Magnetic Hybrid Material Research Articles

Potential of a magnetic hybrid material produced using water hyacinth (Eichhornia crassipes) for removal of inorganic and organic pollutants from aqueous media

Abstract Investigation was made of the potential of in natura water hyacinth for use in the synthesis of a magnetic hybrid suitable for the removal of metals and pharmaceuticals from aqueous media. XRD and FTIR analyses confirmed that the synthesis method was effective in obtaining the hybrid (denoted AGMG). Assays to evaluate the influence of pH on the removal of copper, zinc, nickel, cobalt, and ibuprofen (IBP) showed higher removal percentages at pH 4–5 for the metals and at pH 3 for IBP. The processes showed fast kinetics, with the removal rates in the first 5 min exceeding 50% for the metals and 90% for IBP. The maximum AGMG adsorptive capacities (qmax, in mg g−1) were 18.3 for Cu(II), 10.1 for Zn(II), 7.33 for Ni(II), and 1.02 mg g−1 for IBP. The following order of selectivity was obtained in tests employing mixed solutions of the three metals: Cu > Zn > Ni. The AGMG was reused in four cycles for the metals and in six cycles for IBP, with reuse efficiencies in the ranges 72–77% and 70–100%, respectively. The metal-saturated AGMG remaining after the reuse assays showed catalytic activity in the reduction of 4-nitrophenol with NaBH4 and could be reused in ten reduction cycles, with conversion rates from 89 to 100% and times from 21 to 26 s.

Pyrocatechol violet impregnated magnetic graphene oxide for magnetic solid phase microextraction of copper in water, black tea and diet supplements

Pyrocatechol violet impregnated magnetic graphene oxide hybrid material (PV-MGO) was prepared as magnetic solid phase microextraction for separation and preconcentration of copper before its determination by flame atomic absorption spectrometry. PV-MGO hybrid material was characterized using field emission scanning electron microscope (FE-SEM, SEM-Mapping), scanning transmission electron microscopy (STEM), energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Raman spectroscopy. Effects of various parameters such as pH, eluent type, vortex time, amount of magnetic adsorbent were investigated. Under the optimized conditions the MSPE-FAAS procedure presents limit of detection (LOD) of 4.0 μg L−1, limit of quantification (LOQ) of 13.3 μg L−1, preconcentration factor of 20 and relative standard deviation (RSD) 4.93%. The accuracy of the method was confirmed by the analysis of the certified reference materials (NCS ZC73032 Celery, CRM025-050 metals on soil, TMDA-64.2 fortified water) and addition-recovery tests. The present method was successfully applied to water, black tea and diet supplements.

Magnetic Solid-Phase Extraction of Organic Compounds Based on Graphene Oxide Nanocomposites.

Graphene oxide (GO) is a chemical compound with a form similar to graphene that consists of one-atom-thick two-dimensional layers of sp2-bonded carbon. Graphene oxide exhibits high hydrophilicity and dispersibility. Thus, it is difficult to be separated from aqueous solutions. Therefore, functionalization with magnetic nanoparticles is performed in order to prepare a magnetic GO nanocomposite that combines the sufficient adsorption capacity of graphene oxide and the convenience of magnetic separation. Moreover, the magnetic material can be further functionalized with different groups to prevent aggregation and extends its potential application. Until today, a plethora of magnetic GO hybrid materials have been synthesized and successfully employed for the magnetic solid-phase extraction of organic compounds from environmental, agricultural, biological, and food samples. The developed GO nanocomposites exhibit satisfactory stability in aqueous solutions, as well as sufficient surface area. Thus, they are considered as an alternative to conventional sorbents by enriching the analytical toolbox for the analysis of trace organic compounds.

Click chemical assembly and validation of bio-functionalized superparamagnetic hybrid microspheres

Surface derivatized magnetic nanoparticles have been commonly used for magnetic separation. Facile mechanisms are needed to be developed for the design of bio-functionalized magnetic hybrid materials, where the surfaces can be re-generated for the re-use of the developed platforms. Superparamagnetic iron oxide nanoparticles with a diameter below 10 nm were synthesized via a novel microwave-assisted hydrothermal method in the presence of citrate ions, which allowed to obtain uniform and negatively charged nanoparticles. These were then coupled with Poly-l-lysine (PLL), forming micrometer-sized self-assembled spherical entities. Cross-linking the PLL within these microspheres with glutaraldehyde stabilized them chemically and mechanically. The active bio-functionality was introduced by a protein grafting methodology, using m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (SMBS). The Moringa oleifera Coagulant Protein (MOCP) from a seed extract was employed for its characteristic coagulation activity. The performance of the MOCP functionalized microspheres was evaluated as a function of turbidity removal of problematic colloidal clay from water via magnetic separation, resulting in over 80% of activity within 15 min. Surface of these hybrid materials can be re-generated by treatment with alcohol, allowing their easy magnetic separation and re-use. The rapid and strong response with tunable magnetic property makes these hybrid microspheres a powerful tool for many potential applications, due to the general applicability of the developed methodology.

Metal-Organic Framework@Carbon Hybrid Magnetic Material as an Efficient Adsorbent for Pollutant Extraction.

The preparation of a hybrid magnetic metal-organic framework (MOF)@carbon from a MOF-derived porous carbon is reported. MOF-74(Co) is used as a precursor for the synthesis of a magnetic carbon with homogeneous cobalt particle distribution (C-MOF-74) by a direct carbonization step. The cobalt particles present in the carbon are partially converted to zeolitic imidazolate framework (ZIF)-67 by reaction with 2-methylimidazole to obtain a core-shell ZIF-67@C-MOF-74. The effect of the reaction time and 2-methylimidazole concentration in the conversion procedure is studied by X-ray diffraction and scanning microscopy. Because of its high surface area, dual porosity, and magnetic properties, ZIF-67@C-MOF-74 exhibits high extraction capacity (180 mg g-1), fast adsorption rate, and excellent recyclability for Congo red adsorption. In addition, the prepared material shows high efficiency in the extraction of different phenolic compounds. The developed procedure can be easily adapted to different carbons and MOFs, thus potentially enabling the preparation of a wide number of new hybrid materials.

Magnetic \u03b3Fe2O3@Sh@Cu2O: an efficient solid-phase catalyst for reducing agent and base-free click synthesis of 1,4-disubstituted-1,2,3-triazoles

A hybrid magnetic material γFe2O3@Sh@cu2O was easily prepared from Shilajit (Sh) decorated Fe3O4 and copper acetate. The prepared magnetic hybrid material was fully characterized using different analysis, including Fourier transform infrared (FT-IR), X-ray diffraction (XRD), inductively coupled plasma (ICP), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM) thermal gravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET). All these analysis revealed that during coating of Fe3O4@Sh using copper salt (II), synchronized redox sorption of CuII to CuI occurs at the same time as the oxidation of Fe3O4 to γFe2O3. This magnetic catalyst exhibited excellent catalytic activity for regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles via one pot three-component click reaction of sodium azide, terminal alkynes and benzyl halides in the absence of any reducing agent. High yields, short reaction time, high turnover number and frequency (TON = 3.5 * 105 and TOF = 1.0 * 106 h−1 respectively), easy separation, and efficient recycling of the catalyst are the strengths of the present method.

Facile synthesis of polydivinylbenzene coated magnetic polydopamine coupled with pressurized liquid extraction for the extraction and cleanup of polycyclic aromatic hydrocarbons in soils

Due to the trace levels of polycyclic aromatic hydrocarbons (PAHs) in soil and the complexity of soil matrices, effective sample pretreatment methods are of great significance to obtain accurate analytical results. In this paper, polydopamine (PDA) encapsulated Fe3O4 particles were used as seeds for in situ polymerization of divinylbenzene (DVB) to derive magnetic hybrid material Fe3O4@PDA@PDVB. Coupled with pressurized liquid extraction, Fe3O4@PDA@PDVB was investigated as a selective adsorbent for the extraction and cleanup of PAHs in soil. The prepared magnetic material was characterized and demonstrated to possess strong hydrophobicity and superparamagnetism. Under optimal conditions, Fe3O4@PDA@PDVB can effectively extract 15 PAHs from a 30% methanol solution within 2 min, and it is more selective for PAHs than for n-alkane in soil extracts. The matrix effect significantly decreased after extraction by the prepared material, which showed superiority to a silica gel column method (EPA 3630C Method). The developed method was linear (5–1000 ng g−1) with coefficient of determination (R2) ranging from 0.9986–0.9998, and the limits of detection were 0.13–0.54 ng g−1. Additionally, repetitive experiments indicated that the prepared material was reproducible and reusable with relative standard deviations below 8.4% and 8.6%, respectively. Finally, the new method was successfully employed to determine the concentrations of PAHs in genuine soil and standard reference material, and the results were comparable to those of widely utilized EPA methodology.

A flower-like hybrid material composed of Fe3O4, graphene oxide and CdSe nanodots for magnetic solid phase extraction of ibuprofen prior to its quantification by HPLC detection.

A flower-like Fe3O4/GO/CdSe nanodot magnetic hybrid material was produced and applied to magnetic solid-phase extraction of ibuprofen from pharmaceuticals, water, and urine samples. The material was characterized by X-ray diffraction, Raman spectroscopy and field emission scanning electron microscopy and SEM-EDX. The pH value, volume of sample solution, amount of sorbent, type and volume of elution solvent and extraction time were optimized. Following elution with acetone, ibuprofen was quantified by HPLC-DAD detection. The recoveries of ibuprofen from spiked real samples ranged between 87 and 109%, and the intra-day and inter-day relative standard deviations from 1.25 to 3.02%. The limit of detection, limit of quantification and preconcentration factor are 0.36ng·mL-1,1.20ng·mL-1 and 150, respectively. Graphical abstract Schematic representation of the combination of flower-like Fe3O4/GO/CdSe nanodot-based magnetic solid phase extraction (MSPE) and high-performance liquid chromatography (HPLC) procedure for the extraction and analysis of ibuprofen in pharmaceuticals, water, and urine samples.

Iron mining wastes collected from Mariana disaster: Reuse and application as catalyst in a heterogeneous electro-Fenton process

A simple and environmental friendly strategy for recycling iron mining wastes from the Mariana disaster, one of the biggest environmental disasters in Brazil, involved the synthesis of a magnetic hybrid (HbLM) material at ambient temperature. XRD analysis revealed formation of the cobalt ferrite phase, while FTIR and TGA confirmed the presence of NOM in the structures. The HbLM showed high surface area of about 167.9 m2 g−1. Heterogeneous electro-Fenton (EF)-HbLM process achieved the total decolorization of a model pollutant, the Acid blue 29 diazo dye, after 20 min of electrolysis; while the electrochemical oxidation with hydrogen peroxide generation (EO-H2O2) only led to 62% of color removal. The limit current density was 33.3 mA cm−2, above this value the parasitic reactions overlapped, consequently the efficiency of the process decreased. At pH 3.0, complete color removal was achieved after 20 min of treatment while 60 min were necessary at pH 7.0 (natural pH). This means that, at neutral pH, the process is feasible and the acidification of the medium is not necessary to promote the main reactions. This work provides an example of a system to remove toxic contaminants from wastewater following the principles of green chemistry and industrial symbiosis, with sequential reuse of wastes and the generation of new raw materials with added commercial and technological values.

Magnetic hybridized Fe3O4/HKUST-1 composite modified with graphite oxide to remove thiophene from model fuels

To improve the desulfurization adsorption performance of the magnetic hybrid material Fe3O4/HKUST-1, an innovative adsorbent Fe3O4/GO/HKUST-1 was synthesized. The desulfurization performance of Fe3O4/GO/HKUST-1 increased 24%, and the adsorption capacity increased to 38.21 mg/g because of a higher surface area and higher porosity than the parent materials. Moreover, the desulfurization capacity of Fe3O4/GO/HKUST-1 decreased 10% after five adsorption desorption cycles. Therefore, excellent adsorption properties and reusability make Fe3O4/GO/HKUST-1 attractive in the field of fuel desulfurization.

Enhancement of electrical conductivity and magnetic properties of bimetallic Schiff base complex on grafting to MWCNTs

In present work, we report a newly synthesized nano-inorganic hybrid magnetic material, [SBCu(II)Gd(III)]@MWCNT-COOH which is obtained by anchoring of a copper(II)–gadolinium(III) heteronuclear bimetallic complex, [triaqua(2-hydroxy-1,3-bis(3-methoxysalicylaldiminato)Cu(II)Gd(III)dinitrato)]nitrate monohydrate, [SBCu(II)Gd(III)] to carboxylated multiwalled carbon nanotubes (MWCNT-COOH) through a chemical method. MWCNT-COOH have been loaded with a number of [SBCu(II)Gd(III)] molecules on their surfaces, which generated multinuclear metal centers. [SBCu(II)Gd(III)]@MWCNT-COOH was characterized by FT-IR, UV–Vis, TGA, powder XRD, Raman spectroscopy, TEM, HRSEM, EDAX and elemental mapping. The DC electrical conductivity of materials was evaluated using two probe method suggesting that [SBCu(II)Gd(III)]@MWCNT-COOH is more conducting than [SBCu(II)Gd(III)]. The increased conductivity of [SBCu(II)Gd(III)]@MWCNT-COOH is confirmed by CV and EIS study. The capacitive and dielectric properties of the materials were investigated by Mott–Schottky electrochemical analysis. The positive value of slope signified n-type semiconducting nature of materials. The lower slope for [SBCu(II)Gd(III)] signified the strong dielectric behavior of the material. The positive shift in flat-band potential of [SBCu(II)Gd(III)]@MWCNT-COOH compared to [SBCu(II)Gd(III)] indicated its more conducting nature. Further small optical band gap obtained for [SBCu(II)Gd(III)]@MWCNT-COOH than [SBCu(II)Gd(III)] by UV–Vis studies suggested better conductivity of nano-inorganic hybrid material. Field dependent magnetization revealed enhanced saturation magnetization, remanent magnetization and coercivity of [SBCu(II)Gd(III)]@MWCNT-COOH due to generation of multinuclear metal centers on carboxylated MWCNTs. The temperature dependent magnetization measurement exhibited overlapping of field cooled and zero field cooled curves in entire temperature range (2–300 K), suggests intrinsic ferromagnetism in [SBCu(II)Gd(III)]@MWCNT-COOH. Hence, trend in variation of magnetization with magnetic field and temperature opens its utility in spin-based electronic devices.

A novel iron (III) organic-inorganic hybrid with a thermochromic transition: Synthesis and structural characterisation of the dicystaminium dichloride aquapentachloridoferrate (III), monohydrate (C4H14N2S2)2[FeCl5(H2O)]Cl2*H2O

The magnetic hybrid material, based on the aquapentachloridoferrate (III), [FeCl5(H2O)]2- and on the dicystaminium cation H2Cys, is reported for the first time in this paper exhibiting an interesting thermochromic behaviour. It was prepared as orange single crystals, suitable for single crystal X-ray diffraction, with the chemical formula (C4H14N2S2)2[FeCl5(H2O)]Cl2*H2O (1). The characterization by X-ray diffraction was carried out at room temperature 296 K and at 120 K. The new derivative displays an asymmetric unit, formed by two H2Cys cations, one anionic complex [FeCl5(H2O)]2- and two Cl−, that ensure the electroneutrality, all trapped in the matrix with one water molecule. It crystallizes in the triclinic P1¯space group with the following unit cell parameter at 120 K and 296 K respectively: a = 10.7913(4) Å, b = 11.4145(5) Å, c = 11.4225(5) Å and α = 99.010(4) °, β = 102.529(4) °, γ = 90.466(3); a = 10.8747(4) Å, b = 11.4717(5) Å, c = 11.5483(4) Å and α = 98.907(3) °, β = 103.169(3) ° γ = 90.635(3). The compound was also characterized by IR spectroscopy and by DSC analysis and its magnetic behaviour was investigated.

A novel peroxidase from Arabian balsam (Commiphora gileadensis) stems: Its purification, characterization and immobilization on a carboxymethylcellulose/Fe3O4 magnetic hybrid material

A novel plant peroxidase was isolated from the stem of Arabian balsam (Commiphora gileadensis) and purified using ammonium sulfate, followed by ion exchange chromatography (DEAE-Sepharose) and gel filtration (Sephcryl S-200). The newly isolated peroxidase was characterized as having a specific activity of 9503.3 unit/mg of protein after 20.3-fold purification, which yielded a recovery of 18.5%. Based on the subunit size, the purified peroxidase was a 40 kDa monomeric structure and presented high thermostability, as it was entirely stable at 55 °C for 30 min and retained approximately 13.6% of its activity at 85 °C. The optimal pH exhibited a broad value range (pH 7.0‐ 7.5). The kinetic parameters for the purified peroxidase were obtained. To increase the enzyme durability, efficiency and reusability, the peroxidase was entrapped onto a carboxymethyl cellulose/Fe3O4 magnetic hybrid material. The immobilized enzyme was characterized by scanning electron microscopy (SEM) and FT-IR spectroscopy. It was tested at different pH values, storage times and temperatures, and its kinetic behavior was assessed. The immobilized enzyme maintained its activity upon storage at 4 and 25 °C for 8 weeks, and upon recycling for up to 15 uses. Arabian balsam peroxidase appears to be candidate for industrial applications.

Generation of nanomagnetic biocomposites by genetic engineering of bacterial magnetosomes

Magnetosomes are magnetic nanoparticles biomineralized by magnetotactic bacteria. They consist of a monocrystalline magnetite core enveloped by the magnetosome membrane, which harbors a set of specialized proteins. For the alphaproteobacterium Magnetospirillum gryphiswaldense genetic techniques were developed for engineering both crystal morphology and the enveloping membrane, thereby generating building blocks for magnetic organic–inorganic hybrid materials. Genetic manipulation of magnetite biomineralization enabled the generation of core-engineered nanoparticles with adjusted magnetic and physicochemical properties. Functionalization of the particle surface was achieved by genetic expression of enzymes and peptides genetically fused to abundant magnetosome anchor proteins. High-level expression allowed the generation of multifunctional nanoparticles with maximized protein-to-particle ratios. This allowed for the tuning of surface properties (charge and hydrodynamic diameter), and the colloidal and enzymatic stability was improved by coating with inorganic and organic shells. The expression of molecular connectors might serve as scaffolds for the introduction of further functionalities. Overall, this demonstrates that the ‘synthetic biology’ approach enables the generation of multifunctional, magnetic hybrid materials with a tuned property spectrum exceeding those of conventional materials, and the combination of different biogenic materials generates fully genetically encoded biocomposites with enhanced potential for various biotechnological and biomedical applications.

A magnetic composite material derived from FeOOH decorated Cu-MOF and its catalytic properties

A Hybrid magnetic composite material Fe3O4@CuxOy/C (where, x = 1–2; y = 0–1) was prepared via pyrolysis of FeOOH decorated Cu3(BTC)2 (where, BTC = 1, 3, 5-benzenetricarboxylic acid) as a precursor. The obtained products was successfully applied to reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as a catalyst. Compared with other reported materials, Fe3O4@CuxOy/C exhibits high catalytic activity with excellent recyclability.

Fe3O4@C Core-Shell Carbon Hybrid Materials as Magnetically Separable Adsorbents for the Removal of Dibenzothiophene in Fuels.

Herein, we demonstrate a new class of core–shell magnetic carbon hybrid materials (Fe3O4@C) for remarkable adsorptive desulfurization of dibenzothiophene (DBT), which have been successfully prepared through hydrocarbonization of glucose on the surface of Fe3O4 and the subsequent pyrolyzation process. The as-obtained Fe3O4@C retains amorphous nature of carbon shells with a large surface area and displays an increase of iron atoms as active sites under elevated pyrolyzation temperature which is favorable in the adsorption of sulfur-containing species through physical and chemical adsorption, respectively. We investigate the adsorption capacity and efficiency of Fe3O4@C as a magnetically adsorbent for the removal of DBT in model oils under various experimental conditions including the adsorbent obtained at different temperatures, the amount of adsorbents, the DBT initial concentration, the regeneration approach, as well as the interference species. Our results demonstrated that the as-obtained Fe3O4@C at 650 °C (Fe3O4@C-650) displays a remarkable estimated adsorption performance (57.5 mg DBT/g for 200 ppmw), extraordinary high desulfurization efficiency (99% for 200 ppmw), and a high selectivity for DBT compared with its derivatives. Moreover, Fe3O4@C can be recovered in a quite easy, economical, and eco-friendly manner by an external magnet after five cycles without significant weight loss, which significantly simplifies the operation procedure and favors the recycle of Fe3O4@C. Combined with the economic and eco-friendly merits, Fe3O4@C offers a new avenue to employ the magnetic carbon materials for industrial applications and provides a promising substitute for adsorptive desulfurization in view of academic, industrial, and environmental aspects.

Magnetic and dispersible FeCoNi-graphene film produced without heat treatment for electromagnetic wave absorption

Magnetic metal and graphene hybrids possess the high dielectric properties of graphene and the high magnetic properties of the metal, which render them suitable as electromagnetic (EM) wave-absorbing materials. In this research, we fabricated an EM wave-absorbing film with excellent performance (reflection loss of −68 dB) based on a FeCoNi@graphene hybrid. We developed a new electroless plating method for fabricating magnetic metal@graphene hybrids without any heat treatment, and the new hybrid material showed a higher saturation magnetization (120.4 emu/g) than that of a hybrid material prepared by conventional electroless plating (56.8 emu/g). The sizes, structures, and oxidation ratios of the FeCoNi nanoparticles on graphene were different depending on the synthesis method, and Ni played an important role in the growth of the FeCoNi nanoparticles. The FeCoNi@graphene hybrid was well dispersed in tetrahydrofuran, and thus, could be fabricated into free-standing and flexible composite films by mixing with thermoplastic polyurethane. The high permeability of the FeCoNi@graphene film resulted in a high EM wave-absorbing performance due to impedance matching. These results provide an important advancement toward not only the commercialization of EM wave-absorbing films for healthcare, electronic reliability, and tactical security applications but also the development of magnetic metal and graphene hybrid materials using a scalable process.

Magnetorheological gels in two and three dimensions: understanding the interplay between single particle motion, internal deformations, and matrix properties

Magnetic hybrid materials are intrinsically heterogeneous in their mechanical properties on different length scales. This gives rise to a number of challenges in the comparison of experimental results to modeling and simulation efforts. This review focused on recent advance on relating the mechanical properties of magnetic hybrid materials to the internal structure of these materials. Special emphasis is given to methods for observing the internal matrix deformations. For 3D and 2D magnetic hybrid materials, we discuss the possibilities and limitations of measuring internal motion and instabilities of the embedded magnetic particles. Although measuring internal matrix deformations in 3D systems is possible, the measurement time for 3D imaging is too long for truly dynamic studies. This limitation can be overcome with 2D imaging in 2D or 3D systems. In all presented systems, measuring the internal deformation also gives the possibility to use the magnetic particles to characterize the mechanical matrix properties locally. The presented experimental advances are put into relation to competing approaches.

Ultrasonic assisted synthesis of magnetic Ni-Ag bimetallic nanoparticles supported on reduced graphene oxide for sonochemical simultaneous removal of sunset yellow and tartrazine dyes by response surface optimization: Application of derivative spectrophotometry

The magnetic Ni-Ag bimetallic nanoparticles supported on reduced graphene oxide (Ni-Ag NPs/rGO) was synthesized and characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). Subsequently, this magnetic hybrid material as a novel adsorbent was applied for the sonochemical simultaneous removal of sunset yellow and tartrazine dyes in combination with first-order derivative spectrophotometric method to resolve the overlap between the spectra of these dyes. With magnetic properties, the adsorbent could easily be collected from aqueous solution using an external magnetic field. The parameters including initial concentration of each dye, adsorbent dosage and sonication time were studied by Box-Behnken design (BBD) and response surface methodology (RSM), while pH was studied by one-at-a-time approach. According to Box-Behnken design based on desirability function (DF), the best experimental conditions was set as initial sunset yellow concentration 10 mgL−1, initial tartrazine concentration 8.5 mgL−1, adsorbent dosage 0.045 g and sonication time of 15 min. The equilibrium data was fitted to different isotherm models and the results revealed the suitability of the Langmuir model. The maximum sorption capacity calculated from the Langmuir model was 28.57 and 26.31 mg g−1 for sunset yellow and tartrazine, respectively. Kinetic data revealed that the adsorption process followed a pseudo-second-order model. The reusability of the magnetite nanoparticles revealed about 8% decrease in the removal efficiency within four consecutive runs.

The Magnetic Hybrid Cu(I)-MOF@Fe3O4 with Hierarchically Engineered Micropores for Highly Efficient Removal of Cr(VI) from Aqueous Solution

It is an urgent topic for public health and environmental protection to remove Cr(VI) from wastewater effectively and conveniently. Herein, we fabricate the novel hybrid magnetic material HPU-13@Fe3O4 (HPU-13 = {[Cu3(L)2]·OH·2CH3CH2OH·10H2O}n; HL = 2-(5-pyridin-4-yl-2H-[1,2,4]triazol-3-yl)pyrimidine), which shows excellent Cr(VI) removal efficiency and is easily employed as a reusable absorbent. The maximum capacities of Cr2O72– and CrO42– adsorbed on HPU-13@Fe3O4 were 398.41 and 471.69 mg/g, respectively, larger than those of reported MOFs used in Cr2O72– and CrO42– adsorption. Adsorption mechanism studies confirmed that the synergistic reaction of Cr(VI) reduction and adsorption was responsible for the high removal efficiency. The above evidence proved that HPU-13@Fe3O4 has the potential functional ability to decontaminate Cr(VI) polluted water systems.