Effect of Varying Amount of Polyethylene Glycol (PEG-600) and 3-Aminopropyltriethoxysilane on the Properties of Chitosan based Reverse Osmosis Membranes

Chitosan and polyethylene glycol (PEG-600) membranes were synthesized and crosslinked with 3-aminopropyltriethoxysilane (APTES). The main purpose of this research work is to synthesize RO membranes which can be used to provide desalinated water for drinking, industrial and agricultural purposes. Hydrogen bonding between chitosan and PEG was confirmed by displacement of the hydroxyl absorption peak at 3237 cm⁻¹ in pure chitosan to lower values in crosslinked membranes by using FTIR. Dynamic mechanical analysis revealed that PEG lowers Tg of the modified membranes vs. pure chitosan from 128.5 °C in control to 120 °C in CS-PEG5. SEM results highlighted porous and anisotropic structure of crosslinked membranes. As the amount of PEG was increased, hydrophilicity of membranes was increased and water absorption increased up to a maximum of 67.34%. Permeation data showed that flux and salt rejection value of the modified membranes was increased up to a maximum of 80% and 40.4%, respectively. Modified films have antibacterial properties against Escherichia coli as compared to control membranes.     

Thermal stability of natural fibers and their polymer composites

Natural fiber-based composites are applied in many structural engineered products from civil constructions to automobile manufacturing due to the properties such as low density, high aspect ratio, biodegradability and ease to work. During the past decades such composites have been thoroughly studied for their mechanical properties and failure behavior and their properties compared with those of synthetic fiber-based composites. Other properties, such as the thermal behavior of natural fibers and composites, have also been studied because they determine the performance of their products possible. It deals with the effect of temperature on adhesive curing, effect of high temperature and fire damage during fabrication. Further, the thermal properties have equal importance in structural applications such as temperature transfer from end to end, load capacity at specific temperature, material behavior and dimensional stability at high temperature. In this respect the isothermal and non-isothermal thermogravimatric analyses are discussed and the improtance of glass transition temperature is studied during prepapration of composites to ensure their ultimate properties. Although there are several works that have been done on thermal behavior, especially thermogravimetric analysis of natural fibers and their composites, there is no review article available specially focused on natural fiber-based composites, hybrid composites, and nanocomposites. The aim of this review was to focus on the advances in the comprehension of thermogravimetric behavior of natural fibers and compare the effect of natural fibers as reinforced materials in polymer composites.     

Synthesis and characterization of a new photochromic alkylene sulfide derivative

A process has been developed for the synthesis of a new photochromic alkylene sulfide derivative. The process involves the synthesis of an alkylene sulfide with terminal free amino groups and a novel unsymmetrical photochromic diarylperfluorocyclopentene containing an aldehyde group, which coupled together to produce the corresponding Schiff base. The structures of the products were confirmed by a range of spectroscopic techniques.     

Novel organic–inorganic composite material as a cation exchanger from a triterpenoidal system of dammar gum: synthesis,characterization and application

A pioneer study has been conducted to synthesize novel hydrogel starting from a non-cellulosic raw material, gum dammar-a triterpenoidal system, and then converting this hydrogel into an organic–inorganic composite zirconium-based ion exchanger. Gum dammar was cross-linked with polyacrylamide zirconium (IV) iodo-oxalate [Gd-cl-poly(AAm)-Zr (IV) iodo-oxalate] by incorporating inorganic precipitates into the polymeric mixture. The polymeric mixture was synthesized using gum dammar (Gd), acrylamide (AAm), N, N′-methylene-bis-acrylamide (MBA) and potassium persulphate (KPS). The reaction conditions for synthesis of hydrogel and ion exchanger such as time (120 min), temperature (70 °C), solvent (4 mL), concentration of monomer (12.97 × 10^?3 mol/L), initiator (1.48 × 10^?4 mol/L), cross-linker (4.22 × 10^?4 mol/L) and ratio of zirconium oxychloride (0.1 M), potassium iodate (0.1 M) and oxalic acid (0.1 M) in ratio 2:3:2 were optimized to obtain maximum ion exchange capacity (2.02 meq/g). The morphology and structure of hydrogel and ion exchanger were studied using FTIR, SEM, XRD and TGA/DTA/DTG. The SEM study was followed by energy dispersive spectroscopy for elemental analysis. The ion exchanger was quite stable in various acids and bases at low concentration but it completely dissolved in acids and bases at high concentrations. Distribution studies showed that the synthesized ion exchanger had high selectivity for Pb²⁺ ions. Thus, the polymeric-inorganic hybrid material showed integration of both inorganic and organic characteristics within the composite material.     

Efficient synthesis of enwrapped CuO@rGO nanowire arrays to improve supercapacitor electrode performance

Journal of Applied Electrochemistry - There has been a growing interest in the performance of supercapacitors (SCs) based on Transition Metal Oxides (TMOs). It has recently been included in...     

Facile Suzuki coupling over ortho-metalated palladium(II) complex anchored on 2D-hexagonal mesoporous organosilica

Phenyl functionalized 2D-hexagonal mesoporous silica material has been synthesized by cationic/non-ionic mixed surfactant templating route. The phenyl group of this mesoporous material is further functionalized via nitration and then reduction of that nitro group to amino functionality, followed by Schiff base condensation and heterogenization of a palladium(II) complex, yielded an ortho-metalated palladium(II) complex anchored in a ordered mesoporous silica matrix. This supported metal complex acts as an efficient catalyst in the Suzuki cross-coupling reaction and shows high selectivity for the bi-aryl products.     

Synthesis of WO3 in nanoscale with the usage of sucrose ester microemulsion and CTAB micelle solution

WO₃ nanoparticles were successfully prepared using first the low temperature hydrolysis method and second the chemical reaction method in water-in-oil sucrose ester microemulsion consisting of S1570, 1-butanol, tetradecane and aqueous phase. In this study WO₃ nanoparticles also were prepared using the CTAB micelle solution. The resultant WO₃ nanoparticles have been investigated with X-ray diffraction (XRD), transmission electron microscopy (TEM), variable pressure scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). The shape and particles size of the resultant WO₃ nanoparticles from both methods in sucrose ester microemulsion show similar spherical shape and size range between 10 and 50 nm. The WO₃ nanoparticles prepared with the CTAB micelle solution show spherical shape with the size range average of 25-50 nm.     

Nanoscale silver cluster embedded in artificial heterogeneous matrix consisting of protein and sodium polyacrylate

Nanoscale silver cluster protected by sodium polyacrylate (PAA) was prepared through the reduction of aqueous silver nitrate solution containing PAA. PAA concentration was varied against a fixed concentration of silver nitrate to optimize the PAA to metal ratio, in which stable colloidal solution of silver nanoparticles of 7 ± 3 nm size could be obtained. These PAA-protected silver nanoparticles in clusters of nanoscale dimension (nanoclusters) were dispersed into the artificial heterogeneous matrix fabricated from aqueous solution of polyacrylate and protein (bovine serum albumin, BSA) by adjusting the pH in the acidic region. PAA-protected Ag-nanoparticle and Ag/PAA-BSA composites were characterized by UV-VIS spectroscopy and TEM.