Synthesis and characterization of polyaniline–titanium(IV)phosphate cation exchange composite: Methanol sensor and isothermal stability in terms of DC electrical conductivity

Electrically conductive composite of polyaniline–titanium(IV)phosphate (PANI–TiP) was synthesized by sol–gel method. The obtained composite was characterized by using Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The composite showed good ion-exchange capacity and isothermal stability in terms of DC electrical conductivity retention at an ambient conditions below 100 °C. The composite material was investigated as alcohol vapors sensor and compared with blank polyaniline. The results showed that the composite was more selective and sensitive towards methanol vapors.     

Solvent extraction kinetics of Sm(Ⅲ),Eu(Ⅲ) and Gd(Ⅲ) with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester

Solvent extraction kinetics of Sm(Ⅲ), Eu(Ⅲ) and Gd(Ⅲ) from hydrochloric acid have been focused on using2-ethylhexyl phosphoric acid-2-ethylhexyl ester(P507) with Anordning for Kontinuerlig Undersokning av Fordelningsfaktore vid Vatske Extraction(AKUFVE). Compared with the conventional set-up, some advantages emerge obviously, for example, fast phase separation, easy operation and convenience of kinetic data acquisition.First of all, the extraction mechanism was discussed based on the dimeric model of P507. Secondly, the effects of stirring speed were investigated and 420 r·min~(-1) was determined of the following experiments. The effects of pH, concentration of rare earth elements(REEs) and P507 on the extraction rate were analyzed. The results indicated that the extraction mechanism changed with the increasing concentration of P507. Then, the experiments with different temperature were carried out. It turned out that the values of apparent activation energy(E_a) for Sm(Ⅲ), Eu(Ⅲ) and Gd(Ⅲ) extracted by P507 were 26.80 kJ·mol~(-1), 13.40 kJ·mol~(-1) and11.10 kJ·mol~(-1) respectively, the resistance of the entire process was limited by diffusion or both of diffusion and reaction. Finally, the correlation equations were obtained, and the theoretical results fit with the experimental data well, most relative error was within ±30%.     

Facile preparation and unique H2 adsorption behavior of three-dimensional novel Pt–Ru hollow sphere assemblies

Three-dimensional long range ordered hollow Pt–Ru sphere assemblies were prepared using a sacrificial three-dimensionally ordered macroporous (3DOM) carbon template. Metallic salts, such as a mixture of RuCl₃ with H₂PtCl₆ were infiltrated into the carbon template, and a reduced Pt–Ru phase was produced on the surface of the 3DOM carbon template by a borohydride reduction reaction. The sacrificial template was then burnt off in air at 650 °C. The diameter of the hollow Pt–Ru spheres could be tailored using a different pore size 3DOM carbon template. Assemblies with an outer diameter of 550 nm showed high BET surface area of 584.3 m²/g. In addition, a high hydrogen adsorption stoichiometry (>0.5 H/M) was obtained on the Pt–Ru sphere assemblies, which indicated that most of the metal atoms on the surface were exposed.     

Synthesis and characterization of 4,4’–(dimethylsilylene) bis( phenyl chloroformate) and 4,4’–(dimethylgermylene)bis(phenyl chloroformate) and their use in the synthesis of poly(urethanes)

Summary The synthesis of 4,4–(dimethylsilylene)bis(phenyl chloroformate) and 4,4–(dimethylgermylene)bis(phenyl chloroformate) is described according to the same route for the synthesis of bisphenol–A bischloroformate. These compounds were characterized using elemental analysis, FT–IR and NMR spectroscopy. Poly(urethanes) derived from these bischlororformates containing silicon or germane in the main chain, were obtained in benzene solution by reaction with 4,4–methylenedianiline in the presence of pyridine. Poly(urethanes) were characterised by spectroscopic methods and the thermal properties (Tg and thermal stability) were compared with the homologue poly(urethane) obtained from bisphenol–A chloroformate.     

Solubility behavior and thermodynamic modeling of sodium monosulfoaluminate (“U-phase”) in cementitious systems

The “U-phase,” a sodium-containing (alumino-ferrite-monosubstituent) AFm phase, has been observed to form in sodium-enriched highly alkaline cementitious systems, for example, of relevance to nuclear waste, and saline industrial brine management. But, minimal information is available of the U-phase's (e.g., solubility or thermodynamic properties) due to its limited stability and its tendency to transform into ettringite or monosulfoaluminate. Herein, the U-phase was systematically synthesized at four temperatures (5, 15, 25, and 50°C) and fully characterized in terms of its thermochemical properties. The average composition of the synthesized U-phase (4CaO·Al₂O₃·1.85SO₃·0.85Na₂O·12H₂O) deviates slightly from typical disclosures in the literature. The solubility product of the U-phase formation was measured from conditions of oversaturation. The measured thermodynamic data accurately predicted experimental observations of U-phase formation in cementitious environments. In general, it was noted that the U-phase forms and persists (i.e., remains stable) at pH > 13.7 and [Na⁺] concentrations superior to 1 mol/L.     

Equilibrium adsorption studies on removal of diclofenac sodium from aqueous solution using sawdust–polyaniline (SD–PAn) composites

In this work, equilibrium adsorption studies were carried out for the removal of antiinflamatory drug diclofenac sodium (DS) from aqueous solutions using sawdust–polyaniline(SD-PAn) composite as a potential sorbent at 20, 30, and 40°C. The composite sorbent was characterized by FTIR and SEM analysis. The particles exhibited porous and rough surface. The equilibrium uptake data was interpreted by the Langmuir, the Freundlic, the Temkin, and the Dubinin–Redushkevich (D -R) isotherm models. The maximum adsorption capacity was found to decrease with increase in temperature, thus indicating exothermic nature of the adsorption process. The thermodynamic parameters were evaluated using Langmuir, Flory–Huggins, Frumkin, and modified-Frumkin models. The negative values of ΔG_ads⁰ and ΔH⁰ indicated spontaneous and exothermic nature of the adsorption process, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125:1382–1390, 2012     

Electrochemical and density functional theory study of bis(cyclopentadienyl) mono(β-diketonato) titanium(IV) cationic complexes

The electrochemical behaviour of fluorinated bis(cyclopentadienyl) mono(β-diketonato) titanium(IV) complexes, of general formula [Cp₂Ti(R′COCHCOR)]⁺ClO₄⁻ with Cp = cyclopentadienyl and R′, R = CF₃, C₄H₃S; CF₃, C₄H₃O; CF₃, Ph (C₆H₅); CF₃, CH₃; CH₃, CH₃; Ph, Ph and Ph, CH₃ is described. Both metal and ligand based redox processes are observed. The chemically and electrochemically reversible Ti^IV/Ti^III couple is followed by an irreversible ligand reduction at a considerably more negative (cathodic) potential. A comparison of the ligand reduction in its free and chelated state indicates that the β-diketonato ligand (R′COCHCOR)⁻ in [Cp₂Ti(R′COCHCOR)]⁺ClO₄⁻ is electroactive at more negative potentials. A theoretical density functional theory (DFT) study shows that a highly localized metal centred frontier orbital dominates the Ti^IV/Ti^III redox chemistry resulting in a non-linear relationship between the formal redox potential (E°′) and the sum of the group electronegativities of the R and R′ groups, χ_R + χ_R′, of the ligand. Linear relationships, however, are obtained between the DFT calculated electron affinity (EA) of the complexes and χ_R + χ_R′, the pK_a of the free β-diketones R′COCH₂COR and the carbonyl stretching frequency, v_CO, of the complexes. The DFT calculated electronic structure of the second reduced species [Cp₂Ti(β-diketonato)]⁻ shows that it is best described as Ti(III) coupled to a β-diketonato radical.     

Synthesis,characterization and As(III) adsorption behavior of β-cyclodextrin modified hydrous ferric oxide

This study investigates the adsorption of As(III) on β-cyclodextrin modified hydrous ferric oxide (HCC). This is characterized by XRD, FESEM, AFM, XPS, BET, surface site concentration and FTIR. The modification of hydrous ferric oxide (HFO) surface by β-cyclodextrin provides ample OH groups which in turn increase As(III) adsorption on HCC compared to HFO. The adsorption remains almost constant in pH range 3–8 which decreases at higher pH (>8) and followed monolayer and pseudo first order kinetics. It is spontaneous at 303 K with increasing entropy and decreasing enthalpy. Thus HCC is found to be more efficient adsorbent than HFO.     

Surface stabilities of 3C–SiC and H2O adsorption on the (110) surface

First-principles calculations and thermodynamics analyses were combined to study the surface stabilities of 3C–SiC and H₂O adsorption on the (110) surface. The stoichiometric (110) surface was predicted to be generally the most stable. Only at the extremely C-poor condition, the nonstoichiometric Si-terminated (100) could become more energetically favored. The adsorption and dissociation of single H₂O molecule on the 3C–SiC (110) were then comparatively investigated. Calculations show that H₂O molecules prefer to partially dissociate into one hydroxyl OH and one H adsorbed at the top-most Si and C sites, respectively, leading to the formation of a hydrogen network on the surface. The calculated equilibrium adsorption diagram further suggested that the 3C–SiC (110) surface can be only either completely clean or fully covered by the partially dissociated species of H₂O, for a wide range of temperature and the partial potential of H₂O.     

Synthesis and Characterization of Some Poly(1,2-Phenylenedithiocarbamate)–Metal Complexes

Poly(1,2-phenylenedithiocarbamate) (PPDTC) was prepared by the reaction of 2-aminothiophenol with carbon disulfide followed by condensation through the removal of H₂S gas. PPDTC was used as a ligand to prepare four poly(1,2-phenylenedithiocarbamate)–metal complexes of iron(II), cobalt(II), copper(II), and lead(II), by refluxing with the metal salts. The polymer and its metal complexes were investigated by elemental analyses, UV–visible and IR spectroscopy, inherent viscosity, and magnetic susceptibility. The DC electrical conductivity variation with the temperature in the range 298–498 K of PPDTC and its polymeric copper complex was measured. Both polymer and polymer metal complexes showed an increase in electrical conductivity with an increase in temperature: typical semiconductor behavior. The proposed structure of the complexes is (MLX₂·mH₂O) _n .     

Multilayered polypyrrole–SiO2 composite coatings for functionalization of stainless steel: Characterization and corrosion protection behavior

Two different multilayered composite polypyrrole/SiO₂ coatings were synthesized on 304 stainless steel. Electrochemical and electrophoretic depositions were used to grow polypyrrole and SiO₂ layers, respectively. Coatings were characterized by glow discharge optical emission spectroscopy to observe repartition of elements within different layers, by scanning electron microscopy to observe surface morphology and by electrochemistry to investigate corrosion protection behavior. The electrophoretic approach enables good incorporation of SiO₂ particles. This incorporation was more extensive and more homogeneous than for coatings obtained with the mixing method related in previous works. Moreover, incorporation and repartition of SiO₂ particles are greatly enhanced when the silica layer is grown directly on the steel surface. Corrosion protection of the stainless steel substrate was improved when multilayered composite polypyrrole/SiO₂ coatings were used.     

Synthesis and Characterization of 6,6ˊ-bis(1-(2-ethylhexyl)-1H-1,2,3-triazol-4-yl)-2,2ˊ-bipyridine (EH–BTzBP) for Actinide/Lanthanide Extraction and Separation

A new N-donor extractant, 6,6ˊ-bis(1-(2-ethylhexyl)-1H-1,2,3-triazol-4-yl)-2,2ˊ-bipyridine (EH-BTzBP), was synthesized and tested for Am(III)/Ln(III) extraction and separation. EH-BTzBP in combination with 2-bromohexanoic acid (as lipophilic anion source) selectively extracts Am(III) from acidic solutions (HNO₃ ≤ 0.1M) with Am(III)/Eu(III) separation factors of about 70. Phase transfer kinetics is rapid, back-extraction of metal ions posed no issues, and there is no evidence of ligand degradation by acid hydrolysis or contact with hydrogen peroxide (which simulates some effects of radiolysis).     

The thermal and microstructural behavior of a R2O–RO–(ZnO)–Al2O3–(TiO2)–SiO2 based macro-crystalline raw glaze system

Macro-crystalline glazes containing significantly large crystals visible to the naked eye are a type of artistic glaze with a decorative and esthetic performance. The use of raw glaze compositions is a cost effective alternative for these types of crystal glazes. In the present study, R₂O–RO–(ZnO)–Al₂O₃–(TiO₂)–SiO₂-based raw glaze system was studied to produce macro-crystalline glazes for Limoges porcelain bodies. The influence of the addition of TiO₂ as a nucleating agent or major phase was evaluated in zinc-based glazes as well as ZnO-free ones. Designed glaze compositions were fired according to a special heat treatment cycle and characterized in terms of thermal and microstructural behavior using a digital microscope, differential thermal analyses, hot stage microscopy, X-ray diffraction, a scanning electron microscope, and energy-dispersive X-ray spectroscopy.     

Preparation of polyacrylamide–montmorillonite nanocomposite and its application in Cr(III) adsorption

The polyacrylamide–montmorillonite “water in water” (PAM-MMT W/W) emulsion was prepared by dispersion polymerization method in the presence of organo-montmorillonite (OMMT). Based on the analysis of the polymerization process, the structure of material was investigated using thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy experiments. Here, the dispersion was determined to be a blend of PAM W/W emulsion and PAM network interspersed by MMT particles, this unique structure of the material was considered to provide better adsorption ability compared to PAM without MMT. Therefore, a PAM-MMT adsorbent was made from the PAM-MMT W/W emulsion, and its adsorption capacity toward Cr(III), one of the heavy metal pollutants from the tannery waste was investigated. The PAM-MMT nanocomposite was demonstrated to have good Cr(III) removal performance, the maximum adsorption capacity of the nanocomposite was found to be 59.74 mg/g at a pH of 5.5 and temperature of 70°C. Results show that pseudo-second-order kinetic model and Langmuir isotherm were applicable for Cr(III) adsorption.     

Characterization of Ce(1−x)ZrxO2 yellow nanopigments synthesized by a green sol-gel method

In this paper, we report on the synthesis of Ce_(1−x)Zr_xO₂ yellow nanopigments (NPs) by a simple green sol-gel method, using gelatin as the stabilization and polymerization agent. Thermogravimetric analysis (TGA) was employed to obtain the optimum gel calcination temperature. The synthesized Ce_(1−x)Zr_xO₂ powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV–vis spectroscopy and CIE-L^*a^*b^* measurement. The XRD patterns of the samples calcined at 600 °C revealed the formation of the desired crystal structures without any secondary phases, confirmed by Raman analysis. The TEM images indicated that the pigments' particle shapes are almost spherical with average particle size of about 8 nm. It was found that by increasing Zr⁺⁴ concentrations the absorption edge of the produced NPs have a red-shift. The produced NPs had brilliant yellow colour, derived from CIE-L^*a^*b^* coordinates.     

Thermal behavior and structural study of ZrO2/poly(ε-caprolactone) hybrids synthesized via sol-gel route

The thermal behavior of pure ZrO₂ and four ZrO₂-based organic-inorganic hybrids (OIHs) containing increasing amount (6, 12, 24 and 50?wt%) of poly(ε-caprolactone) (PCL) (named Z, ZP6, ZP12, ZP24 and ZP50 respectively) has been studied by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC). The FTIR analysis of the gas mixture evolved at defined temperatures from the samples submitted to the TG experiments identified the mechanism of each thermally activated process. The obtained results suggest that the inorganic matrix of the OIHs prepared by this method exerts a stabilizing effect on the polymer, in particular for poor-PCL hybrid materials. In fact, the different thermal behavior of the ZP50 sample suggests that the polymer is not entirely bonded to the -OH groups of the zirconia matrix due to their saturation. For this reason a part of PCL is not affected by the stabilizing effect of the matrix and is subjected to thermal degradation. Finally, by observing their thermal behavior it was possible to select the most suitable temperatures for thermal pretreatment: 400, 600 and 1000?°C. The structural analysis by X-ray diffraction (XRD) revealed that at 400?°C the materials are amorphous, while at 600?°C they are mostly tetragonal, and the content of the tetragonal phase decreases with increasing the amount of PCL in the OIHs. All the materials treated at 1000?°C are monoclinic, but their crystallinity decreases with increasing the PCL content.     

Reactive sintering behavior and enhanced densification of (Ti,Zr)B2–(Zr,Ti)C composites

Reactive hot pressing was used to prepare (Ti,Zr)B₂–(Zr,Ti)C composites from equimolar ZrB₂ and TiC powders. The reaction and solid-solution coupling effect and enhanced densification in ZrB₂-50 mol.% TiC were proposed as contrasted to conventional consolidation of TiB₂-50 mol.% ZrC. The (Ti,Zr)B₂–(Zr,Ti)C composite sintered at a temperature as low as 1750 °C exhibited negligible porosity and average grain sizes of 0.30 μm for (Ti,Zr)B₂ and 0.36 μm for (Zr,Ti)C. Complete reaction and rapid densification of ZrB₂-50 mol.% TiC was achieved at 1800 °C for only 10 min. The densification mechanism was mainly attributed to material transport through lattice diffusion of Ti and Zr atoms with an activation energy of 531 ± 16 kJ/mol. This study revealed for the first time novel insights into rapid densification of refractory fine-grained diboride–carbide composites by reactive hot pressing at relatively low temperatures.     

Synthesis and Structural Characterization of Triorganotin(IV) Derivatives with 2,2′-Thiodiglycolic Acid and 3,3′-Thiodipropionic Acid

The synthesis and structural characterization of four novel triorganotin(IV) complexes, {(R₃Sn)₂[C₂H₄S(COO)₂]} _n (R = Me: 1), {(R₃Sn)₄[C₂H₄S(COO)₂]₂} _n (R = nBu: 2), {(R₃Sn)₂[C₄H₈S(COO)₂]} _n (R = Me: 3; nBu: 4) were obtained by the reaction of 2,2′-thiodiglycolic acid, 3,3′-thiodipropionic acid and the corresponding R₃SnCl (R = Me, nBu) with potassium hydroxide in methanol. All the complexes were characterized by elemental analysis, Fourier transform infrared and nuclear magnetic resonance (¹H, ¹³C, ¹¹⁹Sn) spectroscopies, X-ray crystallography and thermogravimetric analyses. The crystal structures show that 1 has 2D network structure in which 2,2′-thiodiglycolic acid acts as a tetradentate ligand coordinating to the trimethyltin(IV) ions. Complexes 2, 3, and 4 are 3D metal-organic framework structures in which the deprotoned acids act as a tetradentate ligand afforded by four oxygen atoms.