Incorporation Of Fe3O4 Nanoparticles Research Articles

Improved mechanical, magnetic and radiation shielding performance of rubbery polymer magnetic nanocomposites through incorporation of Fe3O4 nanoparticles

The current research investigates the impact of magnetite (Fe3O4) nanoparticles (3–12 wt%) on the properties of rubbery polymer nanocomposites fabricated via melt blending method. The tensile and impact properties were improved at an optimal 6 wt% Fe3O4, revealing a good interfacial interaction. Fe3O4 enhanced the thermal stability, as evidenced by the increased integral procedure decomposition temperature up to 26 %. Fe3O4 increased residual and saturated magnetization the most at 6 wt% loading. The gamma-ray shielding properties were explored with energy ranging from 0.2835 to 2.506 MeV, and effectively at low energies. Increased Fe3O4 content correlated positively with linear attenuation coefficient (LAC), enhancing radiation shielding but reducing neutron shielding. At 0.2835 MeV, the LAC values increased up to 0.12431 cm−1 for 12 wt% Fe3O4, while the fast neutron removal cross-section values decreased from 0.10427 cm−1 to 0.08548 cm−1. These findings highlight the multifunctional potential of Fe3O4-incorporated nanocomposites in radiation shielding applications.

Synthesis and characterisation of novel beta-cyclodextrin based Fe3O4 nanocomposite: adsorption behaviour and photocatalytic dye degradation studies

ABSTRACT Novel Beta-Cyclodextrin-based Fe3O4 nanocomposite has been synthesised through copolymerisation by incorporating Fe3O4 nanoparticles into the polymer matrix. Ultraviolet-Visible (UV-Visible) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric (TGA) analysis, Point of Zero Charge, X-ray diffraction (XRD), and Scanning electron microscopy (SEM) analysis have been used to characterise the Fe3O4 Nanoparticles and β-CDHs@Fe3O4 nanocomposite. The synthesised β-CDHs@Fe3O4 nanocomposite has been utilised for the adsorption of methylene blue (MB) dye from aqueous solutions. The maximum percentage removal of MB dye at optimum pH 7 and was found to be 98.51%. The adsorption capacity (qe) of β-CDHs@Fe3O4 nanocomposite has been found to be 268.09 mg/g at optimum dosages 1.2 g/L, pH 7, temperature 25°C, concentration 100 mg/L and an agitation speed of 200 rpm. Adsorption data have been fitted with three isotherm models namely Langmuir, Freundlich, and Temkin, and it was found to be the best fit with the Langmuir isotherm model. Kinetic studies like the pseudo-first order, pseudo-second order, and intra-particle diffusion model were also performed to study the adsorption mechanism. Further, thermodynamic studies demonstrate that the reaction was exothermic and spontaneous. Photocatalytic degradation of MB dye under visible light has also been studied, and 79.01% degradation of the dye was observed. Also, desorption of the nanocomposite was performed, and it was found to be reusable up to 5 times with 90% dye-desorption in the fifth cycle.

Manipulation of the thermo-rheological properties of stable Fe3O4 nanoparticles-embedded PCM nanoemulsions

Phase Change Material (PCM) nanoemulsions offer numerous benefits as thermal energy storage systems, including high energy storage capacity, rapid thermal response, enhanced stability, and easy integration into existing thermal management systems. This study focuses on producing nanoemulsions with fine droplets of commercial paraffin RT42, stabilized with the anionic surfactant sodium dodecyl sulfate (SDS) using the sonication method. The impact of formulation of PCM nanoemulsions on its thermophysical and rheological characterization has been investigated. The results indicated that the degree of supercooling declined from 12.8 °C to 8.6 °C as the PCM volume fraction varied from 10 to 45 vol%. This decrease was attributed to the enlargement of PCM droplet size from 110 to 164 nm while maintaining a constant PCM-to-surfactant ratio of 10:1. By incorporating Fe3O4 nanoparticles as a nucleating agent at two different concentrations of 1 and 4 %, the supercooling degree decreased from 10.2 °C to 8.2 °C when 4 % Fe3O4 nanoparticles were added. The samples exhibited remarkable stability throughout a period of one year of storage and under dynamic conditions, including 50 freeze-thaw cycles. Rheological investigations and the gelation mechanism through estimation of the attractive and repulsive interaction forces among droplets revealed that nanoemulsions with volume fractions ≥30 % transformed from fluid-like states to viscoelastic gels due to the depletion attractions caused by SDS micelles in the continuous phase. These findings contribute to a better understanding of the factors influencing the formation of viscoelastic PCM nanoemulsion gels and their potential applications across various fields.

Superhydrophobic, Magnetic Aerogels Based on Nanocellulose Fibers Derived from Harakeke for Oily Wastewater Remediation.

Cellulose-based aerogels have been seen as a promising sorbent for oil and organic pollutant cleaning; however, their intrinsic hydrophilicity and difficulty of recycling has hindered their practical application. In this work, a superhydrophobic, magnetic cellulose-based aerogel was fabricated as a highly efficient sorbent for the adsorption of oils and organic solvents. The aerogel was prepared via a simple freeze-drying method, followed by chemical vapor deposition (CVD). The incorporation of Fe3O4 nanoparticles into the aerogel not only makes it responsive to external magnetic field, but also contributes to the better hydrophobicity of the aerogel, in which the water contact angle (WCA) was about 20° higher than the aerogel without loading with Fe3O4 nanoparticles. The adsorption test showed that the resultant aerogel can selectively adsorb a wide range of oils and organic solvents from oil/water mixtures with a high adsorption capacity (up to 113.49 g/g for silicone oil). It can retain about 50% of its adsorption capacity even after 10 adsorption-squeezing cycles, which indicates its outstanding reusability. Moreover, the aerogels can be easily controlled by an external magnet, which is preferred for the adsorption of oily contaminants in harsh environments and enhanced the recyclability of the aerogel. We believe that this study provides a green and convenient approach for the practical fabrication of cellulose-based oil sorbents.

Electrospun Fe3O4-chitosan/polyvinyl alcohol nanofibrous film for improved capture and elimination of foodborne pathogens

This study developed a new “capture and killing” antibacterial approach for efficient elimination of foodborne pathogens. Fe3O4-Chitosan (CS)/polyvinyl alcohol (PVA) nanofibrous films with improved antibacterial and mechanical properties were fabricated by a simple, environmentally friendly, and cost-effective electrospinning technique. The relationship between the physical properties (viscosity, surface tension, and conductivity) and spinnability of CS/PVA as fiber forming matrix was explored. Electrospun Fe3O4-CS/PVA films (0.03–0.12 mm) with smooth and bead-free nanofibrous structures (145–169 nm) were successfully obtained. Compared with the film electrospun from neat CS/PVA, incorporating Fe3O4 nanoparticles (NPs) (1.25–5 wt%) in CS/PVA nanofibrous film promoted bacterial attachment and increased the final inactivated efficiency, showing a difference with Fe3O4 loading and bacterial strain, which had the highest value against Escherichia coli (E. coli) and Staphyloccus aureus (S. aureus) being 90 % and 66.30 %, respectively. The tensile strength and elongation at break of Fe3O4-CS/PVA films enhanced by 46–192 % and 92–141 %, respectively. Results of the cytotoxicity test indicated that the resulting films had high biocompatibility. These promising findings provide a novel strategy for effective foodborne pathogens elimination, which could apply to sterilizing and food packaging to extend the shelf life of liquid food.

Characterization of electrospun polyvinylidene fluoride-loaded iron sand-based Fe3O4 nanoparticles

Iron sand-based Fe3O4 nanoparticles–polyvinylidene fluoride (PVDF) nanofibers were processed inside an electrospinning system at room temperature. The incorporation of Fe3O4 nanoparticles into the PVDF matrix decreases the diameter of the fibers. The presence of the Fe3O4 crystalline phase in the electrospun PVDF-Fe3O4 fiber indicates the unchanged Fe3O4 crystal structure. The surface morphology of the samples was altered considerably after the electrospinning and heating processes. Infrared spectroscopy identification confirmed the PVDF α to β-phase transformation in the PVDF and PVDF-Fe3O4 fibers. The thermal analysis detected a higher residual mass of the PVDF-Fe3O4 sample than that of the pure PVDF at high temperatures. Through the hysteresis characteristics, a ferromagnetic behaviour was observed for all samples. The efficient and low-cost fabrication of the PVDF-Fe3O4 fibers could be considered practical for diverse applications of nanotechnology.

Engineering dual-stimuli responsive poly(vinyl alcohol) nanofibrous membranes for cancer treatment by magnetic hyperthermia

The development of new cancer treatment options, such as multifunctional devices, allows for a more personalized treatment, avoiding the known severe side effects of conventional options. In this context, on-demand drug delivery systems can actively control the rate of drug release offering a precise control of treatment. Magnetically and thermally controlled drug delivery systems have been explored as on-demand devices to treat chronic diseases and cancer tumors. In the present work, dual-stimuli responsive systems were developed by incorporating Fe3O4 magnetic nanoparticles (NPs) and poly(N-isopropylacrylamide) (PNIPAAm) microgels into electrospun polymeric fibers for application in cancer treatment. First, Fe3O4 NPs with an average diameter of 8 nm were synthesized by chemical precipitation technique and stabilized with dimercaptosuccinic acid (DMSA) or oleic acid (OA). PNIPAAm microgels were synthesized by surfactant-free emulsion polymerization (SFEP). Poly(vinyl alcohol) (PVA) was used as a fiber template originating fibers with an average diameter of 179 ± 14 nm. Stress tests of the membranes showed that incorporating both microgels and Fe3O4 NPs in electrospun fibers increases their Young's modulus. Swelling assays indicate that PVA membranes have a swelling ratio of around 3.4 (g/g) and that the presence of microgels does not affect its swelling ability. However, with the incorporation of Fe3O4 NPs, the swelling ratio of the membranes decreases. Magnetic hyperthermia assays show that a higher concentration of NPs leads to a higher heating ability. The composite membrane with the most promising results is the one incorporated with DMSA-coated NPs, since it shows the highest temperature variation, 5.1 °C. To assess the membranes biocompatibility and ability to promote cell proliferation, indirect and direct contact cell viability assays were performed, as well as cell adhesion assays. Following an extract method viability assay, all membrane designs did not reveal cytotoxic effects on dermal fibroblasts and melanoma cancer cells, after 48 h exposure and support long-term viability. The present work demonstrates the potential of dual-stimuli composite membranes for magnetic hyperthermia and may in the future be used as an alternative cancer treatment particularly in anatomically reachable solid tumors.

Magnetically responsive chitosan-pectin films incorporating Fe3O4 nanoparticles with enhanced antimicrobial activity

Chitosan-pectin films with iron oxide (Fe3O4) magnetic nanoparticles were prepared by solution casting in order to produce biopolymer based magnetically active materials. Infrared (FTIR) spectra indicated physical interactions between the matrix and nanoparticles, corroborated by differential scanning calorimetry (DSC) results. In addition, thermal characterization suggested that the interactions between chitosan, pectin and the nanoparticles resulted in a less compact structure, influencing the film mechanical properties. Regarding vibrating-sample magnetometry (VSM) and electrical analysis, chitosan-pectin films with Fe3O4 nanoparticles showed ferrimagnetic behavior, with an increase of the dielectric constant as the nanoparticle concentration increased. Furthermore, films displayed enhanced antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram-positive) bacteria. Therefore, chitosan-pectin films with Fe3O4 magnetic nanoparticles provide promising results for active and intelligent food packaging applications.

Assessment and optimization of As(V) adsorption on hydrogel composite integrating chitosan-polyvinyl alcohol and Fe3O4 nanoparticles and evaluation of their regeneration and reusable capabilities in aqueous media

A modified chitosan-polyvinyl alcohol (PVA) hydrogel was developed by incorporating Fe3O4 nanoparticles. Four chitosan-Fe3O4 (ChFe) hydrogel types were developed based on chitosan:Fe3O4 ratio as 1:0, 1:1, 1:0.5 and 1:0.25. Batch sorption experiments were conducted with different pH, dosage, kinetics, and isotherms. The exhausted ChFe hydrogels were evaluated for their regeneration and reuse capability with different acids and bases. The best hydrogel for arsenic (V) [As(V)] adsorption was 1:0.5 ratio ChFe hydrogel. The highest As(V) adsorption (89 %) was at pH 4 and the adsorption capacity gradually decreased with increasing solution pH. Within the pH 4–6 range, the hydrogel surface became positively charged due to protonation of NH2 and OH groups in the polymer chain and the positive surface attracted H2AsO4− and HAsO42− oxyanions. The experimental kinetic data was well-fitted to the Elovich model (R2 of 0.99) while the Freundlich isotherm model best described the isotherm data (R2 of 0.97). The models predicted chemisorption mechanisms on ChFe hydrogel composites. Electrostatic attractions with NH3+ and OH2+, ligand-exchange inner-sphere complexes formation and bidentate corner-sharing (2C) and bidentate edge-sharing (2E) trimetric surface complexes formation have been proposed as the adsorption mechanism of As(V) into ChFe hydrogel. 0.1 M CH3COOH showed the best regeneration pattern with 75, 96, 81, 53 and 43 % of 1st, 2nd, 3rd, 4th and 5th adsorption respectively. Because of this re-usable capability, the As(V) adsorption capacity is not a single value from one adsorption cycle, but a cumulative value of several adsorption cycles and it was 17.39 mg/g for five adsorption cycles. Open for regeneration and reuse, no post-treatment is needed for adsorbent-water separation, allow applications of the ChFe hydrogel composite in a wide range of applications such as water filtration and purification systems. The modification with ChFe further expands the application capacity since the ChFe can remove other contaminants as well.

Fe3O4 embedded κ-carrageenan/sodium alginate hydrogels for the removal of basic dyes

Here, we introduce κ-carrageenan and sodium alginate based hydrogel (CAG-NaAlg-cl-polyAA) and hydrogel nanocomposite (CAG-NaAlg-cl-polyAA/Fe3O4) through a free radical crosslinking method using acrylic acid/ N,N′- methylenebisacrylamide as a monomer/crosslinker system. The hydrogel is stimuli-responsive and its water absorption efficiency is enhanced through the optimization of synthesis parameters. The synthesized superabsorbents have been sequentially characterized through HR-TEM, powder XRD, FTIR, SEM-EDS, and XPS analysis. The average particle size of Fe3O4 nanoparticles stabilized through the CAG-NaAlg-cl-polyAA hydrogel matrix is 10.7 ± 2.5 nm. The CAG-NaAlg-cl-polyAA hydrogel exhibited > 95 % dye removal efficiency for the removal of basic dyes (auramine O, crystal violet and malachite green), whereas the % dye removal potential of CAG-NaAlg-cl-polyAA/Fe3O4 is enhanced upto 99 % after the incorporation of Fe3O4 nanoparticles. Langmuir adsorption is the most favorable adsorption isotherm with R2 = 0.992 (auramine O, AU), 0.989 (malachite green, MG), and 0.974 (crystal violet, CV). Kinetic studies indicate that the adsorption of AU, CV, and MG follows pseudo 2nd order kinetics. Moreover, the reusability of the fabricated samples upto five consecutive cycles further explores its potential for the separation of basic textile dyes from industrial wastewater.

Toward cheaper light harvesting systems: Using earth-abundant metal oxide nanoparticles in self-assembled peptide-porphyrin nanofibers.

Cheap artificial light harvesting systems, which competently harvest solar energy and promote efficient energy transfer, are highly sought after in the renewable sector. We report the synthesis of self-assembled peptide-porphyrin fibers (SJ 6) fabricated with iron(III) oxide (Fe3 O4 ) nanoparticles as feasible electron acceptors. Charge-complementarity between the negatively charged peptide (20E) and the protonated Zn-tetraphenyl porphyrin (ZnTPyP) led to an ordered assembly of the ZnTPyP molecules, enabling efficient light harvesting. X-ray diffraction data indicates a more ordered structure in SJ 6 compared to 20E and ZnTPyP. The incorporation of Fe3 O4 nanoparticles into SJ 6 showed significant fluorescence quenching, indicating efficient electron flow from the donor to the acceptor. The SJ 6-nFe3 O4 system performed the light reaction of photosynthesis as confirmed by the reduction of 1 mM NAD+ to 0.180 mM NADH upon exposure to visible light (Xe lamp λ > 420 nm) for 1 h. The photochemical regeneration of NADH using the SJ 6-nFe3 O4 system was coupled to glutamate dehydrogenase-catalyzed conversion of α-ketoglutarate to L-glutamate. These results confirm the successful synthesis of an artificial light harvesting peptide-porphyrin system with Fe3 O4 nanoparticles as promising low-cost electron separators.

Droplet-Based Microfluidic Preparation of Shape-Variable Alginate Hydrogel Magnetic Micromotors.

This article introduces a facile droplet-based microfluidic method for the preparation of Fe3O4-incorporated alginate hydrogel magnetic micromotors with variable shapes. By using droplet-based microfluidics and water diffusion, monodisperse (quasi-)spherical microparticles of sodium alginate and Fe3O4 (Na-Alg/Fe3O4) are obtained. The diameter varies from 31.9 to 102.7 µm with the initial concentration of Na-Alginate in dispersed fluid ranging from 0.09 to 9 mg/mL. Calcium chloride (CaCl2) is used for gelation, immediately transforming Na-Alg/Fe3O4 microparticles into Ca-Alginate hydrogel microparticles incorporating Fe3O4 nanoparticles, i.e., Ca-Alg/Fe3O4 micromotors. Spherical, droplet-like, and worm-like shapes are yielded depending on the concentration of CaCl2, which is explained by crosslinking and anisotropic swelling during the gelation. The locomotion of Ca-Alg/Fe3O4 micromotors is activated by applying external magnetic fields. Under the rotating magnetic field (5 mT, 1–15 Hz), spherical Ca-Alg/Fe3O4 micromotors exhibit an average advancing velocity up to 158.2 ± 8.6 µm/s, whereas worm-like Ca-Alg/Fe3O4 micromotors could be rotated for potential advancing. Under the magnetic field gradient (3 T/m), droplet-like Ca-Alg/Fe3O4 micromotors are pulled forward with the average velocity of 70.7 ± 2.8 µm/s. This article provides an inspiring and timesaving approach for the preparation of shape-variable hydrogel micromotors without using complex patterns or sophisticated facilities, which holds potential for biomedical applications such as targeted drug delivery.

Photocatalytic activity of GO/Fe<sub>3</sub>O<sub>4</sub> fabricated by Sri Lankan graphite under visible light irradiation

Graphene oxide (GO) was synthesized using Sri Lankan naturally available graphite and Fe3O4 nanoparticles were successfully incorporated fabricating magnetically separable GO/Fe3O4 nanocomposite. The synthesized nanocomposites were characterized by X-ray diffractometry (XRD), Scanning electron microscopy (SEM), and FT-IR spectroscopy. Crystalline phases of GO and Fe3O4 nanoparticles were identified by XRD patterns, while the presence of functional groups such as –COOH, OH, CH2 was confirmed by FT-IR spectroscopy. SEM images show that Fe3O4 nanoparticles with an average particle size of 107 nm ranging between 56-150 nm are dispersed on GO while restacking and folding of the nanosheets have been observed with incorporation of Fe3O4 nanoparticles. The photocatalytic performance of the photocatalysts was evaluated on photodegradation of methylene blue under visible light irradiation. The GO/Fe3O4 shows better adsorption behavior and excellent photocatalytic activity where it could be successfully used for three cycles without significant activity loss. This is due to the enhanced charge separation resulted due to the presence of GO sheets and better interactions between GO and Fe3O4.

Incorporation of Fe3O4 nanoparticles in three-dimensional carbon nanofiber/carbon nanotube aerogels for high-performance anodes of lithium-ion batteries

Recently, Fe3O4 based materials have been widely investigated to serve as anode materials of lithium-ion batteries (LIBs) because of the high theoretical capacity (924 mA h g−1). Unfortunately, the actual capacity of these materials are low and they suffer from poor cycling stability. Herein, carbon nanotube/carbon nanofiber composite aerogels (CA) were used as scaffold to fabricate Fe3O4-CA composites for anode materials. Fe3O4 nanoparticles were evenly presented on the external surface and internal channel of the 3-dimensional (3D) CA network. The 3D conductive network can buffer the volume expansion of anode materials. Additionally, such structure can prevent the aggregation of Fe3O4. Therefore, the structure of the Fe3O4-CA composite electrode can be maintained during lithiation/delithiation processes. The Fe3O4-CA composites delivered a high reversible capacity of 825.1 mA h g−1 after 100 cycles. Additionally, an ultra-high coulombic efficiency closed to 100% was obtained. The excellent performance of the Fe3O4-CA composites may be due to the synergistic effect of the Fe3O4 nanoparticles and 3D conductive network structure.

Bio-inspired smart surface to achieve controllable locomotion through adjustable anisotropic friction

Anisotropic friction generated by microstructured surfaces is crucial for performing functions such as directional locomotion and adhesion in biological systems. Hence, an epoxy-based shape memory polymer (SMP) incorporating Fe3O4 nanoparticles is used in this study to create a smart surface with oriented structures to mimic anisotropic friction and exploit human-developed controllable locomotion systems. Applying the specific properties of the epoxy-based SMP, fast switching friction can be achieved by adjusting the topography and stiffness of the microstructures on the surface. In addition, the photothermogenesis effect of Fe3O4 nanoparticles induces changes in the asymmetric topography and stiffness on the SMP surface under the irradiation of near-infrared (NIR) light, thereby inducing a rapid switching of the friction force. Furthermore, a microbot is created to demonstrate remotely controlled locomotion, such as unidirectional and round-trip movements, and braking by switching the friction force under NIR light. These results are promising for the design of new intelligent surfaces and interfaces; additionally, they may facilitate the investigation of biological structures and processes.

Enzymatic/Magnetic Hybrid Micromotors for Synergistic Anticancer Therapy.

Micro/nanomotors (MNMs), which propel by transforming various forms of energy into kinetic energy, have emerged as promising therapeutic nanosystems in biomedical applications. However, most MNMs used for anticancer treatment are only powered by one engine or provide a single therapeutic strategy. Although double-engined micromotors for synergistic anticancer therapy can achieve more flexible movement and efficient treatment efficacy, their design remains challenging. In this study, we used a facile preparation method to develop enzymatic/magnetic micromotors for synergetic cancer treatment via chemotherapy and starvation therapy (ST), and the size of micromotors can be easily regulated during the synthetic process. The enzymatic reaction of glucose oxidase, which served as the chemical engine, led to self-propulsion using glucose as a fuel and ST via a reduction in the energy available to cancer cells. Moreover, the incorporation of Fe3O4 nanoparticles as a magnetic engine enhanced the kinetic power and provided control over the direction of movement. Inherent pH-responsive drug release behavior was observed owing to the acidic decomposition of drug carriers in the intracellular microenvironment of cancer cells. This system displayed enhanced anticancer efficacy owing to the synergetic therapeutic strategies and increased cellular uptake in a targeted area because of the improved motion behavior provided by the double engines. Therefore, the demonstrated micromotors are promising candidates for anticancer biomedical microsystems.

Wavelength switchable Q-switched fiber laser based on Fe[formula omitted]O[formula omitted] nanoparticles

We experimentally demonstrate an erbium-doped Q-switched fiber laser at 1.5µm by incorporating Fe3O4 nanoparticles as a saturable absorber. A novel approach for SA formation is demonstrated by using the bubble poking method, through which we can fabricate SA films with different thicknesses with ease by changing the number of times of poking the bubbles. The fabricated SA possesses a modulation depth of ∼3.9% and saturable intensity of ∼0.57 MW/cm2. By inserting the SA into the laser cavity, Q-switched laser output is achieved at a pump threshold of 50mW and the central wavelength can be switched when the pump power is above 70mW. This Q-switched all-fiber laser operates stably with a maximum single pulse energy of 126nJ, a maximum repetition rate of 57.5kHz and a minimum pulse width of 5.7µs.

Facile sonochemical synthesis of nanoparticle modified Bi-MnOx and Fe3O4 deposited Bi-MnOx Nanocomposites for Sensor and Pollutant Degradation Application

Silver quantum dots particles (Ag QDs) and nanoparticles of Magnetite (Fe3O4) were deposited on nanotubes of Bismuth- insitu doped manganese oxide (Bi-MnOx) with porous morphologies via olymer assisted precipitation processes. The Ag QDs particles of very fine particle size and Fe3O4 nanoparticles were incorporated into the Bi-MnOx polymer composite via high power ultra-sonication deposition technique. Spherical nanoparticles of silver (5–15 nm) were deposited on the porous Bi-MnOx surfaces, whereas, in the case of the Fe3O4 which was deposited on Bi-MnOx nanotube composite in the form of nanorods, iron oxide particles were loaded into the tubular structure of the Bi-MnOx. The formation of nanotubes and the incorporation of nanorods were confirmed by the SEM and HR-TEM images. The diffuse reflectance spectra indicate a decrease in the bandgap of the composite after the incorporation of Fe3O4 nanoparticles into the Bi-MnOx nanotube . The nanoparticle-modified Bi-MnOx composite electrode was further characterized for hydrogen peroxide electrochemical sensor applications. Fast removal of toxic hexavalent chromium degradation reaction was carried out on the as-prepared Fe3O4- and Ag QDs particle-modified Bi-MnOx nanotube composites. An efficient sorption and removal of Cr (VI) (above 90% conversion) was achieved within 60 min of reaction on the Ag nanoparticle modfied Bi-MnOx. The results obtained show that the Ag@Bi-MnOx, and Fe3O4-modified porous Bi-MnOx nanotube composite materials demonstrated effective sensing and hexavalent chromium removal activity.

Hybrid nanocomposite of kappa-carrageenan and magnetite as adsorbent material for water purification

A novel polysaccharide based hydrogel; kappa-carrageenan grafted with N-hydroxyethylacrylamide (κC-g-PHEAA) was synthesized via microwave assisted free radical polymerization process. A hybrid nanocomposite has also been made by incorporation of Fe3O4 nanoparticles into the κC-g-PHEAA network. The materials were characterized by FTIR, TGA, XRD, SEM, BET and VSM techniques. The nanocomposite exhibited super-paramagnetic behavior. The κC-g-PHEAA and κC-g-PHEAA/Fe3O4 presented significant adsorption capacity towards cationic dyes, methylene blue (MB) and rhodamine 6G (R6G); and metal ions, Cu(II) and Hg(II) from aqueous solution. The magnetite nanoparticles enhance the adsorption characteristics of the hydrogel and enables easy separation of the adsorbent with an external magnetic field. Adsorption process is observed to follow both Langmuir and Freundlich isotherm models for R6G and Freundlich isotherm model for MB, Cu(II) and Hg(II). The adsorption was found to be a pseudo first order process for MB and pseudo second order process for R6G, Cu(II) and Hg(II). Thermodynamic studies have shown the adsorption of dyes and metal ions to be spontaneous and endothermic in nature. The desorption studies revealed the efficient recovery of adsorbate species. The study indicates that the synthesized adsorbents have potential applications for the removal of dyes and metal ions from wastewater.

Magnetic and Conductive Liquid Metal Gels.

Liquid metals are fast becoming a new class of universal and frictionless additives for the development of multifunctional soft and flexible materials. Herein, nanodroplets of eutectic gallium-indium alloy, which is liquid at room temperature, were used as a platform for the formulation of electrically conductive and magnetically responsive gels with the incorporation of Fe3O4 nanoparticles. The nanoadditives were prepared in situ within a water-based solution of polyvinyl alcohol. A borax cross-linking reaction was then performed to yield multifunctional flexible and self-healing gels. The physicochemical properties and changes in the nanoadditives at each step of the gel preparation method were characterized. Oxidation and complexation reactions between the liquid metal and iron oxide nanoadditives were observed. A mixture of nanosized functional magnetic Fe3O4/Fe2O3 and In-Fe oxide complexes was found to enable the magnetic susceptibility of the gels. The mechanical and self-healing properties of the gels were assessed, and finally, this flexible and multifunctional material was used as an electronic switch via remote magnetic actuation. The developed conductive and magnetic gels demonstrate great potential for the design of soft electronic systems.