Efficient electrocatalysis of formic acid oxidation onto Pd-Cu/poly (2-methoxyaniline)-SDS nanocomposite film

In this work, porous poly (2-methoxyaniline) film prepared in the presence of sodium dodecyl sulfate (P2MA-SDS) is used as a potent support for dispersion of bimetallic palladium-copper nanoparticles (Pd-Cu NPs) towards the electrooxidation of formic acid (HCOOH) in sulfuric acid solution. The Pd-Cu NPs are prepared through galvanic replacement reaction between Pd^II ions and Cu particles. The SEM, EDS, and electrochemical methods were used to characterize the prepared Pd-Cu NPs. The obtained results show that the Pd-Cu exhibited significantly high current density of HCOOH oxidation compared to other catalysts and utilization of Cu NPs enhances the electrocatalytic activity towards electrooxidation. The enhanced performance is related to the synergetic effect between Pd-Cu NPs and P2MA-SDS film. The effects of galvanic replacement time, potential sweep rates, and concentration of HCOOH on the catalytic activity of the electrocatalyst as well as long-term stability are investigated by the various electrochemical techniques.     

Preparation and characterization of aqueous stable electro-spun nanofibers using polyvinyl alcohol/polyvinyl pyrrolidone/zeolite

Cross-linked polyvinyl alcohol/polyvinyl pyrrolidone/zeolite fibers were prepared in the presence of potassium peroxodisulphate (K₂S₂O₈) under the curing process by the electrospinning technique. The narrowest nanofibers of PVA/PVP (50:50) were prepared under optimum experimental conditions of 2.5 × 10^?4 mol of K₂S₂O₈, an applied voltage of 22 KV, the distance of 15 cm and the feed rate of 0.2 mL/h. The progress of the cross-linking was examined by immersion of the prepared nanofibers in water and following the swelling degrees. By raising the K₂S₂O₈ amount and curing time, the cross-linking density was increased. X-ray diffraction (XRD) demonstrated that the crystallinity of the nanofibers was decreased by the increase of K₂S₂O₈ and the lowest crystallinity was observed for PVA/PVP (70:30). The contact angle of nanofibers was decreased from 72° to 34 by increasing PVP ratio from 30 to 70. The morphology of the nanofibers before and after immersion in the simulated body fluid (SBF) was studied using electron scanning microscopy (SEM) and PVA/PVP (70:30) showed the highest changes in the morphology while the lowest one was observed for PVA/PVP (50:50). Moreover, the cross-linked PVA/ PVP with the ratio of 50:50 had the narrowest diameter of 200 ± 100 nm, and by addition of about 0.5% zeolite, it was even reduced more to 150 ± 50 nm. The cross-linked nanofibers (50:50) with 0.5 wt% and 1.5 wt% zeolite nanoparticles showed the tensile modules of 416.26 and 703.52 MPa, respectively, while in the absence of zeolite, it was209.25 MPa. Fibroblast L929 cells were cultured on the cross-linked PVA/PVP/zeolite (50:50:0.5) nanofiber, and the cell proliferation and growth was evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Fibroblasts grew on the surface of scaffold showed good morphology and proliferation after seven days and the absorption amount was increased from 0.075 to 0.78     

A highly selective magnetic solid-phase extraction method for preconcentration of Cd(II) using N,N′-bis(salicylidene)ethylenediamine in water and food samples

Research on Chemical Intermediates - In this work, a highly selective method is presented for the preconcentration of cadmium. The developed magnetic solid-phase extraction is based on the...     

Pore-Level Investigation of Heavy Oil Recovery During Water Alternating Solvent Injection Process

This study concerns with the microscopic and macroscopic fluid distribution and flow behavior during water alternating solvent (WAS) injection process to heavy oil using micromodel generated from thin section of a real rock which has rarely attended in the available literature. In this study, a one-quarter five-spot glass micromodel was deployed to examine the effect of flow media topology on microscopic displacements as well as macroscopic efficiency of WAS process. The micromodel was initially saturated with the heavy oil, and then the hydrocarbon solvent and water were injected alternately into it. The observations confirmed that WAS injection scheme is an effective method for the recovery of the significant amount of residual oil. Using solvent as the leading batch in WAS scheme can really improve the oil recovery by increasing the amount of microscopic sweep efficiency in flow paths, where the molecular diffusion in solvent–heavy oil system occurs. Presence of connate water in WAS scheme can improve the recovery efficiency especially at higher water saturations. Heterogeneity of the medium caused the water to be distributed better in the medium, but the amount of residual oil in the flow area is going to be increased. Small precipitates of asphaltene particles due to solvent injection and localized entrapment of the oil due to heterogeneity effects, water blockage, and deadend pores were observed mainly in this process. The results of this study reveals the pore scale events in WAS injection process and will be helpful for developing reliable simulation models.     

Thermal effect on superhydrophobic performance of stearic acid modified ZnO nanotowers

The thermal desorption of stearic acid on superhydrophobic zinc oxide nanotowers has been investigated. The stearic acid passivated zinc oxide nanotowers provide a very high contact angle of ∼173 ± 1.1° with a very low hysteresis of ∼1.4 ± 0.5° due to the presence of a binary structure composed of several nanosteps on each nanotower of height ∼700 nm that eventually reduces the area of contact between the drop and the nanotowers and trapping more air as revealed by the field emission scanning electron microscopy images. The superhydrophobic performance of these nanotowers, however, declines following annealing at elevated temperatures. Fourier transform infrared spectra show a reduction in the intensity of stearic acid -CH_n peaks at elevated temperatures revealing the cause of the decrease in contact angle and confirming the occurrence of thermal desorption at 184 °C. The corresponding activation energy for desorption determined from our data is 0.34 ± 0.05 eV. It is found that the stearic acid has completely disappeared at 350 °C, making the sample hydrophilic.     

Bifunctional aminosilane-functionalized Fe3O4 nanoparticles as efficient sorbent for preconcentration of cobalt ions from food and water samples

Research on Chemical Intermediates - Magnetic Fe3O4 nanoparticles were synthesized by a coprecipitation method, then their surface was covered and modified by...     

Liquid–Liquid Equilibrium and Thermodynamic Modeling of Aqueous Two-Phase System Containing Polypropylene Glycol and NaClO<Subscript>4</Subscript> at <Emphasis Type="Italic">T</Emphasis> = (288.15 and 298.15) K

In this work the phase equilibrium of an aqueous two phase system (ATPS) containing polypropylene glycol (PPG, molecular weight = 425 kg·mol^?1) and NaClO₄ was investigated at atmospheric pressure and at 288.15 and 298.15 K. Two phase regions and composition of phases were determined. Our results show that as the temperature increases, the two-phase region expands. Also, the extended UNIQUAC (E-UNIQUAC) equation was used to correlate the equilibrium data. To reduce the number of adjustable parameters, ATPSs composed of PEG and PPG were collected from the literature and simultaneously correlated using the E-UNIQUAC model. Also, the effect of temperature on the liquid–liquid equilibrium (LLE) was considered by using temperature-dependent parameters. In the modeling, two different scenarios were supposed. In the first, polymer and salt were treated as solutes (Case A), while in the second, the pseudo-solvent approach was considered (Case B). The results showed good agreement with experimental data in both cases. The average absolute deviation of the model using Case B was about 0.2% and that for Case A was about 2% in the ATPS composed of PEG. Meanwhile, the reported errors in the ATPS containing PPG for Case A and Case B were almost equal.     

An efficient synthesis of pentasubstituted pyrroles: one-pot four-component reaction of arylamine,acetylenedicarboxylate, arylglyoxal,and symmetrical 1,3-dicarbonyl compounds

An efficient and catalyst-free for the synthesis of dialkyl 5-(aryl)-4-(1,3-dicarbonyl)-1-(aryl)-1H-pyrrole-2,3-dicarboxylate via a novel one-pot four-component reaction of arylamine, acetylenedicarboxylate, arylglyoxal, and 1,3-dicarbonyl compounds in ethanol is reported. All the products were obtained in excellent yields and their structures were established from their spectroscopic data.