Magnetic MnFe2O4 Nanoparticles Research Articles

Adsorption of magnetic manganese ferrites to simulated monomeric mercury in flue gases.

Magnetic MnFe2O4 nanoparticles were successfully prepared by the rapid combustion method at 500 °C for 2 h with 30 mL absolute ethanol, and were characterized by SEM, TEM, XRD, VSM, and XPS techniques, their average particle size and the saturation magnetization were about 25.3 nm and 79.53 A·m2/kg, respectively. The magnetic MnFe2O4 nanoparticles were employed in a fixed bed experimental system to investigate the adsorption capacity of Hg0 from air. The MnFe2O4 nanoparticles exhibited the large adsorption performance on Hg0 with the adsorption capacity of 16.27 μg/g at the adsorption temperature of 50 °C with the space velocity of 4.8×104 h-1. The VSM and EDS results illustrated that the prepared MnFe2O4 nanoparticles were stable before and after adsorption and successfully adsorbed Hg0. The TG curves demonstrated that the mercury compound formed after adsorption was HgO, and both physical and chemical adsorption processes were observed. Magnetic MnFe2O4 nanoparticles revealed excellent adsorbance of Hg0 in air, which suggested that MnFe2O4 nanoparticles be promising for the removal of Hg0.

Graphene oxide–MnFe2O4 nanohybrid material as an adsorbent of Congo red dye

The aim of this work is the synthesis and characterization of graphene oxide (GO)–MnFe2O4 nanohybrid material, as well as the study of its performance in the removal of Congo red (CR) dye from aqueous solutions. The GO–MnFe2O4 was prepared via a three-step method. Firstly, GO was produced via a modified Hummers' method, using graphite powder as starting material. Subsequently, GO was functionalized with ionic surfactants, cetyltrimethylammonium bromide and poly(sodium-4-styrenesulfonate). Following this, the functionalized GO was decorated with magnetic MnFe2O4 nanoparticles via an electrostatic self-assembly process using a solvothermal treatment at 200 °C for 12 h. The as-prepared GO–MnFe2O4 nanohybrid material was characterized by several techniques: X-ray diffraction analysis, Fourier-transform infrared spectroscopy, micro-Raman spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, and high-resolution transition electron microscopy with energy-dispersive spectroscopy mapping. The adsorption performance of GO–MnFe2O4 in the removal of CR dye was evaluated at different initial CR concentrations and contact times using an ultraviolet–visible spectrophotometer. In addition, its recyclability performance was investigated for 10 cycles. It is noteworthy that even after the last cycle, the removal efficiency of GO–MnFe2O4 exceeded 65%, indicating that the adsorbent had very good reusability. Finally, the Freundlich isotherm model yielded a better fit for the adsorption data, compared to Langmuir, while adsorption of CR by GO–MnFe2O4 showed pseudo-second-order kinetics.

Magnetic MnFe2O4 nanoparticles anchored on sludge-derived biochar in activating peroxydisulfate for levofloxacin degradation: Mechanism, degradation pathways and cost analysis

The sludge-derived biochar (SBC) was prepared by a low-cost microwave pyrolysis process, and then MnFe2O4 nanoparticles were anchored onto the surface of SBC through a hydrothermal route to construct a magnetic MnFe2O4/SBC composite catalyst. As-obtained MnFe2O4/SBC catalysts were characterized by XRD, FT-IR, Raman, FE-SEM, BET surface area and XPS. The optimized MnFe2O4/SBC(1:3) catalyst showed a higher catalytic activity to activate peroxydisulfate (PDS) for levofloxacin (LVF) degradation than that of SBC, MnFe2O4 and reported magnetic composite catalysts. After 80 min of reaction, 79.5% of LVF in water (10 mg/L) was degraded by MnFe2O4/SBC(1:3) in the presence of PDS (1.5 g/L), and LVF degradation followed the pseudo-second-order kinetics. Calcium carbonate (CaCO3) in SBC participates in PDS activation. XPS analysis, oxidative species capture experiments, EPR and linear sweep voltammetry (LSV) tests confirmed that LVF degradation in MnFe2O4/SBC-PDS oxidation system was achieved through the non-radical (electron transfer, 1O2) and radical (SO4•−, ∙OH and O2•−) pathways, with the former playing a dominant role. The degradation routes of LVF were established based on the degradation intermediates. LVF removal efficiency from real water matrices was improved by means of increasing catalyst dosage and reaction temperature. Cost analysis indicates that MnFe2O4/SBC-PDS oxidation process is a cost-effective method to eliminate the antibiotics in water.

Highly efficient removal of toxic As(V), Cd (II), and Pb(II) ions from water samples using MnFe2O4@SBA-15-(CH2)3-adenine as a recyclable bio-nanoadsorbent

Millions of people nowadays are exposed to highly toxic ions, including arsenic, cadmium, and lead, which all have detrimental effects on human health and cause irreparable damage to the nature and health of living species. It is, therefore, absolutely crucial to remove these toxic ions from ecosystems. Herein, a sponge-like bio-nanocomposite with a core-shell-shell structure consisting of magnetic MnFe2O4 nanoparticles (NPs) as core and mesoporous silica (SBA-15) functionalized with the nucleobase adenine (Ade) as a shell was synthesized to be applied for the adsorptive removal of toxic ions from aqueous media. The prepared material was characterized using various techniques, such as FTIR, XRD, TEM, VSM, and BET. Under optimum conditions, the MnFe2O4@SBA-15@(CH2)3-Ade removed As(V), Cd(II), and Pb(II) ions with greater than 96% efficiency. The kinetic and equilibrium data were satisfactorily described by the pseudo-second-order and the Redlich-Peterson models. The maximum adsorption capacities for As(V), Cd(II), and Pb(II) were calculated to be 21.99 mg g−1, 29.62 mg g−1, and 31.01 mg g−1, respectively. Also, the bio-nanocomposite showed ion removal efficiencies of over 95% during the seventh cycle of adsorption-desorption. Pb (II) ions had a stronger affinity for the active sites of the bio-nanoadsrobent when all of the studied systems (mono-, bi-, and multi-component) were compared. In addition, the practical application of the bio-nanocomposite for ion capture was evaluated in groundwater and industrial wastewater samples. Based on the findings of this study, the MnFe2O4@SBA-15@(CH2)3-Ade can be considered a promising adsorbent for the fast and efficient removal of heavy metals from water matrices.

Efficient One-Pot Synthesis of 1,4-Dihydropyridines Catalyzed by Magnetic MnFe2O4 Nanoparticles.

The efficient one-pot synthesis of some 1,4-dihydropyridines is described by a condensation reaction of some aldehyde derivatives, ethyl acetoacetate and ammonium acetate in the presence of superparamagnetic manganese ferrite nanoparticles at 80 °C. The advantages of this protocol include selectivity, high purity of the products, excellent yields, short reaction times, ease of processing, and environmentally friendly conditions for the synthesis of 1,4-dihydropyridines. In addition, the catalyst can be recovered and reused in multiple runs without significantly reducing the product yield.

Effect of reduced graphene oxide and MnFe2O4 nanoparticles on carbonyl iron for magnetorheological fluids

This study introduces magnetic MnFe2O4 nanoparticles and graphene oxide (GO) nanosheets to enhance magnetorheological (MR) properties and dispersion stability of the carbonyl iron (CI)-based MR fluid. The prepared CI/MnFe2O4/GO was transformed into CI/MnFe2O4/rGO through an annealing process and was used as an additive of the MR fluid. The shape, crystallinity, and magnetic properties of the composite were analyzed via SEM, TEM, EDS, XRD, and vibrating sample magnetometer. In addition, rotational rheometer and Turbiscan were used to examine the MR properties and dispersion stability of the MR fluid, respectively. The CI/MnFe2O4/rGO-based MR fluid exhibited higher shear stress, shear viscosity, and storage modulus than the CI-based MR fluid. The dispersion stability was enhanced due to GO with its low density and a large specific surface area, and the sedimentation ratio was improved approximately by 17% after 24h owing to the reduced difference in the density between the magnetic particles and oil medium.

Influence of temperature on structural, magnetic and thermal properties of superparamagnetic MnFe2O4 nanoparticles

Magnetic nanocrystalline MnFe2O4 nanoparticles with spinel structure were synthesized using co-precipitation technique and the effect of annealing temperature on physicochemical properties were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Vibrating sample magnetometer (VSM), and Thermogravimetric analysis (TGA). XRD confirmed the formation of single-phase cubic spinel structures with crystallite sizes ranging from 11.45 to 16.05 nm. FTIR revealed the formation of spinel ferrite nanoparticles with oleic acid binding. TGA demonstrated the formation of pure MnFe2O4 nanoparticles with improved crystalline structure at 300 °C, which developed secondary phases on annealing at 500 °C followed by cation redistribution at tetrahedral and octahedral sites at 700 °C. The heat treatment decreased the saturation magnetization from 15.85 emu/g to 14.30 emu/g which eventually increased to 14.83 emu/g. All the prepared nanoparticles showed superparamagnetic behavior. The results obtained from all the analyses support each other.

Excellent, Lightweight and Flexible Electromagnetic Interference Shielding Nanocomposites Based on Polypropylene with MnFe2O4 Spinel Ferrite Nanoparticles and Reduced Graphene Oxide.

In this work, various tunable sized spinel ferrite MnFe2O4 nanoparticles (namely MF20, MF40, MF60 and MF80) with reduced graphene oxide (RGO) were embedded in a polypropylene (PP) matrix. The particle size and structural feature of magnetic filler MnFe2O4 nanoparticles were controlled by sonochemical synthesis time 20 min, 40 min, 60 min and 80 min. As a result, the electromagnetic interference shielding characteristics of developed nanocomposites MF20-RGO-PP, MF40-RGO-PP, MF60-RGO-PP and MF80-RGO-PP were also controlled by tuning of magnetic/dielectric loss. The maximum value of total shielding effectiveness (SET) was 71.3 dB for the MF80-RGO-PP nanocomposite sample with a thickness of 0.5 mm in the frequency range (8.2–12.4 GHz). This lightweight, flexible and thin nanocomposite sheet based on the appropriate size of MnFe2O4 nanoparticles with reduced graphene oxide demonstrates a high-performance advanced nanocomposite for cutting-edge electromagnetic interference shielding application.

Z-scheme heterojunction nanocomposite fabricated by decorating magnetic MnFe2O4 nanoparticles on BiOBr nanosheets for enhanced visible light photocatalytic degradation of 2,4-dichlorophenoxyacetic acid and Rhodamine B

In this study, novel Z-scheme BiOBr/MnFe2O4 nanocomposites were successfully fabricated using a simple and surfactant-free hydrothermal synthetic route. The physicochemical and optical characteristics of the photocatalysts were analyzed by various instruments. The obtained BiOBr/MnFe2O4 nanocomposites significantly accelerated the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and Rhodamine B (RhB) when compared with other analyzed photocatalysts under visible light irradiation. Among all samples, the BiOBr/MnFe2O4-10 nanocomposite exhibited the best photocatalytic performance. The improved photoactivity was ascribed to the formation of Z-scheme heterojunction between BiOBr and MnFe2O4, thereby resulting in efficient separation of charge carriers. Photoelectrochemical and photoluminescence analyses were carried out to validate this conclusion. Furthermore, the BiOBr/MnFe2O4 nanocomposite can be easily separated and recycled without significant loss of photoactivity after five consecutive uses. The intermediate products produced during the photodegradation of 2,4-D were also detected. Radical quenching experiments revealed that the hydroxyl radicals played critical roles in the photodegradation reactions. Finally, a possible photocatalytic enhancement mechanism of BiOBr/MnFe2O4 nanocomposites was proposed.

Facile synthesis, antibacterial mechanisms and cytocompatibility of Ag–MnFe2O4 magnetic nanoparticles

Magnetic MnFe2O4 nanoparticles containing 0, 1 and 3 at.% silver, respectively were synthesized by one-pot sol-gel method for antibacterial applications in biomedical fields. Material characterizations indicate that MnFe2O4 begins crystallization at 134 °C and oxidation at 450 °C, the grain size and agglomeration degree increase with the silver content and silver exists as metallic state for the particles. The saturation magnetization decreases with the sintering temperature and slightly increases with the silver content, with the maximum of 50.0 emu/g obtained. Antibacterial tests by plate counting and PI-Hoechst 33342 staining suggest that the antibacterial activity of Ag–MnFe2O4 nanoparticles is silver content-dependent. Silver ions concentration measurement, β-galactosidase activity assay and transmission electron microscopic observation show that the antibacterial activity is dominated by the actions of the released silver ions, rather than the membrane cell impairment or reactive oxygen species-induced oxidative stress mechanism. MC3T3-E1 cell test demonstrates the best cytocompatibility of the nanoparticles with 3 at.% silver, which is likely related to the reduced cell endocytosis of the aggregated particles. The combination of magnetism, antibacterial activity and biocompatibility would make Ag–MnFe2O4 nanoparticles a potential multi-functional material in various biomedical applications.

A Facile Solution Combustion and Gel Calcination Process for the Preparation of Magnetic MnFe₂O₄ Nanoparticles.

A facile solution combustion and gel calcination process for the preparation of magnetic MnFe²O⁴ nanoparticles was introduced. The experimental results showed that the volume of absolute alcohol and the calcination temperature were two key factors to grain size, crystallinity and magnetic properties of MnFe²O⁴ nanoparticles. With the volume of absolute alcohol increasing from 15 to 100 mL, the average grain size of MnFe²O⁴ nanoparticles calcined at 400 °C for 2 h increased from 13.4 nm to 36.0 nm, and the saturation magnetization (Ms) value of MnFe²O⁴ nanoparticles increased from 1.2 emu/g to 105.5 emu/g; while, with the calcination temperature increasing from 400 °C to 800 °C, the average grain size increased from 13.4 nm to 32.9 nm, and the saturation magnetization value increased from 1.2 emu/g to 15.3 emu/g. The specific surface area of MnFe²O⁴ nanoparticles calcined at 400 °C for 2 h with absolute alcohol of 30 mL was measured, which was large of 49.6 m²/g.

Adsorption Behaviors of Congo Red onto Magnetic MnFe2O4 Nanoparticles Prepared via the Rapid Combustion Process

Magnetic MnFe₂O₄ nanoparticles were prepared via the rapid combustion process, the morphology, chemical composition, microstructure and magnetic property of them were investigated by SEM, EDX, XRD, TEM, SAED and VSM. The as-prepared magnetic MnFe₂O₄ nanoparticles calcined at 400 °C for 2 h with absolute alcohol of 50 mL were characterized with the average nanoparticle size of about 55 nm and the specific magnetization of 64.9 Am²/kg. The adsorption kinetics and adsorption isotherms of Congo red (CR) from aqueous solutions onto MnFe₂O₄ nanoparticles were investigated by UV spectroscopy at room temperature; the adsorption kinetics data were in good agreement with the pseudo-second-order kinetic model in the initial CR concentrations of 150-300 mg/L. By comparison of the Langmuir, Freundlich and Temkin models for adsorption isotherms of CR, the Temkin model (correlation coefficient R² ═ 0.9983) could be used to evaluate the adsorption isotherm of CR onto the magnetic MnFe₂O₄ nanoparticles at room temperature, which suggested that the adsorption of CR onto the magnetic MnFe₂O₄ nanoparticles was a hybrid of monolayer and multilayer absorbing mechanism.

Magnetic-controlled aerogels from carboxylated cellulose and MnFe2O4 as a novel adsorbent for removal of Cu(II)

The pore structure of the regenerated cellulose hydrogel was used as a microreactor for generating magnetic MnFe2O4 nanoparticles via in situ co-precipitation technology. Sodium periodate and sodium chlorite were used as oxidants, and the carboxyl modification of magnetic cellulose aerogels was achieved through a two-step oxidation reaction. The method used was convenient and environmental-friendly, and the raw materials were also green and non-toxic. The addition of magnetic nanoparticles promoted the adsorption and enabled the recycling of materials. The results showed that the adsorption equilibrium time was only 120 min and adsorption capacity could be increased by increasing the adsorption temperature. The maximum adsorption capacity of Cu(II) was 73.70 mg/g at 25 °C when the initial concentration of solution was150 mg/L. The adsorption behaviour towards Cu(II) followed the pseudo-secondary reaction kinetics and the Langmuir isotherm adsorption model. According to the results of XPS, carboxyl and hydroxyl groups were the main active adsorption sites for Cu(II). Moreover, all the composite aerogels exhibited good reusability and could be easily separated from the water after adsorption. The pore structure of the regenerated cellulose hydrogel was used as a microreactor for generating magnetic MnFe2O4 nanoparticles via in situ co-precipitation technology. Sodium periodate and sodium chlorite were used as oxidants, and the carboxyl modification of magnetic cellulose aerogels was achieved through a two-step oxidation reaction. According to the results of XPS, carboxyl and hydroxyl groups were the main adsorption sites for Cu(II). Moreover, all the composite aerogels exhibited good reusability and could be easily separated from the water after adsorption.

Mg-Al-La LDH-MnFe2O4 hybrid material for facile removal of anionic dyes from aqueous solutions

The urea hydrolysis method was applied to prepare Mg-Al-La layered double hydroxides (LDH) and its hybrids with different amounts of magnetic MnFe2O4 nanoparticles. The new hybrid materials were characterized by X-ray powder diffraction, FTIR and Raman spectroscopy, AFM, SEM, TEM/EDX microscopic methods, BET specific surface area determination and inductively coupled plasma (ICP). The AFM and TEM/EDX analyses clearly showed MnFe2O4 nanoparticles to be predominantly localized on the surface of LDH sheets. Almost two-fold increase of the specific surface area was observed for the Mg-Al-La LDH-MnFe2O4 hybrids compared to the pristine LDH. All synthesized hybrids were studied for their adsorption capacities of Acid orange 7 dye. The adsorption studies were measured at pH 4.0, 7.0 and 10.0. The resulting data were fitted by Langmuir and Langmuir-Freundlich models. The Langmuir isotherm model exhibited a maximum adsorption capacity of Acid orange 7 dye (687.9 mg/g) for Mg-Al-La LDH-MnFe2O4 hybrid material. The lower pH positively affected higher adsorption capacity of Acid orange 7 dye. The prepared Mg-Al-La LDH-MnFe2O4 hybrid materials thus showed to be new promising adsorbents of anionic dyes.

Synthesis and Enhanced Photocatalysis of Magnetic Reduced Graphene Oxide-MnFe2O4 Nanohybrids

Background: The hybrid photocatalysts constructed with various semiconductor and graphene can show dramatically enhanced photocatalytic activities. The separability of a photocatalyst from degraded pollutant aqueous solution is very important in some cases. Objective: The magnetic MnFe2O4 nanoparticles and reduced graphene oxide were used to construct magnetically separable (rGO)-MnFe2O4 hybrids with high photo- catalytic properties. Method: The pure MnFe2O4 nanoparticles and rGO/MnFe2O4 hybrid photocatalysts were synthesized with a facile hydrothermal process. Results: The nanoparticles showed great sunlight-excited photocatalytic and Fenton- like photocatalytic activities in the photodegradation of dye solution. Introducing rGO resulted in further enhancement of the activity compared to the nanoparticles. The effect of initial dye solution pH and H2O2 on the activities were also studied. The greater activities of the hybrids are ascribed to good interface charge transfer that was verified by the estimation of optical conductivity and band energy level. The hybrids also showed an magnetically separable performance from degraded pollutant solution. Conclusion: This work suggested a facile method to synthesize the magnetic MnFe2O4 nanoparticles and rGO/MnFe2O4 hybrids. The hybrids are an promising photocatalytic materials for environmental applications.

Effects of MnFe2O4 nanoparticles on dielectric properties of Cu0.5Tl0.5Ba2Ca2Cu3O10−δ superconducting phase

Magnetic manganese ferrite (MnFe2O4) nanoparticles were synthesized by sol–gel method and solid-state reaction method was chosen for preparation of the superconducting Cu0.5Tl0.5Ba2Ca2Cu3O10−δ (CuTl-1223) phase. Superconducting-nanoparticles (MnFe2O4)x/CuTl-1223; x = 0–2.0 wt% composites were obtained by adding MnFe2O4 nanoparticles in CuTl-1223 superconducting matrix. The unchanged tetragonal crystal structure of the host CuTl-1223 superconducting phase witnessed that MnFe2O4 nanoparticles were not decomposed and settled at the grain-boundaries. The superconductivity was over all suppressed due to the reduction of superconducting volume fraction and enhanced scattering cross-section of the mobile charge carriers across these magnetic MnFe2O4 nanoparticles settled at the grain-boundaries of the host superconducting CuTl-1223 phase. The frequency dependent dielectric properties of (MnFe2O4)x/CuTl-1223 composites were probed at different operating temperatures. Different dielectric parameters (i.e. ɛ′r, ɛ″r, tanδ and σac) were determined from the experimentally measured capacitance (C) and conductance (G). The variation of these dielectric properties of CuTl-1223 superconducting phase with the variation of test frequency, contents of MnFe2O4 nanoparticles and operating temperature were investigated, correlated, compared and explained. These investigations can be very useful for the selection criteria of the materials for the practical applications.

Synthesis and characterization of carboxymethyl chitosan/Fe3O4 and MnFe2O4 nanocomposites hydrogels for loading and release of curcumin

This paper presents the preparation of hydrogel with magnetic properties derived from carboxymethyl chitosan for controlled drug release performance. The magnetic Fe3O4 and MnFe2O4 nanoparticles with crosslinked Carboxymethyl Chitosan hydrogel were prepared by using epichlorohydrin as the cross-linker. The structure characterization performed by FT-IR. The XRD analysis was applied for evaluation of crystalline phase of MnFe2O4 and Fe3O4 in the hydrogels. The crystallite size of Fe3O4/CMCS and MnFe2O4/CMCS was calculated to be 30.12, and 44.51 nm, respectively. The presence of MnFe2O4 and Fe3O4 in the hydrogels can reason a rough surface morphology which that confirmed by SEM images. The Max. Saturation magnetization value as obtained from hysteresis loop is 105 and 75 Am2/kg for Fe3O4/CMCS and MnFe2O4/CMCS hydrogel, respectively. The Fe3O4 and MnFe2O4 on Carboxymethyl Chitosan hydrogels indicated a pH-sensitive for swelling behavior process. The equal amount of Fe3O4 and MnFe2O4 on hydrogels have high swelling at pH 6.4. The swelling capacity decreased from 214 to 172% and 144–114% at pH 6.4 with attendance of high amount of MnFe2O4 and Fe3O4 on hydrogels compared to other samples, respectively. Drug loading and release performances were investigated by curcumin as a model drug. The maximum curcumin release was obtained 25.1–51.52% at pH = 6.4. The drug releases system demonstrates the high ratio of Fe3O4 and MnFe2O4 containing Carboxymethyl Chitosan sample has a great efficiency in curcumin release. The effect of applied magnetic field on drug release for Fe3O4/CMCS was highest compared to MnFe2O4/CMCS. The results demonstrated that the Fe3O4 and MnFe2O4 nanocomposites hydrogel can be applied for novel drug delivery systems.

Magnetic recoverable MnFe2O4/cellulose nanocrystal composites as an efficient catalyst for decomposition of methylene blue

MnFe2O4/cellulose nanocrystal (MnFe2O4/CNC) composites featured high catalytic activities on the decomposition of methylene blue (MB) were prepared by a novel approach, through which the H+ ions produced during the acid hydrolysis of cellulose are largely consumed. Attributed to their high specific surface areas, small particle size and low band gap, contributing to the generation of large number of reactive hydroxyl radicals from H2O2, the magnetic MnFe2O4 nanoparticles anchoring on CNC demonstrate pronounced improvements of catalytic activities on the decomposition of MB pollutants compared with that of the bare MnFe2O4. Specifically, the degradation degree of MB catalyzed by MnFe2O4/CNC composite containing 20 wt% of CNC is 99%, which suggests more than 60% increase than that in the bare MnFe2O4. More particularly, MnFe2O4/CNC composites featuring excellent magnetic properties exhibit an excellent recycling catalytic performance, suggesting a great promising candidate in application of environmental pollutant treatment.

Novel magnetically separable Ag3PO4/MnFe2O4 nanocomposite and its high photocatalytic degradation performance for organic dyes under solar-light irradiation

Novel magnetically separable Ag3PO4/MnFe2O4 nanocomposite with 30wt% MnFe2O4 was synthesized for the first time by a facile hydrothermal route and the composition and microstructure of the nanocomposite was fully characterized. The photocatalytic activity of Ag3PO4/MnFe2O4 nanocomposite was evaluated in the degradation of methylene blue (MB) and Rhodamine B (RhB) dyes under natural solar-light irradiation with an average light intensity of ~ 185mWcm−2. The results displayed that the degradation efficiency of the Ag3PO4/MnFe2O4 nanocomposite was 98% for methylene blue (MB) and 100% for Rhodamine B (RhB) in 82min. The photocatalytic activity of Ag3PO4/CoFe2O4 was almost 1.5 and 3 times as high as those of the pure Ag3PO4 and CoFe2O4, respectively. The remarkably enhanced photocatalytic performance of Ag3PO4/MnFe2O4 nanocomposite compared with the individual Ag3PO4 and MnFe2O4 was ascribed to its higher specific surface area and the existence of a synergic effect between Ag3PO4 and MnFe2O4 that resulted in efficient separation of electron–hole pairs. Trapping experiments indicated that the photodegradation of dyes was mainly achieved by superoxide radicals (•O2-) attack in Ag3PO4/MnFe2O4 suspension. Furthermore, the possible mechanism of excellent solar-light photoactivity activity of the Ag3PO4/MnFe2O4 nanocomposite was proposed based on the experimental results. Due to the existence of the magnetic MnFe2O4 nanoparticles, the Ag3PO4/MnFe2O4 nanocomposite could be magnetically separated from the reaction mixture by a usual magnet with an intensity of 0.1T (= 1kOe) and reused without any change in structure.

Fabrication of Magnetic Polymer Composite Sorbents and its Application for Recovery of Platinum from Acidic Solution

Magnetic MnFe2O4 nanoparticles (MNPs) were fabricated and entrapped in amine-rich chitosan (CS) sorbents containing multi-walled carbon nanotubes (MWCNTs) or polyethyleneimine (PEI). Magnetic polymer composite sponges (MPCSs) and magnetic polymer composite fibers (MPCFs) were prepared through mixing each of MWCNT and PEI with MNPs-CS solution. The successful fabrication of MPCSs and MPCFs was confirmed through FTIR and VSM analyses. The as-fabricated MPCSs and MPCFs were used for adsorptive recovery of Pt (IV) from acidic solution. The maximum uptakes of Pt (IV) ions by the MPCSs and MPCFs were estimated to be 218.2 ± 8.3 and 371.4 ± 16.8 mg/g, respectively. Moreover, the Pt (IV)-loaded MPCSs and MPCFs were easily separated from aqueous solution under magnetic field after sorption process.