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In this work, a series of thermophysical properties (apparent specific volume, excess molar volume, excess Gibbs energy of activation for viscous flow, coefficient of thermal expansion, excess coefficient of thermal expansion) of poly (ethylene glycol) 600 (PEG600) + methanol, ethanol, 1-propanol, and 2-propanol binary liquid mixtures were determined based on density and viscosity experimental measures at 293.15 K, 298.15 K, and 303.15 K and refractive indices at 298.15 K. After that, the obtained excess parameters were used to analyze the inter-intra molecular interactions in the liquid mixtures. In order to estimate the interaction parameters, the excess molar volume results were fitted to Redlich–Kister polynomial. Moreover, a set of semi-empirical relations were proposed to predict the viscosity of liquid mixtures.

In this study, we synthesized a biodegradable nanocomposite containing starch, polyvinyl alcohol (PVA), and graphene oxide (GO). The non-isothermal degradation kinetics of this nanocomposite was investigated by thermogravimetric analysis. Accordingly, the kinetic parameters, such as activation energy (Ea), exponential factor (A), rate constant (k), and degradation time, were calculated. The calculated kinetic parameters are used to predict the lifetime. The master plot analysis showed that the kinetic function of the thermal degradation changed from A2 to A3 upon addition of GO to the PVA/starch blend. The reaction heat (ΔH), glass transition temperature (Tg), and melting point (Tm) of the PVA/starch film and PVA/starch/GO nanocomposite were determined by the differential scanning calorimetry analysis. Also, the Tg values were determined by dynamic mechanical thermal analyzer. The changes in peak bandwidth, strength, and frequency in the samples are identified by FTIR spectra. The structure and morphology of the nanocomposite were studied by X-ray diffraction analysis and field emission scanning electronic microscope.

In this paper, experimental measurements of densities and viscosities of Ethanol + Diethylenetriamine (DETA) or Aminoethylethanolamine (AEEA) binary liquid mixtures are reported at temperatures of 298.15, 303.15 and 308.15 K and atmospheric pressure over the whole composition range. From the experimental data, excess molar volume, excess coefficient of thermal expansion, excess partial molar volume, isothermal coefficient of excess molar enthalpy, excess Gibbs free energy of activation and excess viscosity were calculated. The sign and magnitude of excess quantities were used to discuss about the nature and strength of molecular interactions in these solutions. The obtained excess molar volumes were correlated with Redlich-Kister polynomial equation. Moreover, the measured values of densities were predicted with Peng-Robinson and PC-SAFT equation of states and the experimental values of viscosities were correlated and predicted by different semi-empirical equations.

New liquid–liquid equilibrium data for polyethylene glycol (PEG) 3000 + CHO 2 K + H 2 O systems were measured at 298.15 K and pH values of 7.95, 8.40 and 9.98. It was found that an increase in pH caused the binodal curve to be displaced downward and the two-phase region to expand. Accordingly, the binodal curve was adjusted to the Pirdashti equation and the tie-line compositions were correlated using the Othmer–Tobias, Bancroft and Hand equations. The study measured the refractive index and densities of several homogeneous binary and ternary solutions. The solutions were used for calibration within a range of 0% to 30% of the mass of the PEG and potassium formate. The density and refractive index data show a linear variation with the mass fraction of the polymer and the salt. The effect of pH on the binodal, tie-line lengths (TLL) and slope of the tie-line (STL) in the systems was examined. It was found that an increase in pH increased the TLL and decreased the STL. It was observed that the density of the aqueous two-phase system was influenced by the TLL. The difference in density between phases (Δ ρ ) increased as the TLL and pH increased. It was found that the TLL and Δ ρ showed a linear relationship. The effective excluded volume (EEV) of the PEG was obtained and it was found that EEV also increased as the pH increased.

In this study, both theoretical and empirical viscosity models were evaluated for binary associating liquid mixtures of water + 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol. The interaction between molecules in the mixtures was analyzed using the calculation of excess energy of flow obtained from Eyring's absolute rate theory. Free volume (FV) viscosity model was coupled with Peng-Robinson (PR) and perturbed-chain statistical associating fluid theory (PC-SAFT) equation of states (EoS); friction theory (FT) was coupled with PR EoS; no significant difference was observed in the modeling results using different EoS. A new mixing rule was found to improve the modeling results of FT coupled with the PR EoS for the binary mixtures studied. The empirical models correlated viscosity of aqueous diol systems well with average absolute percent deviation (AAD%)

The refractive index (nD) and density (ρ) values of the poly(ethylene glycol) (PEG) 1500 + dipotassium tartrate + water ternary system and physical properties of PEG 1500 + water and dipotassium tartrate + water binary solutions have been measured at 298.15 K and atmospheric pressure. Moreover, the refractive index deviation (ΔnD), viscosity deviation (Δη), apparent specific volume (Vφ), excess molar volume (VE), and excess Gibbs energy of activation for viscous flow (ΔG‡E) were calculated from the experimental measurements to analyze the behavior of the binary solutions and the refractive index deviation (ΔnD) and excess molar volume (VE) of the ternary solution. These results were fitted to Redlich–Kister polynomial and Cibulka Equations to estimate the interaction parameters. Adjustments were made to the refractive index and density to obtain a third-order polynomial expansion model and a second-order equation, respectively. The intermolecular interactions between the mixing components were demonstrate...

The densities, viscosities, and refractive indices of monoethanolamine + diethylenetriamine/aminoethylethanolamine binary liquid mixtures were measured at atmospheric pressure and temperatures of 298.15, 303.15 and 308.15 K across the complete composition range. From the experimental data, several thermodynamic properties – including the excess volume, partial molar volume, partial molar volume at infinite dilution, excess Gibbs free energy of flow activation and excess refractive index – were calculated. Excess molar volume and excess refractive index data were correlated to the Redlich-Kister equation, and these properties were used to analyze molecular interactions in the binary mixtures. These volumetric properties were then predicted using the associating version of the PC-SAFT equation of state to test its applicability for amine systems, for which PC-SAFT showed promising results. Finally, viscosities were correlated using various models, including Arrhenius-like and McAllister.

In this paper, experimental values of densities, viscosities and refractive indices of acetonitrile + 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol and poly (ethylene glycol) 200 binary liquid mixtures were measured at temperatures of 293.15, 298.15 and 303.15 K and atmospheric pressure (0.1 MPa) over the whole composition range. From the experimental measurements, different thermophysical properties including the excess molar volume, partial molar volume, partial molar volume at infinite dilution, thermal expansion coefficient, excess thermal expansion coefficient, molar refraction, refractive index deviation and viscosity deviation were calculated. Interactions between molecules in the mixtures are discussed using the obtained thermodynamic results. Moreover, to report the adjustable parameters and determine the prediction and correlation accuracy, models including the Peng-Robinson, Redlich-Kister, Prigogine–Flory–Patterson, Rackett, Lorentz-Lorentz, Andrade and two parameters McAllister equations were applied.

In this study, we applied classical molecular dynamics (MD) simulations to understand the structure, dynamics and transport properties of the room-temperature 1-alkyl-3-methylimidazolium family with tris(perfluoroalkyl)trifluorophosphate ionic liquids, abbreviated as [Cnmim][eFAP]. Calculated densities of ionic liquids agree well with experimental data. Local structures were characterized by studying the center-of-mass (COM) and partial site-site RDFs, combined distribution functions (CDFs) and dihedral angles distribution of n-alkyl side chains in the imidazolium cations. The hydrogen bonding between Fluor atoms of anions and hydrogen atoms of imidazolium ring of cations were studied by contour maps of CDFs. Also, dynamical properties of these ILs such as mean-square displacement (MSDs) for center-of-mass of ions, ionic diffusion coefficients and the cationic transference numbers are calculated by simulation in the NVT ensemble. Results show that the length of alkyl-side chain of cation is the major factor to affect these properties.

A facile and clean electrochemical method has been developed for the synthesis of ternary PdCuNi catalysts on the surface of carbon Vulcan. The composition and morphology of the PdCuNi/C were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX), X‒ray diffraction (XRD), EDX element mapping and transmission electron microscopy (TEM). The effect of Cu and Ni on the electrochemical activity of ternary PdCuNi alloy electrocatalysts was investigated for ethanol oxidation reaction (EOR). Between the different compositions, Pd35%Cu14%Ni2%/C catalyst exhibits superior mass activity which is about 10 times higher than that of commercial Pd/C catalyst. The onset peak potential for ethanol oxidation on Pd35%Cu14%Ni2%/C catalyst shifts to lower potential than that of PdCu/C and Pd/C catalysts. The stability tests revealed that the existing of Cu combined with Ni can improve the poison tolerance of Pd/C catalyst by removal of adsorbed CO-like intermediate species during ethanol oxidation. The experimental work is further investigated by theoretical study based on DFT-D calculations. The experimental and theoretical results exhibited similar trends in electrocatalytic activity of catalyst composition; indicating ternary PdCuNi alloys could be a promising anode catalyst for direct ethanol fuel cells.

The present study investigated liquid-liquid equilibria of polyvinylpyrrolidone (PVP) K30 + tri-sodium citrate + urea (5% and 10% mass) aqueous two-phase systems at 25°C and pH values of 6.2, 7.4, and 10.0. Results showed that the binodal was displaced toward higher concentrations as the urea concentration increased. The effect of pH, polymer/salt (w/w) ratio, urea concentration, tie line length, and slope of tie line on the partition behavior of urea was examined. The viscosity, density, electrical conductivity, and refractive index of PVP (K30) + tri-sodium citrate + urea + water two-phase systems were measured versus pH value. The relation between tie line length and the density and viscosity of the aqueous two-phase systems was also examined.

The current study employed response surface methodology (RSM) with a face-centered central composite design (CCD) to indicate the essential variables on the partition coefficient of guanidine hydrochloride (GuHCl) in the poly (ethylene glycol) (PEG)-phosphate aqueous two-phase system (ATPS). To evaluate the partition coefficients of GuHCl in the mentioned ATPS, the pH (7.0, 8.5 and 10.0), GuHCl concentration (1.0, 3.5 and 6.0% w/w), PEG molecular weight (2,000, 4,000 and 6,000 gmol−1) and PEG/potassium phosphate concentrations ratio were selected as independent variables. A quadratic model is suggested to find the impact of these variables. The suggested model has a strong harmony with the experimental data. The results of the model display that the GuHCl concentration and weight percent of the salt in feed have a large and small influence on the GuHCl partitioning.

Densities and viscosities of formamide (FA) + 1,2-ethanediol (1,2-ED), 1,3-propanediol (1,3-PD) and poly (ethylene glycol) 200 (PEG 200) binary liquid mixtures at temperatures of 293.15, 298.15 and 303.15 K and refractive indices at T = 298.15 K were measured over the entire range of composition and atmospheric pressure (0.1 MPa). From the experimental measurements, several thermophysical properties including the excess molar volumes (VmE), coefficient of thermal expansion αP, excess coefficient of thermal expansion αPE, partial molar volume V − mi , excess refractive index nE and excess viscosity ηE were calculated. The obtained excess parameters were used to discuss the inter-intra molecular interactions in the liquid mixtures. Moreover, the excess properties were correlated with Redlich-Kister polynomial equation and the viscosities were correlated with Eyring–Margules, McAllister and Andrade models. Finally, Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) equation of state were applied to the densities of studied binary mixtures to examine the ability of these models to predict thermodynamic properties.

This work reports density (ρ) and viscosity (η) data for binary system of polyethylene glycol 200 (PEG) and N -methyl-2-pyrrolidone (NMP) over the whole concentration range, at 288.15, 293.15, 298.15, 303.15, and 308.15 K as a function of composition at atmospheric pressure. From the experimental density and viscosity data, excess molar volume (V m E ), viscosity deviation (Δη) and the excess Gibbs free energies of activation for viscous flow (ΔG* E ) were calculated, and the results were fitted to a Redlich– Kister equation to obtain the coefficients and estimate the standard deviations between the experimental and calculated quantities. Based on kinematic viscosity ( ϑ ) data, enthalpy of activation for viscous flow (ΔH*), entropy of activation for viscous flow (ΔS*), and Gibbs energies of activation for viscous flow (ΔG*) were also calculated. In addition, the interactions between the unlike molecules of the PEG and NMP which were supported by FTIR spectra for the binary system of PEG and NMP were studied.

The current study measured liquid–liquid equilibrium data for poly(ethylene glycol) (PEG) 1500 + zinc sulfate + water at 298.15 K and in various pH values (2.54, 3.57, and 4.70). Accordingly, the binodal curve was fitted to the Merchuk equation, and the tie-line compositions were fitted to the equations of Othmer–Tobias and Bancroft. Moreover, the study measured the refractive indices and densities of several homogeneous binary and ternary solutions. These solutions are used for calibration within a range of 0–35 mass % of PEG and 0–30 mass % of ZnSO4. Then, the viscosities, densities, electrical conductivities, and refractive indices of binary (PEG 1500 + water; zinc sulfate + water) and ternary (PEG 1500 + zinc sulfate + water) systems were measured and correlated. According to the results obtained from the density data, there was a linear variation of the polymer and the salt mass fractions. The viscosity data of PEG 1500 solutions were correlated as a function of the mass fractions by using a nonlinea...

Liquid-liquid equilibrium data for poly vinyl pyrrolidone (PVP) K30+K2HPO4+H2O system were measured at 298.15 K and different pH values (7.54, 8.05, and 9.47). A binodal curve was fitted to the Merchuk equation and the tie line compositions were fitted to both the Othmer-Tobias and Bancroft equations. The refractive indices and densities of several homogeneous binary and ternary solutions used for calibration were also measured within a range of 0–30 mass% of PVP and 0–50 mass% of K2HPO4. Then, the viscosities, densities, electrical conductivities, and refractive indices of binary (PVP K30+water; potassium phosphate+water) and ternary (PVP K30+potassium phosphate+water) systems were measured and correlated at different pH values. The density data showed a linear variation of the polymer and salt mass fractions. The viscosity data of PVP K30 solutions were correlated as a function of the mass fractions by using a nonlinear equation. The effects of the tie line lengths on the densities and viscosities of the aqueous two-phase systems were represented. Also, the modified UNIFAC-NRF is used to calculate the phase equilibria of the mention system. The fitted binary interaction parameters of the model were reported.

Pt–CeO 2 electrocatalysts were prepared on the multi-walled carbon nanotube (Pt–CeO 2 –MWCNT) by an electrochemical deposition process. First, CeO 2 is electrodeposited on treated MWCNTs in the optimum deposition conditions. Then, the Pt nanoparticle is electrochemically deposited on CeO 2 /MWCNT electrode by applying a constant potential via chronoamperometry method. The electrocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The electro-oxidation of ethanol (EOR) was studied at room temperature by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) measurements. The onset potential of Pt–CeO 2 –MWCNT shifts to negative compared to the onset potential of Pt–MWCNT. The results indicating CeO 2 could significantly enhance the stability and CO poisoning tolerance of the Pt for alkaline direct ethanol fuel cells (DEFC).

Density, viscosity and refractive index of 1,4-dioxane (1,4-DX) and 1,2-ethanediol (1,2-ED) or 1,3-propanediol (1,3-PD) binary liquid mixtures were measured at temperatures of 293.15, 298.15 and 303.15 K and atmospheric pressure over the entire composition range. From the experimental data, excess molar volumes, excess thermal expansion coefficients, excess refractive indices, excess viscosities and partial molar volumes were determined. The sign and magnitude of excess quantities were used to discuss the nature and strength of molecular interactions in these solutions. Moreover, the obtained thermophysical properties were correlated with different proposed models such as Redlich-Kister, McAlister and Lorentz-Lorenz to examine the ability of these models to predict thermophysical properties. Adjustable parameters for the proposed models are also reported.

The thermodynamic and transport properties of aqueous alkanediol systems at atmospheric pressure were studied over the whole concentration range using the experimental values of density and refractive index at temperatures of 288.15–318.15 K with 5 K interval and viscosity at T = 293.15, 298.15, and 303.15 K. The obtained data were compared with those available in literature. A detailed analysis regarding the behavior of aqueous alkanediols and interactions between the mixture components was performed using different excess thermodynamic properties. Moreover, McAllister model and Grunberg–Nissan and its new proposed models were applied to predict the viscosity data. The validity of the proposed equations was assessed by comparisons between the experimental values and those obtained by the models.

The experimental results for liquid–liquid equilibrium of poly(vinyl pyrrolidone) (K30) + tri-sodium citrate + guanidine hydrochloride (5 and 10 w/w%) aqueous two-phase system at 25°C and different pH values (6.2, 7.4, and 10.0) were studied. The partition behavior of guanidine hydrochloride is known to be a function of several factors. Some of them such as guanidine hydrochloride concentration, pH, polymer/salt ratio (w/w), size, and slant of the tie-lines (STLs) are investigated in this study. At higher guanidine hydrochloride concentrations, the binodal was observed to displace. The behavior of the tie-line size (TLS) seems to be somehow different from the influence of the polymeric phase. The increase of GuHCl concentration decreased the STLs, but the slant and size of the equilibrium tie-lines increased with the pH of the two-phase system. The viscosity (η), density (ρ), electrical conductivity (k), and refractive index (nD) of the poly(vinyl pyrrolidone) (K30) + tri-sodium citrate + guanidine hydroc...

Carbon-supported platinum nanoparticles are successfully synthesized and characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Electrocatalytic activity and stability of the Pt/C catalyst for 1,2-propanediol, 2-propanol and methanol electrooxidation was investigated using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). According to the obtained results, the activity of the Pt/C catalyst for 1,2-propanediol oxidation reaction was higher than that of the other alcohols. Multi-scan cyclic voltammetry after 100 CV cycles revealed that the Pt/C catalyst has great catalytic activity, high poison-tolerance ability and improved electrochemical stability for 1,2-propanediol oxidation compared with methanol and 2-propanol. This indicates a lower poisoning effect of the adsorbed intermediates on the Pt/C performance in 1,2-propanediol oxidation. Infrared spectroscopy measurements after 100 CV cycles in methanol oxidation indicated that adsorbed CO specie is detected on the surface of Pt/C catalyst, but not in 1,2-propanediol oxidation. Comparison of the corresponding EIS measurements after 1st and 100th cycles showed that 1,2-propanediol has the best performance in terms of charge transfer resistance and specific capacitance.

The initial recovery steps for recombinant protein were carried out using aqueous two-phase systems in the presence of guanidine hydrochloride. To investigate the phase behavior of such systems, equilibrium data was obtained for molecular weight fractions of PEG (3000 and 6000) + sodium sulfate (pH 7) + guanidine hydrochloride (5% and 10% mass) + water at 25 °C. Displacement of the binodal toward higher concentrations through an increase in guanidine hydrochloride concentration was clearly observed. A slightly larger two-phase was obtained as the PEG molecular weight increased from PEG 3000 to 6000. The experimental binodal data of the system was successfully correlated with Bleasdale equations (high R 2 and low SE). The effects of molecular weight, guanidine hydrochloride concentration, tie-line length, and slope of tie-line on the partition behaviors of guanidine hydrochloride were examined at constant pH. The compositions of each aqueous phase were calculated using two thermodynamic models for the activity coefficient. The calculated results showed that the extended Pitzer and extended UNIQUAC models can predict the data in the quaternary system well. The fitted binary interaction parameters of the models were reported.

The densities, viscosities, and refractive indices for the binary mixtures of dimethyl carbonate (DMC) + 1-hexanol/1-octanol were measured at atmospheric pressure and temperature of 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15 K over the whole concentration range. Different thermodynamic, transport, and optical properties, such as excess molar volume, partial molar volume, thermal expansion coefficient, isothermal coefficient of pressure excess molar enthalpy, activation energy of flow, excess refractive index, and electronic polarizability were obtained from the experimental data. The results were analyzed in terms of specific molecular interactions and mixing behavior between mixture components with taking into considerations the effect of temperature. Moreover, the thermophysical properties were examined with predictive and correlative equations. The quality of the predictions for the studied systems was evaluated by measuring the deviations and drawing the comparison plots.

This study reports an electrochemical method to fabrication of palladium nanoparticles (Pd NPs) promoted with cuprous oxide (Cu2O) supported on multi-walled carbon nanotube (Pd/Cu2O/MWCNT). First, Cu2O is electrodeposited on treated MWCNTs in the optimum deposition conditions. Then, the Pd nanostructure is electrochemically fabricated on Cu2O/MWCNT electrode by cycling the potential between +0.5 to −1.0 V in negative direction. The prepared electrodes are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The electrocatalytic performance of Pd/Cu2O/MWCNT electrocatalyst for ethanol oxidation reaction (EOR) is investigated by cyclic voltammetric (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) measurements. The formation of the Pd/Cu2O/MWCNT is confirmed by EDX and XRD techniques. The onset potential of Pd/Cu2O/MWCNT shifts to negative values by 120 mV compared to the onset potential of Pd/MWCNT. Much higher If/Ib value is obtained for Pd/Cu2O/MWCNT compared to other Pd-based catalysts indicating Cu2O could significantly enhance the stability and CO poisoning tolerance of the Pd towards ethanol electrooxidation. The results revealed that the prepared Pd/Cu2O/MWCNT catalyst can be a promising anode catalyst for alkaline direct ethanol fuel cells.

In the present study, poly (p-phenylendiamine/titanium dioxide) (PpPDA/TiO 2 ) nanocomposites (NCs) were prepared by in situ polymerization of p-phenylenediamine monomer with of different TiO 2 loading. A facile method was developed to promote the electrocatalytic activity of commercial Pt/C catalyst by ultrasonically mixing Pt/C catalyst and PpPDA/TiO 2 NCs. The PpPDA/TiO 2 NC, Pt/C catalyst and composite catalyst of Pt/C + PpPDA/TiO 2 were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The surface morphology of Pt/C is significantly influenced by the presence of PpPDA/TiO 2 NC as confirmed by SEM observations. Cyclic voltammetry (CV) measurements showed that the PpPDA/TiO 2 NC leads to a significant improvement in the activity and stability of Pt/C for alcohol oxidation especially for ethanol oxidation in alkaline medium. For Pt/C + PpPDA/TiO 2 , the onset potentials shift to negative values by 30 and 160 mV compared to the onset potentials of Pt/C for methanol and ethanol oxidation, respectively. Chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) results also confirmed that this composite catalyst has superior catalytic performance towards ethanol oxidation compared to the pure Pt/C catalyst.

Nonisothermal crystallization kinetics and properties of poly(vinyl alcohol)/octasilane polyhedral oligomeric silsesquioxanes nanocomposite were investigated by differential scanning calorimetry and compared with pure poly(vinyl alcohol). The effects of octasilane polyhedral oligomeric silsesquioxanes content and cooling rate on the degree of crystallinity (Xc), crystallization half time (t1/2), Ozawa exponent (m), and Mo kinetics parameters were studied. The role of thermal treatment on the morphology and structure of the samples was studied by X-ray diffraction and scanning electron microscopy analyses. UV–visible analysis was used to show the polyhedral oligomeric silsesquioxanes effect on the nanocomposite structure. Electrochemical impedance spectroscopy analysis demonstrated that the best conductivity was for the nanocomposite with 1 wt% of octasilane polyhedral oligomeric silsesquioxanes.

This work exploits gas adsorption and small-angle X-ray scattering (SAXS) to determine the morphology of complex nanoporous materials. We resolve multiple classes of porosity including previously undetected large-scale texture that significantly compromises the canonical interpretation of gas adsorption. Specifically, a UVM-7 class mesoporous silica was synthesized that has morphological features on three length scales: macropores due to packing of 150 nm globules, 1.9 nm radius spherical mesopores inside the globules, and >7 nm pockets on and between the globules. The total and external surface areas, as well as the mesopore volume, were determined using gas adsorption (αs-plot) and SAXS. A new approach was applied to the SAXS data using multilevel fitting to determine the surface areas on multiple length scales. The SAXS analysis code is applicable to any two-phase system and is freely available to the public. The total surface area determined by SAXS was 12% greater than that obtained by gas adsorption...

The phase diagrams and compositions of coexisting phases have been determined and correlated for poly(ethylene glycol) (PEG) 3000 + trisodium citrate aqueous two-phase systems (ATPS’s) at 25 °C and different pH values (6.1, 7.5, and 9.0). It was found that an increase in pH caused the binodal curve to be displaced downward and also the expansion of the two-phase region. The experimental binodal data of the mentioned system has been successfully correlated with Bleasdale equations (high R2 and low AARD). Furthermore, the viscosities, densities, electrical conductivity, and refractive index of binary (PEG 3000 + water; trisodium citrate + water) and ternary (PEG 3000 + trisodium citrate + water) systems at the above pH value have been measured and correlated. The density data show a linear variation with mass fraction of the polymer and also the salt. The viscosity data of PEG 3000 solutions were correlated as a function of mass fraction, using a nonlinear equation. The effect of tie line lengths on density...

Cyclic voltammetry (CV) and subsequently galvanic replacement reaction were used to synthesize the Pd–Co/RGO electrocatalyst. The morphology and the structural properties of the prepared catalyst were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) techniques were employed to investigate the electrochemical behavior of the Pd–Co/RGO system as an anode electro-catalyst for ethanol oxidation in alkaline media. For Pd–Co/RGO, it was evidenced that the onset potential and the peak current density are 160 mV lower and 2.5 times higher than that of Pd catalyst, respectively. By comparison of the I f /I b ratios for different electrodes, it can be conclude that the anti-poisoning ability of Pd–Co is improved by RGO as catalyst support. Also, the Pd–Co/RGO catalyst showed excellent catalytic activity, high durability and stability which indeed propose it to be as a promising electrocatalyst for future direct alcohol fuel cells.

The catalytic activity and stability of electrodeposited Pd–Co alloy layers on Au electrode was evaluated for glycerol oxidation reaction (GOR) in an alkaline solution. The morphology and structural characteristics of the Pd and Pd–Co alloy were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The electro-oxidation of glycerol on the Pd/Au and Pd–Co/Au was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) techniques. By varying Co concentration in the deposition solution, it was demonstrated that the Pd (61%)-Co (4%) catalyst [denoted Pd–Co(3)/Au] has the highest electrocatalytic activity. Obtained results showed that the Pd–Co(3)/Au has the excellent activity in terms of the specific peak current density and onset potential compared to pure Pd for oxidation of glycerol. For Pd–Co (3)/Au, the onset potential shifts to negative values by 80 mV compared to the onset potential of Pd/Au. The stability tests indicated that the presence of Co has a significant effect on the poisoning tolerance of the Pd toward glycerol electro-oxidation. Form the obtained results; one can conclude that the Pd–Co alloy exhibits suitable activity as a promising catalyst for alcohol electro-oxidation reactions in fuel cells.

Epoxy-poly p -phenylendiamine (EP/PpPDA) and its nanocomposite with SiO 2 nanoparticles (EP/PpPDA/SiO 2 ) were synthesized and tested as potential corrosion inhibitors of steel in 1 M HCl solution. Performance of EP/PpPDA/SiO 2 and EP/PpPDA coatings on protection of steel against corrosion was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Atomic force microscopy (AFM) and at various temperatures between 298 and 328 K. Changes in the coating resistance and charge-transfer resistance with temperature were analyzed to determine the activation energies of the processes involved. The determined values of activation energy showed that the EP/PpPDA/SiO 2 coating has better anti-corrosion effect than EP/PpPDA. The thermodynamic functions of dissolution processes were also calculated and discussed. The results from AFM observations indicated that the presence of SiO 2 nanoparticles increased the roughness of Epoxy-poly p -phenylendiamine/SiO 2 nanocomposite (EP/PpPDA/SiO 2 ). It was finally concluded that the presence of silica nanoparticles enhance the protection properties of EP/PpPDA coating as a novel potential corrosion inhibitor for steel.

The thermal degradation kinetics of diglycidyl ether of bisphenol-A (DGEBA) cured with tryptophan (Trp) in the presence of silica nanoparticles (SiNP) was investigated by thermogravimetry analysis. The activation energies of the solid-state decomposition process were evaluated using the advanced isoconversional method. The dependence of conversion (degradation) on the temperature and activation energy was determined allowing the calculation of master plots. The experimental master plots agreed with the first-order (F1) kinetic function for both neat epoxy and nanocomposite in the conversion range of 0.45–0.85. Using the kinetic model and the calculated kinetic parameters, the times at half conversion (α = 0.5) were computed for different degradation temperatures. The kinetic analysis showed that the degradation rate of the epoxy nanocomposite was lower than that of the neat epoxy for conversions between 0.45 and 0.85. Therefore, we concluded that adding SiNP to DGEBA/Trp can improve the thermal stability ...

In the present study, a bacterium resistance to heavy metals was isolated from contaminated areas. An eco-friendly and simple method was found to biosynthesis of silver nanoparticles (AgNPs) by reducing of aqueous Ag+ using the heavy metals resistance MKH1 bacterium. The biosynthesized AgNPs were characterized by UV-vis spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. A peak at about 420nm is related to absorption band of AgNPs which confirms by UV-vis spectroscopy. The SEM images showed that the biosynthesized AgNPs have mainly spherical shape with average diameters of 30-60nm. The electro-catalytic properties of AgNPs with different Ag content were investigated by different electrochemical tests. Biosynthesized AgNPs using isolated MKH1 show high catalytic activity and stability towards the oxidation reaction of hydrazine.

In this study, poly(P-phenylenediamine/ZnO) (PpPD/ZnO) nanocomposite (NC) under ultrasonic conditions was synthesized and characterized. The presence of zinc oxide nanoparticles changed the morphology of PpPD considerably as confirmed by SEM observations. Hydrazine electrooxidation at novel modified carbon paste electrodes (CPE) with supported NC was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) techniques. Obtained results showed that the NC increases the surface catalytic activity of CPE toward hydrazine electrooxidation. The electrocatalytic current density increased linearly with hydrazine concentration, and the detection limit and sensitivity are determined to be 24 μM and 0.172 mA cm−2 mM−1, respectively. As revealed by the EIS measurements, the increased conductivity and decreased R ct are owing to the presence of ZnO NPs in the PpPD matrix. The CA results indicated that hydrazine electrooxidation results in higher steady-state current density on CPE/PpDP/ZnO electrode system compared to the CPE/PpDP and CPE electrodes.

This research highlights fabrication, characterization, and performance of a carbon paste electrode modified by a nanocomposite having poly(P-phenylendiamine) (PpDP) and silica nanoparticles as novel potential electrocatalyst for hydrazine oxidation. The core/shell structure morphology and size of PpDP and its nanocomposite were investigated by scanning electron microscopy and transmission electron microscopy techniques. Catalytic activity and stability of the fabricated carbon paste electrode (CPE) was evaluated using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The results confirmed that the nanocomposite significantly enhances the catalytic activity of the CPE. The kinetic parameters of the electron transfer coefficient and diffusion coefficient of hydrazine were also determined and compared. It was also evidenced that the core/shell morphology of the nanocomposite improves effective dispersion of silica nanoparticles facilitating the easier access of hydrazine to the catalytic sites.

Densities, viscosities and refractive indices of the {poly(ethylene glycol) 200 + ethanol} binary liquid system were determined at three temperatures of (298.15, 303.15, and 308.15) K. From the experimental results, the excess molar volume was obtained and correlated with the Prigogine–Flory–Patterson (PFP) and Extended Real Associated Solution (ERAS) models. Several isobaric and isothermal properties consisting of the isobaric thermal expansion coefficient, excess molar isobaric expansion, excess molar isobaric heat capacity, isothermal coefficient of excess molar enthalpy, activation energy of flow, electron polarizibility, and Gibbs energy of activation were calculated from the experimental measurements. Moreover, the viscosity and refractive index values were correlated and predicted with different semi-empirical equations. To assess the validity of these proposed equations, comparisons were made between the experimental and predicted values.

In this study, kinetics of the curing reaction between DGEBA epoxy resin and tryptophan as an environmentally friendly curing agent in the presence of 2,4,5-triphenylimidazole was reported. The role of silica nanoparticles (SiNP) in changing the mechanism of the curing reaction was also studied. The optimum molar ratio of DGEBA/tryptophan and the optimum content of SiNP were determined by calorimetry analyses. Kinetic analysis using the advanced isoconversional method revealed that the system undergoes the vitrification. Thermogravimetric analysis demonstrated that addition of SiNP does not improve the thermal stability of the tryptophan based thermosets. Impedance spectroscopy and also the standard four-probe method were performed to investigate the effect of curing agent and SiNP loading level on the electrical properties of the cured epoxy. The structure and morphology of the nanocomposite were studied by X-ray diffraction analysis, atomic force microscopy and scanning electron microscopy imaging. Dynamic mechanical thermal analysis revealed that the crosslinking density cannot be significantly affected with the addition of SiNP.

The densities ρ and viscosities η of 1,2-ethanediol with 1,2-propanediol or 1,3-propanediol, and 1,2-propanediol with 1,3-propanediol binary liquid mixtures over the entire concentration range at temperatures (298.15 to 308.15) K with 5 K interval were measured. The experimental data were used to calculate the excess molar volume V m E , partial molar volume V ¯ m , i , partial molar volume at infinite dilution V ¯ i ∞ , apparent molar volume V φi , coefficient of thermal expansion α p , excess coefficient of thermal expansion α p E , excess viscosity η E , excess Gibbs energy of activation Δ G * E , and other thermodynamic parameters. A Redlich–Kister equation and Prigogine–Flory–Patterson (PFP) model was applied to correlate the excess molar volume results. Moreover, the viscosity data were correlated with the Grunberg–Nissan, Tamura–Kurata, Hind–Ubbelohde and Katti–Chaudhary equations. Good agreement was found between experimental data and modeling results.

Densities ρ and viscosities η for the binary mixtures of poly(ethylene glycol) + water, + 1,2-ethanediol, + 1,3-propanediol, + 1,4-butanediol over the entire concentration range were determined at temperatures (298.15 to 308.15) K with 5 K interval. The experimental data were used to calculate the excess molar volume V m E , coefficient of thermal expansion α, excess coefficient of thermal expansion α E , excess Gibbs free energy of activation Δ G ∗ E , and other activation parameters (i.e., Δ G ∗ , Δ H ∗ , Δ S ∗ ). The values of excess properties were fitted to Redlich–Kister polynomial equation to estimate the binary coefficients. The excess refractive index n E and electronic polarizability α e of PEG + water binary mixtures were also determined from the experimental values of refractive indices. The viscosity data were correlated with Grunberg–Nissan and Tamura–Kurata equations. Moreover, the Prigogine–Flory–Patterson theory has been used to correlate the excess molar volumes of the studied mixtures.

Polypyrrole (PPy) coatings were synthesized on copper by electrochemical polymerization of pyrrole monomer in aqueous acidic and basic solutions by cyclic voltammetry. The coatings were characterized with CV, UV-visible absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) techniques. The corrosion protection aspects of PPy coatings have been investigated using the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The potentiodynamic polarization measurements show that the PPy coating has ability to protect the copper against corrosion. It was concluded that a complete corrosion protective PPy film could not be obtained through direct electro-oxidation procedure. This may be due to copper dissolution in the monomer oxidation potential range.

In this article, the chemical synthesis and characterization of Al 2 O 3 nanoparticles dispersed into poly ( P -phenylendiamine) (PpDP) was reported. The morphology, conductivity and structure of the nanocomposite was characterized by scanning electron microscopy (SEM), four probe testing and XRD experiment, respectively. Catalytic activity and stability for the oxidation of hydrazine were studied by using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The results show that the nanocomposite significantly enhances the effective surface area and the catalytic activity of the CPE (carbon paste electrode) for oxidation of hydrazine. The results obtained confirmed that the dispersion of the Al 2 O 3 particles is connected with catalytic response to a higher activity. The nanotubular morphology of poly ( P -phenylendiamine) helps in the effective dispersion of Al 2 O 3 particles facilitating the easier access of hydrazine to the catalytic sites. The poly ( P -phenylendiamine) nanotubes modified with Al 2 O 3 nanoparticles cause a great increase in electroactivity and the electro-catalytic properties of CPE for hydrazine oxidation.

This research highlights the influence of alumina nanoparticles on different ageing concepts in order to study ageing consequences on sub-micron structures for a novel nanocomposite based on glycerol diglycidyl ether (GDE) and 3,3-dimethyl glutaric anhydride (DGA). Electrochemical impedance spectroscopy (EIS) was used to evaluate thermal degradation and corrosion resistance of the epoxy in exposure to distilled water and 10 wt% sulphuric acid solution at various times. It was found that the resistance of the epoxy to corrosive electrolyte was significantly improved using alumina nanoparticles. The water uptake behaviour was also evaluated by EIS measurements. The results showed that ageing for 2 months led to increase in the charge transfer resistance. Surface topography and roughness were studied using Atomic Force microscopy (AFM). Ageing was confirmed by the flattening of the surfaces and observed to be significant for the system without nanoalumina. Results from tensile measurements showed that the nanocomposite system gives better mechanical properties after ageing in comparison to the neat GDE system.

The electrochemically induced functionalization of glassy carbon electrode by aryl groups was achieved by reduction of in situ generated diazonium cations in aqueous media. Surface modification experiments were performed by cyclic voltammetry (CV) scanning from +0.5 to −1.1 V. The barrier properties of the grafted layers were evaluated by cyclic voltammetry in the presence of Fe ( CN ) 6 3 - / 4 - electroactive redox probe. The modified electrodes showed very slow electron transfer compared to that unmodified surface. Once the monolayer is switched ON, it supports rapid electron exchange with the redox system but not with dopamine, which requires adsorption to the electrode surfaces. Ab initio density functional theory calculations allow determining HOMO–LUMO gap distance.

The effect of multiwalled carbon nanotubes (MWCNT) on the polymerization kinetics of bisphenol-A diglycidyl ether/1,4-bis(3-aminopropoxy)butane was elucidated by means of dynamic and isothermal differential scanning calorimetry. Comparing the results of total reaction enthalpy and glass-transition temperature measurements for the neat epoxy and epoxy composite containing different mass fractions of MWCNT allowed the optimum formulation to be found as w(MWCNT) = 0.05. Various kinetic models such as n-th-order, Kamal, and Sestak–Berggren equations were used to estimate the kinetic parameters. We found that the curing reaction obeys an autocatalytic mechanism. Based on the results obtained from experimental and calculated reaction rates it was recognized that the model of Sestak–Berggren is the best choice to interpret bisphenol-A diglycidyl ether/1,4-bis(3-aminopropoxy)butane/MWCNT cure. The dispersion of the nanotubes was subjected to X-ray diffraction measurements, and the results exhibited a well-dispersed matrix of epoxy and MWCNT with an amorphous structure.

A novel nanocomposite consisting bisphenol A diglycidyl ether/1,4-Bis(3-aminopropoxy) butane (1,4-APB)/multiwall carbon nanotube (MWCNT) was synthesized and characterized. Kinetics of the reaction was described by applying differential scanning calorimetry (DSC) data to isoconversional methods of Flynn–Wall-Ozawa (FWO), advanced isoconversional method of Vyazovkin, and non-linear integral isoconversional algorithm (NLN). It was found that at the presence of MWCNT the thermal decomposition temperature increased by rising the curing temperature and time. Data from dynamic mechanical thermal analysis (DMTA) showed that the glass transition temperature of the cured nanocomposite is 7 °C higher than that value found for the system without carbon nanotube. Scanning electron microscopy (SEM) was used to observe the fracture surface morphology and results indicated evidence of the interfacial interaction improvement and adhesion strength due to good dispersion of MWCNT.

Poly(3,4-ethylenedioxythiophene) (PEDOTh) films were deposited on glassy carbon (GC) electrodes from organic electrolytes containing the monomer in a solution of acetonitrile (AN). The effect of the supporting electrolyte used during electropolymerization, on the redox behavior, surface morphology, and degree of crystallinity of the films has been investigated by FTIR, cyclic voltammetry, and scanning electron microscopy (SEM) techniques. The use of LiPF6 leads to a higher electropolymerization efficiency and an increase of electroactivity and crystallinity of the polymer. On the basis of voltammetric studies of the Nernst and Butler–Volmer equations, we concluded that BF4−, ClO4−, and PF6− anions are the mobile species during the redox process of the PEDOTh films. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012