysts, the reasons for the differences in the pollutant removal efficiency were analysed, and the optimal pH for the three cobalt based oxides to remove HEDP and MIT was investigated. The results showed that the optimal pH values of the three cobalt based bimetallic oxides are not only influenced by the second metal type, but also by the properties of pollutants. Therefore, suitable cobalt based catalysts can be selected based on the different properties of pollutants, or the composition of cobalt based catalysts can be adjusted to meet the different pH requirements of target wastewater. The three cobalt based bimetallic oxides exhibited good degradation of HEDP and MIT under neutral conditions, which to some extent solved the problem of narrow pH range in the practical application of the electro-Fenton process.

Fabrication of nano-hammer shaped CuO@HApNWs for catalytic degradation of tetracycline

With widespread and excessive use of antibiotics in medicine, poultry farming, and aquaculture, antibiotic residues have become a significant threat to both eco-environment and human health. In this paper, using hydroxyapatite nanowires (HApNWs) as an ecologically compatible carrier, a novel nano-hammer shaped conjunction with HApNW conjugating CuO microspheres (CuO@HApNWs) was successfully synthesized by in-situ agglomeration method. The catalytic degradation performance of the nano-hammer shaped CuO@HApNWs with Fenton-like activation was investigated by using tetracycline (TC) as a representative antibiotic pollutant. Remarkably, it exhibited excellent catalytic activity, which the removal rate of TC got to 92.0% within 40 min, and the pseudo-second-order reaction kinetic constant was 18.33 × 10-3 L mg-1·min-1, which was 26 times and 5 times than that of HApNWs and CuO, respectively. Furthermore, after recycling 6 times, the degradation efficiency of TC still remained above 85 %. Based on radical scavenger tests and electron paramagnetic resonance (EPR) spectroscopy, it demonstrated that the excellent activity of CuO@HApNWs was mainly attributed to the fact that Fenton-like activation promotes the circulation of Cu2+ and Cu+, the generated main active oxygen species (•OH and O2-•) achieve efficient degradation of TC. In summary, the nano-hammer shaped CuO@HApNWs could be in-situ synthesed, and used as an eco-friendly Fenton-like catalyst for effectively catalytic degradation of organic pollutants, which has great potential for wastewater treatment.

Assessing the mechanisms and adjunctive therapy for arsenic-induced liver injury in rats

Environmental arsenic exposure is a significant global public health concern. Previous studies have demonstrated the association between arsenic-induced liver injury and oxidative stress as well as ferroptosis. However, the knowledge of the interactions among these mechanisms remains limited. Moreover, there is a lack of research on potential therapeutic interventions for liver injury resulting from arsenic exposure. To address these limitations, we established a rat model with liver injury caused by arsenic exposure and investigated the impact of the nuclear factor E2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPx4) signaling pathway and ferroptosis on arsenic-induced liver injury. Our findings revealed that arsenic increased Nrf2 expression and decreased GPx4 expression in the rat liver. This was accompanied by a substantial generation of reactive oxygen species and disruption of the antioxidant defense system, ultimately promoting liver injury through ferroptosis. Subsequently, we conducted intervention experiments using Rosa roxburghii Tratt (RRT) in rats exposed to arsenic. The results showed that the detrimental effects mentioned earlier were partially alleviated following RRT intervention. This study offers preliminary evidence that persistent activation of Nrf2 by arsenic triggers an adaptive antioxidant response, leading to liver injury through the promotion of ferroptosis. Additionally, we discovered that RRT inhibits Nrf2-mediated adaptive antioxidant responses by reducing hepatic ferroptosis, thereby mitigating liver injury caused by arsenic exposure in rats. Our study contributes to a deeper understanding of the molecular mechanisms underlying liver injury resulting from arsenic exposure. Furthermore, our findings may facilitate the identification of a potential edible and medicinal plant extracts that could be utilized to develop a more effective adjunctive treatment approach.

Strategies for enhancing performance of perovskite bismuth ferrite photocatalysts (BiFeO3): A comprehensive review

Organic pollutants pose a significant threat to water safety, and their degradation is of paramount importance. Photocatalytic technology has emerged as a promising approach for environmental remediation, and Bismuth ferrite (BiFeO3) has been shown to exhibit remarkable potential for photocatalytic degradation of water pollutants, with its excellent crystal structure properties and visible light photocatalytic activity. This review presents an overview of the crystal properties and photocatalytic mechanism of perovskite bismuth ferrite (BiFeO3), as well as a summary of various strategies for enhancing its efficiency in photocatalytic degradation of organic pollutants. These strategies include pure phase preparation, microscopic modulation, composite modification of BiFeO3, and the integration of Fenton-like reactions and external field-assisted methods to improve its photocatalytic performance. The review emphasizes the impact of each strategy on photocatalytic enhancement. By providing comprehensive strategies for improving the efficiency of BiFeO3 photocatalysis, this review inspires new insights for efficient degradation of organic pollutants using BiFeO3 photocatalysis and contributes to the development of photocatalysis in environmental remediation.

Efficient removal of chloroform from groundwater using activated percarbonate by cellulose nanofiber-supported Fe/Cu nanocomposites

Chloroform (CF) is a recalcitrant halogenated methane (HM) that has received widespread attention due to its frequent detection in groundwater and its potential carcinogenic risk. In this study, TEMPO-oxidized cellulose nanofiber-supported iron/copper bimetallic nanoparticles (TOCNF-Fe/Cu), a novel composite catalyst, was synthesized to activate sodium percarbonate (SPC) for the removal of CF from groundwater. The results showed that over 96.3% of CF could be removed in a neutral reaction medium (pH 6.5-9) within 180 min using 0.66 g L-1 of TOCNF (0.32)-Fe/Cu (1) and 1 mM of SPC, which outperforms typical advanced oxidation processes. The reaction mechanism of the TOCNF-Fe/Cu-SPC system for the CF removal was elucidated. As demonstrated through electron paramagnetic resonance and quenching experiments, the TOCNF-Fe/Cu-SPC system was found to include •OH and O2•-, where the latter played a dominant role in the CF removal. DFT calculations indicated that TOCNF improved the electron transport capability of Fe/Cu and reduced the transition state energy. The Fe species on the surface of TOCNF-Fe/Cu were identified as the primary active sites for SPC activation, whereas the Cu species were beneficial to the regeneration of the Fe species. Additionally, TOCNF-Fe/Cu was found to have good recyclability and stability. The feasibility of the TOCNF-Fe/Cu-SPC system was further confirmed by applying it for the efficient removal of composite HMs from actually contaminated groundwater. Overall, the TOCNF-Fe/Cu-SPC system is an attractive candidate for the treatment of HM-contaminated groundwater.

Co-amplification of luminol-based electrochemiluminescence immunosensors based on multiple enzyme catalysis of bimetallic oxides CoCeOx and NiMnO3 for the detection of CYFRA21-1

The accelerated energy supply of co-reactants is an extremely effective strategy for achieving highly sensitive electrochemiluminescence analysis, and binary metal oxides would be an excellent tool for this purpose owing to the nano-enzyme acceleration of mixed metal valence states. Herein, an electrochemiluminescent (ECL) immunosensor for monitoring the concentration of cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) was developed based on a co-amplification strategy triggered by two bimetallic oxides, CoCeO_x and NiMnO₃, with luminol as the luminophore. CoCeO_x derived from an MOF exhibits a large specific surface area and excellent loading capacity as a sensing substrate, and the peroxidase properties enable the catalysis of hydrogen peroxide to provide energy supply to the underlying radicals. The dual enzymatic properties of flower-like NiMnO₃ were employed as probe carriers for luminol enrichment. The peroxidase properties built on Ni²⁺/Ni³⁺ and Mn³⁺/Mn⁴⁺ binary redox pairs resulted in the integration of highly oxidative hydroxyl radicals, and the oxidase properties provided additional superoxide radicals via dissolved oxygen. The practically proven multi-enzyme-catalyzed sandwich-type ECL sensor easily accomplished an accurate immunoassay of CYFRA21-1, harvesting a detection limit of 0.3 pg mL^-1 in the linear range of 0.001-150 ng mL^-1. In conclusion, this work explores the cyclic catalytic amplification of mixed-valence binary metal oxides with nano-enzyme activity in the field of ECL and develops an effective pathway for ECL immunoassay.

Cobalt ferrite as an electromagnetically boosted metal oxide hetero-Fenton catalyst for water treatment

The cobalt ferrite Fenton catalysts were obtained by the flow co-precipitation method. FTIR, XRD, and Mössbauer spectroscopy confirmed the spinel structure. The crystallite size of the as-synthesized sample is 12 nm, while the samples annealed at 400 and 600 °C have crystallite sizes of 16 and 18 nm, respectively. The as-synthesized sample has a grain size of 0.1-5.0 μm in size, while the annealed samples have grain sizes of 0.5 μm-15 μm. The degree of structure inversion ranges from 0.87 to 0.97. The catalytic activity of cobalt ferrites has been tested in the decomposition of hydrogen peroxide and the oxidation of caffeine. The annealing of the CoFe₂O₄ increases its catalytic activity in both model reactions, with the optimal annealing temperature being 400 °C. The reaction order has been found to increase with increasing H₂O₂ concentration. Electromagnetic heating accelerates the catalytic reaction more than 2 times. As a result, the degree of caffeine decomposition increases from 40% to 85%. The used catalysts have insignificant changes in crystallite size and distribution of cations. Thus, the electromagnetically heated cobalt ferrite can be a controlled catalyst in water purification technology.

Heterogeneous Fenton water purification catalyzed by iron phosphide (FeP)

Heterogeneous Fenton reaction has a great application potential in water purification, but efficient catalysts are still lacking. Iron phosphide (FeP) has a higher activity than the conventional Fe-based catalysts for Fenton reactions, but its ability as a Fenton catalyst to directly activate H₂O₂ remains unreported. Herein, we demonstrate that the fabricated FeP has a lower electron transfer resistance than the typical conventional Fe-based catalysts, i.e., Fe₂O₃, Fe₃O₄, and FeOOH, and thus could active H₂O₂ to produce hydroxyl radicals more efficiently. In the heterogeneous Fenton reactions for sodium benzoate degradation, the FeP catalyst presents a superior activity with a reaction rate constant more than 20 times those of the other catalysts (i.e., Fe₂O₃, Fe₃O₄, and FeOOH). Moreover, it also exhibits a great catalytic activity in the treatment of real water samples and has a good stability in the cycling tests. Furthermore, the FeP could be loaded onto a centimeter-sized porous carbon support and the prepared macro-sized catalyst exhibits an excellent water treatment performance and can be well recycled. This work reveals a great potential of FeP as a catalyst for heterogeneous Fenton reactions and may inspire further development and practical application of highly efficient catalysts for water purification.

Integration of CuS/ZnIn2S4 flower-like heterojunctions and (MnCo)Fe2O4 nanozyme for signal amplification and their application to ultrasensitive PEC aptasensing of cancer biomarker

Vascular endothelial growth factor 165 (VEGF₁₆₅) is a crucial regulator of angiogenesis and works as a major protein biomarker of cancer metastasis. Therefore, its quantitative detection is pivotal in clinic. In this work, CuS/ZnIn₂S₄ flower-like heterojunctions had strong and stable photocurrents, which behaved as photoactive material to construct a photoelectrochemical (PEC) aptasensor for detecting VEGF₁₆₅, combined by home-prepared (MnCo)Fe₂O₄ nanozyme-mediated signal amplification. The interfacial photo-induced electron transfer mechanism was chiefly discussed by UV-vis diffuse reflectance spectroscopy in details. Specifically, the (MnCo)Fe₂O₄ modified VEGF₁₆₅ aptamer was released from the PEC aptasensing platform for its highly specific affinity to target VEGF₁₆₅, which terminated the color precipitation reaction, ultimately recovering the PEC signals. The developed sensor displayed a wider linear range from 1 × 10^-2 to 1 × 10⁴ pg mL^-1 with a smaller limit of detection (LOD) of 0.1 fg mL^-1. This study provides some valuable insights for building other ultrasensitive aptasensors for clinical assays of cancer biomarkers in practice.

Recent advances in advanced oxidation processes (AOPs) for the treatment of nitro- and alkyl-phenolic compounds

The presence of phenolic compounds in the aquatic environment has posed severe risks due to their toxicity. Among the phenolic families, nitro- and alkyl-phenolic compounds have been categorized as precedence contaminants by the United States Environmental Protection Agency (US EPA). Therefore, efficient treatment methods for wastewater containing nitro- and alkyl-phenolic compounds are urgently needed. Due to the advantages of creating reactive species and generating efficient degradation of hazardous contaminants in wastewater, advanced oxidation processes (AOPs) are well-known in the field of treating toxic contaminants. In this review paper, the recent directions in AOPs, catalysts, mechanisms, and kinetics of AOPs are comprehensively reviewed. Furthermore, the conclusion summarizes the research findings, future prospects, and opportunities for this study. The main direction of AOPs lies on the optimization of catalyst and operating parameters, with industrial applications remain as the main challenge. This review article is expected to present a summary and in-depth understanding of AOPs development; and thus, inspiring scientists to accelerate the evolution of AOPs in industrial applications.

The Collision between g-C3 N4 and QDs in the Fields of Energy and Environment: Synergistic Effects for Efficient Photocatalysis

Recently, graphitic carbon nitride (g-C₃ N₄ ) has attracted increasing interest due to its visible light absorption, suitable energy band structure, and excellent stability. However, low specific surface area, finite visible light response range (<460 nm), and rapid photogenerated electron-hole (e^- -h⁺ ) pairs recombination of the pristine g-C₃ N₄ limit its practical applications. The small size of quantum dots (QDs) endows the properties of abundant active sites, wide absorption spectrum, and adjustable bandgap, but inevitable aggregation. Studies have confirmed that the integration of g-C₃ N₄ and QDs not only overcomes these limitations of individual component, but also successfully inherits each advantage. Encouraged by these advantages, the synthetic strategies and the fundamental of QDs/g-C₃ N₄ composites are briefly elaborated in this review. Particularly, the synergistic effects of QDs/g-C₃ N₄ composites are analyzed comprehensively, including the enhancement of the photocatalytic performance and the avoidance of aggregation. Then, the photocatalytic applications of QDs/g-C₃ N₄ composites in the fields of environment and energy are described and further combined with DFT calculation to further reveal the reaction mechanisms. Moreover, the stability and reusability of QDs/g-C₃ N₄ composites are analyzed. Finally, the future development of these composites and the solution of existing problems are prospected.

Fe2O3/diatomite materials as efficient photo-Fenton catalysts for ciprofloxacin removal

In this study, we used Fe₂O₃/diatomite material system toward ciprofloxacin (CIP) photo-Fenton removal in water under visible light (vis) excitation. The characterization of Fe₂O₃/diatomite catalysts was determined by X-ray diffraction patterns, Fourier-transform infrared analysis, inductively coupled plasma mass spectrometry, and scanning electron microscopy. The photo-Fenton catalytic activity of the Fe₂O₃/diatomite was appraised by the removal efficiency of the CIP throughout the effect of the H₂O₂ with various parameters such as initial pH, catalyst amount, and H₂O₂ amount. The results indicate that 0.2 gL^-1 Fe₂O₃/diatomite catalysts achieved the highest performance at approximately 90.03% with a 50 μL H₂O₂ concentration. Furthermore, the Fe₂O₃/diatomite catalysts have high stability, with over 80% CIP removed after five cycles. This study is inspired to develop a potential material for photo-Fenton degradation of antibiotics in wastewater.

New insight into the mechanism of ferric hydroxide-based heterogeneous Fenton-like reaction

The heterogeneous Fenton-like reaction (HeFR) has always been a research focus for environmental applications. However, it has long been difficult to reach a consensus on the reaction mechanism because the process of metal ions dissolution and its role were not well understood. In this paper, we propose the courses of organics-mediated coordination or/and reduction dissolution of ferric hydroxide to initiate the autocatalytic kinetics of phenol degradation and illustrate it through density functional theory (DFT) and experiments. With the increase of hydrogen peroxide concentration, the degradation of phenol changes from autocatalytic kinetics to first-order kinetics. Furthermore, a novel "limit segmentation method" initiated by us indicates that homogeneous reaction plays a decisive role in the phenol degradation process. The dominant roles of the reactive organics in both iron dissolution and the iron cycle and of the homogeneous reaction in the whole degradation process in the ferric hydroxide-based HeFR system are brand-new insights that pave the pathway for future research.

Stoichiometric excesses of H2O2 as dosimetry strategy: proof of concept for UVC-H2O2, dark-Fenton, and UVC-Fenton

Hydrochlorothiazide (HCT) is a pharmaceutical micropollutant highly toxic to the environment, being absolutely necessary to oxidize it completely to CO₂. Here, the variables stoichiometric H2O2 excess for (a) degradation and (b) mineralization are defined and used as metric to quantify the dosimetry of the H₂O₂. So that, dose of H₂O₂ qualifies being under- and over-dose respectively for values below and above such standards. In this work, these concepts have been elucidated across AOPs regarding the H₂O₂ degradation excess, whereas only UVC-Fenton was used regarding the H₂O₂ mineralization excess. At a H₂O₂ mineralization excess of 0.68 (equivalent to degradation excess of 36.74), oxidation via UVC-H₂O₂ enables absolute (100%) HCT degradation within 60 min; however, the mineralization of HCT demonstrated limited optimization for all AOPs employed in the beaker-like reactor of this work, being the underlying reasons investigated hereby. At best, 26.70% HCT mineralization was observed within 60 min of UVC photo-Fenton using an initial 2.00 H₂O₂ mineralization excess. Such mineralization of 26.7% is unexpectedly low considering that, in addition, the residual H₂O₂ concentration almost fully depletes within 30 min of UVC-Fenton oxidation. Taken all that together, the loss of H₂O₂ due its decomposition induced by the risen temperature from 28 to 70ºC very likely were the underlying reason preventing better mineralization performance. We successfully demonstrated 18% of mean efficiency of radical •OH consumption signals that the overheating is indeed a designer problem with the photo-reactor since a well-refrigerated photo-reactor shows a mean efficiency of 38% for the same H₂O₂ excess.

Recent Advances in the Development of Novel Iron–Copper Bimetallic Photo Fenton Catalysts

Advanced oxidation processes (AOPs) have been postulated as viable, innovative, and efficient technologies for the removal of pollutants from water bodies. Among AOPs, photo-Fenton processes have been shown to be effective for the degradation of various types of organic compounds in industrial wastewater. Monometallic iron catalysts are limited in practical applications due to their low catalytic activity, poor stability, and recyclability. On the other hand, the development of catalysts based on copper oxides has become a current research topic due to their advantages such as strong light absorption, high mobility of charge carriers, low environmental toxicity, long-term stability, and low production cost. For these reasons, great efforts have been made to improve the practical applications of heterogeneous catalysts, and the bimetallic iron–copper materials have become a focus of research. In this context, this review focuses on the compilation of the most relevant studies on the recent progress in the application of bimetallic iron–copper materials in heterogeneous photo–Fenton-like reactions for the degradation of pollutants in wastewater. Special attention is paid to the removal efficiencies obtained and the reaction mechanisms involved in the photo–Fenton treatments with the different catalysts.

Preparation of hydrochar bio-based catalyst for fenton process in dye-containing wastewater treatment

The use of synthetic dyes in the textile industry pollutes a huge amount of water. Thus, wastewater discharged from many textile companies to the receiving environment without being treated causes serious environmental and human health problems. The development of new techniques has become imperative. In this study, it was aimed to remove anionic dye (RR180) and cationic dye (BR18) by Fenton-like and adsorption process with hydrochars obtained from laurel leaves and watermelon peels. In the comparison of the adsorption and Fenton-like processes used in the dye removal of the produced bio-based materials, the Fenton-like process was selected in order to enhance the highest removal efficiency. The effects of various operating factors such as solution pH, amount of catalysts, hydrogen peroxide (H₂O₂) concentration, and initial dye concentration were evaluated on both dyes removal. The experimental results demonstrated that 99.8% RR180 dye and 98.8% BR18 dye removal efficiency were observed for an initial dye concentration of 100 mg/L with an adsorbent concentration of 1 g/L, H₂O₂ concentration of 15 μL/L, and optimum pH at the end of 60 min of reaction time. It was observed that an increase in initial dye concentration caused to decrease the dye removal efficiency. The optimum pH for the highest RR180 and BR18 dye removal was 4 and 6, respectively. It was observed that the increase in H₂O₂ concentration in the solution also decreased the dye removal efficiency. It turned out that catalysts obtained from hydrochars are an effective process for the high removal performance of cationic and anionic dyes.

Green, zero-waste pathway to fabricate supported nanocatalysts and anti-kinetoplastid agents from sugarcane bagasse

The conversion processes of sugarcane into direct-consumption sugar and juice are generating a tremendous amount of waste, the so-called sugarcane bagasse (SCB). Biochar preparation is among the practical solutions aiming to manage and valorize SCB into high added-value functional material (FM). Herein, we propose a novel zero-waste pathway to fabricate two FMs from one biomass. The SCB was first macerated and ultrasonicated to obtain the natural extract that served as bio-reducing medium. Then, the H₂O/EtOH-extracted SCB was in-situ impregnated with a bimetallic solution of copper and silver nitrates. The process produced an intermediate composite (FM₀), Ag/Cu-Ag⁺/Cu²⁺-loaded SCB which was carbonized to elaborate Ag/Cu-Biochar (FM₁), free Ag/Cu nanoparticles (FM₂) were obtained by microwaving the residual liquid waste. FM₁ exhibited high catalytic activity for the total Fenton-like degradation of methylene blue. The experimental data followed the pseudo-first and the pseudo-second order rate laws with apparent degradation rate constants K₁ 45 10^-3 min^-1 and K₂ 0.115 g.mg^-1.min^-1, respectively. FM₀, FM₁ and FM₂ were tested as new anti-kinetoplastid materials against two flagellated protozoans namely the Leishmania spp and the Trypanosoma cruzi. Notably, Ag/Cu (FM₂) showed exceptional leishmanicidal and trypanocidal effects with IC₅₀ values of 2.909 ± 0.051, 3.580 ± 0.016 and 3.020 ± 0.372 ppm for L.donovani, L. amazonensis and Trypanosoma cruzi, respectively. In this way, we combine green chemistry and agrowaste valorization in a full zero-waste process, to address the 3rd (indicator 3.3.5) and 6th (indicator 6.3.1) United Nations sustainable development goals, ″Good Health and Well-Being″ and ″Clean Water and Sanitation″.

Ferroptosis As a Mechanism for Health Effects of Essential Trace Elements and Potentially Toxic Trace Elements

Ferroptosis is a unique form of programmed cell death driven by iron-dependent phospholipid peroxidation that was proposed in recent years. It plays an important role in processes of various trace element-related diseases and is regulated by redox homeostasis and various cellular metabolic pathways (iron, amino acids, lipids, sugars), as well as disease-related signaling pathways. Some limited pioneering studies have demonstrated ferroptosis as a mechanism for the health effects of essential trace elements and potentially toxic trace elements, with crosstalk among them. The aim of this review is to bring together research articles and identify key direct and indirect evidence regarding essential trace elements (iron, selenium, zinc, copper, chromium, manganese) and potentially toxic trace elements (arsenic, aluminum, mercury) and their possible roles in ferroptosis. Our review may help determine future research priorities and opportunities.

A triphenylphosphine coordinated Cu(I) Fenton-like agent with ferrocene moieties for enhanced chemodynamic therapy

A triphenylphosphine coordinated Cu(I) complex of Fc-OD-Cu was rationally designed for chemodynamic therapy (CDT) of cancer. The complex was capable of generating a highly toxic hydroxyl radical (˙OH) via a Fenton-like reaction induced by Cu(I) moieties and simultaneously mediated by ferrocene moieties. As a result, the CDT efficiency of Fc-OD-Cu is higher than that of Ba-OD-Cu (without ferrocene moieties) and Fc-OD (without Cu(I) moieties).

Sol-gel synthesis of TiO2 on Co3O4-coated sporopollenin exine microcapsules (SECs) and photocatalytic performance of new semiconductor heterojunction material

In this study, a new approach was developed to prepare mesoporous hybrid TiO₂/Co₃O₄ coated on Juglans sporopollenin exine microcapsules (SECs). TiO₂ was synthesized on Co₃O₄-coated SECs used as substrate, by sol-gel method. The obtained semiconductor/semiconductor hetero-junction hybrid materials were characterized with X-ray diffractometry (XRD), UV-Vis absorption spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), particle size distribution, specific surface area, and zeta potential measurements. Photocatalytic performances of hybrid materials were tested for Reactive Black 5 dye under both UV and visible light. Equilibrium pH of the solution containing 10 mg/L Reactive Black 5 dye and 0.1% wt/v TiO₂/Co₃O₄ was around 4.7. After irradiation in the solar box, more than 98% of the Reactive Black 5 was photocatalytically degraded within 60 min.

Application of sludge biochar nanomaterials in Fenton-like processes: Degradation of organic pollutants, sediment remediation, sludge dewatering

In today's society, wastewater sludge has become solid waste, and the preparation of wastewater sludge into sludge biochar nanomaterials (SBCs) for resource utilization has become a promising method. SBCs have advantages over other biomasses, including their complex composition, wide range of raw materials, and especially the presence of various transition metals with catalytic properties. Heterogeneous Fenton processes using SBCs as catalyst carriers have shown great potential in the removal of pollutants. In this review, the synthesis methods of SBCs are reviewed and the effects of different synthesis methods on their physicochemical properties are discussed. Furthermore, the successful applications of raw SBCs, metal-modified SBCs, and Fenton sludge-SBCs in organic pollutant degradation, sediment remediation, and sludge dewatering are reviewed. The mechanisms occurring with different metals as active sites are explored, and the review shows that the degradation efficiency and stability of SBCs are very satisfactory. We also provide an outlook on the future development of SBCs. We hope that this review will help readers gain a clearer and deeper understanding of SBCs and promote the development of SBCs.

A novel, Z-scheme ZnO@AC@FeO photocatalyst, suitable for the intensification of photo-mediated peroxymonosulfate activation: Performance, reactivity and bisphenol A degradation pathways

In this study, the intensification of a UVC-based PMS activation treatment is performed by a novel photocatalyst. Using ZnO nanoparticles coupled with activated carbon (AC), impregnated by ferroferric oxides (FO, magnetite), as an effective Z-scheme photocatalyst (ZACFO), the effective Bisphenol A (BP-A) removal was attained. Several techniques were applied for the characterization of the as-prepared catalyst and proved the successful preparation of ZACFO. The photocatalytic activity of pristine ZnO was significantly improved after its combination with ACFO. It was found that the fabrication of ZACFO heterostructures could inhibit the charge carriers recombination and also accelerate the charge separation of photo-induced e^-/h⁺ pairs. Under this UVC-based photocatalysis-mediated PMS activation system, ZACFO showed an excellent potential as compared to the single constituent catalysts. The complete degradation of 20 mg/L concentration of BP-A was attained in just 20 min with excellent reaction rate constant of 27.3 × 10^-2 min^-1. Besides, over 60% of TOC was eliminated by the integrated ZACFO/PMS/UV system within 60 min of reaction. The minor inhibition by most matrix components, the high recycling capability with minor metals' leaching and the effectiveness in complex matrices, constitute this composite method an efficient and promising process for treating real wastewater samples. Finally, based on the photo-produced reactive intermediates and by-products identified, the Z-scheme photocatalytic mechanism and the plausible pathway of BP-A degradation were proposed comprehensively. The presence and role of radical and non-radical pathways in the decontamination process of BP-A over ZACFO/PMS/UV system was confirmed.

Altered zirconium dioxide based photocatalyst for enhancement of organic pollutants degradation: A review

Heterogeneous advanced oxidation processes are a promising approach for cost-efficient removal of pollutants using semiconductors. Zirconium dioxide (ZrO₂) is an auspicious material for photocatalytic activity owning to its suitable bandgap, stability, and low cost. However, ZrO₂ suffers from fast recombination rate, and poor light harvesting ability. Nonetheless, extra modification has also shown improvements and therefore is worth investigating. The endeavour of this paper initially discusses the fundamentals with respect to reactive species, classification, and synthesis methods for ZrO₂. Furthermore, with particular consideration to stability and reusability, several additional modification approaches for ZrO₂-based photocatalysts such as doping and noble metals loading. Furthermore, the formation of heterojunctions has also been shown to boost photocatalytic activity while inhibiting charge carrier recombination. Finally, photocatalyst separation via magnetic-based photocatalysts are elucidated. As a result, ZrO₂-based photocatalysts are regarded as a promising emerging technology that warrants further development and research.

Fabrication of Fe/Bi bimetallic magnetic nano-oxides (IBBMNOs) as efficient remediator for hexavalent chromium from aqueous environment

In this study, highly efficient Fe/Bi bimetallic magnetic nanooxides (IBBMNOs) were used as adsorbent for the removal of Cr(VI) from an aqueous environment. The IBBMNOs were synthesized by a simple and facile chemical reduction method. After that, different analytical techniques were used to characterize the resultant nanomaterial. According to characterization results, the IBBMNOs are highly porous look like cotton beads with an average size of 60-69 nm. BET results show that IBBMNOs are highly porous with a high surface area. After optimizing different parameters such as pH, adsorbent dose, and time study, an excellent adsorption capacity was achieved up to 185 mg/g in 10 min. The calculated data of the adsorption process was well fitted with Langmuir and pseudo-first-order kinetic model. The prepared materials have good usability as compared to reported adsorbent materials can be used for five different cycles with good removal efficiency of chromium ion from aqueous samples. Schematic illustration of adsorption of Cr(VI) from aqueous solution by IBBMNOs.

Cu-Ce oxide Co-loaded silicon nanocapsules for hydrogen peroxide self-supplied Fenton-like catalysis and synergistically antibacterial therapy

Antibacterial strategies based on reactive oxygen species (ROS) have opened up a new avenue for overcoming the great challenges of antibiotics topic including lack of broad-spectrum antibiotics and the emergence of super-resistant bacteria. Herein, we leveraged a strategy of constructing synergistic catalytic active sites to develop a simple yet efficient Fenton-like active nanocomposite, and investigated its catalysis mechanism and antibacterial performance thoroughly. This strategy provides a new direction for boosting the catalytic activity of nanocomposite catalysts for wide application. Specifically, by uniformly loading copper oxide and ceria onto the surface of silica nanocapsules (SiO₂ NCs), we fabricated a bimetallic oxide nanocomposite Cu_0.75Ce_0.62O₂@SiO₂ NC, which performed superior Fenton-like capability in a wide pH range without additional exogenetic hydrogen peroxide (H₂O₂). Such excellent catalytic activity was originated from the charge interaction between the two metal oxide components, where formation of Cu⁺ and oxygen vacancies (OVs) was mutually reinforcing, resulting in a synergistic effect to produce H₂O₂ and catalyze the generation of •OH under the slight acid condition (pH = 6.0). In view of the outstanding Fenton-like activity, the Cu_0.75Ce_0.62O₂@SiO₂ NC was employed in antimicrobial testing, which demonstrated exceptional high in vitro antimicrobial efficacy against both the S. aureus and E. coli in a neutral environment (pH = 7.4). The excellent performance of the bimetallic nanocomposite Cu_0.75Ce_0.62O₂@SiO₂ NC, including its facile and mild preparation, high water-solubility and stability, superior catalytic and antimicrobial performances, manifests a promising broad-spectrum antibiotic that can be anticipated to deal with the contamination of the environment by bacteria.

The application of transition metal-modified biochar in sulfate radical based advanced oxidation processes

Sulfate radical (SO₄^•-) based advanced oxidation processes (SR-AOPs) is a very important chemical oxidation technology for the degradation of recalcitrant organic pollutants in water and has been well developed. Recently, transition metals or their oxides-modified biochar has been widely used as the catalyst to catalyze peroxymonosulfate (PMS) and peroxydisulfate (PS) in SR-AOPs due to their outstanding properties (e.g., large surface area, high stability, abound catalytic sites, and diversity of material design, etc.). These composite materials not only combine the respective beneficial characteristics of biochar and transition metals (or their oxides) but also often present synergistic effects between the components. In this review, we present the synthesis of different types of transition metal (or metal oxides)/biochar-based catalysts and their application in SR-AOPs. The catalytic mechanism, including the generation process of free radicals and other reaction pathways on the surface of the catalyst were also carefully discussed. Particular attention has been paid to the synergistic effects between the components that result in enhanced catalytic performance. At the end of this review, the future development prospects of this technology are proposed.

MOF/POM hybrids as catalysts for organic transformations

Insertion of molecular metal oxides, e.g. polyoxometalates (POMs), into metal-organic frameworks (MOFs) opens up new research opportunities in various fields, particularly in catalysis. POM/MOF composites have strong acidity, oxygen-rich surface, and redox capacity due to typical characteristics of POMs and the large surface area, highly organized structures, tunable pore size, and shape are due to MOFs. Such hybrid materials have gained a lot of attention due to astonishing structural features, and hence have potential applications in organic catalysis, sorption and separation, proton conduction, magnetism, lithium-ion batteries, supercapacitors, electrochemistry, medicine, bio-fuel, and so on. The exceptional chemical and physical characteristics of POMOFs make them useful as catalysts in simple organic transformations with high capacity and selectivity. Here, the thorough catalytic study starts with a brief introduction related to POMs and MOFs, and is followed by the synthetic strategies and applications of these materials in several catalytic organic transformations. Furthermore, catalytic conversions like oxidation, condensation, esterification, and some other types of catalytic reactions including photocatalytic reactions are discussed in length with their plausible catalytic mechanisms. The disadvantages of the POMOFs and difficulties faced in the field have also been explored briefly from our perspectives.

Confinement-Enhanced Selective Oxidation of Lignin Derivatives to Formic Acid Over Fe-Cu/ZSM-5 Catalysts Under Mild Conditions

Aqueous-phase oxidation by H₂ O₂ , known as the Fenton-type process, provides an attractive route to convert recalcitrant lignin derivatives to valuable chemicals under mild conditions. The development of this technology is, however, limited by the uncontrolled selectivity, resulting from the highly reactive nature of H₂ O₂ and the thermodynamically favored deep oxidation to form CO₂ . This study demonstrated that formic acid could be produced with a high selectivity (up to 80.3 % at 313 K) from the Fenton-type oxidation of guaiacol and several other lignin derivatives over a bimetallic Fe-Cu catalyst supported on a ZSM-5 zeolite. Combined experimental and theoretical investigations unveiled that the micropores of the zeolite support, which contained active metal sites, preferred to adsorb C₂ -C₄ intermediates over formic acid because of its stronger dispersive interaction with the larger guest molecules. This confinement effect significantly suppressed the secondary oxidation of formic acid, accounting for the uniquely high formic acid selectivity over Fe-Cu/ZSM-5.

Enhanced catalytic performance of Cu-doped MnFe2O4 magnetic ferrites: Tetracycline hydrochloride attacked by superoxide radicals efficiently in a strong alkaline environment

It is important to develop a catalyst that can maintain good activity in alkaline environment for Fenton or Fenton-like reactions. In order to achieve stable Fenton catalytic degradation in a wide pH range, this study reports Cu-doped MnFe₂O₄ heterogeneous catalysts still has excellent effect when the pH is extended to 11 for removing organic pollutants, such as tetracycline hydrochloride (TC-HCl). The synergistic effect among Fe, Mn and Cu ions has been proved to enhanced the catalytic activity in this work. When the molar ratio of Cu/Mn = 4:1, the porous Cu_0·8Mn_0·2Fe₂O₄ materials had the highest photo-Fenton catalytic activity compared with pure MnFe₂O₄, CuFe₂O₄ and other Cu_xMn_1-xFe₂O₄. The XPS showed that Cu_0·8Mn_0·2Fe₂O₄ formed oxygen vacancies, which exposed more active sites to attract more H₂O₂ for TC-HCl degradation. Results indicated 94.3% of TC-HCl was efficiently degraded by 0.1 g/L Cu_0·8Mn_0·2Fe₂O₄ with 50 mM H₂O₂ at pH = 11 under 30 min visible light irradiation, and the corresponding apparent rate constant was 0.08286 min^-1. With free radicals quenching experiment, O₂^- was responsible for the high catalytic degradation and OH was participated in the photo-Fenton reaction. To sum up, Cu_0·8Mn_0·2Fe₂O₄ exhibited high activity, great stability and easily recyclable, which eliminated the pH limitation of the Fenton reaction and provided practical application performance for water purification.

Derivatives of metal-organic frameworks for heterogeneous Fenton-like processes: From preparation to performance and mechanisms in wastewater purification - A mini review

Organic pollution is an ever-growing issue in aquatic environment, Fenton-like processes have gained widespread acceptance due to their high oxidative potential and environmental compatibility. Derivatives of metal-organic frameworks (MOFs) are emerging heterogeneous Fenton-like catalysts, which have advantages of large surface area, diversity of structures, and abundant active sites. This work focuses on the recent advances in MOFs derivatives including metal compounds and metal incorporated carbons for Fenton-like processes. First, preparation strategies, structures and compositions are introduced. And then, the removal of organic pollutant in Fenton, electro-Fenton, and photo-Fenton process catalyzed by MOFs derivative is summarized, respectively. The contents particularly devote efforts to build connections among preparation, structures, compositions, and performance. Furthermore, the mechanisms of improving performance are discussed in detail. Finally, the perspectives of MOFs derivatives toward Fenton-like applications are proposed.

Fulvic acid degradation in Fenton-like system with bimetallic magnetic carbon aerogel Cu-Fe@CS as catalyst: Response surface optimization, kinetic and mechanism

In this study, Cu-Fe bimetallic magnetic chitosan carbon aerogel catalyst (Cu-Fe@CS) was prepared by the sol-gel method to degrade Fulvic acid (FA) in Fenton-like system. Degradation experiment results showed bimetallic catalyst Cu-Fe@CS can degrade more FA than monometallic catalysts (Cu@CS and Fe@CS) due to the synergistic effect between the copper and iron. Plackett Buiman (PB) design showed that pH and temperature exhibited significant influence on FA degradation. The significant factors were optimized by Central Composite Design (CCD), the results revealed that the maximum FA removal reached 96.59% under the conditions of pH 4.07 and temperature 93.77 °C, the corresponding TOC removal reached 77.7%. The kinetic analysis implied that the reaction followed pseudo-first order kinetic with correlation coefficient (R²) = 0.9939. The Arrhenius fitting analysis revealed that Cu-Fe@CS had a lower activation energy (Ea) than Cu@CS and Fe@CS, meaning that reaction was easier to occur in Fenten-like system with Cu-Fe@CS. Catalyst still remained the higher FA and TOC removals of 96.28% and 77.33% after six runs, respectively. The FA removal was reduced by 65.53% with 12 mmol tertiary butanol (TBA) as scavenger, indicating that •OH played an important role in FA degradation. Finally, the catalytic degradation mechanism was proposed.

Interlayer Structure Manipulation of Iron Oxychloride by Potassium Cation Intercalation to Steer H2O2 Activation Pathway

Structural regulation of the active centers is often pivotal in controlling the catalytic functions, especially in iron-based oxidation systems. Here, we discovered a significantly altered catalytic oxidation pathway via a simple cation intercalation into a layered iron oxychloride (FeOCl) scaffold. Upon intercalation of FeOCl with potassium iodide (KI), a new stable phase of K⁺-intercalated FeOCl (K-FeOCl) was formed with slided layers, distorted coordination, and formed high-spin Fe(II) species compared to the pristine FeOCl precursor. This structural manipulation steers the catalytic H₂O₂ activation from a traditional Fenton-like pathway on FeOCl to a nonradical ferryl (Fe(IV)═O) pathway. Consequently, the K-FeOCl catalyst can efficiently remove various organic pollutants with almost 2 orders of magnitude faster reaction kinetics than other Fe-based materials via an oxidative coupling or polymerization pathway. A reaction-filtration coupled process based on K-FeOCl was finally demonstrated and could potentially reduce the energy consumption by almost 50%, holding great promise in sustainable pollutant removal technologies.