Simple Co-precipitation Method Research Articles

In Situ Growth of Sodium Manganese Hexacyanoferrate on Carbon Nanotubes for High-Performance Sodium-Ion Batteries.

Sodium manganese hexacyanoferrate (NaMnHCF) has emerged as a research hotspot among Prussian blue analogs for sodium-ion battery cathode materials due to its advantages of high voltage, high specific capacity, and abundant raw materials. However, its practical application is limited by its poor electronic conductivity. In this study, we aim to solve this problem through the in situ growth of NaMnHCF on carbon nanotubes (CNTs) using a simple coprecipitation method. The results show that the overall electronic conductivity of NaMnHCF is significantly improved after the introduction of CNTs. The NaMnHCF@10%CNT sample presents a specific capacity of 90 mA h g-1, even at a current density of 20 C (2400 mA g-1). The study shows that the optimized composite exhibits a superior electrochemical performance at different mass loadings (from low to high), which is attributed to the enhanced electron transport and shortened electron pathway. Surprisingly, the cycling performance of the composites was also improved, resulting from decreased polarization and the subsequent reduction in the side reactions at the cathode/electrolyte interface. Furthermore, we revealed the evolution of potential plateau roots from the extraction of crystal water during the charge-discharge process of NaMnHCF based on the experimental results. This study is instructive not only for the practical application of NaMnHCF materials but also for advancing our scientific understanding of the behavior of crystal water during the charge-discharge process.

Fabrication of Ni and Mn co-doped ZnFe2O4 spinel ferrites and their nanocomposites with rGO as an efficient photocatalyst for the remediation of organic dyes

Herein, we have synthesized Ni and Mn co-doped ZnFe2O4 ferrites using the simple co-precipitation method and their nanocomposites (NCs) with 10 % rGO using the ultra-sonication route. The structural investigation revealed the successful formation of single-phase ZnFe2O4 NPs with cubic spinel ferrite geometry. The crystallite size was determined to be in the range of 21 nm to 28 nm. The current–voltage (I-V) analysis revealed that Ni and Mn co-doping and the addition of rGO nanosheets in ZnFe2O4 NPs boosted the electrical responses of the fabricated Zn1-xNixFe2-yMnyO4/rGO NCs. The BET analysis indicates an increase in the surface area of Zn1-xNixFe2-yMnyO4/rGO NCs (132 m2/g) that might be attributed to the inclusion of rGO nanosheets, which prevents the NPs from agglomeration. The photocatalytic evaluation of the pristine ZnFe2O4 NPs, Ni and Mn co-doped Zn1-xNixFe2-yMnyO4 NPs, and Zn1-xNixFe2-yMnyO4/rGO NCs photocatalysts was tested by photodegradation of malachite green (MG) dye under sunlight irradiation. Results exhibited improved photocatalytic responses and degraded 94.6 % of MG dye in 45 min using Zn1-xNixFe2-yMnyO4/rGO NCs, which was much higher compared to the Ni and Mn co-doped Zn1-xNixFe2-yMnyO4 NPs (58.7 %) and pristine ZnFe2O4 NPs (38.3 %). The increased degradation potential of Zn1-xNixFe2-yMnyO4/rGO NCs was accredited to the highly conducting nature and 2D nano-sheets of rGO, which efficiently inhibited the recombination of charge carrier species. Ultimately, the remarkable photocatalytic capability exhibited by Zn1-xNixFe2-yMnyO4/rGO NCs implies that the synthesized NCs could have auspicious practical applications in the elimination of dyes from wastewater.

Phase Transition of Thermally Treated Polyhedral Nano Nickel Oxide with Reduced Band Gap

Nickel oxide (NiO) is a semiconducting material which exhibits a unique electronic structure. Because of its distinctive electronic properties, NiO stands as an intriguing candidate for various applications in optoelectronics, photo catalysis, and energy devices such as solar cells. In the present work efforts have been made to tailor the band gap of NiO. A simple co-precipitation method followed by heat treatment is utilized to synthesize the material. Prior to heat treatment, x-ray diffraction study of the as synthesized material showed the presence of nickel hydroxide [Ni(OH)2]. On calcination for one hour at 1000oC, a single phase NiO wasrevealed. After heat treatment it was noticed that the particle size was found to be increased. The absorption spectra of [Ni(OH)2] and NiO were recorded using UV-Vis spectroscopy method. Using Tauc plot a band gap of 4.2 eV and 1.8 eV for Ni(OH)2 and NiO was observed respectively. It is observed that a significant decrease in band gap of NiO was noticed. Surface morphological study was carried out by using FESEM, which revealed the transformation of sheet like structures of [Ni(OH)2] to polyhedral shaped NiO on calcination. The presence of nickel and oxygen was confirmed by the energy dispersive spectrometry analysis.

Nickel and cobalt-based tungstate nanocomposites as promising electrocatalysts in alkaline direct methanol fuel cells.

In this work, a non-precious group metal (non-PGM) electrocatalyst based on transition metals is introduced as a promising solution for enhancing the efficiency of direct methanol fuel cell (DMFC). Nickel-cobalt mixed tungstate was prepared using a simple co-precipitation method with different molar ratios of Ni, Co and W. The prepared materials were tested and validated using different characterization techniques. It was observed using SEM that the materials are agglomerated amorphous random circular nanocomposite structures. The electrochemical performance of the prepared electrocatalysts revealed that the best nanocomposite was the one with the Ni : Co : W ratio of 1 : 1 : 1.5 (W1.5). This composite showed a higher current density of 229 mA cm-2 towards methanol oxidation at a scan rate of 50 mV s-1 in 1 M methanol at 0.6 V, with the lowest onset potential of 0.33 V. The obtained results present a new strong non-PGM material for direct methanol electro-oxidation reactions and open new doors for economic and earth-abundant electrocatalysts as an alternative to expensive commercially available catalysts.

Engineering of Co3O4 electrode via Ni and Cu-doping for supercapacitor application.

Although cobalt oxides show great promise as supercapacitor electrode materials, their slow kinetics and low conductivity make them unsuitable for widespread application. We developed Ni and Cu-doped Co3O4 nanoparticles (NPs) via a simple chemical co-precipitation method without the aid of a surfactant. The samples were analyzed for their composition, function group, band gap, structure/morphology, thermal property, surface area and electrochemical property using X-ray diffraction (XRD), ICP-OES, Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-visible (UV-Vis), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and/or Differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET), and Impedance Spectroscopy (EIS), Cyclic voltammetry (CV), respectively. Notably, for the prepared sample, the addition of Cu to Co3O4 NPs results in a 11.5-fold increase in specific surface area (573.78m2g-1) and a decrease in charge transfer resistance. As a result, the Ni doped Co3O4 electrode exhibits a high specific capacitance of 749Fg-1, 1.75 times greater than the pristine Co3O4 electrode's 426Fg-1. The electrode's enhanced surface area and electronic conductivity are credited with the significant improvement in electrochemical performance. The produced Ni doped Co3O4 electrode has the potential to be employed in supercapacitor systems, as the obtained findings amply demonstrated.

Simple co-precipitation synthesis of activated carbon-cobalt ferrite (AC-CoFe2O4) nanocomposites: enhanced photocatalytic dye degradation and antimicrobial activity

Abstract In this present work, spinel cobalt ferrite nanoparticles (CoFe2O4 NPs) and activated carbon-CoFe2O4 nanocomposites (AC-CoFeO4 NCs) were synthesized by simple co-precipitation method and used for photocatalytic dye degradation (PCD) of rhodamine-B (Rh-B) dye. The antimicrobial study of the as-synthesized CoFe2O4 NPs was also performed. The as-synthesized CoFe2O4 NPs and AC-CoFe2O4 NCs were analyzed by ultraviolet spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) studies, scanning electron spectroscopy (FE-SEM) techniques. Powder XRD analysis showed that the as-synthesized CoFeO4 NPs and AC-CoFeO4 NCs had average particle size of 18 nm and 46 nm, respectively. The FE-SEM showed that the CoFe2O4 samples have sphere like morphology and were well decorated on activated carbon in order to provide high surface area. AC-CoFe2O4 NCs have effectively used for the PCD of Rh-B dye with high efficiency. Furthermore, spinel CoFe2O4 NPs acted as a more effective antimicrobial agent against Gram-negative and Gram-positive bacterial strains. Moreover, AC-CoFe2O4 NCs can be used as the precursor materials for supercapacitor, sensors etc.

Design of TiO2/ZIF‐8 heterojunction with enhanced visible‐light photocatalytic activity under mild conditions

AbstractThe development of new composite materials is of great significance to improve the photocatalytic degradation efficiency. In this article, the TiO2/ZIF‐8 composite materials (TZCM) have been designed via the combination of hydrothermal‐assisted liquid phase deposition and the simple coprecipitation method. The experimental results indicate that the TiO2 and ZIF‐8 nanoparticles can be tightly bonded together by chemical bonds. Moreover, the TZCM also exhibit a significantly increased specific surface area and a reduced band gap width, which would provide more active sites and realize the visible‐light response during the photocatalytic process. The photodegradation rate and the corresponding first‐order reaction rate of methylene blue within 24 min by TiO2/ZIF‐8 composite material (e.g., sample TZCM‐3) is 93.36% and 0.1376 min−1, which is 31 times and 17 times that of pristine TiO2 and ZIF‐8, respectively. According to the photoelectrochemical experiments, the separation efficiency of photogenerated electrons and holes in TZCM sample during the photocatalytic process could be significantly enhanced.

Characterization and Antibacterial Potential of Iron Oxide Nanoparticles in Eradicating Uropathogenic E. coli.

Proper management and control measurements are needed to stop the spread of highly pathogenic E. coli isolates that cause urinary tract infections (UTI) by developing new antibacterial agents to ensure the safety of public health. Therefore, the present investigations were used to achieve the synthesis of iron oxide nanoparticles (IONPs) via a simple coprecipitation method using ferric nitrates Fe (NO3)3 as the precursor and hydrazine solution as the precipitator and to explore the antibacterial activity against eradicating Uropathogenic Escherichia coli (E. coli). The synthesized IONPs were further studied using a UV-vis spectrophotometer, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopic (SEM) analysis. The maximum surface plasmon resonance peak was observed as absorption at 320 nm in a colloidal solution to validate the synthesis of IONPs. The FT-IR analysis was used to identify different photoactive functional groups that were responsible for the reduction of Fe (NO3)3 to IONPs. The crystalline nature of synthesized IONPs was revealed by XRD patterns with an average particle size ranging as 29 nm. The SEM image was employed to recognize the irregular morphology of synthesized nanoparticles. Moreover, significant antibacterial activity was observed at 1 mg/mL stock solution but after (125, 250, and 500 μg/mL) dilution, the synthesized IONPs showed moderate activity and became inactive at lower concentrations. The morphological and biochemical tests were used to confirm the presence of E. coli in the samples. Furthermore, the minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) were carried out to determine the inhibitory concentrations for the isolated bacteria. The isolated E. coli were also subjected to antibiotic sensitivity testing that showed high resistance to antibiotics such as penicillin and amoxicillin. Thus, the findings of this study were to use IONPs against antibiotic resistance that has been developed in an inappropriate way.

Synthesis of Highly Luminescent Silica-Coated Upconversion Nanoparticles from Lanthanide Oxides or Nitrates Using Co-Precipitation and Sol-Gel Methods.

Upconversion nanoparticles (UCNPs) are under consideration for their use as bioimaging probes with enhanced optical performance for real time follow-up under non-invasive conditions. Photostable and core-shell NaYF4:Yb3+, Er3+-SiO2 UCNPs obtained by a novel and simple co-precipitation method from lanthanide nitrates or oxides were herein synthesized for the first time. The sol-gel Stöber method followed by oven or supercritical gel drying was used to confer biocompatible surface properties to UCNPs by the formation of an ultrathin silica coating. Upconversion (UC) spectra were studied to evaluate the fluorescence of UCNPs upon red/near infrared (NIR) irradiation. ζ-potential measurements, TEM analyses, XRD patterns and long-term physicochemical stability were also assessed and confirmed that the UCNPs co-precipitation synthesis is a shape- and phase-controlling approach. The bio- and hemocompatibility of the UCNPs formulation with the highest fluorescence intensity was evaluated with murine fibroblasts and human blood, respectively, and provided excellent results that endorse the efficacy of the silica gel coating. The herein synthesized UCNPs can be regarded as efficient fluorescent probes for bioimaging purposes with the high luminescence, physicochemical stability and biocompatibility required for biomedical applications.

Designing the major active site of Cu atom for OER via a composite electrocatalyst of Agx@HEO: Experiment and theory

Copper element with low chemical activity is hard to be used as the major active site for oxygen evolution reaction (OER). To improve its OER performance, a specialized structural and chemical environments need be designed. In this work, the composite electrocatalyst of Agn@HEO were synthesized by a simple co-precipitation plus annealing methods. With the aid of the elemental Ag0 atom, part of Cu ions in high entropy oxide (HEO) phases were gradually transferred to the elemental Cu0 atoms and mixed with Ag0 atom for CuAg alloy. This transition evidently altered the chemical environments of Cu element. Thanks to the largest molar percentage of Cu0 atom, the designed Ag1@HEO specimen exhibited the fairly low experimental OER overpotential of 249 (308) mV at the current density of 10 (100) mA cm−2 with the small Tafel slope of 55.2 mV dec-1 and stable electrocatalytic activity. Based on the density functional theory simulation, the theoretical OER overpotential of Cu active site could be adjusted along with the ridges of “volcanic” in both atomic and ionic environments, and achieved the smallest value of 213 mV as the d band center of Cu0 atom had a suitable value near the “volcanic” peak. This design strategy would be adopted to provide an effective enhancement scheme for OER on Cu active site.

Spectroscopic properties and thermal stability of a Mn4+-doped polyfluoride phosphor for application in solid-state lighting

In this study, an efficient polyfluoride red-emitting phosphor, Cs3RbGe2F12:Mn4+ (denoted as CRGF:Mn), has been synthesized using a simple co-precipitation method. The crystal and electronic structures, spectroscopic properties, and photoluminescence thermal stability of CRGF:Mn have been systematically characterized. The results show that Mn4+ ions experience a strong crystal field and present a series of intense red emission peaks under blue light excitation. Moreover, CRGF:Mn exhibits a high color purity (95.1 %), high internal quantum efficiency (82.4 %), and enhanced photoluminescence thermal stability at 150 °C, with an intensity of 113 % relative to room temperature. A warm white light-emitting diode exhibiting a low correlated color temperature (3572 K), high color rendering index (90.7), and suitable luminous efficiency (132.6 lm/W) was prepared using CRGF:Mn as a red component, demonstrating viable application in solid-state lighting.

Experimental evaluation of kinetics and biochemical characteristics of MnO2 nanoparticles as high throughput peroxidase-mimetic nanomaterials

Despite the well-known concepts on the intrinsic peroxidase-like activity of MnO2 nanoparticles, up to date, their biochemical and kinetics characteristics were not investigated, especially, the current information about their performances toward n-electron oxidation of 3, 3′-diaminobezedine for producing indamine polymers is on limitation. Therefore, herein, the MnO2 nanoparticles were synthesized by a simple low-cost co-precipitation method and then characterized by XRD, SEM, and DLS analysis. Besides, their peroxidase-like activity was evaluated upon standard peroxidase enzyme assay, revealing high intrinsic peroxidase-like activity for the as-mentioned MnO2 nanozymes. Considering their high intrinsic peroxidase-like activity, their optimal biochemical characteristics were quantified by probing the progress of -electron irreversible oxidation of 3, 3′-diaminobezedine in the presence of MnO2 nanozymes as peroxidase mimics. The maximal activity of the as-mentioned MnO2 nanoparticles with high intrinsic peroxidase-like activity was observed when the pH and temperature of the reaction media were fixed over 3.0–6.0 and 23℃–25℃, in order, revealing very high pH and thermal stability of the as-prepared nanoparticles. The salt stability of these nanoparticles was also checked using NaCl as model salt, revealing that the nanozymatic activity was stable over a salt concentration as high as 3–7 M. In addition, the affinity constant (Km) and maximum velocity of the nanozyme-catalyzed oxidation of 3, 3′-diaminobezedine were found to be 1.6 mM and 47 nM sec−1, in turn.

Electric double layer capacitive adsorption and faradaic pseudo-capacitance behavior of ZnFe-PANI/CNT electrode for phosphate removal in capacitive deionization

Capacitive deionization technology possesses puissant competitiveness in the field of water treatment due to its low cost and high efficiency. In this study, polyaniline (PANI) doped and carboxyl intercalated metal hydroxide composite (ZnFe-PANI/CNT) was developed by a simple co-precipitation method, and used as anode electrode for phosphate removal in sewage. The results show that ZnFe-PANI/CNT electrode can efficiently remove phosphate at concentration of 2–10 mg/L at a wide range of pH (3–10) by electric double layer capacitive adsorption and pseudocapacitive adsorption. The concentration of phosphate in the effluent was as low as 0.095 mg/L, and the coexisting anions (Cl−, NO3−, SO42− and HCO3−) hardly inhibited the phosphate adsorption by ZnFe-PANI/CNT composite electrode. In addition, under the optimal phosphate adsorption conditions (pH = 7 and applied voltage of 1.2 V), the energy consumption of CDI system was calculated as low as 0.00274 kWh/g P and 0.017 kWh/m3 water, realizing the expectation of low cost and high efficiency operation.

Solar photoactive magnesium substituted copper ferrite photocatalysts for Rose Bengal treatment

In the present investigation, we have reported solar photo active, cost effective and magnetically recoverable magnesium substituted copper ferrites successfully prepared by simple co-precipitation method. The prepared materials were characterized for structural and microstructural analysis using PXRD, SEM, EDS, FT-IR and UV–Visible spectroscopy. It was observed that, when copper introduces into magnesium ferrite system light absorption shifted to visible region, this is due to formation of metastable energy levels just below the conduction band of magnesium ferrites. As a result an MgCuFe2O4 catalyst exhibits excellent efficiency under solar light irradiation. These catalysts are stable for longer period even after many runs and magnetically separable. Based on the analysis result these nanomaterials can be used as potential environmental and energy applications under natural sunlight irradiation.

Modelling the magnetization data of Fe3O4 nanoparticles above blocking temperature

Nanoparticles of Fe3O4 are prepared by simple co-precipitation method. The sample is characterized using an x-ray diffractometer, transmission electron microscope, and vibrating sample magnetometer. The x-ray diffraction pattern of the sample clearly shows that it is a single-phase magnetite. The transmission electron micrograph shows that the sample has a narrow distribution in particle size with average particle size of 9.9 nm. The SAED pattern only shows the diffraction planes correspond to magnetite and no other phase impurity is detected. The calculated thickness of the magnetic disordered shell due to the reduction in particle size is found to be 1.7 nm. The magnetization of the sample is measured as a function of temperature and applied magnetic field. The zero-field cooled and field cooled curves of the sample are measured in the presence of 250 Oe applied magnetic field and both the curves bifurcate at 170 K. The peak in the zero-field curve indicates that the sample has a blocking temperature of around 100 K. The magnetization as a function of applied magnetic field data at 200, 225, 250, 275 and 300 K are measured (up to ±20 kOe). These magnetization data are used for the fitting to analyze the magnetic behavior of Fe3O4 nanoparticles. . The magnetization of nanoparticles systems is influenced by several factors such as particle size distribution, disordered surface, magnetocrystalline anisotropy, magnetic moment distribution and magnetic interactions. The ignorance of such factors while analyzing the magnetization data leads to discrepancies in the results. The surface effects are sensitive to the reduction in particle size leading to the spin frustrations on the surface suggesting a magnetic disordered layer which affect the magnetic behavior of nanoparticles. This work presents the analysis of the magnetization data in an appropriate magnetization expression which takes into consideration the effect of magnetic moment distribution. This distribution in the magnetic moment is found to be significantly influenced the magnetization analysis and affected by the magnetic disordered surface which accounts for the presence of magnetic anisotropy and magnetic interactions on the particles surface. The results and observations are discussed in detail.

Photocatalytic activity of Fe3O4–Fe2O3 particles supported on mordenite under visible light exposure for methylene blue degradation

Dyes pollution is a serious environmental problem and heterogeneous catalysis has been proposed as a remediation method. In this study, a set of catalysts of synthetic mordenite with iron oxides was synthesized by a simple chemical co-precipitation method assisted by subsequent thermal treatment with an oxidation process. Physicochemical characterization of prepared materials was performed by a variety of techniques, including XRD, SEM, EDS, SBET, UV–Vis DR, and XPS. Photocatalytic methylene blue (MB) degradation by the synthesized catalyst was evaluated with visible light excitation. From the studied set of catalysts, the sample prepared with a thermal treatment at 100 °C in air atmosphere for 3 h was capable of degrading ~ 90% of MB after 120 min with visible light of λ = 420 nm exposition and a small portion of H2O2 added. The catalyst used three processes to degrade MB: (1) adsorption of organic residues in the mordenite matrix support for electrostatic interactions, (2) photocatalysis heterogeneous reaction with visible light and (3) Fenton reaction catalyst with a small portion to H2O2 by Fe3O4–Fe2O3 presence. The catalytic efficiency to dye degradation was improved by a simple and economical thermal treatment without changing reaction conditions like pH, temperature, dose, or other. Studied mordenite iron oxide catalysts can be retrieved and reused at least five times without noticeable degradation, taking advantage of their magnetic properties. These catalysts could be proposed an economical, simple, and non-toxic alternative for eliminating organic dye pollution using visible light or solar irradiation in wastewater remediation related to textile, food, and pharmaceutical industries.

KCl mediated Ag/Co@Fe2O3/C3N4 heterojunction as a highly efficient visible photocatalyst for tetracycline degradation: Application of machine learning

In this work a new KCl mediated Ag/Co@Fe2O3/C3N4 heterojunction was synthesized by a simple coprecipitation method and was characterized. The band gap of the synthesized heterojunction was calculated as 2.1ev indicating its good potential for using as visible light photocatalyst. The synthesized heterostructure was used for photodegradation of tetracycline and the experimental conditions were optimized. The results showed with 0.04g of heterostructure catalyst, the degradation of tetracycline 50ppm can be perform in a short time (40 min ) with efficiency 100%. The enhanced photoactivity of this catalyst is due to unique structure of KCl mediated Ag/Co@Fe2O3/C3N4 heterojunction that can decrease the charge recombination and therefore, leading highly efficient visible light photocatalyst. Experimental data also were analyzed using various regression models based on machine learning techniques, particularly neural networks. The outcomes reveal the effectiveness of neural network models as they demonstrate negligible Mean Root Squared Error (MRSE) values and nearly perfect R-squared scores. This highlights the excellence and accuracy of the neural network models in capturing and predicting the patterns and trends within the experimental data.

Investigating the electrochemical and antibacterial activities of nickel pyrophosphate [a-Ni2P2O7] nanostructures

Nickel pyrophosphate nanostructures have been synthesized by a simple co-precipitation method. Annealing temperature affected the crystal structure formation of α-Ni2P2O7 and altered the surface morphology. By increasing the annealing temperature from 350 °C to 900 °C, the morphology of the material varies from irregularly shaped agglomerated particles to dumbbell-shaped nanoparticles respectively. The electrochemical performance of α-Ni2P2O7 nanoflakes (NP-2) and dumbbell-shaped (NP-3) nanoparticles is tested at 1 M KOH electrolyte solution, which provides the maximum specific capacitance of 146 and 121 F g−1 at a current density of 0.8 A g−1 respectively. Furthermore, the antibacterial activity of NP-2 nanoflakes is tested against different pathogenic Gram-positive and Gram-negative bacteria. The highest value of the inhibition zone exhibits the good antibiotic nature of the α-Ni2P2O7 nanoflakes.

Facilely prepared heterogeneous Fenton catalyst Fe(Fe0.69Al0.31)2O4@C for catalytic wet peroxide oxidation of ciprofloxacin in batch and continuous reactor: Reaction intermediates and toxicity evaluation

Herein, by using a simple co-precipitation method Al-doped magnetite spinel nanoparticle encapsulated in the carbon matrix Fe(Fe0.69Al0.31)2O4@C was synthesised and its catalytic activity was examined as a heterogeneous Fenton catalyst towards the catalytic wet peroxide oxidation (CWPO) of antibiotic pollutant 20 ppm ciprofloxacin (CIP) in batch and continuous reactors. Under the optimized conditions, 0.5 g·L-1 Fe(Fe0.69Al0.31)2O4@C in batch reactor mineralized 51 % of CIP was achieved within 180 min at 50 °C and pH 3 by utilizing 1.2 mM or 4S H2O2 (S = stoichiometry; 47 mol H2O2:1 mol CIP) which is significantly less concentration compared to other heterogeneous Fenton catalysts. Impressive long-lasting catalytic activity was demonstrated in the up-flow fixed bed reactor, for 110 h with 44 % TOC removal and less than 1 ppm Fe leaching in the effluent water. Kinetic studies on the rate of decomposition of H2O2 revealed that Fe(Fe0.69Al0.31)2O4@C effectively decomposed the H2O2 like the homogeneous Fenton catalyst. The XPS results confirmed the influence of Al on iron ions in the magnetite structure through a substantial shift in higher binding energy for Fe3+ and introduced a more electropositive character on the Fe3+(δ+) that successively expedites the kinetically slow Fe3+ reduction reaction with H2O2 to produce HOO•. The π electrons of the graphitic carbon facilitate the electron transfer between the carbon matrix and Fe(Fe0.69Al0.31)2O4 nanoparticles to enhance the CIP degradation. The acute toxicity assessment studies validated the non-toxic nature of the effluent water obtained from batch and continuous reactors. A degradation pathway was proposed based on the eleven intermediate products identified using LC-HRMS analysis.

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.