Electro-Fenton treatment of synthetic organic dyes: Influence of operational parameters and kinetic study

This work investigates oxidative decolorization of two different dyes, Methylene blue and Titan yellow in aqueous solution using an environmentally friendly advanced electro-chemical oxidation (electro-Fenton) process. The effect of operating conditions like H₂O₂ concentration, current density, initial dye concentration was studied in a batch stirred cell. Individual decolorization decay kinetics for both dyes was investigated. The second-order absolute rate constants (L mol^?1 s^?1) between hydroxyl radical and dye have been calculated from experimental data by fitting it to the decolorization model. The apparent kinetic constants, k _app (s^?1) for Methylene blue and Titan yellow dye decolorization were also determined. The experimental data showed a good fit to the theoretical model, which can predict data in a wide range of % dye decolorization. This process also reduces COD of the dye solution, and the unit energy demand (UED) in kWh/kg COD removed for different electrical current has been reported.     

Synthesis,characterization, and properties of new siloxane grafted copolyimides

Three new siloxane containing grafted copolyimides have been prepared by one‐pot solution imidization technique. The polymers are made by the reaction of 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) with commercially available diamine 4,4′‐oxydianiline (ODA) with variation of silicon containing diamine, namely 3,5‐diaminobenzoate terminated polydimethylsiloxane (DBPDMS), as a comonomer to 10, 20, and 30 wt %. The films of the polymers were prepared by casting the polymer solution in dichloromethane. The polymers have been well‐characterized by GPC, IR, and NMR techniques. Thermal stabilities and decomposition behavior of the copolyimides were studied by DSC and TGA. The water contact angle values of the films indicate hydrophobic nature of the polymers. Thermal, flame retardant, mechanical, and surface properties of these polymers have been compared with the homopolyimide and with polyimides where polysiloxane is incorporated in the main chain. DSC revealed melting of the grafted siloxane chain at sub‐ambient temperature and a glass transition corresponding to the main polymer chain above 200°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of graphene and Ni-decorated graphene using flower petals as the precursor material

A simple method is reported for preparing graphene and nickel-decorated graphene from the petals of lotus and hibiscus flowers by heating the original petals and petals soaked in a nickel(II) chloride solution ranging 800–1600 °C under a flowing argon atmosphere for 0.5 h. The products have been characterized by scanning and transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Graphene prepared at high temperature (>1200 °C) is purer than that obtained at a lower temperature (800 °C). The presence of nickel has been found to have improved the quality of the graphene and electron density near the Fermi energy level.     

Anomalous electrical transport properties of PVA–Ag composite films below room temperature

The direct current (dc) and alternate current (ac) electrical transport property of polyvinyl alcohol–silver (PVA–Ag) composites has been investigated within a temperature range of 77 ≤ T ≤ 300 K and in the frequency range of 20 Hz to 1 MHz in the presence as well as in the absence of a transverse magnetic field up to 1 T. The dc conductivity follows variable range hopping model. The magnetoconductivity of the samples undergoes a change from negative to positive values with the incorporation of Ag in PVA matrix, which can be interpreted by the dominancy of the forward interference effect prevailing over the wave function shrinkage effect. The ac conductivity follows a power law of frequency, whereas the temperature dependence of frequency exponent “s” can be explained by correlated barrier hopping model. The dielectric behavior of the samples has been governed by the grain and interfacial grain boundary resistance and capacitance. Two activation behaviors are observed from the analysis of grain and interfacial grain boundary contributions. POLYM. COMPOS., 33:1941–1950, 2012. © 2012 Society of Plastics Engineers     

Effect of Temperature on Reliability Issues of Ferroelectric Dopant Segregated Schottky Barrier Tunnel Field Effect Transistor (Fe DS-SBTFET)

This paper addresses reliability issues associated with temperature of Ferroelectric Dopant Segregated Schottky Barrier Tunnel Field Effect Transistor (Fe DS-SBTFET). The simulated results are compared with Dopant Segregated Schottky Barrier TFET (DS-SBTFET). This is achieved by varying the operating temperature from 300 to 500 K. DC parameters such as I_ON/I_OFF ratio, drain current characteristics and subthreshold swing (SS) for a range of temperature have been highlighted. Moreover, the influence of temperature on various RF figure of merits such as gate capacitance (C_GG), intrinsic delay, cutoff frequency (f_T) etc. have been investigated. The device linearity has been analyzed by considering the effect of temperature variation on linearity parameters like g_m2, g_m3, 1-dB compression point, VIP₂, VIP₃ and IIP₃. The device characteristics get upgraded by the increase in cut-off frequency and reduction in intrinsic delay at elevated temperature.

     

The Effect of Addition of High-Melting Monoacylglycerol and Candelilla Wax on Pea and Faba Bean Protein Foam-Templated Oleogelation

Use of oleogels prepared from hydrocolloids has recently gained considerable attention as an alternative for trans and saturated fats. Lately, pulse proteins such as faba bean protein and pea protein have been successfully used to prepare oleogels using a foam-templated approach. Although the pulse proteins are healthy oleogelators, high oil loss and low quality of cake baked using pulse protein-stabilized oleogels due to its poor rheological properties challenged its use. The present study explored whether the addition of small amount of high-melting monoglyceride (MAG) or candelilla wax (CW) can be used to improve the oil binding capacity, rheological properties, and baking qualities of pulse protein-stabilized oleogels composed of 5% faba bean or pea protein concentrate with 0.25% xanthan gum foams. Different concentrations (0.5–3%) of MAG or CW were dissolved in canola oil at 80 °C, followed by addition into the freeze-dried protein-polysaccharide foams (pH 7) and quickly transferred to a refrigerator to facilitate the formation of oleogels. The crystallized additives were found to be reinforcing the protein foam network in the oleogels. With increase in concentration of CW and MAG, the oil binding capacity, firmness, cohesiveness, and storage moduli of the oleogels were increased. Oleogels with and without MAG or CW were then characterized and tested for their performance as a shortening replacer in model baked cakes. Findings showed improved textural properties of cake upon addition of MAG in the foam-templated oleogels, however, compared to the shortening, negative effect on cake hardness and chewiness was still observed with the oleogels.     

Poly(N-vinylpyrrolidone)-stabilized colloidal graphene-reinforced poly(ethylene-co-methyl acrylate) to mitigate electromagnetic radiation pollution

Polymer Bulletin - Electrically conducting flexible polymeric nanocomposite has been fabricated through wet mixing method where conducting inclusion was acoustically exfoliated pristine graphene...     

Enhanced near-infrared to green upconversion from Er3+-doped oxyfluoride glass and glass ceramics containing BaGdF5 nanocrystals

In this work, effect of glass composition as well as ceramization on visible and near-infrared (NIR) luminescence properties along with their decay dynamics of Er³⁺ ions has been compared considering two different oxyfluoride glasses yielding BaF₂ and BaGdF₅ nanocrystals. Both the glass systems have exhibited an intense normal and upconversion green emission under ultraviolet (378 nm) and NIR (978 nm) excitations, respectively. A remarkable enhancement of these emission intensities is observed for gadolinium-(Gd) containing glasses. Interestingly, NIR fluorescence intensity from Er³⁺ ions at 1540 nm has showed marginal decrease in gadolinium-containing glass which is attributed to occurrence of strong excited-state absorption (ESA) due to higher fluorine content ensuing an augmentation of upconversion green emission with a concomitant decrease in NIR emission. The quadratic dependence of upconversion green emission intensity on its pump power for all the samples revealed biphotonic absorption process from ground-state ⁴I_15/2 to the excited-state ⁴I_11/2 followed by ESA of second photon to the ⁴F_7/2 level. The intense green upconversion emission as well as enhanced NIR fluorescence lifetimes indicate the suitability of these glass/glass ceramics for upconversion lasers and amplification in the third telecom window.     

Impact of adhesive ingredients on adhesion between rubber and brass-plated steel wire in tire

Proficiency on underlying mechanism of rubber-metal adhesion has been increased significantly in the last few decades. Researchers have investigated the effect of various ingredients, such as hexamethoxymethyl melamine, resorcinol, cobalt stearate, and silica, on rubber-metal interface. The role of each ingredient on rubber-metal interfacial adhesion is still a subject of scrutiny. In this article, a typical belt skim compound of truck radial tire is selected and the effect of each adhesive ingredient on adhesion strength is explored. Out of these ingredients, the effect of cobalt stearate is found noteworthy. It has improved adhesion strength by 12% (without aging) and by 11% (humid-aged), respectively, over control compound. For detailed understanding of the effect of cobalt stearate on adhesion, scanning electron microscopy and energy dispersive spectroscopy are utilized to ascertain the rubber coverage and distribution of elements. X-ray photoelectron spectroscopy results helped us to understand the impact of Cu_XS layer depth on rubber-metal adhesion. The depth profile of the Cu_XS layer was found to be one of the dominant factors of rubber-metal adhesion retention. Thus, this study has made an attempt to find the impact of different adhesive ingredients on the formation of Cu_XS layer depth at rubber-metal interface and establish a correlation with adhesion strength simultaneously.     

Microstructure and mechanical performance examination of 3D printed acrylonitrile butadiene styrene thermoplastic parts

Fused filament fabrication (FFF) is a process where thermoplastic materials are heated to its melting point and then extruded, layer by layer, to create a three dimensional printed part. Printing occurs in a layered manner, which leads to creation of voids (air gaps) in the 3D printed parts. These voids act as centers for crack initiation, propagation and therefore resulting bulk mechanical properties are lower. This paper focuses on microstructural characterization and analysis of fused filament fabricated tensile test coupons made from acrylonitrile butadiene styrene polymer, at various design conditions. Comparable tensile modulus with injection molded specimens was obtained for FFF design condition that is, slice height (0.1778 mm), raster width (0.4064 mm), raster to raster air gap (−0.0015 mm), contour to raster air gap (−0.0508 mm) and raster angle (0°). Scanning electron microscope studies provided an understanding as to why FFF processed specimens yielded lower failure strain and an insight into the presence of intralayer voids in specimens having lower tensile modulus. The study confirmed that though bulk mechanicals were affected by the combined effect of inter, intra and interfacial voids, intravoids had a predominant influence.