Systematic review on applicability of magnetic iron-oxides integrated photocatalysts for degradation of organic pollutants in water

Owing to biocompatibility, abundance, and low cost, magnetic iron oxides are well suited for the design of efficient and magnetically separable photocatalysts for water treatment. This review presents a detailed survey of magnetic iron oxide–integrated photocatalysts (MIOIPs), in which we have discussed essential conditions needed for designing of efficient MIOIPs for water purification. The synthesis methods and detailed experimental setups for fabrication of MIOIPs were discussed, and the integration manners of iron oxides (Fe2O3, Fe3O4, FeO, and ferrites) with binary, ternary, and quaternary non-magnetic photocatalysts have been categorized. The mechanistic view of enhanced photocatalytic activity caused by different MIOIPs under various light sources was also elaborately argued. The role of various reactive species in photocatalytic oxidative degrading of organic pollutants was investigated. Altogether, this review article has compressively considered and discussed various signs of advancements made toward the synthesis of MIOIPs and their stability, recyclability, and catalytic efficacy for wastewater treatment

Superparamagnetic ZnFe2O4 nanoparticles-reduced graphene oxide-polyurethane resin based nanocomposites for electromagnetic interference shielding application

Superparamagnetic ZnFe2O4 spinel ferrite nanoparticles were prepared by the sonochemical synthesis method at different ultra-sonication times of 25 min (ZS25), 50 min (ZS50), and 100 min (ZS100). The structural properties of ZnFe2O4 spinel ferrite nanoparticles were controlled via sonochemical synthesis time. The average crystallite size increases from 3.0 nm to 4.0 nm with a rise of sonication time from 25 min to 100 min. The change of physical properties of ZnFe2O4 nanoparticles with the increase of sonication time was observed. The prepared ZnFe2O4 nanoparticles show superparamagnetic behavior. The prepared ZnFe2O4 nanoparticles (ZS25, ZS50, and ZS100) and reduced graphene oxide (RGO) were embedded in a polyurethane resin (PUR) matrix as a shield against electromagnetic pollution. The ultra-sonication method has been used for the preparation of nanocomposites. The total shielding effectiveness (SET) value for the prepared nanocomposites was studied at a thickness of 1 mm in the range of 8.2–12.4 GHz. The high attenuation constant (α) value of the prepared ZS100-RGO-PUR nanocomposite as compared with other samples recommended high absorption of electromagnetic waves. The existence of electric-magnetic nanofillers in the resin matrix delivered the inclusive acts of magnetic loss, dielectric loss, appropriate attenuation constant, and effective impedance matching. The synergistic effect of ZnFe2O4 and RGO in the PUR matrix led to high interfacial polarization and, consequently, significant absorption of the electromagnetic waves. The outcomes and methods also assure an inventive and competent approach to develop lightweight and flexible polyurethane resin matrix-based nanocomposites, consisting of superparamagnetic zinc ferrite nanoparticles and reduced graphene oxide as a shield against electromagnetic pollution. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Czech Science Foundation project at the Centre of Polymer Systems, Tomas Bata University in Zlin, Czech Republic [GA19-23647S]; Tomas Bata University in Zlin [IGA/CPS/2020/003]Grantová Agentura České Republiky, GA ČR: GA19-23647S; Univerzita Tomáše Bati ve Zlíně: IGA/CPS/2020/00

Self-organization of an optomagnetic CoFe2O4-ZnS nanocomposite : preparation and characterization

We report an advanced method for the self-organization of an optomagnetic nanocomposite composed of both fluorescent clusters (ZnS quantum dots, QDs) and magnetic nanoparticles (CoFe2O4). ZnS nanocrystals were prepared via an aqueous method at different temperatures (25, 50, 75, and 100 degrees C). Their structural, optical and chemical properties were comprehensively characterized by X-ray diffraction (XRD), UV-vis, photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), transmission electron microscopy (TEM), and infrared spectroscopy (FT-IR). The highest PL intensity was observed for the cubic ZnS nanoparticles synthesized at 75 degrees C which were then stabilized electrosterically using thioglycolic acid. The photophysical analysis of the capped QDs with a particle size in the range 9-25 nm revealed that the emission intensity and the optical band gap increases compared to uncapped nanocrystals (3.88 to 4.02 eV). These band gaps are wider than that of bulk ZnS resulting from the quantum confinement effect. Magnetic nanoparticles were synthesized via a co-precipitation route and a sol-gel process was used to form the functionalized, silica-coated CoFe2O4. Finally, thiol coordination was used for binding the QDs to the surface of the magnetic nanoparticles. The fluorescence intensity and magnetic properties of the nanocomposites are related to the ratio of ZnS and CoFe2O4. An optomagnetic nanocomposite with small size (12-45 nm), acceptable saturation magnetization (about 6.7 emu g(-1)), and satisfactory luminescence characteristics was successfully synthesized. These systems are promising candidates for biological and photocatalytic applications

Carbon nanotube template-assisted synthesis of zinc ferrite nanochains

We synthesized zinc ferrite nanochains assembled from nanoparticles using a carbon nanotubes (CNTs) template method The resulting nanochains were systematically characterized with respect to crystal structure morphology elemental composition magnetic properties and specific surface area by X-ray diffraction (XRD) transmission electron microscopy (TEM) field emission scanning electron microscopy (FESEM) X-ray photoelectron spectroscopy (XPS) superconducting quantum interference device (SQUID) magnetometry and the N(2) adsorption method The morphology results showed that the zinc ferrite particles with diameters of 10-20 rim were structurally linked to form nanochains The magnetic property investigation indicated that the zinc ferrite nanochains exhibited ferromagnetic behavior and possessed a saturation magnetization of 45 4 emu g(-1) at 300K We addressed the growth mechanism by analyzing the experimental conditions and characterization results This method may be applicable to synthesizing other metal oxide nanochains as wellArticleMATERIALS CHEMISTRY AND PHYSICS. 124(2-3):1029-1033 (2010)journal articl

Zinc oxide and zinc hydroxide formation via aqueous precipitation: Effect of the preparation route and lysozyme addition

Aqueous precipitation products of Zn(NO3)2 and NaOH obtained by changing the method of combining the reactants and by using lysozyme as an additive were investigated. In the case of single addition method, octahedral ε-Zn(OH)2 and plate-like β-Zn(OH)2 structures formed in the absence and in the presence of lysozyme, respectively. Calcination of these Zn(OH)2 samples at 700 °C yielded porous ZnO structures by conserving the template crystals. When zinc source was added dropwise into NaOH solution, predominantly clover-like ZnO crystals were obtained independent of lysozyme addition. Mixed spherical and elongated ZnO morphology was observed when NaOH was added dropwise into Zn(NO3)2 solution containing lysozyme. Lysozyme contents of the precipitation products were estimated as in the range of ∼5-20% and FTIR indicated no significant conformational change of lysozyme in the composite. These results suggest that lysozyme-ZnO/Zn(OH)2 composite materials may have a value as an antibacterial material

Sonochemical synthesis and characterization of a novel hetro-binuclear metal organic nano polymer based on picolinic acid ligand

Nanoparticles of one new lead and K coordination polymer (CP), {[Pb(pyc)(N)K].½HO} (1) Hpyc = picolinic acid ligand, has been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compound 1 imply that the Pb ion is seven coordinated. The thermal stability of compound 1 has been studied by thermogravimetric (TG) and differential scanning calorimetry (DSC). The role of temperature, reaction time and ultrasound irradiation power on the size and morphfology of the nano-structured compound obtained from 1, have been investigated. Results indicate that an increase of temperature and sonication power and a decrease in time reaction led to a decrease of particle size

Review on magnetic spinel ferrite (MFe2O4) nanoparticles: From synthesis to application

Magnetic spinel ferrite materials offer various applications in biomedical, water treatment, and industrial electronic devices, which has sparked a lot of attention. This review focuses on the synthesis, characterization, and applications of spinel ferrites in a variety of fields, particularly spinel ferrites with doping. Spinel ferrites nanoparticles doped with the elements have remarkable electrical and magnetic properties, allowing them to be used in a wide range of applications such as magnetic fields, microwave absorbers, and biomedicine. Furthermore, the physical properties of spinel ferrites can be modified by substituting metallic atoms, resulting in improved performance. The most recent and noteworthy applications of magnetic ferrite nanoparticles are reviewed and discussed in this review. This review goes over the synthesis, doping and applications of different types of metal ferrite nanoparticles, as well as views on how to choose the appropriate magnetic ferrites based on the intended application

Electrospun nanofibers of manganese oxides with mixed phase for supercapacitor

Energy EngineeringElectrospinning technique produces continuous fibers of various structures and composition with diameters ranging from a few micrometers to nanometers. Particularly, the three-dimensional (3D) non-woven fiber matrix contains a large porous network structure which is highly suitable for electrode applications that can facilitate the access of electrolytes into the active species. For that, we have fabricated the inorganic manganese oxide (MnOx) nanofibers (NFs) of varying composition by electrospinning technique for supercapacitor applications. MnOx is promising for pseudocapacitor due to their fine specific capacitance, low cost, and environmental benignity. In this study, we prepared the electrospun NFs of Mn(OAc)2/poly(vinyl pyrrolidone) (PVP) composite by using electrospinning technique. The as-prepared inorganic NFs were annealed at different temperatures to remove the polymer matrix and resulted in the MnOx NFs of varying composition. Interestingly, we found that the capacitance of MnOx NFs annealed at 500 oC is highest among all samples with contained a mixed phase of Mn2O3 and Mn3O4.ope

Low-temperature wet chemistry synthetic approaches towards ferrites

Ferrites are a broad class of iron-containing oxides that includes spinel ferrites MFe2O4, perovskites MFeO3, and hexagonal ferrites (hexaferrites) such as BaFe12O19. These materials have a wide array of applications owing to their diverse properties: notable instances include catalysis, piezoelectric components, magnetic components, biomedical applications, heterogeneous catalysis and photocatalysis. Given the growing importance of environmentally friendly, low-temperature methodologies to obtain functional materials, there is a growing interest in synthetic approaches which are compatible with the principles of “green chemistry”. In this context, wet chemistry represents an attractive choice, and furthermore offers the possibility of scale-up for manufacture of materials in volumes for practical application. Though there is a sizeable amount of literature on the synthesis of ferrites, the most common approaches require treatments at temperatures above 200 °C, either as the main synthetic procedure itself (thermal decomposition), or as a post-synthetic step (for example, calcination after sol–gel autocombustion). This review aims at summarising, categorising, classifying and critically discussing the different low-temperature (<200 °C), wet chemistry approaches employed in recent years for the synthesis of ferrites. This will include hydrothermal, solvothermal, sonochemical, and microwave methods, with examples taken from literature making reference to the various sub-classes of ferrites