Synthesis and characterization of phosphotungstic acid/activated carbon as a novel ultrasound oxidative desulfurization catalyst

Phosphotungstic acid/activated carbon (PTA/AC) catalysts with various AC sizes or PTA content have been synthesized and characterized by N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy and temperature programmed desorption of ammonia. These catalysts were then evaluated in terms of the removal of dibenzothiophene (DBT) by ultrasound-assisted oxidative desulfurization process. The results showed that the DBT conversion obviously increased with the decrease of AC support size and the increase of PTA content. After supporting PTA on AC, the DBT conversion can be improved by 38.9% after ultrasound irradiation for 10 min. In addition, the stability tests of PTA/AC showed that the catalytic oxidative activity of PTA/AC was nearly kept constant after ultrasound irradiation for 20 min, which makes it a promising catalyst to use in ultrasound-assisted oxidative desulfurization process.     

Synthesis of highly dispersed phosphotungstic acid encapsulated in MIL-100(Fe) catalyst and its performance in heterogeneous oxidative desulfurization

Highly efficient HPW(x)/MIL-100(Fe) catalysts with different phosphotungstic acid (HPW) loading (x, wt%) were successfully synthesized by a one-step hydrothermal method and characterized by XRD, SEM, FTIR, and BET. The influences of HPW loading, catalyst dosage, temperature, and O/S molar ratio on oxidative desulfurization (ODS) were investigated. The results indicated that the HPW(x)/MIL-100(Fe) retained the structure of its parent MIL-100(Fe). The MIL-100(Fe) presented a high surface area, which is beneficial to dispersion of HPW. The HPW(x)/MIL-100(Fe) with HPW loading of 40% exhibited excellent ODS activity. At a temperature of 50?°C, a catalyst dosage of 0.06?g, and an O/S molar ratio of 4, 100% desulfurization was achieved within 90?min for benzothiophene, dibenzothiophene, and 4,6-dimethyl-dibenzothiophene. The high catalytic activity of HPW(x)/MIL-100(Fe) can be attributed to highly dispersed HPW active sites with a high specific surface area.     

Synthesis of a hypercrosslinked,ionic, mesoporous polymer monolith and its application in deep oxidative desulfurization

In this study, we used a facile and scalable strategy to produce a hypercrosslinked, ionic, mesoporous polymer monolith (HCIMPM). On the basis of structure‐directing polymeric crosslinking, the interconnected nanonetwork was formed through the in situ crosslinking of the homopolymer poly(vinyl imidazole) via a quaternization reaction, and its textural properties could be effectively adjusted by the block copolymer poly(ethylene oxide)‐block‐poly(propylene oxide)‐block‐poly(ethylene oxide)(PEO₂₀PPO₇₀PEO₂₀). The maximum specific surface area and pore volume were 212 m²/g and 1.08 cm³/g, respectively. Furthermore, the synthetic framework could be functionalized via the loading of PW₁₂ through ion exchange. The obtained HCIMPM with PW₁₂O₄₀^3? (PW‐HCIMPM) was applied in the oxidative desulfurization, and approximately 100% sulfur removal could be achieved in the model oil with hydrogen peroxide (30 wt %) as an oxidant. Moreover, the solid catalyst could be recovered readily and recycled at least six times without a significant decrease in the desulfurization efficiency. As for real diesel, we also observed that almost all of the original sulfur compounds could be converted in 120 min. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46280.     

非晶态TiO2-SiO2复合氧化物合成及其汽油氧化脱硫性能

采用沉淀法制备不同TiO₂含量的TiO₂-SiO₂复合氧化物,并用XRD、FT-IR、UV-VIS及TEM对样品进行表征,结果表明,TiO₂-SiO₂复合氧化物为非晶态结构。以过氧化氢-乙酸作为氧化体系,TiO₂-SiO₂复合氧化物为催化剂,考察TiO₂含量、反应温度、反应时间、过氧化氢用量和催化剂用量对汽油催化氧化脱硫效果的影响。结果表明,TiO₂质量分数为40%的TiO₂-SiO₂复合氧化物催化汽油氧化脱硫效果最好,在汽油用量10 g、冰醋酸用量0.5 mL、30%过氧化氢用量0.6 mL、催化剂用量为汽油质量的4%、反应时间60 min和反应温度40 ℃最佳条件下,汽油脱硫率为78%。     

Synthesis,characterization, and application of a new chelating resin functionalized with dithiooxamide

Chloromethylated polystyrene‐divinylbenzene has been functionalized with dithiooxamide. The resulting chelating resin (DTOA) has been characterized by elemental analyses, infrared spectroscopy, thermogravimetric analysis, and metal ion sorption capacities. It has been used for the preconcentration and separation of Cu(II), Zn(II), Cd(II), and Pb(II) prior to their determination by FAAS. Parameters such as the amount of the resin, effect of pH, equilibration rate, sorption and desorption of metal ions, and effect of diverse ions have been studied. The maximum sorption capacities found are 0.97, 0.12, 0.08, and 0.12 mmol g^?1 for Cu(II), Zn(II), Cd(II), and Pb(II) at pH 6.0, 5.5, 1.0, and 5.5, respectively. The preconcentration factors are 100, 100, 50, and 50 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. Recoveries of the metal ions were 96 ± 5, 97 ± 6, 96 ± 5, and 96 ± 5 at 95% confidence level, whereas the limits of detection are 2.0, 1.3, 2.5, and 25.0 μg L^?1 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The calibration curves were linear up to 12 μg mL^?1 (R² = 1.000), 2 μg mL^?1 (R² = 0.998), 2 μg ml^?1 (R² = 1.000), and 5 μg mL^?1 (R² = 0.979) for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The reliability of the method has been tested by analyzing certified samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2281–2285, 2007     

Electropolymerization of a poly(3,4-ethylenedioxythiophene) and functionalized, multi-walled, carbon nanotubes counter electrode for dye-sensitized solar cells and characterization of its performance

Composite films of poly(3,4-ethylenedioxythiophene) and functionalized, multi-walled, carbon nanotubes (PEDOT–MWCNT) were fabricated by a simple oxidative electropolymerization method. These films were formed on fluorine-doped, tin oxide, glass substrates as counter electrodes (CEs) of platinum-free, dye-sensitized solar cells (DSSCs). The surface morphology, formation mechanism and electrochemical nature of PEDOT–MWCNT films were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and alternating current (AC) impedance spectroscopy. The SEM and AFM images showed that PEDOT–MWCNT films were more porous than PEDOT films. CV and AC impedance spectroscopy revealed that the PEDOT–MWCNT electrode had higher electrocatalytic activity for the I₃⁻/I⁻ redox reaction and a smaller charge transfer resistance than the PEDOT electrodes. The energy conversion efficiency of the DSSC with a PEDOT–MWCNT CE was 13.0% higher than with a PEDOT CE using the same conditions with a ruthenium sensitizer.     

Synthesis, characterization and electrochromic properties of a conducting copolymer of pyrrole functionalized polystyrene with pyrrole

A well-defined polystyrene (PSt) based polymer containing at one end-chain 3,5-dibromobenzene moiety, prepared by atom transfer radical polymerization (ATRP), was modified in two reaction steps. First one constitutes a Suzuki coupling reaction between aromatic dibromine functional polymer and 3-aminophenylboronic acid, when a diamino-containing intermediate was obtained. The second step is a condensation reaction between the diamino functional polystyrene and 2-pyrrole aldehyde. Thus, a polymer containing a conjugated sequence having pyrollyl groups at the extremities was synthesized. The presence of oxidable pyrrole groups in the structure of the polymer permitted further electropolymerization. The structures of intermediate polymers were analyzed by spectral methods (¹H NMR, FTIR). Electrochemical copolymerization of pyrrole functionalized polymer (PStPy) with pyrrole was carried out in acetonitrile (ACN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couple. Characterization of the resulting copolymer were performed via Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), spectroelectrochemical analysis, and kinetic study. Spectroelectrochemical analysis show that the copolymer of PStPy with Py has an electronic band gap (due to π-π* transition) of 2.4 eV at 393 nm, with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Via kinetic studies, the optical contrast %ΔT was found to be 20% for P(PStPy-co-Py). Results showed that the time required to reach 95% of the ultimate T was 1.7 s for the P(PStPy-co-Py).     

Synthesis,characterization, and cure of allyl and propargyl functionalized indene as a thermoset composite matrix resin

Two highly functionalized resins were synthesized by the phase transfer reaction of indene with propargyl bromide or allyl chloride in the presence of strong base. The resins consisted of a mixture of tri- and tetrafunctional indenes with 60–80% of the product being tetrafunctional. The allylated (AL) and propargylated (PL) indene resins were thermally cured without added catalysts. Both resins exhibited a broad, highly exothermic cure with a peak energy at 320°C for AL resin and 282°C for PL resin. Thermal degradation of cured AL resin was found to begin at approximately 400°C with a carbon yield of 20% of its initial weight at 1000°C. Carbon yields for cured PL resin were excellent, with 68% retention of weight at 1000°C. Unidirectional, carbon fiber composites were fabricated from the substituted indene resins. AL–carbon fiber composites gave modulus values of 126 GPa and strength values of 967 MPa, while PL–carbon fiber composites gave modulus values of 116 GPa and strength values of 935 MPa in three-point bending tests. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 475–482, 1998     

Synthesis,processing and characterization of a bioactive glass composition for bone regeneration

This paper reports on the experimental evaluation of a novel melt-quenched glass belonging to the CaO–MgO–SiO₂–P₂O₅–Na₂O–CaF₂ system as potential material for biomedical applications in bone regeneration. The glass composition has been designed in the primary crystallisation field of pseudo-wollastonite in CaO–MgO–SiO₂ ternary phase diagram. The rise of pH upon immersion in SBF solution was slower for the novel glass in comparison to 45S5 Bioglass^®. Nevertheless, both glasses exhibited similar behaviour in early formation of crystalline apatite demonstrating their osteoinductive features. The in vivo investigations in rabbits demonstrated good compatibility between the glass and surrounding tissue along the whole implantation period with negligible adverse reactions. The clinical evaluation of glass has been conducted in accordance with the ethical guidelines and regulations.     

Colloidal Co nanoparticles supported on SiO2: Synthesis, characterization and catalytic properties for steam reforming of ethanol

Colloidal Co nanoparticles with sizes in the 3–8 nm range were obtained by thermal decomposition of Co₂(CO)₈ in the presence of ligands and impregnated on SiO₂ to prepare SiO₂-supported Co nanocatalysts. The catalysts showed activity for the steam reforming of ethanol with higher values for smaller Co particles. H₂ adsorption results and Fourier transform infrared spectroscopy of adsorbed CO suggested that the fraction of accessible Co sites also depended on the synthesis conditions. Precipitation of the Co nanoparticles with methanol instead of ethanol before impregnation had a positive effect on the density of accessible Co sites to catalysis; similar result was verified by increasing the thermal treatment temperature under H₂ flow before the reaction. Based on the distribution of products with temperature of reaction, a mechanism for steam reforming of ethanol on SiO₂-supported Co nanocatalysts is suggested.     

Synthesis,characterization, and performance evaluation of PES/EDA‐functionalized TiO2 mixed matrix membranes for CO2/CH4 separation

Poor adhesion between hydrophobic polymers and hydrophilic inorganic fillers is a challenge that encumbers a high separation performance of mixed matrix membrane (MMM). In this study, Titanium(IV) oxide (TiO₂) nanoparticles were functionalized using ethylenediamine (EDA) before embedment in poly(ether sulfone) (PES) polymer matrix. MMMs were synthesized through dry phase inversion technique. Membranes morphology and nanoparticles dispersion was drastically enhanced posterior amine modification indicating an improved adhesion between the polymer and filler particles. Membranes thermal stability was likewise improved as higher degradation temperatures were perceived for PES/EDA–TiO₂ MMMs. Gas separation evaluation for pure carbon dioxide (CO₂) and methane (CH₄) gases revealed a remarkably enhanced separation performance upon amine‐grafting of TiO₂ as EDA‐TiO₂ MMMs exhibited a higher separation performance as compared to MMMs with pristine TiO₂. The highest ideal separation factor achieved was 41.52 with CO₂ permeability of 10.11 Barrer at an optimum loading of 5% wt of EDA‐TiO₂ which is threefold higher as compared to neat PES membrane and approximately twofold higher than MMMs with pristine TiO₂, respectively, at the same filler loading. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45346.     

Synthesis,characterization, and performance assessment of a perovskite-type nano photocatalyst for degradation of thiamethoxam

It is essential to remove thiamethoxam (THMX) from surface water as it negatively impacts the ecology and neurological systems of insects. Hence, a study was conducted to degrade THMX with different compositions of LaFeO₃/g-C₃N₄ (LFCN) composites. Several methods, including X-ray powder diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), and field emission scanning electron microscopy (FESEM), were applied to characterize the synthesized photocatalyst. The influence of many parameters on degradation, for example, THMX concentration, dosage of catalyst, and pH were studied experimentally. The degradation was highest under both UV-C and sunlight for the synthesized catalyst, 1% LaFeO₃/g-C₃N₄ (LFCN1), in comparison to graphitic carbon nitride (g-CN), and bare lanthanum ferrite (LF). The degradation was around 95% for LFCN1 under UV-C light having an intensity of 15 W/m² whereas degradation was 71.8% with LFCN1 photocatalyst under sunlight at neutral pH in 120 min of reaction time. The increased activity of LFCN1 was attributable to an improved surface area and a lower band gap. The study of reaction kinetics indicated second-order behaviour. Additionally, a probable mechanism for degradation was put forth.     

Synthesis,characterization, and swelling behavior evaluation of hydrogels based on Gum ghatti and acrylamide for selective absorption of saline from different petroleum fraction–saline emulsions

In this research article, the synthesis of Gum ghatti and acrylamide based superabsorbents under pressure with N,N′‐methylene bisacrylamide as a crosslinker and an ascorbic acid–potassium persulfate redox pair as an initiator is reported. To study the impact of the different reaction variables on the water absorbance of the candidate polymer, different reaction parameters, including the reaction time, amount of solvent, pH of the medium, initiator ratio, pressure, and monomer and crosslinker concentrations, were optimized. The candidate polymer was characterized with different techniques, including Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, differential thermogravimetry, and X‐ray diffraction. The crosslinked product was found to be thermally more stable than the initial backbone. The swelling capacity of the synthesized polymer was investigated in deionized water as a function of time, temperature, and pH of the swelling medium. Moreover, the effects of the ionic strengths of different cations on the swelling capacity of the candidate polymer were studied with different salt solutions. The tendency of absorbency for these hydrogels in salt solutions was found to be in the following order: Na⁺ > Ba²⁺ > Fe³⁺ > Sn⁴⁺ for NaCl, BaCl₂, FeCl₃, and SnCl₄ salt solutions. Further, the candidate polymer was used for the selective absorption of saline water from different petroleum fraction–saline emulsions. The results showed that the saline absorption capacities of the hydrogels were 667, 610, 646, and 680% in kerosene–saline, diesel–saline, petrol–saline, and petroleum ether–saline emulsions, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of a surface imprinting silica gel polymer functionalized with phosphonic acid groups for selective adsorption of Fe(III) from aqueous solution

A Fe(III) ion‐imprinted silica gel polymer functionalized with phosphonic acid groups (IIP‐PA/SiO₂) was prepared with surface imprinting technique by using Fe(III) ion as template ion, grafted silica gel as support, and vinylphosphonic acid as functional monomer. The polymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller, and thermogravimetric analysis. The synthesized imprinted silica gel polymer was used as a sorbent for Fe(III) adsorption. The adsorption properties, such as the effect of solution pH, adsorption kinetic, adsorption isotherm, adsorption selectivity as well as the regeneration of sorbent were studied. The results showd that the prepared sorbent (IIP‐PA/SiO₂) had a short adsorption equilibrium time (12 min) and high adsorption capacity (29.92 mg g^?1) for Fe(III) at the optimal pH of 2.0. The selectivity coefficients of the sorbent for Fe(III) in presence of Cr(III), M_n (II), and Zn(II) were 51.76, 27.86, and 207. 76, respectively. Moreover, the adsorption capacity of the prepared sorbent did not decrease significantly after six repeated use. Thus, the prepared ion‐imprinted silica gel polymer was a promising candidate sorbent for the selective adsorption of Fe(III) from aqueous solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45165.     

Synthesis and characterization of a long, rigid photoswitchable cross-linker for promoting peptide and protein conformational change

Azobenzene-based photoswitchable compounds can be use to photocontrol a variety of biochemical systems. In some cases, their effectiveness may be limited by the size of the conformational change that the switch undergoes. To produce an azobenzene photoswitch that undergoes a large end-to-end distance change upon isomerization, we synthesized 3,3'-diazene-1,2-diylbis{6-[2-sulfonato-4-(chloroacetylamino)phenylethynyl]benzene sulfonic acid} (DDPBA). This long, rigid, water-soluble, thiol-reactive cross-linker undergoes an end-to-end distance change of approximately 13 A upon isomerization. DDPBA was successfully cross-linked to peptides through cysteine side chains. The photoswitch undergoes trans-to-cis photoisomerization maximally when irradiated at 400 nm, although the efficiency of production of the cis isomer is lower than for simpler azobenzenes. Under steady-state illumination conditions, the percentage of cis form produced increases as temperature increases; approximately 56 % cis is obtained at 60 degrees C. Thermal relaxation occurs with a half-life of approximately 75 min at room temperature. When DDPBA was attached to an alpha-helical peptide with two cysteine residues at i and i+14 positions, an increase in helix content was observed after photoirradiation. When cross-linked to another peptide with two cysteine residues spaced at i and i+21 positions, a decrease in helix content after trans-to-cis isomerization was observed. Due to the small percentage of cis form produced under the experimental conditions, the CD signal changes were small. However, the large structural change upon photoisomerization provided by this cross-linker can potentially be used to photoswitch other biochemical systems.     

新型介孔有机硅高沸物裂解催化剂的合成、表征及活性

以十二胺（C₁₂）为模板剂, 3-氨丙基三乙氧基硅烷（APTES）与正硅酸四乙酯（TEOS）为原料,在中性条件下,利用共缩聚法合成了含胺MCM型介孔催化剂。采用X射线粉末衍射（XRD）、N₂吸附-脱附、红外（IR）及热重分析（TGA）等手段对催化剂进行表征,结果表明,氨丙基已引入介孔MCM,但过量氨丙基引入会破坏催化剂介孔结构,导致催化剂比表面积和比孔容降低。考察了氨丙基含量和催化剂用量对裂解反应的影响,最佳条件下,单体产率和高沸物转化率分别为63.3%和76.6%。     

Synthesis and characterization of maleated glycidyl 3‐pentadecenyl phenyl ether as a functionalized plasticizer for styrene–butadiene rubber/carbon black/silica composites

Maleated glycidyl 3‐pentadecenyl phenyl ether (M‐GPPE) was synthesized from glycidyl 3‐pentadecenyl phenyl ether (GPPE), a renewable derivative from cardanol, with maleic anhydride (MAH) by grafting copolymerization. The resulting M‐GPPE was used as a functionalized plasticizer for a styrene–butadiene rubber (SBR)/carbon black (CB)/silica composite. The effects of M‐GPPE on the development of the filler network, the extent of silica dispersion, the curing characteristics, and the mechanical performance of the composites were studied. Meanwhile, a comparative study was performed between M‐GPPE and aromatic oil, a traditional plasticizer used in SBR filler formulations. Gel permeation chromatography and IR and ¹H‐NMR analysis results confirmed the occurrence of the grafting reaction between GPPE and MAH and the potential structure of M‐GPPE. The thermostability of GPPE was improved by grafting copolymerization with MAH, as shown by thermogravimetric analysis results. The presence of M‐GPPE resulted in a shorter curing time and better aging properties in the SBR composite compared with GPPE. The mechanical properties, dynamic mechanical analysis, and transmission electron microscopy analysis showed that the maleate of GPPE could enhance the compatibility between SBR and silica, improve the dispersion of silica in SBR, and partially replace the aromatic oil in the SBR/CB/silica composite formulation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40462.     

Synthesis,characterization and ceramization of a novel vinyl-rich liquid precursor for Si(O)C ceramic

Polymethylsilane (PMS) was partially modified with 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane ([CH₃(CH₂åCH)SiO]₄, D4Vi) via conventional hydrosilylation. The as-synthesized vinyl-rich liquid precursor (V-PMS) was characterized by the viscosity test, gel-permeation chromatography, Fourier-transform infrared spectroscopy, nuclear magnetic resonances spectroscopy. The results indicate that the obtained precursor is well soluble in common solvents and exhibits a controllable viscosity of 326.9–714.6 mPa s at room temperature. The thermal properties of V-PMS were investigated by differential scanning calorimetry and thermogravimetric analysis. The V-PMS can be cured readily at 150 °C in inert atomosphere. The ceramic yield of V-PMS reaches 81% at 1200 °C, 38% higher than that of PMS. The final pyrolytic residue is hard, dense monolithic up to 1400 °C under Ar atmospheres. The controllable viscosity, excellent thermal curability and high ceramic yield enable the liquid precursor a promising material to shape various Si(O)C ceramic materials for high-temperature application.     

Synthesis,characterization and electrochemical evaluation of anticorrosion property of a tetrapolymer for carbon steel in strong acid media

A novel tetrapolymer(TP) consisting of carboxylate, sulphonate, phosphonate and sulfur dioxide based comonomers was synthesized using Butler cyclopoymerization technique. The synthesized tetrapolymer was characterized using FTIR,1 H-NMR,~(13)CNMR and elemental analysis. The performance of the tetrapolymer as a corrosion inhibitor for St37 carbon steel in 15% HCl and 15% H_2SO_4 acid media was assessed using electrochemical impedance spectroscopy(EIS), linear polarization resistance(LPR), potentiodynamic polarization(PDP) and electrochemical frequency modulation(EFM) techniques. The influence of addition of a small amount of KI on the corrosion inhibition efficiency of TP was also assessed. Results obtained showed that the tetrapolymer moderately inhibited the corrosion of St37 steel in the acid media with protection efficiency of 79.5% and 61.1% at the optimum concentration of 1000 mg·L~(-1) studied in HCl and H_2SO_4 media respectively. On addition of 5 mmol·L~(-1) KI to the optimum tetrapolymer concentration, the protection efficiency was upgraded to 90.6% and 93.5% in HCl and H_2SO_4 environment, respectively. The enhanced performance of the polymer in the presence of KI is due to synergistic action deduced from synergism parameter(S1) which was found to be greater than unity.The tetrapolymer afforded the corrosion inhibition of St37 steel in the acid media by virtue of adsorption of the polymer molecules on the steel surface which was confirmed by ATR-FTIR analysis of the adsorbed film extracted from the steel surface. TP + KI formed complex with St37 steel surface in H_2SO_4 solution but not in HCl solution.