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.     

Highly efficient photocatalytic degradation of methylene blue using carbonaceous WO<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> composites

Recent improvements in the performance of photocatalysts made it possible to tackle pollution through environment friendly methods. This study investigates the modification of the photocatalytic activity of TiO₂ by employing WO₃ and conductive polymers, namely, polyaniline (Pani) and polypyrrole (Ppy). Basing on our previous improvement of TiO₂ using a conductive polymer and activated carbon (AC), this study determines the activated carbon forms of TiO₂. The prepared composites are characterized using X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, Brunauer–Emmet–Teller, and UV–Vis spectroscopy. The specific surface area of the mesoporous composites is as follows: WO₃/TiO₂·AC (Pani) > WO₃/TiO₂·AC (Ppy) > WO₃/TiO₂·Pani > WO₃/TiO₂·Ppy (127 > 98 > 68 > 44 m² g^?1), which exhibited a similar trend to the photocatalytic performances (100 > 95 > 91 > 72 % conversion rate). This result could be attributed to higher porosity, surge of charge separation, and photo-responding range extension induced by the synergistic effect of WO₃, conducting polymers, and TiO₂ in the samples.     

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.     

Technical note The effect of rate of decay of rain path profile on microwave communication

The attenuation of radio waves due to rain can be predicted with a good degree of accuracy, provided the rain rate characteristics over the entire path of propagation are known. The attenuation due to rain is usually deduced on the basis of point rain rate, which can lead to inaccuracy in the estimation of attenuation. We use the concept of rate of decay of rain path profile to estimate the attenuation due to rain. The attenuation has been deduced at 11GHz and 13.4 GHz for 56 elevation angle by using the theory of decay rate of rain path profile, its controlling factor, gamma, and rain rate distribution over Delhi, a tropical station in India. The theoretically-estimated attenuation is compared with observed values, as well as with values obtained using the International Radio Consultative Committee (CCIR) method. The CCIR model is found to overestimate the attenuation.     

Effect of amount, size, and spatial distribution of intermetallics on incipient localization during plastic deformation

Virtual microstructures having a systematic variation of amount, mean size, standard deviation of size, and spatial arrangement of intermetallics have been synthesized, and their deformation behavior in uniaxial tension has been evaluated using finite element analysis. Four spatial arrangements of intermetallics have been considered in this work, namely: random, clustered, and two-ordered structures. Various mathematical quantities have been developed to quantify the severity of deformation including plastic work density distribution (PWDD), percentile work-density volume criterion (PWC), and percentile stress volume criterion (PSC). This approach eliminates the need for an external trigger in FEA to achieve localization. The method developed has led to a better understanding of the effect of different microstructural attributes on the process of deformation. This has resulted in guidelines for optimizing the microstructure to minimize material damage and thereby maximize ductility.