Fe3O4/BiOCl photocatalyst with magnetic recovery property for solar-light-responsive removal of Rhodamine B dye

Efficient photocatalysis of organic dyes under simulated sunlight irradiation by a novel magnetic CuFe2O4@porphyrin nanofiber hybrid material fabricated via self-assembly

The use of synthetic dyes as dyes is increasing so that the waste is polluting the environment. One of the dangerous wastes that damages the environment and causes health problems is rhodamine B dye. The removal of rhodamine B dye is carried out by adsorption using an adsorbent that has been modified to provide magnetic properties. The aim of the research is to synthesize magnetic adsorbent nanoparticles using the co-precipitation method and use them to reduce the concentration of rhodamine B dye in artificial wastewater at various time variations. The study shows that magnetic nanoparticle adsorbents were successfully synthesized using the precipitation method. The adsorbent particles provide a magnetic effect on external magnetic forces, which shows that the adsorbent nanoparticles are magnetic. The application of magnetic adsorbent nanoparticles showed that the longer the adsorption time, the percentage of rhodamine B dye removal increased. The highest removal was obtained at 86% at an adsorption time of 90 minutes and an adsorbent mass of 4 g.

M-type strontium ferrite photocatalysts were successfully synthesized by three different methods including combustion assisted sol-gel method, microwave irradiation assisted sol-gel method and conventional sol-gel method. The phase structure, surface morphology, optical properties, magnetic properties and photocatalytic activity of the M-type strontium ferrite photocatalyst are strongly dependent on the synthetic route. The effects of the irradiation time, catalyst loading, initial dye concentration and pH value on the photocatalytic activity of the M-type strontium ferrite photocatalyst have been systematically studied. The M-type strontium ferrite photocatalyst synthesized by a microwave irradiation assisted sol-gel method exhibits an excellent optical properties, magnetic properties and photocatalytic activity. The optimum irradiation time, catalyst loading, initial dye concentration and pH value of the M-type strontium ferrite photocatalyst is 180 min, 3 g l−1, 25 mg l−1 and 10, respectively. The recycle experiments show that the M-type strontium ferrite photocatalyst has good magnetic separation recovery ability. The hydroxyl radicals (•OH) play a key role for the M-type strontium ferrite photocatalyst for photocatalytic degradation of the rhodamine B dye.

Magnetic nanoparticles are a promising alternative as a support in adsorption processes, aiming at the easy recovery of the aqueous medium. A faujasite zeolite (FAU) surface was decorated with magnesium ferrite (MgFe2O4) nanoparticles. FAU is a porous adsorbent with high specific surface area (SSA) and chemical stability. The FAU:MgFe2O4 nanocomposite 3:1 ratio (w w−1) promotes the combination of the surface and magnetic properties. The results showed the effectiveness of the MgFe2O4 immobilization on the FAU surface, exhibiting a high SSA of 400 m2 g−1. The saturation magnetization (Ms) was verified as 5.9 emu g−1 for MgFe2O4 and 0.47 emu g−1 for FAU:MgFe2O4, an environmentally friendly system with soft magnetic characteristics. The magnetic nanocomposite achieved high adsorption values of around 94% removal for Co2+ and Mn2+ ions. Regarding its reuse, the nanocomposite preserved adsorption activity of above 65% until the third cycle. Thus, the FAU:MgFe2O4 nanocomposite presented favorable adsorptive, magnetic, and recovery properties for reuse cycles in polluted water.

Facile synthesis of superparamagnetic β-CD-MnFe2O4 as a peroxymonosulfate activator for efficient removal of 2,4- dichlorophenol: structure, performance, and mechanism

Magnetic chitosan hydrogel has aroused immense attention in recent years due to their biomedical significance and magnetic responsiveness. Here, A new electrodeposition method is reported for the fabrication of a novel CuNi-based magnetic chitosan freestanding film (MCFF) in an acidic chitosan plating bath containing SDS-modified CuNi NPs. Contrary to chitosan’s anodic and cathodic deposition, which typically involves electrochemical oxidation, the synthetic process is triggered by coordination of chitosan with Cu and Ni ions in situ generated by the controlled surface dissolution of the suspended NPs with the acidic plating bath. The NPs provide not only the ions required for chitosan growth but also become entrapped during electrodeposition, thereby endowing the composite with magnetic properties. The obtained MCFF offers a wide range of features, including good mechanical strength, magnetic properties, homogeneity, and morphological transparency. Besides the fundamental interest of the synthesis itself, sufficient mechanical strength ensures that the hydrogel can be used by either peeling it off of the electrode or by directly building a complex hydrogel electrode. Its fast and easy magnetic steering, separation and recovery, large surface area, lack of secondary pollution, and strong chelating capability could lead to it finding applications as an electrochemical detector or adsorbent.

Wet synthesis of magnetically retrievable Mn/Nd co-doped cobalt ferrites for visible light-driven photocatalytic annihilation of azo dye

Photocatalytic degradation of bisphenol A by temperature-sensitive magnetic hydrogel with enhanced service life

Composite magnetic aluminum hydroxide at iron oxide nanomaterials, Al(OH)3@Fe3O4, with a well-defined core-shell structure, were used as pretreatment adsorbents for the removal of silica in brackish water. The Al(OH)3 outer shell confers silica adsorption capacity, and the superparamagnetic Fe3O4 core allows material separation and magnetic recovery. The as-prepared nanomaterials (2 g L-1) remove ∼95 and ∼80% silica from Si-rich solutions with 0.5 and 2 mM initial silica concentrations, respectively. Regeneration under basic conditions was evaluated, and post-adsorption treatment with 0.05 M NaOH yielded optimal material reusability. After four regeneration cycles, the Al(OH)3@Fe3O4 nanomaterials retain their magnetic property while still being able to remove ∼40% silica from solutions at an adsorbent concentration of 2 g L-1. The mechanism of silica adsorption onto the surface of the nanomaterials was probed using several spectroscopic techniques. ATR-FTIR (attenuated total reflection-Fourier transform infrared) integrated with two-dimensional correlation analysis shows that silica species vary from Q2 to Q4 with adsorption time corresponding to silica polymerization. 29Si solid-state NMR spectra show an upfield chemical shift displacement of the Q2 signal, which indicates the formation of Q4 units, suggesting silica polymerization onto the Al(OH)3 shell. In addition, a laboratory-scale reverse osmosis setup was used to evaluate Al(OH)3@Fe3O4 as pretreatment materials for silica removal. Results show that silica scaling was significantly alleviated, and water recovery was enhanced when feed waters were pretreated with the magnetic nanomaterials. Taken together, our study highlights the promise of magnetic Al(OH)3@Fe3O4 nanomaterials in treating brackish water and achieving higher water recovery for inland desalination.

Bio-inspired magnetic superhydrophobic PU-PDA-Fe3O4-Ag for effective oil-water separation and its antibacterial activity

In the present paper the composite materials based on Fe3O4/TiO2 and Fe3O4/SiO2/TiO2 ox-ides, synthesized by the hydrothermal peroxide method, were studied. At the first stage, magnet-ite nanoparticles were precipitated by ammonium hydroxide from a mixture of aqueous solutions of iron(II) sulfate and iron(III) chloride under continuous exposure to ultrasound, after which they were washed with distilled water. At the second stage, the resulting hydrated magnetite particles were stabilized with polyvinyl alcohol (PVA) by dispersing them under the action of ultrasound in a hot saturated aqueous PVA solution. At the third stage, the photocatalytically active particles based on titanium oxide were introduced into the composite by mixing the stabilized magnetite suspension with an aqueous solution of peroxotitanic acid (optionally introducing a sol of silicic acid), followed by hydrothermal treatment of the mixture at 180°C for 24 hours, washing, and drying under vacuum followed by calcination in a muffle furnace. The effect of the molar content of iron and titanium on the properties of the samples, the introduction of silicon dioxide into them, as well as various calcination temperatures, were studied. The photocatalytic properties of the synthesized samples during photodegradation of methyl orange and methylene blue, as well as their magnetic recovery from suspension, were studied. The physicochemical characterization of the samples was performed using high-resolution scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, powder X-ray diffraction, low-temperature nitrogen sorption porosimetry, inductively coupled plasma mass spectrometry, thermal analysis (TG–DSC), combined with mass spectrometry of gaseous thermolysis products. The optimal conditions for the synthesis of composites exhibiting the best combination of photocatalytic and magnetic properties were determined. The resulting photocatalysts can be used to purify water from dyes, followed by extraction using a magnet

Functionalized electrospun polymer microfibrous membranes were fabricated by electrospinning and further surface-functionalized with magnetic iron oxide (FexOy) nanoparticles to yield magnetoactive nanocomposite fibrous adsorbents. The latter were characterized in respect to their morphology, mechanical properties and magnetic properties while they were further evaluated as substrates for removing Ofloxacin (OFL) from synthetic aqueous media and secondary urban wastewater (UWW) under varying physicochemical parameters, including the concentration of the pharmaceutical pollutant, the solution pH and the membranes’ magnetic content. The magnetic-functionalized fibrous adsorbents demonstrated significantly enhanced adsorption efficacy in comparison to their non-functionalized fibrous analogues while their magnetic properties enabled their magnetic recovery and regeneration.

Bauxite residue (BR) is a by-product of the Bayer process for alumina production. The physical and chemical characteristics of BR from gibbsitic bauxite such as the fine particle size distribution and mineralogical phases (hematite, sodalite, goethite, anatase, gibbsite and quartz) prevent its wide use and limit the recovery of elements by conventional physical operations. As an example, the magnetic recovery of hematite from gibbsitic RB is unfeasible. An alternative to enable a magnetic concentration operation would be to obtain higher magnetic susceptibility phases, whose magnetic properties could overcome the processing limitation determined by the fine size of the RB particles. In this work, a Brazilian BR from gibbsitic bauxite processing with an iron and titanium concentration of 47.03% Fe2O3 and 5.45% TiO2 was re-digested in presence of iron(II) sulphate 7-hydrate (FeSO4•7H2O), at high temperature (230ºC) and high caustic concentration (370 g/l Na2CO3). Magnetite, ulvite (titanium-magnetite) and cancrinite minerals were obtained. The results demonstrated that this route may be promising for magnetic iron recovery, especially if side reactions were minimized. For future studies, one should evaluate the threshold for the conversion when the severity of conditions was diminished, as well as, the assessment of magnetic properties and the evaluation of potential recovery of the magnetic product.KeywordsBauxite residueIronTitaniumMagnetiteRecovery

4D printing of the ferrite permanent magnet BaFe12O19 and its intelligent shape memory effect

Water, a precious and demanding substance on planet Earth, needs appropriate remediation for global welfare. Magnetic materials play a key role in water remediation due to their magnetic, surface functionalization, and recovery properties. Among the magnetic materials, magnetic iron oxide nanoparticles (MIONPs) are eco-friendly and signify a better performance. The systems offer robustness in stability and also economically relevant solutions. These nanoparticles are of a defined size range, and when combined with their eco-friendly modes of synthesis, desired magnetic properties, and surface modifications, they tend to prove significant for water remediation applications. The agglomeration issues of MIONPs can be minimized by specific surface modification based on the desired application. This chapter briefly discusses the source of various water pollutions, methods available for water remediation, structure, and properties of magnetic materials and their application toward wastewater treatment. The importance of integration of various nanocomposites, polymers and layered double hydroxides with MIONPs for water remediation are also reviewed in detail.