Ions For Fe3 Research Articles

Experimental Simulation of Sorption Processes of Heavy Metals on Natural Clay Minerals

The sorption of iron (III) and copper (II) ions on natural clay minerals of deposits of Buryatia is investigated. The adsorption of ions of these metals depends on pH of solution, clay loading, concentration of metals ions and also on the temperature of adsorption carrying out and regularities of influence of these parameters on adsorption efficiency are determined. Kinetic regularities of adsorption of ions of Fe3+ and Cu2+ on natural clays are consistent with kinetics model of pseudo- second order. The isotherms of equilibrium adsorption of above-mentioned ions on natural clay are described by Langmuir equation with the correlation coefficient of R2 equal 0.994. Results of testing of clays in the process of purification of adit wastewater of iron and copper ions testify to a possibility of effective use of natural clays of Buryatia in sewage treatment from ions of heavy metals.

Identification of activated NaOH carbon of synthesis of sea pandanus leaves (P. odorifer) for Fe3+ and Cu2+ ions adsorption

This research aims to characterize activated NaOH carbon of sea pandanus leaves (P. odorifer) which include water content, ash content, volatile content, carbon content and adsorption capacity of iodine. Further, we investigate adsorption capacity of activated NaOH carbon to Fe3+ and Cu2+ ions, and its adsorption type. Sea pandanus leaves (P. odorifer) was taken from Trisik Beach in Kulonprogo. The carbonation process is carried out at a temperature of 500 °C, followed by chemical activation using 1% NaOH solution and physical activation with a temperature of 700 °C while carbon dioxide gas flowed for 2 hours. Identification of capacity of activated carbon to heavy metals is conducted in batch. The characterization results show that water content and iodine adsorption capacity of activated NaOH carbon complied with SNI 06-3730-1995, respectively of 5.38% and 2463.63 mg/g. While the volatile content (59.09%), ash content (17.88%), carbon content (17.66%) did not fulfill SNI 06-3730-1995. The adsorption capacity of activated NaOH carbon to heavy metal ions of Fe3+ and Cu2+ respectively is 0.895 and 0.996 mg/g.

Effect of substituted concentration on structure and magnetic properties of Y3Fe5-xInxO12

Abstract: This study examines the effect of substituted concentration on the structure and magnetic properties of Y3Fe5-xInxO12 (x = 0.1 ÷ 0.7) powder samples prepared using the sol-gel method. The morphological properties of the samples were analysed using XRD, SEM. The single phase of garnet was obtained in x = 0.1 ÷ 0.6 samples. The lattice parameters of the samples exhibit a linear increase with the increasing In3+ content, which can be explained by a substitution of In3+ ions for Fe3+ ions, considering the larger ionic radius of In3+ compared with that of Fe3+. Crystallite sizes were determined via the XRD data which are of 38 – 49 nm while the particle sizes were estimated from SEM images to be in range of 50 - 100 nm. Magnetization and Curie temperature of the single phase samples were studied by magnetization curves in fields up to 10 kOe and in the temperature range from 80 K to 560K. With the increase of In3+, the magnetization gradually increases while the Curie temperature decreases due to the occupation of In atoms at the a sites and the reduction of intersublattice interaction, respectively.
 Keywords: Yttrium iron garnet, Indium substitution, cation distribution, magnetization, Curie temperature.
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Gallol-containing homopolymers and block copolymers: ROMP synthesis and gelation properties by metal-coordination and oxidation

Gallol-functionalized polymers are highly desirable for their addressable functions in the fields of materials science, nanotechnology and biomedicine, owing to gallol's unique chemistry including excellent chelating properties to metals, easily oxidability and superior ability to bind proteins. Herein, we report the controlled synthesis of the first polynorbornene-based side-chain gallol-containing homopolymers and block copolymers with pendent triethylene glycol (TEG) moieties by the ring-opening metathesis polymerization (ROMP) using the 3rd generation Grubbs catalyst 1 as the initiator. We describe the direct synthetic route by the ROMP of a gallol-containing norbornene monomer, and the indirect approach via an acetoxyl protection/deprotection route. Among the tested metal ions of Fe3+, Mg2+, Cr3+ and Al3+, Fe3+ is the most effective metal ion to induce the gelation of the present gallol-containing polymers, and UV–visible spectroscopy indicates that bis-coordinated state dominates for the interaction between side-chain gallol groups and Fe3+ ions in DMF. The gelation rate, interior structure, thermal and mechanical properties of the Fe3+-induced metallogels can be effectively tuned by changing the gallol/Fe3+ molar ratio, polymeric molecular weight, and by introducing of organic TEG block. Furthermore, the oxidant-induced organogels were fabricated by adding the oxidant of NaIO4 into the DMF solution of the gallol-containing polymers, and the gelation rate highly depends on the gallol/IO4− molar ratio and the introduction of TEG block. We are convinced that the effective synthesis of well-defined gallol-containing polymers, as illustrated by the present work, will pave the way for their functional applications as smart organogels, coatings, adhesives, capsules, etc.

Improvement of the magnetic moment of NiZn ferrites induced by substitution of Nd3+ ions for Fe3+ ions

Four types of Ni-Zn based ferrites materials having the general formula Ni0.5Zn0.5NdxFe2−xO4 (0.0 ≤ x ≤ 0.12) have been successfully synthesized by calcining oxalates in air and the influence of Nd content on the structure and magnetic properties of Ni0.5Zn0.5NdxFe2−xO4 is studied. X-ray diffraction examination confirms that a high-crystallized Ni0.5Zn0.5NdxFe2−xO4 with cubic spinel structure is obtained when the precursor is calcined at 1000 °C in air for 2 h. The substitutions of Nd3+ ions for partial Fe3+ ions do not change the spinel crystalline structure of MFe2O4. The incorporation of Nd3+ ions in place of Fe3+ ions in Ni-Zn ferrites increases the average crystallite size. Specific saturation magnetization decreases with increase in Nd content. This is because Nd3+ ions with smaller magnetic moment preferentially fill the octahedral sites. In addition, antiferromagnetic FeNdO3 increases with increase in Nd content. In this study, Ni0.5Zn0.5Nd0.08Fe1.92O4, calcined at 1000 °C, exhibits the highest magnetic moment (4.2954 μB) and the lowest coercivity (28.82 Oe).

Interaction between Diethyldithiocarbamate and Cu(II) on Gold in Non-Cyanide Wastewater.

A surface-enhanced Raman scattering (SERS) detection method for environmental copper ions (Cu2+) was developed according to the vibrational spectral change of diethyldithiocarbamate (DDTC) on gold nanoparticles (AuNPs). The ultraviolet-visible (UV-Vis) absorption spectra indicated that DDTC formed a complex with Cu2+, showing a prominent peak at ~450 nm. We found Raman spectral changes in DDTC from ~1490 cm−1 to ~1504 cm−1 on AuNPs at a high concentration of Cu2+ above 1 μM. The other ions of Zn2+, Pb2+, Ni2+, NH4+, Mn2+, Mg2+, K+, Hg2+, Fe2+, Fe3+, Cr3+, Co2+, Cd2+, and Ca2+ did not produce such spectral changes, even after they reacted with DDTC. The electroplating industrial wastewater samples were tested under the interference of highly concentrated ions of Fe3+, Ni2+, and Zn2+. The Raman spectroscopy-based quantification of Cu2+ ions was able to be achieved for the wastewater after treatment with alkaline chlorination, whereas the cyanide-containing water did not show any spectral changes, due to the complexation of the cyanide with the Cu2+ ions. A micromolar range detection limit of Cu2+ ions could be achieved by analyzing the Raman spectra of DDTC in the cyanide-removed water.

Improvement of the Magnetization of Barium Hexaferrites Induced by Substitution of Nd3+ Ions for Fe3+ Ions

Barium hexagonal ferrites (BaNd x Fe12−x O 19) have been synthesized by initial high-energy milling of the precursors and calcining subsequently. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). XRD and SEM examinations reveal that a high-crystallized hexagonal BaNd x Fe12−x O 19 with lamellar morphology is obtained when the precursor is calcined at 1200∘C in air for 3 h. The hexagonal crystalline structure of BaFe12 O 19 is not changed after doping Nd3+ ions in BaFe12 O 19. However, lattice parameters a and b values increase with an increase in Nd content at first, then decrease. Nd substitution may improve the magnetic properties of BaNd x Fe12−x O 19. BaNd0.1Fe11.9 O 19, obtained at 1050∘C, has the highest specific saturation magnetization value (80.81 emu/g) and magnetic moment (16.21 μ B); BaNd0.2Fe11.8 O 19, obtained at 950∘C, has the highest coercivity value, 4075.19 Oe.

A Rhodamine-based Dual Chemosensor for the Simultaneous Detection of Fe3+ and Cu2.

A Rhodamine-based dual chemosensor L1 for simultaneously detecting Fe3+ and Cu2+ was designed and synthesized. The spectroscopic properties of L1 were analyzed, and its recognition mechanism was speculated. We found that the addition of Fe3+ induced a great fluorescence enhancement, while Cu2+ induced a strong UV-Vis absorption enhancement. The results revealed that L1 was highly selective for recognizing Fe3+ and Cu2+ in UV-Vis spectroscopy in CH3OH-H2O (1/1, v/v, pH 7.2) with the interference of other metal ions. A good linear relationship between the fluorescence intensities of L1 and the concentration of Fe3+, as well as the UV-Vis absorption intensities of L1 and the concentration of Cu2+ was observed, respectively. The detection limit was 9.2 × 10-8 M (5.5 μg/L) for Fe3+ and 3.8 × 10-8 M (2.4 μg/L) for Cu2+, respectively. The detection capacity for targeted metal ions of Fe3+ and Cu2+ were studied, which are less than 5 min. Job's plot method for L1 with Fe3+ and ESI-MS for L1 with Cu2+ indicated a 1:1 stoichiometry in the complex. The results may provide an effective strategy for the design of new dual chemosensors for the rapid detection of targeted metal ions.

Detection of Copper(II) Ions Using Glycine on Hydrazine-Adsorbed Gold Nanoparticles via Raman Spectroscopy.

A facile, selective, and sensitive detection method for the Cu2+ ions in environmental and biological solutions has been newly developed by observing the unique CN stretching peaks at ~2108 cm−1 upon the dissociative adsorption of glycine (GLY) in hydrazine buffer on gold nanoparticles (AuNPs). The relative abundance of Cu species on AuNPs was identified from X-ray photoelectron spectroscopy analysis. UV-Vis spectra also indicated that the Au particles aggregated to result in the color change owing to the destabilization induced by the GLY-Cu2+ complex. The CN stretching band at ~2108 cm−1 could be observed to indicate the formation of the CN species from GLY on the hydrazine-covered AuNP surfaces. The other ions of Fe3+, Fe2+, Hg2+, Mg2+, Mn2+, Ni2+, Zn2+, Cr3+, Co2+, Cd2+, Pb2+, Ca2+, NH4+, Na+, and K+ at high concentrations of 50 µM did not produce such spectral changes. The detection limit based on the CN band for the determination of the Cu2+ ion could be estimated to be as low as 500 nM in distilled water and 1 µM in river water, respectively. We attempted to apply our method to estimate intracellular ion detection in cancer cells for more practical purposes.

Improvement of the coercivity of rod-like NiCuMg ferrites induced by substitution of Dy3+ ions for Fe3+ ions

Four kinds of Ni–Cu–Mg based ferrites materials having the general formula Ni0.5Cu0.25Mg0.25Dy x Fe2−x O4 (0.0 ≤ x ≤ 0.24) have been successfully synthesized using the solvothermal method. X-ray diffraction and scanning electron microscope examinations confirm that a rod-like Ni0.5Cu0.25Mg0.25Dy x Fe2−x O4 with cubic spinel structure is obtained when the precursor is calcined above 850 °C in air for 3 h. Single phase Ni0.5Cu0.25Mg0.25Fe2O4 is obtained at 850 °C, but all samples consist of the main spinel phase in combination of a small amount of foreign Dy2O3 and/or DyFeO3 phases after doping Dy3+. When the precursor is calcined at 1000 °C, the lattice parameters of the ferrites initially decrease after doping Dy3+(x = 0.08), but then become larger with additional Dy3+ doping. The addition of Dy3+ decreases the average crystallite size, and results in higher coercivity (Hc) and squareness (M r/M s) as compared to un-substituted Ni–Cu–Mg ferrites. In this study, Ni0.5Cu0.25Mg0.25Dy0.24Fe1.76O4, obtained at 1000 °C, exhibits the highest coercivity of 149.29 Oe and squareness (0.3055).

Magnetic and magnetostrictive properties of RE-doped Cu-Co ferrite fabricated from spent lithium-ion batteries

Magnetostrictive Cu0.1Co0.9RExFe2-xO4 (RE=Ho, Gd or Sm) was fabricated by a sol-gel auto-combustion technique using spent lithium-ion batteries as raw materials. X-ray diffraction analysis confirmed the spinel structure of the RE-incorporated samples with limited RE solubility. Field-emission scanning electron microscopy and Fourier transform infrared spectroscopy revealed a layered structure composed of particles and the cation distribution. Magnetic hysteresis loops and magnetostriction strain curves showed that the saturation magnetization, magnetostriction coefficient and strain derivative were significantly modified due to the substitution of larger ionic radius RE3+ ions for Fe3+ ions, influencing the interaction between the tetrahedral and octahedral sites.

Structural, electrical and magnetic properties of dilutely Y doped NiFe2O4 nanoparticles

Present study is focused on the structural, electrical and magnetic properties of dilutely Y doped NiFe2O4 nanoparticles. X-ray diffraction confirms the phase formation and shows that samples prepared using sol-gel method exhibit pure spinel phase except that of x = 0.05. Analysis of diffraction pattern and scanning electron microscopy images demonstrate that crystallite as well as particle sizes are increasing with concentration of Y. Presence of impurity phase is further confirmed by Raman measurement. There is no significant change in vibrational modes up to the solubility limit (x = 0.03), however, these modes are shifted towards higher wavenumber for 5% Y doped Ni ferrite due to impure phase. Incorporation of dilute amount of Y ions in host lattice results in an enhancement in the saturation magnetization, coercivity and resistivity. The enhanced saturation magnetization and resistivity is understood on the basis of exchange interactions induced by the substitution of Y3+ ions for Fe3+ ions at B-site.

Crystal structure, magnetic properties, and raman spectra of solid solutions BaFe12–x Al x O19

The crystal structures of solid solutions of hexagonal ferrites BaFe12–x Al x O19 (x = 0.1–1.2) have been studied using X-ray diffraction. It has been found that, at normal conditions, the samples are characterized by space group P63/mmc. It has been noted that the diamagnetic substitution of Al3+ ions for Fe3+ leads to a decrease in the unit cell parameters due to the smaller aluminum ion radius. The field dependences of the specific magnetic moment have been studied in fields of ±2 T at 5 and 300 K using vibrating magnetometry. It has been found that the specific magnetic moment decreases from 49.6 emu/g (x = 0.1) to 32 emu/g (x = 1.2) as the concentration of the diamagnetic ions increases. The microstructure has been studied using scanning electron microscopy. The Raman spectra have been measured in the range of 200–800 cm–1.

Electrocatalytic Oxidation Reactions of Pt Hexapod Nanoparticles

The Pt nanoparticles were synthesized using a polyol process in the presence of additives such as FeCl3, NaNO3, and PVP. In particular, the Pt nanoparticles with a hexapod structure (Pt-FNP) were formed without agglomeration in the presence of additive ions of Fe3+ and NO3− with PVP. The Pt-FNP exhibited an improved electrocatalytic activity for electro-oxidation reactions of methanol, ethanol, and formic acid due to dominant {111} facets formed as a result of a slow growth rate during the chemical process.

Magnetic study of M-type Ru–Ti doped strontium hexaferrite nanocrystalline particles

We carried out a systematic study on the effect of the substitution of Ti2+ and Ru4+ ions for Fe3+ ions on the structural and magnetic properties of the strontium ferrite SrFe12−2xRuxTixO19 nanoparticles with (0≤x≤0.3), using x-ray diffraction, Quantum Design PPMS-9 magnetometry, and electrical resistivity. A clear irreversibility between the zero-field-cooled and field-cooled curves was observed below room temperature and the zero-field-cooled magnetization curves displayed a broad peak at a temperature TM. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data showed some kind of a transition from insulator to perfect insulator around TM. The high-temperature magnetization measurements exhibited sharp peaks just below Tc indicating a superparamagnetic behavior. With Ru–Ti substitution, the saturation magnetization at 5 K showed small variations were it slightly increased with increasing x up to 0.2, and then decrease for x = 0.3, while the coercivity decreased monotonically, recording a reduction of about 78% at x = 0.3. These results were discussed in light of the cationic distributions based on the results of the structural refinements.

Magnetic Properties and Mössbauer spectroscopy of NdFe1-xMnxO3

The effect of particle reduction to nanoscale size and substitution of Mn3+ ions for Fe3+ ions on the crystal structure, lattice dynamics, Mössbauer spectra and magnetic properties in NdFe1-xMnxO3 compounds have been studied. X-ray powder diffraction and Raman spectroscopy revealed that the Jahn-Teller distortion of lattice dominates for samples with x > 0.4. The average particle size of NdFeO3 nanoparticles (NAP) increases with annealing at 600°C from about 15 nm to 25 nm. The presence of superparamagnetic particles was indicated by Mössbauer measurements in NdFeO3 NAP system. Sextets in NdFe1-xMnxO3 Mössbauer spectra can be modelled with several local environments of Fe3+ induced by substitution. The reduction of dimensionality and the substitution induce a decrease of the Néel temperature TN1 from 691 K to 544 K for NAP or to 356 K for x = 0.4, however the temperature of spin reorientation TSR increases with substitution. The saturated magnetization obtained at 1.9 K increases and ferromagnetic component is removed below TSR with the substitution.

A colloidal pseudocapacitor: Direct use of Fe(NO3)3 in electrode can lead to a high performance alkaline supercapacitor system

An electrochemical system including functioned Fe(NO3)3 and alkaline electrolyte is constructed to study the charge storage mechanism upon both thermodynamic calculations and electrochemical measurements. The thermodynamic calculation results demonstrate that increasing KOH concentration of alkaline electrolyte can enhance electrolyte activity but decrease the peak potential, which agrees well with that of electrochemical measurement. The present results indicate that the proposed pseudocapacitive redox reactions are between Fe3+ and Fe2+ in our salt electrode of Fe(NO3)3 system, in which the solid Fe3+ in FeOOH colloids serves as the active anode component and free Fe3+ on the colloidal electrodes serves as the cathode component. The active central ions of Fe3+ in Fe(NO3)3⋅9H2O can be fixed on the electrodes by the surrounding ligands (OH− and NO3−) and can be in-situ transformed into colloidal Fe4NO3(OH)11 and goethite (α-FeOOH). Electrochemical results indicate that the current proposed colloidal pseudocapacitor system warrants the high-efficiency utilization of electroactive central Fe3+ ions, showing high energy density of 58.4Wh/kg at the power density of 8.4kW/kg as an anode material. Meanwhile, our designed pseudocapacitor system can function well as a supercapacitor cathode. This colloidal pseudocapacitor system can offer a facile and efficient route for the design of advanced supercapacitors.

Antiferromagnetic superexchange interaction between Fe3+ ions in Fe3+ doped wide-gap oxide of β-Ga2−Fe O3 (x=0.1, 0.2, 0.3, 0.4)

In the Fe 3+ doped wide-gap oxide of β-Ga 2− x Fe x O 3 ( x =0.1, 0.2, 0.3, 0.4), Rietveld refinements of the X-ray diffraction data show that the Fe 3+ ions are preferentially occupied on the octahedral sites. From the measurements of magnetization as a function of magnetic field and inverse molar susceptibility as a function of temperature, it is found that the superexchange interaction between Fe 3+ ions via an intermediate oxygen ion is antiferromagnetic. The optical bandgap ( E g ) is found to decrease monotonically in energy upon increasing the Fe 3+ concentration. Below the E g edge, optical absorption subspectra are observed to occur at ~1.8 and ~2.7 eV, which are attributed to the d – d transitions of the crystal-field splitting of 3 d 5 multiplets of the octahedral Fe 3+ ion. • Preferential replacement of Ga 3+ by Fe 3+ ions occurs on the octahedral sites of β-Ga 2 O 3 . • The superexchange interaction between Fe 3+ ions in β-Ga 2 O 3 is antiferromagnetic. • The optical bandgap decreases monotonically upon increasing Fe 3+ content.

INFLUENCE OF PHYSICOCHEMICAL FACTORS ON DEHYDROGENASE ACTIVITY OF BACILLUS SUBTILIS IMB B-7023

Aim. The investigation of the influence of some physicochemical factors on dehydrogenase activity of Bacillus subtilis IMB B-7023. Methods. The bacteria were cultivated in the periodic process. Dehydrogenase activity was evaluated on reduction of 2,3,5-tetrazolium chloride to triphenilphormazane, the concentration of which was determined by photocolorymetrical methods. Results. It was defined that dehydrogenase activity reached the greatest significance in the given strain at the temperature of 37 °C in the media having pH 7.0. The highest indices of dehydrogenase activity have been obtained in the content of 10 g/l glucose in it. It was determined that ions of Mg2+ and Ca2+ have stimulated dehydrogenase activity of Bacillus subtilis, and ions of Fe3+, on the contrary, suppressed it. Сonclusion. Actual presence of high sensitiveness of the dehydrogenase complex of these bacteria to physicochemical factors of the environment can be used for making up the prognoses of the given strain activity under certain factors of the environment in its use as a complex bacterial preparation in agroecosystems.

Investigation of magnetic properties of MnZn-substituted strontium ferrite nanopowders prepared via conventional ceramic technique followed by a high energy ball milling

Strontium ferrite powders with substitution of Mn2+ and Zn2+ ions for Fe3+ ions according to the formula SrMnxZnxFe12−2xO19, wherein x ranging from 0 to 1 with a step of 0.2, has been pre-milled via conventional ceramic method and calcined at 1200°C for 4h in the air. In order to get nanopowders, the obtained powders were milled again in a high energy SPEX mill for 1h and 15min. XRD study was performed to investigation the phases and structural properties of samples. Lattice parameters and mean crystallite sizes of the milled powders were determined from the XRD data and Scherrer׳s formula. Size of particles was studied by TEM. The DC electrical resistivities of the milled samples have been measured by the two-point probe method. In addition, room temperature magnetizations and coercivities of the samples in a magnetic field of 14.7kOe have been determined from the hysteresis loops. The behavior of magnetizations of samples has been discussed based on core–shell model and according to the site occupation of substituted cations on the sublattices. The discussion of site occupation also supports the increase of lattice parameters as x increases.