Highly-efficient capture of chromium (VI) ions on electrospun polyacrylonitrile/diaminoglyoxime nanofiber: thermal stability, decomposition kinetics and tensile strength

In this study, a new polyacrylonitrile/diaminoglyoxime-based nanofiber was developed using electrospinning thanks to their outstanding chemical-mechanical properties used as effective adsorbents for the Cr(VI) removal without any secondary pollution. However, thermal stability and degradation of these nonpolymeric-mats could limit their application. The electrospun polyacrylonitrile with different percentages of diaminoglyoxime (%) nanofibers have their average diameters between 70 and 85 nm. The DSC technique was used to characterize the thermal stability of the manufactured polyacrylonitrile/diaminoglyoxime nanofiber. Decomposition kinetic parameters of the mats via the non-isothermal approaches and thermodynamic parameters (ΔG#, ΔH# and ΔS#) were determined. Polyacrylonitrile/diaminoglyoxime(30%) reached maximum adsorption capacity of 348.7 mg g−1 for Cr(VI) ions. After conducting the adsorption–desorption test for 20 times, polyacrylonitrile/diaminoglyoxime(30%) nanofiber exhibited excellent regeneration and stable desorption efficiency of over 73%. Compared with complicated industrial-sized chemicals for adsorbing Cr(VI), the nanofiber mat proposed herein is a simple one-step electrospinning process, which is extremely successful for industrial applications, cheap and without harmful by-products. Polyacrylonitrile/diaminoglyoxime (30%) was proposed as an appropriate material to adsorb Cr(VI) ions

High Current Density Chronopotentiometric Electrosynthesis and SEM Characterization of Hexanethiol-Monolayer-Protected Silver Planar Nanotriangles (Ag@C6SH)

This work reports for the first time electrosynthesis of hexanethiol capped silver nanotriangles cores (Ag@C6SH NCs) by a rapid, clean, and simple Double Pulse Chronopotentiometric (DCP) method in nonaqueous media, using a Taguchi orthogonal array L8 design to identify the optimized experimental conditions. It was found that the size and shape of the product could be tuned by the current density, electrolysis time, electrode distance, and amount of NaBH4% used. The Ag@C6SH NCs in different shapes and sizes (in the range of 30 to 44 nm as an average estimation) were synthesized, under different experimental conditions. Finally, the as-prepared nanoclusters electrosynthesized at optimized conditions were characterized by SEM, XRD, and UV-Vis spectroscopy. The average particle size of the triangular/pyramidal shape (Ag@C6SH NCs), obtained under optimized experimental conditions, was 30.5±2.0 nm but the majority of nanoparticles in TC3 SEM are so much finer

Facile and Effective Synthesis of Praseodymium Tungstate Nanoparticles through an Optimized Procedure and Investigation of Photocatalytic Activity

Regarding the importance of nanoparticles in today’s world, and in the light of the fact that their preparation can be a rather difficult task, we focused on the applicability of a simplistic direct precipitation approach for the preparation of praseodymium tungstate nanoparticles. To maximize the effectiveness of the method, a Taguchi robust design approach was applied to optimize the reaction in terms of the operating conditions influencing its outcome and the results were monitored by characterization of the Pr2(WO4)3 nanoparticles. Among the four parameters studied we found the dimensions of the produced nanoparticles to be determined by the concentrations of Pr3+ and WO43− solutions and the reaction temperature, while the flow rate of adding the cation solutions to the anion solution was found to leave very negligible effects on the product characteristics. To confirm the effect of the optimizations on the outcomes of the reaction, SEM, TEM, EDX, XRD, FT-IR and UV-Vis structural and morphological characterizations of the products were performed, the results of which were in agreement with those statistically predicted in the optimization procedure. Furthermore, as-synthesized praseodymium tungstate nanoparticles under ultraviolet light exhibited an efficient photocatalyst property in the photocatalytic degradation of methylene blue