Mössbauer studies of styrene-acrylonitrile copolymers containing ferric chloride

Acrylonitrile-styrene /AN-St/ copolymers of different compositions were prepared, with and without ferric chloride by free radical polymerization. It was found using Mössbauer spectroscopy that reduction of Fe³⁺ to Fe²⁺ takes place during the polymerization. The addition of ferric chloride and the reduction of Fe³⁺ was found to influence the thermal stability of the copolymers.     

聚乙烯醇在强碱性水溶液中与Fe(Ⅲ)离子间的配位-交联反应

在不断搅拌1×10~(-4)m~3 pH>13的5％ PVA碱性水溶液中,缓慢地添加1×10~(-4)kgFeCl_36H_2O,溶液中即析出红棕色树胶状物.以XPS、ESR和IR等研究该析出物的组分及其形成过程.推定PVA部分羟基在上述条件下发生脱质子反应而提供L~-配位体,Fe(Ⅲ)盐水解生成初生Fe(OH)_3的Fe~(3+),它既有空轨道,又有较强的正电场,故能吸引PVA高分子配位体L~-上的氧而形成O→Fe配位键,从而发生L~-与Fe~(3+)离子间的交联反应,生成多核Fe(Ⅲ)-PVA配位聚合物而析出红棕色树胶状物。     

Acrylonitrile - alkyl acrylate copolymers containing ferric chloride: A Mössbauer study

Acrylonitrile (AN)-methyl acrylate (MA), acrylonitrile (AN)-ethyl acrylate (EA), acrylonitrile (AN)-butyl acrylate (BA) copolymers with and without doping with ferric chloride were prepared by free radical polymerization at 70°C. Mössbauer spectrum shows no reduction of ferric species to ferrous during the copolymerization. TGA studies show that the addition of ferric chloride changes the thermal decomposition pattern of the copolymer. TGA analysis shows that the inclusion of ferric chloride stabilizes the copolymers by 20–25°C. Mössbauer studies of the copolymers heated at 300°C and 500°C for 15 min showed that during the thermal degration, Fe³⁺ species was reduced to Fe²⁺ and then finally it formed -Fe₂O₃.     

Performance Evaluation of Hybrid Gas–Liquid Pulse Discharge Plasma-Induced Degradation of Polyvinyl Alcohol-Containing Wastewater

A multi-needle-to-plate pulsed discharge plasma reactor was designed to investigate its potential for polyvinyl alcohol-containing wastewater (PVA) treatment. The effects of some operational parameters such as PVA initial concentration, pulse peak discharge voltage, air flow rate, solution pH value, and iron additives on PVA degradation were examined. The results indicated that PVA could be effectively degraded from aqueous solutions. PVA degradation efficiency was 76.0 % within 60 min’s discharge plasma treatment with 1.5 mmol L^?1 Fe²⁺ addition. Decreasing PVA initial concentration and increasing pulse peak discharge voltage were both beneficial for PVA degradation. There existed appropriate air flow rate for obtaining great PVA degradation efficiency in the present study. A little acid environment was conducive to PVA degradation. The presence of Fe²⁺ and Cu²⁺ could both benefit PVA degradation, and the increment of Fe²⁺ and Cu²⁺ concentrations to a certain extent could enhance its degradation efficiency, as well as energy yield. PVA possible degradation mechanisms were discussed, and the degradation processes were mainly triggered by the reactions of PVA with \(^{ \cdot } {\text{OH}}\) radicals.     

A comparative DFT study of Fe3+ and Fe2+ ions adsorption on (100) and (110) surfaces of pyrite: An electrochemical point of view

Pyrite acts as a catalyst in the mineral processing, and the speed of ferric ion reduction and mineral decomposition increases with increasing cathodic points. In this study, the ferric ion interaction on the (100) and (110) surfaces of pyrite was studied using the density functional theory calculations. The analysis of stability, density of states, and electron density were performed to understand the interaction between the ferric ion and pyrite surfaces. The results showed that pyrite surface is chemically active and tends to absorb ferric ion between two surface sulfur atoms. The hyperconjugation between the 3d orbital of ferric ion and the 3p or 3d orbitals of surface atoms provides the conditions for the Fe³⁺ ion adsorption. The molecular orbital (MO) and electron density analyses indicate that the 3p orbitals of S atoms play a more important role in bonds formations relative to the 3d orbitals. The (110) surface is more active, and the adsorption energy is larger than that of surface (100), which is the result of decreased cation coordination and the presence of sulfur at the surface. Subsequently, the interaction of the Fe²⁺ ion, as product of Fe³⁺ ion reduction and its competitor for adsorption, on the surfaces was studied. The Fe^{2 +} ion adsorbs stronger at the surface of (110), and the adsorption energies at (100) and (110) surfaces were obtained as −24 and −47 kcal/mol, respectively. In general, the Fe³⁺ ion is a stronger oxidizing agent than Fe²⁺ on pyrite surfaces.     

Real-time monitoring flexible hydrogels based on dual physically cross-linked network for promoting wound healing

To achieve smart and personalized medicine, the development of hydrogel dressings with sensing properties and biotherapeutic properties that can act as a sensor to monitor of human health in real-time while speeding up wound healing face great challenge. In the present study, a biocompatible dual-network composite hydrogel (DNCGel) sensor was obtained via a simple process. The dual network hydrogel is constructed by the interpenetration of a flexible network formed of poly(vinyl alcohol) (PVA) physical cross-linked by repeated freeze-thawing and a rigid network of iron-chelated xanthan gum (XG) impregnated with Fe³⁺ interpenetration. The pure PVA/XG hydrogels were chelated with ferric ions by immersion to improve the gel strength (compressive modulus and tensile modulus can reach up to 0.62 MPa and 0.079 MPa, respectively), conductivity (conductivity values ranging from 9 × 10⁻⁴ S/cm to 1 × 10⁻³ S/cm) and bacterial inhibition properties (up to 98.56%). Subsequently, the effects of the ratio of PVA and XG and the immersion time of Fe³⁺ on the hydrogels were investigated, and DNGel3 was given the most priority on a comprehensive consideration. It was demonstrated that the DNCGel exhibit good biocompatibility in vitro, effectively facilitate wound healing in vivo (up to 97.8% healing rate) under electrical stimulation, and monitors human movement in real time. This work provides a novel avenue to explore multifunctional intelligent hydrogels that hold great promise in biomedical fields such as smart wound dressings and flexible wearable sensors.     

Ellipsometric investigations of Fe3+-doped polyvinyl alcohol films

In this work, we study the inclusion mechanism of Fe³⁺ ions in a polyvinyl alcohol (PVA) matrix. Thin films of pure and FeCl₃-doped PVA on silicon substrates, prepared by the spin-coating method, are investigated using spectroscopic ellipsometry (SE) and Fourier transform infrared (FT-IR) spectroscopy. SE measurements of PVA and Fe³⁺-doped thin films are carried out at an incidence angle of 75° over the wavelength range of 0.24–1.1 μm. An optical model is used to obtain the refractive index (n) and the extinction coefficient (k). The gap energy E _g is afterwards evaluated. The Fe³⁺ doping is found to affect strongly the optical parameters of the polymer films. In fact, an increase in the refractive index with doping is observed, resulting from the intermolecular hydrogen bonding between Fe³⁺ ions with the adjacent OH group of PVA. The increase of the thin films' absorption with doping is estimated by the k spectral profile analysis. The gap energy is then calculated and shows an important decrease with the Fe³⁺ filling, more pronounced for low doped samples. Such a behavior is confirmed by FT-IR analysis.     

Ion-beam-induced reduction of iron oxide supported on porous glass

When ferric oxide supported on porous glass was irradiated by 40 keV He⁺ ions, the reduction of Fe³⁺ to Fe²⁺ species occurred. The yield of Fe²⁺ species, which was monitored by the Mössbauer spectroscopic measurement, increased with increasing total dose, and went up to ca. 80%. This unexpectedly large yield meant that the effect was exerted beyond the range of the incident He⁺ ions. Clear dose rate dependence of the Fe²⁺ yield was also observed. We examined the possibility that the reduction of the Fe³⁺ species was caused by some type of gaseous reductant produced by radiolysis of surface chemical species such as physisorbed water molecules and surface hydroxyls.     

Radiation chemical and magnetic resonance studies of aqueous agarose gels containing ferrous ions

Aqueous agarose gels containing ferrous ions sustain a radiolytic chain reaction, producing Fe³⁺. G(Fe³⁺)-values up to 156 have been observed, independent of dose rate between 0.434 and 3.74 Gy min^-1. Dissolved oxygen is needed to maintain the chain reaction, and initial ferric yields are increased if the gel is oxygen saturated, or if the Fe²⁺ concentration is decreased. Longitudinal proton magnetic relaxation rates are increased in proportion to ferric production, permitting visualizing of dose levels in these gels by magnetic resonance imaging techniques. There is a potential for application to radiation therapy treatment planning.     

三维介孔氨基三亚甲基膦酸锆的合成及其担载铁催化剂的甲醛催化氧化活性

以氧氯化锆和氨基三亚甲基膦酸(ATMP)为原料合成了一种新型介孔材料氨基三亚甲基膦酸锆(NTAZP)。使用XRD、FTIR、TG-DTA和SEM等手段对所合成的介孔材料进行了结构表征和形貌分析。然后以NTAZP为载体,用Fe(NO3)3水溶液处理,得到担载Fe3+的氨基三亚甲基膦酸锆。研究结果表明,Fe3+被吸附到载体孔道中后,NTAZP结构未被破坏,Fe3+离子与NTAZP孔壁骨架上的N发生了配位作用。铁担载NTAZP(NTAZP-Fe3+)对甲醛氧化具有良好的催化活性,催化反应条件温和,催化剂稳定性良好。以载体NTAZP担载铁还避免了Fe3+进入水体,催化剂得以回收利用,避免造成二次污染。NTAZP-Fe3+是一种高效绿色的新型小分子醛类化合物氧化催化剂。     

Investigation of multiplet splitting of Fe 2p XPS spectra and bonding in iron compounds

Ferrous (Fe²⁺) and ferric (Fe³⁺) compounds were investigated by XPS to determine the usefulness of calculated multiplet peaks to fit high‐resolution iron 2p_3/2 spectra from high‐spin compounds. The multiplets were found to fit most spectra well, particularly when contributions attributed to surface peaks and shake‐up satellites were included. This information was useful for fitting of the complex Fe 2p_3/2 spectra for Fe₃O₄ where both Fe²⁺ and Fe³⁺ species are present. It was found that as the ionic bond character of the iron —ligand bond increased, the binding energy associated with either the ferrous or ferric 2p_3/2 photoelectron peak also increased. This was determined to be due to the decrease in shielding of the iron cation by the more increasingly electronegative ligands. It was also observed that the difference in energy between a high‐spin iron 2p_3/2 peak and its corresponding shake‐up satellite peak increased as the electronegativity of the ligand increased. The extrinsic loss spectra for ion oxides are also reported; these are as characteristic of each species as are the photoelectron peaks. Copyright © 2004 John Wiley & Sons, Ltd.     

Methyl methacrylate-n-butyl methacrylate copolymer containing ferric chloride: Mössbauer study

Methyl methacrylate /MMA/-n-butyl methacrylate /nBuMA/ copolymer containing anhydrous ferric chloride was prepared by free radical polymerization at 70 °C. TGA studies showed that the addition of ferric chloride increases the thermal stability of copolymer by 90 °C. Mössbauer studies of the copolymer were carried out to determine the oxidation state and environments of iron in the copolymer. Mössbauer studies of the copolymer heated at 150 °C, 300 °C and 500 °C for 1 h showed that during the thermal degradation, no reduction of Fe³⁺ takes place.     

Using Zeolite/Polyvinyl alcohol/sodium alginate nanocomposite beads for removal of some heavy metals from wastewater

Functionalized Polyvinyl alcohol/sodium alginate (PVA/SA) beads were synthesized via blending Polyvinyl alcohol (PVA) with sodium alginate (SA) and the glutaraldehyde was used as a cross-linking agent. The zeolite nanoparticles (Zeo NPs) incorporated PVA/SA resulting Zeo/PVA/SA nanocomposite (NC) beads were synthesized for removal of some heavy metal from wastewater. The synthesizes beads were characterized via Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), particle size analyzer (PSA), and scanning electron microscope (SEM). The adsorption kinetics of the selected metal ions onto Zeo/PVA/SA NC beads followed the pseudo-first-order model (PFO) and the adsorption isotherm model was well fitted by the Langmuir model. Moreover, the thermodynamic studies were also examined; the outcomes showed that the adsorption mechanisms of the selective metal ions were endothermic, the chemical in nature, spontaneous adsorption on the surface of the Zeo/PVA/SA NC beads. The removal efficiency using Zeo/PVA/SA NC modified beads reached maximum at the pH value of 6.0 for Pb²⁺, Cd²⁺, Sr²⁺, Cu²⁺, Zn²⁺, Ni²⁺, Mn²⁺ and Li²⁺ with 99.5, 99.2, 98.8, 97.2, 95.6, 93.1, 92.4 and 74.5%, respectively, while the highest removal are achieved at pH = 5 for Fe³⁺ and Al³⁺ with 96.5 and 94.9%, respectively and decreased at lower or higher pH values. The survival count (%) of the E. coli cells were 34% on the SA beads, 11% on the PVA/SA, and 1% on the Zeo/PVA/SA NC modified beads, after 120 min exposure at 25 °C. Reusability experimental displays that the synthesized beads preserved a significant decrease in the sorption capacity after 10 repeating cycles. The Zeo/PVA/SA NC beads were able to eliminate 60–99.8% of Al³⁺, Fe³⁺, Cr³⁺, Co²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Ni²⁺, Cu²⁺, Li²⁺, Sr²⁺, Si²⁺, V²⁺, and Pb²⁺ ions from the natural wastewater samples collected from 10th Ramadan City, Cairo, Egypt.     

Friedel-Crafts Polymers. 6. Friedel-Crafts Polycondensation of p-Xylylerte Dibromide with Salicylic Acid and β-Resorcyiic Acid

Polymers were prepared by condensing p-xylylene dibromide separately with salicylic acid and β-resorcylic acid in the presence of anhydrous ferric chloride in dioxane. The polymer samples_were characterized by elemental analysis, by IR spectral study, by M determined by vapor pressure osmometry, by nonaqueous conducto-metric titration in pyridine, by TGA in air, and by viscosity measurements of polymer solutions in DMF. Polymeric metal chelates of Cu²⁺, Co²⁺, Zn²⁺, Ni²⁺, and Fe³⁺ with polymer samples were prepared and characterized by elemental analysis, by IR spectral study, and by TGA in air. The chelation ion-exchange properties of the polymer samples were studied by employing the batch equilibration method.     

Ferric hydrous oxide sols I. Monodispersed basic iron(III) sulfate particles

The methods of preparation of basic ferric sulfate sols consisting of particles uniform in shape of extremely narrow size distribution are described in detail. To produce such sols, acidic solutions containing ferric ions and sulfate ions were aged at elevated temperatures for a few hours. Solids formed from solutions containing a mixture of a ferric salt with a metal sulfate consisted of Fe₃(SO₄)₂(OH)₅· 2H₂O, which is the basic formulation for the alunite mineral group, whereas particles formed from ferric sulfate solutions also included Fe₄(SO₄)-(OH)₁₀ in varying proportions. The morphology of the particles was strongly dependent on the [Fe³⁺]: [SO₄²⁻] ratio in solution. Changes in the cation (K⁺, NH₄⁺, Na⁺) of the sulfate salt used in the mixture with ferric nitrate solutions greatly affected the particle size and also exhibited some effect on the lattice parameters. Certain cations (Mg²⁺, Ni²⁺, Cu²⁺) completely inhibited particle formation. During the first few hours of growth of the Fe₃(SO₄)₂-(OH)₅· 2H₂0 particles their diameters increased essentially linearly with time, indicating that the rate determining step was the surface reaction. The relevance of these systems to the study of corrosion of iron and steel is discussed.     

MgFe-Cl-LDHs的合成、结构及其插层组装性能研究

合成出了层间含Cl-的MgFe型层状双羟基氢氧化物（MgFe-Cl-LDHs），通过X射线衍射(XRD)、红外光谱(FT-IR)、热重及差热分析(TG-DTA)和元素分析等手段对其组成和结构特征进行了分析。研究表明：在共沉淀条件下，可制得晶体结构规整的MgFe-Cl-LDHs，且其结构规整性随组成中Mg²⁺/Fe³⁺物质的量比的增大而增强；LDHs层板六配位的金属离子与层板羟基层、层板羟基层与层间结构水的相互作用不随Mg²⁺/Fe³⁺物质的量比的改变而改变，而层板主体与层间客体阴离子之间的静电引力随Mg²⁺/Fe³⁺物质的量比的增大而降低。另外，其超分子结构特征使层间Cl^-能与有机阴离子CH₂CHC₆H₄SO₃^-和CH₃(CH₂)₁₁SO₃^-发生离子交换，形成以双分子层垂直于层板的交错有序的排布结构模式。     

A fluorescent sensor based on quinazoline ketone derivatives for selectivity of Fe3+

In this work, we provided a fluorescent sensor based on a compound containing fluorophore quinazoline ketone for detecting metal ions. 2-Methyl-4(3 H)-quinazoline thione was synthesised as a fluorescent probe for tervalent ferric ion (Fe³⁺) detection. Fluorescent determination of 2-methyl-4(3 H)-quinazoline thione indicated its maximum emission wavelength of 306.5 nm. The fluorescence interference and titration experiments have shown that the compound has a high selective fluorescence response to Fe³⁺. With an increase in the Fe³⁺ ion concentration, the fluorescence emission strength gradually weakened, and a slight red shift appeared. With Job’s method, 2-methyl-4(3 H)-quinazoline thione was proved to form a 1:2 complex with Fe³⁺. The results revealed that 2-methyl-4(3 H)-quinazoline thione could be used as a fluorescent probe for the recognition of Fe³⁺ with high selectivity.     

Combination of cellulosic materials and metallic ions

Cellulosic materials (DP, SCP) and PVA fibers were treated with four kinds of metallic ions (Ca²⁺, Fe²⁺, Fe³⁺, Ce⁴⁺), and the adsorption behavior was studied to elucidate the manner in which the celluloses and the metallic ions were combined. The effects of treatment temperature, time, and concentration upon the amount of the metallic ions adsorbed were examined. With Ca²⁺ and Fe²⁺, the effects of such factors on the adsorption were slight, while with Fe³⁺ and Ce⁴⁺ the effects of time, temperature, and ion concentration were pronounced. Also, it was evident that the amount (molar) of equilibrium adsorption of Ca²⁺ or Fe²⁺ was approximately the same as the content of carboxyl groups in the cellulose sample, and the amount of equilibrium adsorption of Fe³⁺ or Ce⁴⁺ was approximately the same as that of total carbonyl group content. When the samples which had adsorbed these metallic ions were treated with 0.1N hydrochloric acid, the Ca²⁺ and Fe²⁺ were completely desorbed while about 80% of the adsorbed Fe³⁺ and Ce⁴⁺ remained. These results indicate that there are two types of combinations of cellulosic materials and metallic ions involved: one is thought to be an ionic bond, while the other is considered to be a chelate bond.     

Ferric Chloride Complexes in Aqueous Solution: An EXAFS Study

A series of concentrated aqueous solutions of ferric chloride with different chloride:iron(III) ratios has been studied by means of EXAFS to determine the structure around the iron(III) ion of the dominating species in such solutions. The dominating species in dilute acidic aqueous solution of ferric chloride, at less than 1 mmol·dm^?3, are the hydrated iron(III) and chloride ions, while in concentrated aqueous solution and in solutions with an excess of chloride ions, up to 1.0 mol·dm^?3, it is the trans-[FeCl₂(H₂O)₄]⁺ complex. Possible higher chloroferrate(III) or dimeric [Fe₂Cl₆] complexes at room temperature, as proposed in the literature, were not observed in any of the studied solutions in spite of an excess of chloride ions of 1 mol·dm^?3.     

Photoinduced electron transfer reactions at methylene blue adsorbed nafion and clay coated electrodes

Nafion and montmorillonite clay adsorbed methylene blue coated onto platinum electrode were prepared. These dye modified electrodes were used as photoelectrodes in a photogalvanic cell in the presence of Fe²⁺ ions. The photoelectrochemical investigations showed that the dye coated electrodes behaved as cathode upon irradiation whereas the plain platinum electrode dipped in a homogeneous solution containing methylene blue and Fe²⁺ ions behaved as anode. It is suggested that the intermediate complex formed between the photoreduced methylene blue and ferric ion lead to the reductive reaction at the coated electrode.