Magnetite Loading Research Articles

Natural magnetite as an effective and long-lasting catalyst for CWPO of azole pesticides in a continuous up-flow fixed-bed reactor

The global occurrence of micropollutants in water bodies has raised concerns about potential negative effects on aquatic ecosystems and human health. EU regulations to mitigate such widespread pollution have already been implemented and are expected to become increasingly stringent in the next few years. Catalytic wet peroxide oxidation (CWPO) has proved to be a promising alternative for micropollutant removal from water, but most studies were performed in batch mode, often involving complex, expensive, and hardly recoverable catalysts, that are prone to deactivation. This work aims to demonstrate the feasibility of a fixed-bed reactor (FBR) packed with natural magnetite powder for the removal of a representative mixture of azole pesticides, recently listed in the EU Watch Lists. The performance of the system was evaluated by analyzing the impact of H2O2 dose (3.6–13.4 mg L−1), magnetite load (2–8 g), inlet flow rate (0.25–1 mL min−1), and initial micropollutant concentration (100–1000 µg L−1) over 300 h of continuous operation. Azole pesticide conversion values above 80% were achieved under selected operating conditions (WFe3O4 = 8 g, [H2O2]0 = 6.7 mg L−1, flow rate = 0.5 mL min−1, pH0 = 5, T = 25 °C). Notably, the catalytic system showed a high stability upon 500 h in operation, with limited iron leaching (< 0.1 mg L−1). As a proof of concept, the feasibility of the system was confirmed using a real wastewater treatment plant (WWTP) effluent spiked with the mixture of azole pesticides. These results represent a clear advance for the application of CWPO as a tertiary treatment in WWTPs and open the door for the scale-up of FBR packed with natural magnetite.

The catalytic effect of calcium oxide and magnetite loading on magnetically supported calcium oxide-zeolite catalyst for biodiesel production from used cooking oil

This research focuses on developing a magnetically supported catalyst for efficient transesterification reaction of used cooking oil (UCO). The catalyst consists of calcium oxide (CaO) and ZSM-5 zeolite, which were synthesized using waste chicken eggshell and rice husk. Meanwhile, magnetite (Fe3O4) was used as a magnetic component. Various magnetic zeolite-supported CaO catalysts (CaZ/Fe) were prepared with different amounts of CaO (10, 30, 50, and 80 wt% of zeolite) and Fe3O4 (1:0.5, 1:1, 1:1.5 and 1:2 of CaO-zeolite:Fe3O4 ratio). The results identified the 50CaZ/0.5Fe catalyst as the most effective. The catalyst displayed a high surface area, strong basicity, and ideal morphology, thus contributing to a higher biodiesel yield of 91%. The recovery rate of the 50CaZ/0.5Fe catalyst was 88%, suggesting minimal loss and easy catalyst separation post-reaction using an external magnetic field. It also displayed superior stability, obtaining 85% biodiesel yield after 4 uses. The activation energy calculated in the kinetic study was 14.085 kJ/mol. Moreover, the properties of the synthesized biodiesel met the standards set by the ASTM D6751. Overall, the 50CaZ/0.5Fe catalyst with good magnetic behaviour and exhibits excellent catalytic activity suggested that this catalyst is promising for application in biodiesel production.

Enhanced methane production via anaerobic digestion assisted with Fe3O4 nanoparticles supported on microporous granular activated carbon

Granular activated carbon (GAC) was used as supporting material for different loading of magnetite (Fe3O4) nanoparticles using the wet impregnation method, for its use as biocatalysts during the anaerobic digestion (AD). The highest responses in terms of methane productivity were achieved with the two modified materials using 1.5% and 3% of Fe3O4. With (1.5%)Fe3O4/GAC, the conversion efficiency to methane was 97.1%, with a methane yield of 388.1 mL CH4/g COD, which was higher than the control without GAC, achieving only 72.1% of conversion and a yield of 286.6 mL CH4/g COD, representing an increment of ∼ 26% for these two parameters with the modified material. Also, the (1.5%)Fe3O4/GAC promotes the highest consumption of volatile fatty acids (VFAs) and ethanol compared to other cultures. The improvement in the AD by the modified materials could be attributable to its surface chemistry composed of a greater extent of Fe2+ and Fe3+, the external surface area, and the electron-accepting capacity. In addition, the close association between microorganisms and the (1.5%)Fe3O4/GAC biocatalyst within the anaerobic medium could be evidence that the direct interspecies electron transfer (DIET) process is occurring.

Electrospinning of Magnetite-Polyacrylonitrile Composites for the Production of Oxygen Reduction Reaction Catalysts.

In this study, electrospun carbon fiber electrodes were prepared by the carbonization of PAN-Fe3O4 electrospun fibers at 800 °C for their use as catalysts in the oxygen reduction reaction in an alkaline electrolyte. Magnetic nanofiber mats were fabricated using a needle-free electrospinning method by incorporating magnetic nanoparticles into a polymer solution. Electrochemical tests revealed that the oxygen reduction reaction (ORR) activity is optimized at an intermediate magnetite loading of 30% wt. These catalysts not only show better performance compared to their counterparts but also achieve high selectivity to water at low potentials. The onset and half-wave potentials of 0.92 and 0.76 V shown by these samples are only slightly behind those of the commercial Pt 20%-carbon black ORR catalyst. The obtained results point out that the electrospinning of PAN-Fe3O4 solutions allows the preparation of advanced N-Fe ORR catalysts in fibrillar morphology.

Enhancing Biodegradation of Industrial Wastewater into Methane-Rich Biogas Using an Up-Flow Anaerobic Sludge Blanket Reactor

Anaerobic digestion (AD), the oldest technology used for treating waste, converts organic matter into biogas in the absence of oxygen. The current efforts focuses on improving the digestion of a local industrial wastewater to produce biogas and treat water for reuse. A lab-scale up-flow anaerobic sludge blanket (UASB) reactor operated at 37 °C was employed for the biodegradation the industrial wastewater. A one-factor-at-a-time (OFAT) approach was used to study the effects of influent chemical oxygen demand (CODin), hydraulic retention time (HRT), and magnetic nanoparticles (magnetite) on UASB biogas and COD elimination from digestate wastewater. The optimum HRT for the biodegradation of municipal wastewater was found to be 21 days with contaminants’ removals of 94%, 90.1%, and 98.9% for COD, color, and turbidity, respectively. The addition of magnetite resulted in 225 mL of cumulative biogas produced with 73% methane content, and treatability efficiency of 85%. The most influential factor was magnetite load, which stimulated the microbial activity via redox catalytic reaction in degrading the high organic wastewater (9590 mg COD/L) into biogas production. The prospects of upgrading lab-scale of this technological concept for bioenergy production is viable to mitigate wastewater management and fossil fuel environmental challenges.

Synthesis of porous magnetic zeolite-based material and its performance on removal of Cd2+ ion and methylene blue from aqueous solution

In this study, the natural clinoptilolite zeolite was hydrothermally treated and then combined with porous silica-coated magnetic particles to prepare a porous magnetic zeolite-based material. Process parameters such as NaOH concentration, hydrothermal temperature and time, pH value, and Fe3O4/Na2SiO3 ratio were optimized. XRD, XPS, N2 adsorption-desorption technique, SEM-EDX, TEM, FTIR, etc. were employed to investigate the composition and structure of the materials. Cd2+ ion and methylene blue were adopted to evaluate the contamination removal performance of the materials. The results showed that hydrothermal treatment under an alkaline environment could transform clinoptilolite to Na–P zeolite with a low Si/Al ratio and relatively high Cd2+ adsorption capacity. Porous silica-coated magnetite loading could significantly increase the specific surface area of the material and render it magnetic. The as-prepared porous magnetic zeolite-based material exhibited much higher Cd2+ ion and methylene blue removal performance than the raw natural clinoptilolite zeolite.

Magnetite-Bacillus subtilis synergy on the metabolic selection of products in electrofermentation system

The study examines the role of magnetite (1–150 mg/L) at the interface of Bacillus subtilis-electrode under poised-condition (-0.2 V) for product-formation and catalytic-conduct with the relative-gene-expression encoding lactate dehydrogenase (lctE), pyruvate dehydrogenase (pdhA), acetate kinase (ackA), pyruvate carboxylase (pycA), and NADH dehydrogenase (ndh). The magnetite load of 25 mg/L showed positive influence on acidogenesis resulting in H2 production of 264.7 mol/mL and fatty acids synthesis of 3.6 g/L. Additionally, this condition showed higher succinic acid productivity (2.8 g/L) which correlates with the upregulated pycA gene and fumarate to succinate redox peak. With 10 mg/L loading, production of higher acetic acid (3.1 g/L) along with H2 (181.6 mol/mL) was depicted wherein upregulation of pdhA, ackA and ndh genes was observed. In absence of magnetite, lctE gene was upregulated which resulted higher lactate production. The findings suggest that the mutual-interactions between magnetite-active sites of specific enzymes enhances the biocatalytic activity triggering product-formation.

Adsorption of Iron (II) Ion by Using Magnetite-Bentonite-Based Monolith from Water

In this study, iron removal was carried out by the adsorption process as a well-known method of removing heavy metal. Natural bentonite with magnetic properties in a monolithic form or Magnetite-Bentonite-based Monolith (MBM) adsorbent was used as an adsorbent to remove Iron (II) ion from the aqueous solution. The magnetic properties of adsorbents are obtained by adding magnetite (Fe3O4), which is synthesized by the coprecipitation process. The characterization of magnetic properties was performed using the Vibrating Sample Magnetometer (VSM). VSM results showed that the magnetic particles were ferromagnetic. Adsorption efficiency, isotherm model, and adsorption kinetics were investigated in a batch system with iron solution concentration varied from 2 to 10 mg/L and magnetite loading at 2% and 5% w/w. The highest removal efficiency obtained reached 89% with a 5% magnetite loading. The best fit to the data was obtained with the Langmuir isotherm (non-linear) with maximum monolayer adsorption capacity (Qo) at 5% magnetic loading MBM adsorbent is 0.203 mg/g with Langmuir constants KL and aL are 2.055 L/g and 10.122 L/mg respectively. The pseudo-first-order (non-linear) kinetic model provides the best correlation of the experimental data with the rate of adsorption (k1) with magnetite loading 2% and 5%, respectively are 0.024 min-1 and 0.022 min-1.

Catalytic Wet Peroxide Oxidation of Cylindrospermopsin over Magnetite in a Continuous Fixed-Bed Reactor

The development of cost-efficient and environmentally friendly technologies for the removal of cyanotoxins from water is crucial, given the increasingly frequent appearance of toxic cyanobacterial blooms. In this work, the application of catalytic wet peroxide oxidation (CWPO) promoted by natural magnetite for the removal of the highly toxic cyanotoxin cylindrospermopsin (CYN) has been investigated. A fixed-bed reactor packed with magnetite powder and granules was used to treat a continuous flow of CYN-bearing water. Experiments were carried out under ambient conditions and circumneutral pH (pH0 = 5). The effect of the main variables of the process, viz. magnetite load (8–14 g), feed flow rate (0.1–0.25 mL min−1), H2O2 dose (0.5–8 mg L−1) and initial CYN concentration (25–100 μg L−1), were systematically analyzed. CYN conversion values and kinetic constants were calculated to evaluate the feasibility of the catalytic system. The process was highly effective in the removal of the cyanotoxin, achieving up to 80% CYN conversion under optimized conditions (flow rate = 0.2 mL min−1, [H2O2]0 = 5 mg L−1, WFe3O4 = 14 g, pH0 = 5, T = 25 °C). It also showed reasonable activity (~55% CYN conversion) in two real samples (pond and river water). The decay on CYN conversion in these cases was mainly due to the scavenging of hydroxyl radicals by the co-existing species present in the matrices. Remarkably, the catalytic system showed high stability with limited iron leaching (the iron leached at the end of the experiments represented less than 0.2 wt.% of the catalyst’s initial iron content) in all cases. Its stability was further confirmed in a long-term continuous experiment (60 h time on stream). Furthermore, the magnetite granules at the top layer of the packed bed avoided the loss of magnetite powder from the reactor, confirming the suitability of the system for continuous long-term application.

Fabrication of Fe3O4/O‐Carboxylmethyl Chitosan Magnetic Particle Assembles in Inverse Miniemulsions for Loading and Release of Bovine Serum Albumin

AbstractFe3O4/O‐carboxylmethyl chitosan (OCMC) magnetic particle assembles (MPAs) with high magnetite loading and superparamagnetism were controllably prepared through Schiff base crosslinking reaction of OCMC‐stabilized Fe3O4 magnetic nanoparticles (OCMC‐Fe3O4 MNPs) in the dispersed phase of inverse miniemulsions. The Fe3O4/OCMC MPAs were composed of many tiny Fe3O4 MNPs, and they did not only inherit the good superparamagnetism of OCMC‐Fe3O4 MNPs, but also displayed high collective magnetic response to an external magnetic field. The crosslinked network of OCMC offered a good structural integrity of the Fe3O4/OCMC MPAs either in inverse emulsions or in aqueous dispersions within a wide pH range. The Fe3O4/OCMC MPAs displayed a reversible pH‐dependent loading and release behavior of a model protein, bovine serum albumin, exhibiting a great potential in functioning as nanocarriers for loading and release of biomacromolecules.

Adsorption and magnetic solid-phase extraction of NSAIDs from pharmaceutical wastewater using magnetic carbon nanotubes: Effect of sorbent dimensions, magnetite loading and competitive adsorption study

Abstract Magnetic carbon nanotubes (MCNT) of different dimensions and different magnetite-to-carbon nanotube (Mag:CNT) ratios were prepared and characterized for magnetic solid phase extraction (MSPE) of some non-steroidal anti-inflammatory drugs (NSAIDs) (ketoprofen (KET), diclofenac sodium (DIC) and ibuprofen (IBU)) from water prior to their HPLC determination. The results revealed that the best mixing ratio of (Mag:CNT) was at (1:1) ratio; long CNT was better than short CNT; the best external diameter was 60–100 nm. This sorbent was labeled as L-MCNT60-100 nm (1:1). The optimum MSPE-HPLC method was as follows: 150 mg of L-MCNT60-100 nm (1:1) sorbent was added to 50 mL solution containing KET, DIC and IBU at pH 5. The solution was shaken for 30 min and the sorbent was separated from the solution using an external magnet. The adsorbed analytes were eluted using 5 mL of 10% ammonia in methanol and the eluent was then injected into HPLC instrument. Figures of merit were estimated to be as follows (KET, DIC and IBU, respectively): detection limits: 0.4, 0.5, 0.5 μ g L−1; sensitivity: 3.13, 3.40, 1.46 L mg−1; %RSD range: [2.6–7.2], [2.2–5.1], [2.7–6.4] %; bias range (%): [(-26.8)–(14.0)], [(-7.4)–(17.0)], [(-8.4)–(17.8)]%. Application on tap water and pharmaceutical wastewater gave spiked recovery as follows: Tap water: KET: 103.7%( ± 5.4); DIC: 110.3%( ± 5.3); IBU: 70.1%( ± 6.5); Pharmaceutical wastewater: KET: 58.8%( ± 7.2); DIC: 48.9%( ± 5.9); IBU: 100.5%( ± 8.2). Adsorption studies were conducted to measure the adsorption capacity of the adsorbents where the effect of MCNT dimensions, magnetite loading and competitive adsorption were investigated.

Nano-magnetic walnut shell-rice husk for Cd(II) sorption: design and optimization using artificial intelligence and design expert

This study attempted to investigate the use of nanomagnetic activated carbon prepared from walnut shell and rice husk wastes for removal of Cd(II) from aqueous solution via application of ANN and design expert as adsorbent preparation design and optimization tools. The novel adsorbent was characterized using SEM, FTIR, EDS and BET. The result from 2-level factorial design expert revealed 78.58% Cd(II) sorption efficiency could be achieved for adsorbent prepared at optimum calcination temperature, calcination time, SS-RH mixing ratio and magnetite loading of 859.20 °C, 2.32 h, 2.54 and 5.56 wt% respectively. Sensitivity analysis by both proposed methodologies revealed calcination temperature as most influential factor in adsorbent preparation. Average relative errors and R2 values of 1.2931% and 4.806%; and 0.9967 and 0.9055 obtained respectively for developed ANN model with 4-9-1 architecture and 2-level factorial design expert revealed ANN model as better prediction and optimization tool for Cd(II) sorption using NM-WS-RH-AC. Laboratory analysis revealed presence of –OH, –NH and COO− groups on adsorbent surface; presence of Cd(II) after adsorption; change in adsorbent textural and morphological structure after Cd(II) adsorption; and increase in its surface area and average pore diameter due to magnetization. Average relatively stable desorption strength of 62.74% towards Cd(II) was exhibited by adsorbent for four consecutive cycles using 0.1M HNO3. Prepared adsorbent is effective in removing Cd(II) from solution than commercial activated carbon with economically viable regeneration attribute.

Symbiosis of Silica Biomorphs and Magnetite Mesocrystals

AbstractSilica biomorphs are extraordinary inorganic superstructures formed via autocatalytic co‐precipitation and bottom‐up self‐assembly of alkaline‐earth carbonates and silica. However, they show no inherent functionality except for their striking textural motifs and curved morphologies. This work presents strategies to magnetize silica biomorphs, thus creating thermally stable ceramic microswimmers with unique elaborate shapes. This is achieved by growing super paramagnetic magnetite mesocrystals on and around the complex curved surfaces of biomorphs, while keeping their morphology and maintaining mesocrystal integrity. Selective mesocrystal formation on certain parts of the substrates is induced by chemical modification of the biomorph surface, increasing the loading of magnetite on the silica–carbonate structures and, in suitable cases, rendering them able to respond to external magnetic fields and move as microswimmer entities. In this way, the complex ultrastructure of silica biomorphs is successfully used as a template for functional ceramics. Furthermore, selective dissolution of the carbonate core from the biomorphs leads to hollow magnetic structures that could be filled with actives, thus serving as microcarriers with considerable loading capacity.

Core/shell PA6 @ Fe3O4 nanofibers: Magnetic and shielding behavior

One of the main challenges in the reduction of the electromagnetic wave is to develop lightweight absorber material with a wide absorption frequency. Hence, developing shielding materials that could shield electromagnetic radiation to prevent interference is highly desired for protection. The combination between the unique properties of polyamide (PA6) with free surfactant magnetite nanoparticle as core/shell nanofibers (PA6 @ Fe3O4) provides a promising low-cost, environmentally-friendly and electromagnetic shielding properties. Free surfactant magnetite nanoparticles (39 ± 3.5 nm average size) were prepared by the co-precipitation process and incorporated directly into the polyamide solution before the electrospinning technique. The mean average size of the prepared magnetite nanoparticles is compared based on X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM). The morphology, thermal stability and magnetic behavior of the resultant magnetite nanofibers (150 ± 25 nm average size) were investigated using high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM), respectively. Shielding effectiveness for magnetite polyamide core/shell nanofibers was measured at frequency 30 MHz–1.5 GHz. The results showed that core/shell nanofibers provide not only well-dispersed magnetite nanoparticles in the polyamide matrix but also controllable sized nanofibers with high magnetization. In addition, even with low magnetite loading of 1.7%, the fabricated nanofiber shows high thermal stability with good performance as electromagnetic shielding nanofiber. Therefore, magnetite polyamide core/shell nanofiber could be considered as a promising material for shielding application.

Abstract 246: Glioblastoma cell-modified cell membrane lipid-extracted nanoparticles (CLENs) for imaging and treatment: Influence of magnetic nanoparticle on physiochemical properties of CLENs, cellular uptake, and cytotoxicity

Abstract Background: Glioblastoma multiforme (GBM), located in the cerebral hemispheres of the brain, is the most aggressive form of cancer. Surgery associated with chemotherapy with radiation treatment is the defined way to treat the disease. The delivery of chemotherapeutic agents frequently result in serious side effects. To address this issue we have taken the first steps in the development of CLENs (cell membrane lipid-extracted nanoliposomes) to enhance selective delivery of drugs to the brain. Method: The CLENs used for the experiments were composed of various ratios of DOPC, DOTAP, cholesterol, and lipid extract (LE) material derived from the target cells (i.e., U87-MG), and DPPE-PEG5000 (PEG). Studies include the determination of drug (cisplatin) loading, magnetite (MAG-C) loading in CLENs, quantitative studies for particle size, zeta potential, SQUID (superconducting quantum interference device) measurements, and fluorescence detection to study cellular interactions. Results: The average size for the CLENs fell within the range of 130 to 190 nm. The zeta potential reported for CLENs was negatively-charged. The inclusion of 15mol % LE resulted in the most significant cellular uptake by target cell U87-MG. Overall, the uptake by these cells was less compared to CLENS previously published for other organ tissue environments such as with breast tissue. The inclusion of cationic lipid DOTAP in CLENs did not alter the size distribution; however, the values for zeta potential increased from -8 ± 5 to 12 ± 6 mv. The additional inclusion of DOTAP in CLENs increased cellular uptake approximately 4-fold compared to CLENs without DOTAP (fluorescence intensity (A.U) from 145 ± 52 to 525 ± 49)). The inclusion of DOTAP increased the efficiency of loading Cisplatin in CLENs by approximately 30%. Studies involving the incorporation of MAG-C in U87-MG CLENs are currently underway, as well magnetization studies involving SQUID. Conclusion: All CLENs demonstrated practical physicochemical properties similar to conventional liposomes. The cellular uptake results suggested that cellular uptake of CLENs in vitro, although relatively low overall, varied according to the total LE content. Furthermore, the inclusion of DOTAP in CLENs significantly increased uptake and the efficiency of drug loading. Citation Format: Woongjae Song, Robert Campbell. Glioblastoma cell-modified cell membrane lipid-extracted nanoparticles (CLENs) for imaging and treatment: Influence of magnetic nanoparticle on physiochemical properties of CLENs, cellular uptake, and cytotoxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 246.

Redistribution of Electron Equivalents between Magnetite and Aqueous Fe2+ Induced by a Model Quinone Compound AQDS.

The complex interactions between magnetite and aqueous Fe2+ (Fe2+(aq)) pertain to many biogeochemical redox processes in anoxic subsurface environments. The effect of natural organic matter, abundant in these same environments, on Fe2+(aq)-magnetite interactions is an additional complex that remains poorly understood. We investigated the influence of a model quinone molecule anthraquinone-2,6-disulfonate (AQDS) on Fe2+(aq)-magnetite interactions by systematically studying equilibrium Fe2+(aq) concentrations, rates and extents of AQDS reduction, and structural versus surface-localized Fe(II)/Fe(III) ratios in magnetite under different controlled experimental conditions. The equilibrium concentration of Fe2+(aq) in Fe2+-amended magnetite suspensions with AQDS proportionally changes with solution pH or initial AQDS concentration, but independent of magnetite loadings through the solid concentrations that were studied here. The rates and extents of AQDS reduction by Fe2+-amended magnetite proportionally increased with solution pH, magnetite loading, and initial Fe2+(aq) concentration, which correlates with the corresponding change of reduction potentials for the Fe2+-magnetite system. AQDS reduction by surface-associated Fe(II) in the Fe2+-magnetite suspensions induces solid-state migration of electron equivalents from particle interiors to the near-surface region and the production of nonmagnetic Fe(II)-containing species, which inhibits Fe2+(aq) incorporation or electron injection into the magnetite structure. This study demonstrates the significant influence of quinones on reductive activity of the Fe2+-magnetite system.

Characterizing the thermal and mechanical properties and improvement in sound insulation performance of magnetite containing nonwovens depending on coating conditions

The scope of this work consists in studying the effects of different processing parameters such as magnetite grinding, magnetite loading amount, type of coating polymer and also sound frequency on the sound insulation property of layered nonwoven structures. Thermal stability and mechanical properties were also investigated. To achieve this goal, nonwoven fabrics were coated with styrene butadiene copolymer latex and ethylene vinyl acetate polymers by using raw and ground magnetite in three different amounts, i.e., 100, 200 and 400 g/m2. Sound transmission loss measurements were performed on the samples using an impedance tube equipped with four microphones. Independent of the coating polymer, addition of magnetite improved thermal stability and mechanical properties. But, sound insulation property was substantially changed depending on the coating polymer. Magnetite incorporation provided noticeable improvements in the ethylene vinyl acetate coated samples (increment values of 3–16 dB), while the effect of magnetite usage was limited in the latex coated samples (0.1–2.9 dB).

Functionalization of activated carbons with magnetic Iron oxide nanoparticles for removal of copper ions from aqueous solution

Magnetic activated carbon particles (MACP) were fabricated using a facile co-precipitation method and employed as an adsorbent for the removal of Cu ions from aqueous solutions. The application of magnetic Fe3O4 nanoparticles significantly enhanced the adsorption capacity and regeneration efficiency of the MACP adsorbents. The Fe3O4 magnetite loading onto the carbon matrix is a crucial factor for an efficient removal of copper ions. The Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) adsorption models were used to validate the adsorption isotherms. Both the equilibrium rate constant (Langmuir model) and the adsorption energy (D-R model) show an increase in the deposition of magnetite nanoparticles. The presence of magnetic Fe3O4 nanoparticles further facilitates the regeneration efficiency of Cu-adsorbed intermediates from the MACP adsorbents. Superior magnetic property enabled via the utilization of Fe3O4 nanoparticles significantly enhanced the separation efficiency and regeneration of spent MACP adsorbents. Therefore, the design procedure explained in this work for preparing the MACP adsorbents can be adopted for various environmental applications dealing with separation processes.

The material characterization and gamma attenuation properties of Portland cement-Fe3O4 composites for potential dry cask applications

The effect of nanosized magnetite (Fe3O4) additions on the microstructural, mechanical and gamma attenuation properties of White Ordinary Portland cement (WOPC) pastes was investigated. The microstructure of a set of cement composites with Fe3O4 content ranging from 0 to 50 wt% was examined using X-ray diffraction and Scanning Electron Microscopy (SEM) techniques. Magnetite additions did not influence the hydration products of Portland cement after 28 days of curing. SEM showed uniform distribution of magnetite nanoparticles in the cement hydration products of composites with less than 10 wt% Fe3O4. Aggregation of magnetite nanoparticles occurred when high loading of magnetite was added to the cement (20, 40 and 50 wt%). Compressive strength and stress-strain curves were also measured to characterize the mechanical performance of the composites. A maximum compressive strength of 60 MPa was obtained for cement pastes reinforced with 10 wt% Fe3O4, which represents an enhancement of 50% over the plain WPOC paste. Composites loaded with 50 wt% Fe3O4 yielded to a reduction of compressive strength (35 MPa) of 5% over the reference paste. Mechanical behavior of the material was explained in terms of their microstructure, i.e. uniform magnetite embedded in the paste has a reinforcement effect due to the promotion of hydration process and the filling effect of the particles. Heterogeneous distribution of magnetite particles due to agglomeration acted to weaken the cementitious matrix by creation of pores. Finally, transmission experiments and Monte Carlo simulations were conducted to evaluate the shielding properties of the composites when exposed to a Cs-137 gamma source (0.662 MeV). The addition of Fe3O4 improves the shielding capability of Portland cement pastes with enhancements ranging between 3.1 and 2.6% for samples with 2.5 and 50 wt% Fe3O4 respectively. No simple relationship exists between the attenuation properties and magnetite loading. Changes in the attenuation coefficients of the composites are explained in terms of the chemical composition and microstructural effects.

TiO2/Fe3O4/Ag nanophotocatalysts in solar fuel production: New approach to using a flexible lightweight sustainable textile fabric

Abstract There has been always a desire for simultaneous pollutants degradation and fuel gas formation to solve the energy and environmental challenges of today's world. In this regard, photocatalytic decomposition of organic compounds along with solar fuel production has been highly concerned. In this approach, magnetic titania nanophotocatalysts have been used for the photocatalytic generation of fuel gases using acetic acid decomposition. TiO2/Fe3O4/Ag nanocomposites were found to be effective in the photocatalytic transformation of acetic acid to produce CO2 and CH4 as the main gaseous products along with very small quantities of H2. The effect of low and heavy loading of magnetite and silver on photocatalytic gas formation at the nanocomposite surface has been also addressed. The amount of CO2 and CH4 gases evolved after 17 h irradiation was increased from 32 and 13 μmolh−1g−1 for bare TiO2 P25 to 1169 and 992 μmolh−1g−1 for TiO2/Fe3O4/Ag nanocomposite. Moreover, the ratio of the formation rates of methane to carbon dioxide evolution was increased from 0.38 for bare TiO2 P25 to 0.85 for TiO2/Fe3O4/Ag nanocomposite indicating the transition to photo-Kolbe reaction along with some alcohol formation as the main possible reaction pathways. In addition, this study designed a new approach to develop durable flexible lightweight polyester textile fabric as an innovative sustainable immobilized substrate for photo transformation of acetic acid to produce fuel gaseous products. The results indicated that more than the successful cooperation of magnetite and silver in enhanced separation of electron-hole pairs, surface phenomena such as surface wettability as proved by contact angle test are responsible for the photocatalytic activities of a fibrous substrate in aqueous systems.