Magnetic NiFe2O4 Nanoparticles Research Articles

Ethyl esters synthesis catalyzed by lipase B from Candida antarctica immobilized on NiFe2O4 magnetic nanoparticles

The development of heterogeneous biocatalysts allows the expansion of the application of enzymes in different industrial processes, favoring the establishment of clean technologies. This work investigates the capacity of nickel ferrite magnetic nanoparticles (NiFe2O4) as a support for lipase B from Candida antarctica (CalB) immobilization. The adsorption capacity of the support revealed a maximum value of 15 mgprotein/gsupport, according to the Langmuir isotherm model. Efficiency immobilization by physical adsorption was low (21.3 %), and CalB was covalently immobilized after functionalization of NiFe2O4 with APTMS (3-aminopropyl trimethoxysilane) and activation with glutaraldehyde (GA), showing higher immobilization yield (62.9 %). The spinel ferrite NiFe2O4 was characterized by many physicochemical analyses. The enzyme derivatives obtained (NiFe2O4-CalB and NiFe2O4-APTMS-GA-CalB) were evaluated in the synthesis of alkyl esters. Despite no production was observed in the transesterification reactions, esterification led to 37.3 ± 1.0 % and 62.1 ± 0.2 % of oleic acid conversions using NiFe2O4-APTMS-GA-CalB and NiFe2O4-CalB, respectively. After 4 cycles, NiFe2O4-CalB maintained 92 % of its initial activity. Nickel ferrite magnetic nanoparticles form an efficient heterogeneous catalyst with lipase, which could be used to remove the content of free fatty acids (FFAs), like oleic acid, present in cheap raw materials to produce biodiesel.

NiFe2O4 magnetic nanoparticles supported on MIL-101(Fe) as bimetallic adsorbent for boosted capture ability toward levofloxacin

Levofloxacin (LVX) capture with microcrystalline particles of monometallic metal-organic frameworks (MOFs) is definitely restricted and challenged by its difficulties in solid-liquid separation and enhanced of adsorption capacity issues. Meanwhile, the development of magnetic MOFs with excellent adsorption capabilities and outstanding recyclability is crucial. Herein, a novel magnetic Fe/Ni bimetal MOFs composite (MIL-101(Fe)@NiFe2O4, MNFO) for LVX capture has been effectively fabricated for LVX capture, utilizing MIL-101(Fe) as the primary adsorbent and NiFe2O4 nanoparticles as the magnetic element. Attributed to the synergistic ability of bimetal ions (Fe2+ and Ni2+), MNFO exhibits a significant adsorption capacity (335 mg/g) and rapid adsorption rate (10 min) towards LVX. The adsorption capacity indicates an increasing-then-decreasing trend with an increase of the pH values. Additionally, the adsorption data are well fitted by the Freundlich and pseudo-second-order kinetic models. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. In addition, the adsorbent demonstrated excellent reusability, as it could be readily recovered from the liquid phase through the magnetic properties of NiFe2O4. Remarkably, it retained approximately 90 % of its adsorption capacity of the uptakes after 5 cycles. This study offers a innovative approach to the development of highly efficient adsorbents for capturing LVX from water.

Application of NiFe2O4 nanoparticles towards the detection of ovarian cancer marker

In this work, we explored the potential application of NiFe2O4 magnetic nanoparticles in sensing platforms due to their cost-effectiveness and good magnetic properties. The spinel-type metal oxide was prepared using the conventional hydrothermal synthesis method. The structural, morphological, and magnetic properties of the as-synthesized NiFe2O4 nanoparticles were discussed. The nanoparticles were functionalized with cystamine, glutaraldehyde, and PVDF and then modified with the CA 125 antibody to obtain the immunosensor. FTIR and electrochemical analyses reveal immobilization of the antibody on the surface of the NiFe2O4 magnetic nanoparticles. The immunosensor developed in this work was made on a printed circuit board, allowing it to be used as a point-of-care device. The immunosensor showed excellent stability, reproducibility, specificity, and selectivity. Our findings are of great significance for developing novel, high-performance point-of-care electrochemical biosensors to be applied in detecting the CA 125 antigen, a widely used biomarker for the prognosis of ovarian cancer.

Direct purification and immobilization of his-tagged enzymes using unmodified nickel ferrite NiFe2O4 magnetic nanoparticles

Purification of valuable engineered proteins and enzymes can be laborious, costly, and generating large amount of chemical waste. Whilst enzyme immobilization can enhance recycling and reuse of enzymes, conventional methods for immobilizing engineered enzymes from purified samples are also inefficient with multiple-step protocols, regarding both the carrier preparation and enzyme binding. Nickel ferrite magnetic nanoparticles (NiFe2O4 MNPs) offer distinct advantages in both purification and immobilization of enzymes. In this work, we demonstrate the preparation of NiFe2O4 MNPs via a one-step solvothermal synthesis and their use in direct enzyme binding from cell lysates. These NiFe2O4 MNPs have showed an average diameter of 8.9 ± 1.7 nm from TEM analysis and a magnetization at saturation (Ms) value of 53.0 emu g–1 from SQUID measurement. The nickel binding sites of the MNP surface allow direct binding of three his-tagged enzymes, d-phenylglycine aminotransferase (d-PhgAT), Halomonas elongata ω-transaminase (HeωT), and glucose dehydrogenase from Bacillus subtilis (BsGDH). It was found that the enzymatic activities of all immobilized samples directly prepared from cell lysates were comparable to those prepared from the conventional immobilization method using purified enzymes. Remarkably, d-PhgAT supported on NiFe2O4 MNPs also showed similar activity to the purified free enzyme. By comparing on both carrier preparation and enzyme immobilization protocols, use of NiFe2O4 MNPs for direct enzyme immobilization from cell lysate can significantly reduce the number of steps, time, and use of chemicals. Therefore, NiFe2O4 MNPs can offer considerable advantages for use in both enzyme immobilization and protein purification in pharmaceutical and other chemical industries.

Zinc- doped nickel ferrite nanoparticles for ESR, hyperhtermia and thier cytotoxicity in mouse muscle fibroblast (BLO-11) and human breast cancer (MDA-MB-231) cell lines

Spinel structured nickel ferrite (NiFe2O4) nanoparticles (NPs) are used in catalysis, magnetic, and microwave electronic devices. To study the magnetic interplay between half and above-filled d-orbitals in spinel structured transition metal cations: Fe3+ (3d5), Ni2+ (3d8), and Zn2+ (3d10), narrow size distributed, well crystallined zinc substituted NiFe2O4 magnetic nanoparticles (MNPs) were synthesized by solvothermal reflux method. Structural, morphological, magnetic, magnetic hyperthermia, and cytotoxicity properties of Zn0.15Ni0.85Fe2O4 (code: ZN1), Zn0.35Ni0.65Fe2O4 (code: ZN2), and Zn0.45Ni0.55Fe2O4 (code: ZN3) NPs were systematically studied. Both X-ray diffraction and electron diffraction profiles confirmed that all synthesized samples were crystallined in a cubic spinel structure. Further, the formation of octahedral and tetrahedral ligands in spinel structure is confirmed by Fourier transformed infrared (FTIR) spectra. In addition, metal cations and oxygen anions oxidation states were determined from X-ray photoelectron spectroscopy (XPS). Quantification of metal cations present in all samples was done by X-ray energy dispersive spectra. Macroscopic magnetic properties of NPs were studied by magnetometer and microscopic magnetic properties were studied by electron spin resonance (ESR) spectra. Superparamagnetic hyperthermia (SPMH) properties of NPs were studied by adiabatic hyperthermia curves using an induction heater. Biocompatibility properties of all NPs were studied by cell viability-based cytotoxicity assay on (BLO-11) mouse muscle fibroblast and (MDA-MB-231) human breast cancer cell lines. The above studies revealed that Zn2+ substitution initially enhances saturation mass magnetization (Ms) of NiFe2O4 and then reduces Ms when Zn2+ concentration is> 30 % due to zero octahedral site preference energy of Zn2+ and reduced superexchange strength in octahedral sublattice. This influences magnetic hyperthermia and cytotoxicity properties of NPs and is described here.

Biosynthesis of NiFe2O4 nanoparticles using Murayya koenigii for photocatalytic dye degradation and antibacterial application

Biosynthesis of nickel ferrite (NiFe2O4) nanoparticles (NPs) using an aqueous extract of Murraya koenigii (M. koenigii) leaves is a novel, environmentally benign and cost effective method. NiFe2O4 NPs were characterized by different spectroscopic and microscopic techniques, including Ultraviolet–Visible (UV–Vis) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, Thermogravimetric Analysis (TGA), Transmission Electron Microscopy (TEM), High-Resolution Scanning Electron Microscopy (HRSEM), Energy-dispersive X-ray spectrometry (EDX) and Vibrating-Sample Magnetometer (VSM). The observed results revealed that prepared NiFe2O4 NPs are highly pure, crystalline, partially spherical with an average size of 2–6 nm and attribute magnetic properties. The magnetization of the obtained biosynthesized nanoparticles is noticed ∼5.2 emu/g at 10 K Oe. The NiFe2O4 NPs exhibited a heterogeneous photo Fenton's catalytic feature in the presence of oxalic acid at ambient conditions. The effects of pH, dosage of NiFe2O4 catalyst and doses of oxalic acid on the degradation efficiency of 10 mg/L MB dye were assessed. The optimal degradation efficiency of ⁓ 98.5% was achieved within 70 min, and the observed results elucidated that the photocatalytic reactions follow first-order chemical kinetics. Thermodynamic parameters such as activation energy (Ea), enthalpy of activation (ΔH‡), entropy of activation (ΔS‡), and free energy of activation (ΔG‡) were evaluated, applying Arrhenius and activated complex theory ascertained the endothermic, less random and nonspontaneous features of photocatalytic process. NiFe2O4 NPs were also tested against different bacteria and found to have antibacterial properties. Hence, magnetic NiFe2O4 NPs can be exploited for its multifunctional applications, and specifically for the remediation of dye-contaminated wastewater.

Simple Co-precipitation synthesis and characterization of magnetic spinel NiFe2O4 nanoparticles

Nickel ferrite nanoparticles were synthesized using Iron (III) nitrate and nickel nitrate as the starting materials along with the hydrazine hydrate via co-precipitation process and the final product obtained calcined at 700 °C. The structural and optical properties of the synthesised product were determined using various characterization techniques viz. UV–visible spectrometry, X-ray diffractometer (XRD), transmission electron microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM) and vibrating sample magnetometer (VSM). The NiFe2O4 nanoparticles showed absorption at ∼ 356 nm corresponds to band gap of 4.1 eV. The elemental analysis was carried out using X – ray Fluorescence (XRF) and Energy Dispersive Spectroscopy (EDS). The synthesized NiFe2O4 were 10–15 nm in size, and exhibited high saturation magnetization value of 72.66 emu/g.

Efficient Green Synthesis of (Fe3O4) and (NiFe2O4) Nanoparticles Using Star Anise (Illicium verum) Extract and Their Biomedical Activity against Some Cancer Cells.

Magnetite Fe3O4 and spinel (2:1) and (4:1) NiFe2O4 magnetic nanoparticles (MNPs) were prepared by simple and affordable co-precipitation methods using an extract of star anise (Illicium verum) as a green reducing agent. The morphology and chemical composition of these MNPs were confirmed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV–visible spectroscopy, and X-ray diffraction (XRD). The synthesized magnetite Fe3O4 and spinel (2:1) and (4:1) NiFe2O4 MNPs were in the size range of 0.1–1 µm. The MNPs had irregular clustered platelets (magnetite Fe3O4) and pyramidal structures (spinel (2:1) and (4:1) NiFe2O4 NPs). The average sizes of the synthesized magnetite Fe3O4, and spinel (2:1) and (4:1) NiFe2O4 MNPs calculated using XRD analysis were 66.8, 72.5, and 72.9 nm, respectively. In addition to the characteristic absorption peaks of magnetite Fe3O4, those of spinel (2:1) and (4:1) NiFe2O4 MNPs were detected at ~300–350 nm and ~700 nm, respectively. Overall, the results of this study indicate that the synthesized magnetite Fe3O4, and spinel (2:1) and (4:1) NiFe2O4 MNPs showed high biomedical activities against liver carcinoma cells and non-small lung adenocarcinoma cells.

Activation of peroxymonosulfate by nanoscaled NiFe2O4 magnetic particles for the degradation of 2,4-dichlorophenoxyacetic acid in water: Efficiency, mechanism and degradation pathways

Well-crystallized magnetic NiFe2O4 nanoparticles were applied to activate peroxymonosulfate (PMS) for degrading 2,4-dichlorophenoxyacctic acid (2,4-D) in water. The performance of NiFe2O4 synthesized with different metals (Ni and Fe) and citric acid ([Men+]T /CA) molar ratio was investigated. The synthesized NiFe2O4 with the molar ratio of [Men+]T /CA of 1:1 showed the best performance to activate PMS, exerting a positive effect on 2,4-D degradation. The removal efficiency of 2,4-D reached 97.5 % in the NiFe2O4(1:1)/PMS system. Various water matrix factors, including solution pH, reaction temperature and inorganic ions were considered during the removal of 2,4-D. The quenching tests and ESR spectra displayed that the generation of reactive oxygen species (ROS) in the NiFe2O4(1:1)/PMS system, ·OH and SO4·- played the predominant role during 2,4-D degradation. The cycles of Fe2+/Fe3+ and Ni2+/Ni3+ on the surface of the catalysts prompted the decomposition of HSO5- for ·OH and SO4·- generation. The degradation mechanism of 2,4-D was declared by the density functional theory (DFT) calculations. The Cl and O in the structure of 2,4-D were rich in electrons, which were possible reaction sites for ROS. And the degradation mechanism of 2,4-D mainly includes decarboxylation, –OH substitution of Cl and H, and opening ring of benzene structure.

Investigation of Performance on Photovoltaic/Thermal (PV/T) System Using Magnetic Nanofluids

Photovoltaic/Thermal (PV/T) systems provide hot fluid (usually water) production as well as electrical energy production. In addition, since the overheating of the PV systems is prevented by the heat drawn by the thermal system, the electricity production performance of the PVs increases. Nanofluids are offered as a solution to increase the heat absorbed in the thermal system. The main physical events that lead to a significant improvement in the heat transfer performance of nanofluids can be summarized as follows: (i) The thermal conductivity of the prepared nanofluid increases at certain rates because the thermal conductivity of the solid metal is higher than that of the basic fluid, (ii) The heat transfer surface area increases due to the increase in the thermal conductivity of the fluid, (iii) Increase in the effective thermal capacity of the fluid, (iv) Increase in the thermal conductivity of the fluid and turbulent volume due to high fluid activity. In this study, by using nanofluids obtained by adding 1% Fe2O3, Fe3O4 and NiFe2O4 magnetic nanoparticles by weight to the basic fluid water, a bidirectional performance increase was achieved by increasing the thermal heat transfer of the PV/T system while providing more cooling of the PV system. In the experimental study, a 14% improvement in electricity production was achieved in NiFe2O4 nanofluid by drawing more heat from the heated PV panels by utilizing the high thermal conductivity of nanofluids. Since the amount of heat absorbed in the thermal system is high, an average of 104% temperature (∆T) increase in the hot fluid temperature compared to the base fluid water was obtained in the NiFe2O4 nanofluid.

NiFe2O4 nanospheres with size-tunable magnetic and electrochemical properties for superior supercapacitor electrode performance

Hereby, we present our efforts to understand the influence of ferric ions in the preparation of NiFe2O4 magnetic nanoparticles (MNPs) by facile chemical oxidation method. The variation in the Ferric ions content provoked size tunability of the MNPs (particle size reduced with increasing ferric ions content). The effect of ferric ions content on the prepared MNPs were analyzed for phase, morphological and magnetic characteristics by using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Vibrating Sample Magnetometer (VSM) and Thermomagnetic Analysis (TMA) measurements. The saturation magnetization and coercivity values were observed to be 45 emu/g and 90 Oe for the nanoparticles prepared without ferric ions. The size depended reduction in magnetization and coercivity values were evident for increased ferric ion concentration. The curie transition temperature was observed to be 584 °C from TMA analysis. The cyclic voltammogram, galvanostatic charge/discharge and electrochemical impedance measurements were carried out to evaluate the electrochemical characteristics of prepared NiFe2O4 nanoparticles for supercapacitor application. The highest specific capacitance of 277 F/g was observed for the NiFe2O4 nanoparticles that prepared with 50 % of ferric ions (NF50). From the cyclic stability study, 101 % of capacitance retention was demonstrated up to 5000 cycles. An asymmetric two-electrode cell that fabricated with NF50 exhibited a maximum specific capacitance of 56 F/g (with an applied current density of 1 A/g) and higher energy density of 22.5 Wh/ Kg (with a power density of 0.85 kW/Kg). The cyclic stability study of the cell revealed the increased capacity retention (126 % up to 5000 cycles) due to the particle size reduction. The observed enhancements in the magnetic and electrochemical properties with the size reduction are discussed in-detail. The facile strategy presented by this work would give insights for high-performance supercapacitor electrode material.

Synthesis and Characterization of NiFe2O4 Magnetic Nanoparticles for Magnetic Resonance Imaging Application

NiFe2O4 magnetic nanoparticles (MNPs) were synthesized by co-precipitation of iron (III) chloride hexahydrate and nickel (II) chloride hexahydrate in the solution containing 45% hydrazine at 80∘C. Phase, morphology, oxidation state and magnetic properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). In this research, pure NiFe2O4 MNPs synthesized in the solution with the pH of 10 with saturation magnetization of 49.839[Formula: see text]emu/g were detected and were able to be used for magnetic resonance imaging (MRI) application with very high contrast. Highlights: [Formula: see text] NiFe2O4 is used as magnetic nanoparticles. [Formula: see text] They have an excellent saturation magnetization. [Formula: see text] The promising material is used for magnetic resonance imaging application.

Phosphotungestic acid supported mesoporous MCM-41 coated NiFe2O4 magnetic nanoparticles as highly effective green nanocatalysts for coumarin and xanthene synthesis

Phosphotungestic acid supported mesoporous MCM-41 coated NiFe2O4 magnetic nanoparticles as highly effective green nanocatalysts for coumarin and xanthene synthesis

Functionalized NiFe2O4/mesopore silica anchored to guanidine nanocomposite as a catalyst for synthesis of 4H-chromenes under ultrasonic irradiation

A synergetic effect of nanocatalyst and ultrasonic irradiation was examined for the synthesis of 4H-chromenes from benzaldehyde, cyclohexanone, and malononitrile. It was observed this contributory improved the reaction that was used for the synthesis of the highly pure products in short reaction times and highest yields. The nanocomposite includes the guanidine anchored on to magnetic NiFe2O4 nanoparticles were used as the active base nanocatalyst for the sonication synthesis of 4H-chromenes compounds. The product was separated with simple filtration and purify with recrystallization by ethanol solvent. After completing the reaction, a nanocatalyst was collected and reused in 6 runs of model reaction. This nanocomposite has a magnetic core and a very active base surface area shell. The nanocatalyst was provided by the simple technique and identified by using FT-IR spectrum, scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Brunauer–Emmett–Teller (BET). This nanocomposite was used for the synthesized various derivatives of 4H-chromenes under ultrasonic irradiation. The organic products were identified by FT-IR and 1H-NMR.

Synthesis and characterization of NiFe2O4 magnetic nanoparticles with different coating materials for magnetic particle imaging (MPI)

Magnetic nanoparticles (MNPs) are widely used in biomedical applications. Biocompatibility and superparamagnetic response of the MNPs make them viable, especially as contrast agents in magnetic resonance imaging (MRI) and tracer agents in magnetic particle imaging (MPI). Nickel ferrites (NiFe2O4) coated with citric acid (CA) and polyacrylic acid (PAA) were synthesized by hydrothermal process. Nickel ferrites were structurally characterized by fourier transformed infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and thermogravimetric analysis (TGA). Nickel ferrites were also magnetically evaluated with electron-spin resonance (ESR), and physical properties measurement system (PPMS). The samples crystallite size of 9–12 nm achieved with XRD is in good agreement with the magnetic domain size that was obtained by PPMS results. Furthermore, nickel ferrites were also evaluated with magnetic particle spectroscopy (MPS) to determine the expected performance in MPI scanner. MPS results of NiFe2O4@PAA showed minimum relaxation time and high resolution (FWHM, mT) as compared to Vivotrax (magnetic insight) and Perimag (micromod) commercial reference tracers used in MPI. All results show that nickel ferrites have a great potential to become an optimum tracer agent for MPI.

One-step selective affinity purification and immobilization of His-tagged enzyme by recyclable magnetic nanoparticles.

The NiFe2O4 magnetic nanoparticles (NF‐MNPs) were prepared for one‐step selective affinity purification and immobilization of His‐tagged recombinant glucose dehydrogenase (GluDH). The prepared nanoparticles were characterized by a Fourier‐transform infrared spectrophotometer and microscopy. The immobilization and purification of His‐tagged GluDH on NF‐MNPs were investigated. The optimal immobilization conditions were obtained that mixed cell lysis and carriers in a ratio of 0.13 in pH 8.0 Tris‐HCl buffer at 30℃ and incubated for 2 h. The highest activity recovery and protein bindings were 71.39% and 38.50 μg mg–1 support, respectively. The immobilized GluDH exhibited high thermostability, pH‐stability and it can retain more than 65% of the initial enzyme after 10 cycles for the conversion of glucose to gluconolactone. Comparing with a commercial Ni‐NTA resin, the NF‐MNPs displayed a higher specific affinity with His‐tagged recombinant GluDH.

Magnetic NiFe2O4 nanoparticles decorated on N-doped BiOBr nanosheets for expeditious visible light photocatalytic phenol degradation and hexavalent chromium reduction via a Z-scheme heterojunction mechanism

In the present work, new Z-scheme N-BiOBr/NiFe2O4 nanocomposites were successfully constructed by a facile hydrothermal method. Various analytical characterization techniques were employed to examine the physicochemical and optical absorption properties of prepared photocatalysts. The prepared N-BiOBr/NiFe2O4 nanocomposites considerably enhanced the simultaneous visible light removal of phenol and Cr(VI) when compared with single-phase component photocatalysts. Especially, the N-BiOBr/NiFe2O4-15 nanocomposite demonstrated the top-flight photoactivity. The formed Z-scheme system in the nanocomposite significantly decreased the charge carrier recombination and improved the photoactivity. Photoluminescence and photoelectrochemical measurements were conducted to confirm the evidence of efficient charge carrier separation by the nanocomposites. Moreover, the N-BiOBr/NiFe2O4-15 nanocomposite can be magnetically separated and possessed good recycle performance up to five successive runs. The active species capturing experiments demonstrated that the hydroxyl radicals can degrade the phenol efficiently and that photogenerated electrons can reduce the Cr(VI). Finally, the mechanism of excellent photoactivity of N-BiOBr/NiFe2O4 nanocomposite was discussed.

Diastereoselective Synthesis of Some Spiroheterocycles Using Base Reusable Heterogeneous Achiral Nanocatalyst in Aqueous Media

AbstractThis research is based on the synthesis of some new diastereoselective spiroheterocycles relying on the application of nanocatalysts designed from the functionalized magnetic nanoparticles with tetrazole. Also, the achievement of suitable product with stereopurity through base catalytic path. Water as a green solvent, NiFe2O4 magnetic nanoparticles as a separable and reusable catalyst and using simple and high efficiency method are some important advantages of this research.

Magnetic NiFe2O4/MWCNTs functionalized cellulose bioadsorbent with enhanced adsorption property and rapid separation

Magnetic NiFe2O4 nanoparticles and multi-walled carbon nanotubes functionalized cellulose composite (m-NiFe2O4/MWCNTs@cellulose) as a magnetic bioadsorbent was prepared and used for effectively removing Congo Red (CR) from aqueous solution. The chemical and physical properties of the prepared m-NiFe2O4/MWCNTs@cellulose were characterized by XRD, TGA, FT-IR, VSM, SEM and TEM. Batch experiments were carried out to investigate the adsorption capacity and mechanisms. Effects of different adsorption parameters such as initial CR concentration, adsorbent dosage and temperature were studied. Results demonstrated that m-NiFe2O4/MWCNTs@cellulose had high adsorption capacity for CR from aqueous solution. The obtained experimental data fitted well with the pseudo-second-order equation and followed the Langmuir isotherm model with a maximum adsorption capacity of 95.70 mg g−1 for CR. The m-NiFe2O4/MWCNTs@cellulose with rapid magnetic separation and high adsorption capacity can be a promising and recyclable engineering biomaterials for purification and treatment of practical wastewater.

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.