CuFe2O4 Magnetic Nanoparticles Research Articles

Magnetic CuFe2O4 Nanoparticles Immobilized on Modified Rice Husk-Derived Zeolite for Chlorogenic Acid Adsorption

Adsorption has emerged as a promising method for removing polyphenols in water remediation. This work explores chlorogenic acid (CGA) adsorption on zeolite-based magnetic nanocomposites synthesized from rice husk waste. In particular, enhanced adsorbing materials were attained using a hydrothermal zeolite precursor (Z18) synthesized from rice husk and possessing a remarkable specific surface area (217.69 m2 g−1). A composite material was prepared by immobilizing magnetic copper ferrite on Z18 (Z18:CuFe2O4) to recover the zeolite adsorbent. In addition, Z18 was modified (Z18 M) with a mixture of 3-aminopropyltriethoxysilane (APTES) and trimethylchlorosilane (TMCS) to improve the affinity towards organic compounds in the final nanocomposite system (Z18 M:CuFe2O4). While the unmodified composite demonstrated inconsequential CGA removal rates, Z18 M:CuFe2O4 could adsorb 89.35% of CGA within the first hour of operation. Z18 M:CuFe2O4 showed no toxicity for seed germination and achieved a mass recovery of 85% (due to a saturation magnetization of 4.1 emu g−1) when an external magnetic field was applied. These results suggest that adsorbing magnetic nanocomposites are amenable to CGA polyphenol removal from wastewater. Furthermore, the reuse, revalorization, and conversion into value-added materials of agro-industrial waste may allow the opportunity to implement sustainability and work towards a circular economy.

Magnetic CuFe2O4 nanoparticles immobilized on mesoporous alumina as highly efficient peroxymonosulfate activator for enhanced degradation of tetracycline hydrochloride

Nanoscaled magnetic copper ferrite (CuFe2O4) is widely used as a peroxymonosulfate (PMS) activator but suffers from agglomeration owing to its inherent magnetic properties and high surface energy. In this work, spinel structured CuFe2O4 anchored on mesoporous alumina (denoted as CFO@AO) were synthesized, characterized, and applied as a PMS activator for the removal of tetracycline hydrochloride (TC·HCl). Approximately 97.5 % of TC·HCl was decomposed within 10 min in 30 %–CFO@AO (0.2 g/L)/PMS (0.3 g/L) system, and the corresponding kinetic rate constant of 30 %–CFO@AO/PMS (0.417 min−1) was around 1.57 times higher than that of CuFe2O4/PMS (0.266 min−1), which indicating that the existence of synergistic catalysis between CuFe2O4 and Al2O3 enhanced the degradation of TC·HCl. Moreover, nano-sized CuFe2O4 were successfully anchored on the surface of Al2O3 because of FeOAl bond, which could account for the enhanced catalytic activity, superior pH flexibility, and high chemical stability and reusability of 30 %–CFO@AO. Quenching experimentals, electron paramagnetic resonance, and methyl phenyl sulfoxide (PMSO) chemical probe assays confirmed that both radical oxidation (OH) and non-radical oxidation (1O2 and Fe(IV)O) were proposed in the developed CFO@AO/PMS system, and OH played a key role in the process. Meanwhile, the PMS activation mechanism by CFO@AO composite was also analyzed based on the results of adsorption energy, which was calculated via DFT. Based on UPLC–MS technique, a possible degradation pathway for TC·HCl destruction in 30 %–CFO@AO/PMS system was proposed. The toxicity assessment showed that the catalytic degradation of TC·HCl in 30 %–CFO@AO/PMS system reduced the toxicity of most of degradation intermediates. Present work proved that CuFe2O4@Al2O3 composite is an efficient, environment-friendly, and recyclable heterogeneous catalyst for practical wastewater treatment via PMS activation.

Fabrication, characterization and performance evaluation of an amplified electrochemical sensor based on MOFs nanocomposite for leukemia drug Imatinib determination

In this research, the synthesis, fabrication steps and characterization of a new modified glassy carbon electrode (GCE) with CuFe2O4 magnetic nanoparticles combined with zeolitic imidazolate framework (ZIF-8) embedded graphene quantum dots (GQDs), (CuFe2O4/ZIF-8@GQDs), for electrodetermination of the imatinib (IMB), anti-cancer drug, are reported. The synthesized nanocomposite was characterized using X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FE-SEM). The GCE modified with CuFe2O4/ZIF-8@GQDs nanocomposite shows high electrocatalytic activity toward the oxidation of IMB compared with the bare GCE, GQDs/GCE, ZIF-8@GQDs/GCE, CuFe2O4/GCE and CuFe2O4@GQDs/GCE. The resulted electrocatalytic activity of the CuFe2O4/ZIF-8@GQDs/GCE can be attributed to the synergistic effect of the outstanding magnetic, electrical properties of the CuFe2O4/ZIF-8@GQDs and high conductivity of GQDs, as well as the high electron transport rate of the nanocomposite. Under optimized conditions, the developed sensor, CuFe2O4/ZIF-8@GQDs/GCE, has static properties such as wide linear range responses (0.02–11.85 and 11.85–94.20 μM), low detection limit (1.2 nM), high sensitivity (5.655 μA μM−1), long-term signal stability and reproducibility (RSD = 2.23%). It should be noted that the CuFe2O4/ZIF-8@GQDs/GCE sensor could be used for determination of IMB in biological and pharmaceutical samples, indicating its feasibility for real analysis.

CuFe2O4 Magnetic Nanoparticles as Heterogeneous Catalysts for Synthesis of Dihydropyrimidinones as Inhibitors of SARS-CoV-2 Surface Proteins—Insights from Molecular Docking Studies

In this study, we present the highly efficient and rapid synthesis of substituted dihydropyrimidinone derivatives through an ultrasound-accelerated approach. We utilize copper ferrite (CuFe2O4) magnetic nanoparticles as heterogeneous catalysts, employing the well-known Biginelli reaction, under solvent-free conditions. The impact of the solvent, catalyst amount, and catalyst type on the reaction performance is thoroughly investigated. Our method offers several notable advantages, including facile catalyst separation, catalyst reusability for up to three cycles with the minimal loss of activity, a straightforward procedure, mild reaction conditions, and impressive yields, ranging from 79% to 95%, within short reaction times of 20 to 40 min. Furthermore, in the context of fighting COVID-19, we explore the potential of substituted dihydropyrimidinone derivatives as inhibitors of three crucial SARS-CoV-2 proteins. These proteins, glycoproteins, and proteases play pivotal roles in the entry, replication, and spread of the virus. Peptides and antiviral drugs targeting these proteins hold great promise in the development of effective treatments. Through theoretical molecular docking studies, we compare the binding properties of the synthesized dihydropyrimidinone derivatives with the widely used hydroxychloroquine molecule as a reference. Our findings reveal that some of the tested molecules exhibit superior binding characteristics compared to hydroxychloroquine, while others demonstrate comparable results. These results highlight the potential of our synthesized derivatives as effective inhibitors in the fight against SARS-CoV-2.

Strategic One-pot Synthesis of Glycosyl Annulated Phosphorylated/ Thiophosphorylated 1,2,3-Triazole Derivatives Using CuFe2O4 Nanoparticles as Heterogeneous Catalyst, their DFT and Molecular Docking Studies as Triazole Fungicides

Abstract:In the present study, we have introduced an efficient solvent-free protocol for the synthesis of glycosyl annulated phosphorylated/thiophosphorylated 1,2,3-triazole derivatives using reusable CuFe2O4 magnetic nanoparticles as a heterogeneous catalyst with the protocols of popular click chemistry approach. Quantum chemical calculations of all the reactants and products have been calculated using density functional theory with Spartan-18 software. In addition, the molecular docking studies of all the glycosyl annulated phosphorylated/thiophosphorylated 1,2,3- triazole derivatives have been studied as effective fungicides against CaCYP51 (PDB ID 5EQB), protein of P. infestans effector target site (PDB ID: 2NAR), and SsCYP51(PDB code: 6CR2) using Autodock Vina and Discovery Studio software. Among the three different proteins, the binding energies of the compounds (5a-d) with CaCYP51 (PDB ID 5EQB) have shown better results in the range of 7.0 to 7.4 kcal/mol. Hence, these compounds may be used as strong fungicides for the inhibition of CaCYP51 (PDB ID 5EQB). In conclusion, the synthesized compounds may be better useful in agrochemical applications as vital fungicides.

Magnetic CuFe2O4 nanoparticles anchored on N-doped carbon for activated peroxymonosulfate removal of oxytetracycline from water: Radical and non-radical pathways

In this work, magnetic CuFe2O4 was prepared for the removal of oxytetracycline (OTC) by a self-propagating combustion synthesis method. Almost complete degradation (99.65%) of OTC was achieved within 25 min at [OTC]0 = 10 mg/L, [PMS]0 = 0.05 mM, CuFe2O4 = 0.1 g/L under pH = 6.8 at 25 °C for deionized water. Specially, the addition CO32− and HCO3− induced the CO3•- appearance enhancing the selective degradation to electron-rich OTC molecule. The prepared CuFe2O4 catalyst exhibited desirable OTC removal rate (87.91%) even in hospital wastewater. The reactive substances were analyzed by free radical quenching experiments and electron paramagnetic resonance (EPR), and the results demonstrated that 1O2 and •OH were the main active substances. Liquid chromatography-mass spectrometry (LC-MS) was used to analyze the intermediates produced during the degradation of OTC and thus to speculate on the possible degradation pathways. Ecotoxicological studies were conducted to unveil large-scale application prospect.

Systematically engineered GO with magnetic CuFe2O4 to enhance bone regeneration on 3D printed PCL scaffold

Composition and processing can profoundly influence the physicomechanical features and cellular function of tissue-engineered scaffolds to regenerate new bone tissue. Here, we developed 3D printed scaffolds containing GO sheets decorated with magnetic CuFe2O4 nanoparticles (NPs). Field emission scanning electron microscopic (FESEM) images depict the formation of high density CuFe2O4 NPs (22 ± 3 nm) uniformly distributed on the surface of GO sheets. Moreover, FESEM images taken from the surface of scaffolds confirm a highly regular structure and desirable printability of the composite material. The incorporation of 8 wt.% GO@CuFe2O4 assist to fabricate PCL-based scaffold with greater mechanical strength (71 ± 0.5 MPa), higher electrical conductivity (2 × 10−8 S/m) and saturation magnetization (1.6 emu/g) as well as better hydrophilicity (74°± 2.4°) than PCL/GO scaffold. Such improvement in physicomechanical properties of the prepared scaffold accelerates pre-osteoblast proliferation, spreading, alkaline phosphatase activity as well as calcium deposition on the scaffold surface and thus, it is an intriguing candidate for useful reconstruction of injured bone tissue.

Fabrication of Cu0-composited CuFe2O4 magnetic nanoparticles on diatomite support for efficient degradation of tetracycline hydrochloride by a Fenton-like system

Paramagnetic Cu/CuFe2O4/DE composites were fabricated by a one-step solvothermal method to design a heterogeneous Fenton-like catalyst to degrade tetracycline hydrochloride (TC). The Cu/CuFe2O4/DE were characterized by SEM, TEM, XRD, BET, and XPS methods. The catalytic activity of CuFe2O4 was improved using diatomite and Cu0. Diatomite (DE) enhanced the dispersity of Cu/CuFe2O4, minimized metal ions leaching, and improved stability. The Cu0 is used for the regeneration of Fe3+. The synergy between Cu+/Cu2+ and Fe2+/Fe3+ redox pairs promotes hydroxyl radical production upon H2O2 decomposition. The synthesized materials were characterized by SEM, TEM, XRD, BET, and XPS, and their catalytic activities were discussed and analyzed. 95.5 % TC was degraded within 90 min (initial conditions, pH = 5.0 and [TC] 50 mg/L), and showing excellent anti-interference ability to the presence of SO42-, Cl-, NO3-, CO32- and humic acid (HA).The presence of active species, viz., •OH and •O2- radicals generated in the Cu/CuFe2O4/DE/H2O2 system were detected by ESR quenching measurements. The •OH and •O2- mediated TC degraded pathways were proposed using the intermediates identified by LC-MS data. The novel heterogeneous Fenton-like process developed using Cu/CuFe2O4/DE/H2O2 is robust for TC degradation as exemplified in its stability and reusability measurements.

Magnetic CuFe2O4 Nanoparticles with Pseudocapacitive Properties for Electrical Energy Storage.

This investigation is motivated by increasing interest in the development of magnetically ordered pseudocapacitors (MOPC), which exhibit interesting magnetocapacitive effects. Here, advanced pseudocapacitive properties of magnetic CuFe2O4 nanoparticles in negative potential range are reported, suggesting that CuFe2O4 is a promising MOPC and advanced negative electrode material for supercapacitors. A high capacitance of 2.76 F cm−2 is achieved at a low electrode resistance in a relatively large potential window of 0.8 V. The cyclic voltammograms and galvanostatic charge–discharge data show nearly ideal pseudocapacitive behavior. Good electrochemical performance is achieved at a high active mass loading due to the use of chelating molecules of ammonium salt of purpuric acid (ASPA) as a co-dispersant for CuFe2O4 nanoparticles and conductive multiwalled carbon nanotube (MCNT) additives. The adsorption of ASPA on different materials is linked to structural features of ASPA, which allows for different interaction and adsorption mechanisms. The combination of advanced magnetic and pseudocapacitive properties in a negative potential range in a single MOPC material provides a platform for various effects related to the influence of pseudocapacitive/magnetic properties on magnetic/pseudocapacitive behavior.

Fabrication of a highly efficient multilayer microwaves insulator based on CuFe2O4/(Pb1−xLax)/(Zr1−yTiy)O3 (composite: 7/60/40) (0 ≤ x, y ≤ 1) and Cu-doped g-C3N4 nanograins

Nowadays, microwave pollution is a major concern around the world. Therefore, the construction of multilayer microwave absorbers with low thickness and wide bandwidth has been investigated. A novel multilayer broadband microwave insulator with high performance containing fillers comprised of copper ferrite spinel (CuFe2O4) nanograins (NGs), lead zirconium titanate ceramic (Pb1−xLax)(Zr1−yTiy)O3 (composite: 7/60/40) (0≤x,y ≤ 1) (PLZT) nanoparticles (NPs), and copper-doped carbon nitride graphitic (Cu-doped g-C3N4) nanosheets (NS) based on epoxy resin has been successfully prepared. The crystal structure and morphology of synthesized nanograins were specified using XRD, SEM, and EDX/mapping analysis. In addition, the microwave absorption properties of the resulting multilayer microwave insulator were evaluated using a vector network analyzer (VSM) in the frequency range of 8–12 GHz. Response surface methodology (RSM) was applied to the design of experiments to reduce the experimental time and cost, and obtain the optimal conditions. The weight percentage (wt.%) of CuFe2O4 magnetic nanograins, (Pb1−xLax)(Zr1−yTiy)O3 (0 ≤ x,y ≤ 1) dielectric NGs, Cu-doped g-C3N4 electric conductivity nanosheets, and thickness of the designed insulators were optimized using the RSM method to attain a multilayer microwave insulator with the optimal microwaves absorption efficiency. The minimum reflection loss (maximum absorption efficiency) was determined to be < –30 dB (absorption >99.9%) for the optimized multilayer microwaves insulator under the conditions of 3.0 wt% CuFe2O4 magnetic nanoparticles, 5 wt% (Pb1−xLax)(Zr1−yTiy)O3 (0≤x,y ≤ 1) dielectric NGs, 1.0 wt% Cu-doped g-C3N4 electric conductive nanosheets with 1 mm thickness in the microwave frequency range of 8–12 GHz (X-band). The highest attenuation coefficient (>500 dB/m) showed that the microwaves energy was weakened. In addition, the minimum reflection coefficient (maximum transmission coefficient) was calculated to be ∼0.01 (RL = −35 dB, AL = 99.99%). Finally, the obtained results show that these factors and their levels were correctly selected for the fabrication of high-performance multilayer microwave insulators.

Graphene oxide-CuFe2O4 nanohybrid material as an adsorbent of Congo red dye

This work evaluates the performance of graphene oxide (GO) - copper ferrite (CuFe2O4) nanohybrid in the removal of Congo Red (CR) dye from aqueous solutions. The adsorbent was prepared via a three-step method. Firstly, GO was produced via a modified Hummers method, using graphite powder as starting material. Following this, GO surface was treated with ionic surfactants, cetyltrimethylammonium bromide (CTAB) and poly(sodium-4-styrenesulfonate) (PSS). Subsequently, the functionalized GO was decorated with magnetic CuFe2O4 nanoparticles via an electrostatic self-assembly process using a solvothermal treatment. The as-synthesized CuFe2O4-GO nanohybrid was characterized by X-Ray Diffraction (XRD) Analysis, Fourier Transform Infrared (FT-IR) Spectroscopy, micro-Raman Spectroscopy, Thermogravimetric Analysis (TGA), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transition Electron Microscopy (HR-TEM) with Energy Dispersive Spectroscopy (EDS) mapping, as well as, N2 Adsorption/Desorption measurements. We investigated the CR adsorption of the GO-CuFe2O4 nanohybrid at various initial CR concentrations and contact times. Both Langmuir and Freundlich models were employed to describe the adsorption isotherms, while the adsorption kinetics of CR by GO-CuFe2O4 were found to be pseudo-second order. Our results demonstrate that GO-CuFe2O4 is an attractive adsorbent for the efficient removal of CR dye from wastewater.

Efficient remediation of chlorpyrifos pesticide from contaminated water by superparamagnetic adsorbent based on Arabic gum-grafted-polyamidoxime

A novel organic/inorganic biosorbent hydrogel nanocomposite based on Arabic Gum-grafted-polyamidoxime and CuFe2O4 magnetic nanoparticles (AG-g-PAO/CuFe2O4) was prepared in three steps. The prepared hydrogel nanocomposite was well characterized using Fourier transform infrared (FT-IR), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), CHN, zeta potential, and Brunauer-Emmett-Teller (BET) analyses. The adsorption efficiency of the AG-g-PAO/CuFe2O4 for removing an organophosphorus pesticide (OPP) (chlorpyrifos) from aqueous solutions was studied. Effect of different experimental conditions such as the pH of the solution, adsorbent dosage, contact time, initial concentration on adsorption efficiency was evaluated. The experimental adsorption data described well by the Langmuir isotherm model and the maximum adsorption capacity (Qmax) of the prepared biosorbent for chlorpyrifos was found 769.23 mg/g. The adsorption kinetic data were well fitted by the pseudo-second-order model. It was suggested that the chlorpyrifos was adsorbed onto AG-g-PAO/CuFe2O4 hydrogel biosorbent mainly through electrostatic interaction and hydrogen bonding. The result of adsorption-desorption experiments revealed that the AG-g-PAO/CuFe2O4 can be excellently regenerated and reused after three sequential runs without a considerable decline in its adsorption performance.

Synthesis of mesoporous CuFe2O4@SiO2 core-shell nanocomposite for simultaneous drug release and hyperthermia applications

In the present work, magnetic CuFe2O4 nanoparticles were synthesized through a sol-gel combustion. The synthesized CuFe2O4 were coated with mesoporous SiO2. The synthesized CuFe2O4@SiO2 nanocomposite was investigated for drug release and hyperthermia applications. The products were studied by X-ray diffraction analysis, Fourier-transform infrared spectroscopy, simultaneous thermal analysis, Brunauer-Emmett-Teller surface area, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometer. TEM images showed the formation of silica coating with a thickness of 14 nm around copper ferrite. The surface area of the samples increases from 2.59 to 199.2 m2/g after the surface modification of ferrites nanoparticles with silica. The CuFe2O4@SiO2 exhibited high ibuprofen loading and controlled drug release. These improvements resulted from the nanocomposite's mesoporous structure and high surface area. Coating CuFe2O4 nanoparticles with mesoporous silica reduced the cytotoxicity and improved drug release properties. However, this coating reduced the hyperthermia ability. The formed CuFe2O4@SiO2 nanocomposites show high potential for simultaneous drug release and hyperthermia applications with prospective use for biomedical applications.

MgO doped magnetic graphene derivative as a competent heterogeneous catalyst producing biofuels via transesterification: Process optimization through Response Surface Methodology (RSM)

In the last few decades, production of alternative fuels has been a global concern among the environmental scientists in view of scarcity of fossil fuels and increasing global warming. Biodiesels are being synthesized as green fuel by transesterification of different oils and fats over diverse synthetically developed novel heterogeneous catalysts. In this present work,a magnetically reusable hybrid nanocatalyst of basic nature has been designed for the production of biodiesels by transesterification of waste corn oil and rapeseed oil in presence of methanol. During the synthesis of catalyst, magnetic CuFe2O4 nanoparticles were amalgamated with graphene oxide (GO) by using pistachio leaf extract and subsequently MgO nanoparticles were impregnated over it. The catalyst was physicochemically characterized by FT-IR, SEM, TEM, EDX, elemental mapping, XRD, VSM and TGA studies. The reaction parameters like reaction time, the methanol/oil molar ratio and the catalyst loading were optimized through Response Surface Methodology (RSM) using Box-Behnken experimental design. In addition, the catalysts was magnetically retrieved quite easily and reused five times in succession without considerable loss in its reactivity in the transesterification reaction.

High magnetic fluid hyperthermia efficiency in copper ferrite nanoparticles prepared by solvothermal and hydrothermal methods

CuFe2O4 magnetic nanoparticles (MNPs) of two different morphologies and high magnetic heating efficiency are prepared using hydrothermal (CF) and solvothermal (CFPG) methods. Temperature dependent magnetization measurements indicate the presence of superparamagnetic phase at room temperature. The saturation magnetization for CFPG MNPs (~32.7 emu/g) is found to be ~ 31% higher than the CF MNPs, which is due to nearly collinear Neel type alignment of the magnetic moments in the tetrahedral and octahedral sites with a low Yafet-Kittel angle of ~ 5.980 and lower thickness of the magnetically disordered shell, which are confirmed from the cation distributions, non-zero spin canting angles and sub-spectral area analyses using low temperature (~5 K) in-field (~5 T) Mössbauer spectroscopy. The maximum specific absorption rate for CFPG MNPs is found to be ~ 192 ± 7 W/g, which is significantly higher than the previously reported values for copper ferrite MNPs. The high heating efficiency of CFPG MNPs is attributed to the near-resonant relaxation dynamics (ωτ ~ 1, where ω and τ indicate the angular frequency of the applied field and effective relaxation time, respectively). Heating efficiency is found to decrease with increasing sample concentration due to an enhancement in dipolar interactions, which is found to be in agreement with the quasi-static calculations. In vitro cytotoxicity studies indicate good bio-compatibility of the CFPG MNPs against human colon epithelial cells (HT-29) due to the presence of polyethylene glycol coating. The observed high heating efficiency along with negligible room temperature coercivity and superior bio-compatibility indicate the suitability of the solvothermally synthesized CuFe2O4 MNPs for magnetic fluid hyperthermia.

An efficient base and H2O2 free protocol for the synthesis of phenols in water and oxygen using spinel CuFe2O4 magnetic nanoparticles

An efficient base and H2O2 free protocol was used for the synthesis of phenols from boronic acids using biogenic CuFe2O4 magnetic nanoparticles as catalyst at room temperature in water and oxygen. The catalyst was prepared using the flowers of Lantana camara. The size of the nanoparticles was 4.27 nm. Base free and ligand free protocol, less time, excellent yields, room temperature, biogenic synthesis of the catalyst, use of O2 as an environmentally friendly oxidant are the advantages of the present protocol. The recyclability of the catalyst was for 5 cycles without loss of magnetic property or catalytic activity.

Assessing short-term effects of magnetite ferrite nanoparticles on Daphnia magna.

Magnetic nanoparticles (MNPs) are used in a wide range of sectors ranging from electronics to biomedicine, as well as in eutrophicated lake restoration due to their high P, N, and heavy metal adsorption capacity. This study assessed the effects of MNPs on mortality and morphometric changes of D. magna. According to the SEM, the synthesised MNPs were found to have spherical nanoparticles, be uniformly distributed, and have a homolithic size distribution of 50-110 nm. The EDX spectra confirmed the elemental structure and purities of these MNPs. A total of 396 neonates were used for short-term bioassays (96 h) through the MNPs in the laboratory (16:8 photoperiod). Experiments were applied in triplicate for each concentration of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs and their respective control groups. Mortality and morphological measurements of each individual were recorded every 24 h. In the probit analysis, the 96-h LC50 (p < 0.05) for CuFe2O4, CoFe2O4, and NiFe2O4 MNPs was calculated to be 1.455 mg L-1, 39.834 mg L-1, and 21.730 mg L-1, respectively. CuFe2O4 MNPs were found to be more toxic than the other two MNPs. The concentrations of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs drastically affected life span and morphologic growth of D. magna as a result of a short time exposure. The results of this study are useful for assessing what risks they pose to freshwater ecosystems.

Adsorption Mechanism and Electrochemical Performance of Congo Red onto Magnetic CuFe2O4 Nanoparticles

Magnetic CuFe2O4 nanoparticles were synthesized by the facile alcohol-solution combustion approach, and they were characterized by transmission electron microscopy (TEM), energy dispersive X-ray Spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The magnetic CuFe2O4 nanoparticles were employed to adsorb Congo red (CR) from aqueous medium. The study of magnetic CuFe2O4 nanoparticles for CR adsorption at room temperature was performed, and the Langmuir isotherm and pseudo-second kinetics model matched well with the adsorption process, those suggested that the mechanism of CuFe2O4 nanoparticles for CR adsorption followed the adsorption behavior of monolayer. The adsorbance descended with the increase of pH value, especially the pH value exceeded 7, and the adsorbance amounted to 77% of the initial one via 10 recycles. While, the electrochemical performances of bare magnetic glassy carbon electrode (MGCE), MGCE/CuFe2O4 nanoparticles, and MGCE/nanoparticles adsorbed CR were measured by EIS and CV.

Magnetically separable modified sulfuric acid (CuFe2O4@SiO2-OSO3H): Preparation, characterization and catalytic application for the synthesis of 1,8-dioxo-octahydroxanthenes

A nanomagnetic acidic catalyst (CuFe2O4@SiO2-OSO3H) was prepared by the chemical anchoring of sulfuric acid onto the surface of modified CuFe2O4 magnetic nanoparticles and characterized using FT-IR, SEM, EDX, and VSM techniques. The results confirmed that the sulfuric acid is well dispersed on the surface of the nanomagnetic support. The catalytic activity of CuFe2O4@SiO2-OSO3H was evaluated in the synthesis of 1,8-dioxo-octahydroxanthenes under solvent-free conditions. The reactions using this nanomagnetic acidic catalyst could be carried out in lower than 12 min with excellent yields. Also, the catalyst was easily isolated from the reaction mixture by an external magnet and used at least four times without significant loss of activity.

Synthesis of magnetic CuFe2O4 nanoparticles as green catalyst for toluene oxidation under solvent-free conditions

A green method was developed for the synthesis of CuFe2O4 magnetic nanoparticles using a Neem leave extract. The prepared nanoparticles with an average size of 19.7 nm were used as an effective catalyst for the oxidation of various aryl alkanes in moderate to excellent yields under solvent-free conditions. The catalyst was characterized by powder- XRD, SEM and TEM study. The key advantages of this protocol are simple preparation, a recyclable heterogeneous catalytic system, and benign reaction condition with good to excellent yields with high selectivity toward acid (42–87%).