Solvent extraction — the challenges of a “mature” technology

The solvent extraction area is perceived by some chemical engineers as being mature and fully developed. The present review shows that this is not the case. Many chemical engineering problems must be solved before equipment can be confidently designed from first principles. The review also outlines progress in extraction process chemistry, and in new techniques such as membrane extraction.     

The “alexandrite effect” in gemstones

The term “alexandrite effect” is used in gemology to describe a distinct change of color appearance when a gemstone is switched from daylight to incandescent light. Gemstones that exhibit the alexandrite effect can actually be divided into four categories based upon the value of the calculated absolute hue-angle change of the material under different pairs of illuminants. the alexandrite effect is a non-color-constancy phenomenon. It can be explained by a combination of both chromaticity adaptations to the different light sources, and vision system responses to the spectral distribution of the light emitted by alexandrite effect gemstones when they are illuminated alternatively by the different light sources.     

Mossgas “gas-to-liquid” diesel fuels—an environmentally friendly option

This paper presents a brief summary and comparison of heavy vehicle emissions using Mossgas synthetically derived diesel as opposed to a US Regular Federal 49-state number 2 diesel fuel. A series of engine dynamometer and heavy-duty chassis dynamometer tests were performed at West Virginia University early in 1999.

The Mossgas gas-to-liquid (GTL) low sulphur diesel fuel is produced primarily by the conversion of olefins to distillate (COD) process in conjunction with a high temperature Fisher–Tropsch technology process.

Findings were that there were significant emission benefits when using Mossgas GTL diesel fuel. Oxides of nitrogen (NO_x) and particulate matter (PM) emissions were substantially lower when compared to normal fossil fuel-derived diesel. Additionally the benefits have been found to cut across different engine technologies, various test cycles, engine age (1991–1999), as with or without engine aftertreatment catalysts.

The Mossgas GTL diesel meets the world-wide challenge to produce environmentally friendly transportation fuels and sets the benchmark for future diesel specifications. Accordingly Mossgas has petitioned the US Department of Energy to register this fuel as an alternative fuel under its EPACT program [1 and 2].     

Fatty acids characterization in “Alicante” and “Jijona” nougat bars,two Spanish sweets

In this work the fatty acids in two typical Spanish sweets have been characterized: Alicante and Jijona nougat bars, using gas chromatography with a flame-ionization detector. The majority of the fatty acids in these two sweets are unsaturated, and only a low proportion is saturated, which turns them into a type of food with low influence on cholesterol resulting in low atherogenic power, due to the low amount of saturated fatty acids, which is far from constituting 1/3 of the total sum of fatty acids granted by a diet, a limit that has been advised by a great number of International Scientific Committees.     

“HETEROGENIZING” HOMOGENEOUS CATALYSTS

For many years, it has been customary to classify catalysts as “homogeneous” or “heterogeneous.” The former commonly operate through the formation of “intermediate compounds,” and the latter, by adsorption of the reactants on the catalyst surface. The line between the two is a fine one, for the distinction between adsorption and compound formation is not at all clear, and seems to be becoming less and less clear as we learn more about adsorption. In recent years, several writers [l-7] have stressed the point that there is a good deal of overlap between homogeneous and heterogeneous catalysis. Experimental evidence supporting this point of view is accumulating, and while we are not prepared to say that there is no distinction, we can say with certainty that many homogeneous catalysts can be converted into heterogeneous ones, retaining the advantages of great activity and selectivity inherent in homogeneity and, at the same time, assuming the ready recovery which is the great advantage of heterogenity. In practice, of course, the matter is not quite that simple, for other factors must be considered. On the whole, however, many advantages have been found in the use of heterogenized homogeneous catalysts.     

Theory of “Cohesive” vs “Adhesive” Separation in an Adhering System

It is shown that there is limited validitity to the doctrine that true interfacial separation, in an adhering system, is highly improbable. An analysis employing the Griffith-Irwin crack theory yields these results: The important parameters are, difference in elastic moduli, ΔE; differences in g, the energy dissipation per unit crack extension; thickness, Δ₁ or δ₂, of the region where dissipation occurs; and the presence or absence of strong interfacial bonds. If the forces across the interface are appreciably weaker than the cohesive forces in either phase, there is a strong minimum in g at the interface. For flaws of equal size, an interfacial flaw will be the site of initiation of failure. If strong interfacial bonds are present, then if Δg and ΔE have the same sign, failure is most probable, deep within one phase. If Δg and ΔE have opposite signs, failure may be initiated, and may propagate, at a distance δ from the interface, in the phase with lower g. This may be mistaken for weak-boundary layer failure.     

Toward “Rubbery” nanoparticles

The synthesis of electrically Conducting Natural Rubber (CNR) nanoparticles from natural rubber (cis 1, 4 polyisoprene) by a simple chemical doping technique is reported for the first time. Much before the establishment of conjugation as a precondition for polymers to be conducting a typical nonconjugated polymer like cis 1,4 polyisoprene was shown to develop intrinsic conductivity on doping. However, the possibility of developing conducting nanoparticles of natural rubber by doping has never been explored. Doping of natural rubber solution with Antimony pentchloride is found to lead to the formation of nanosized rubber particles with improved thermal stability and lower degradation characteristics than that of pristine rubber. Transmission electron microscopy and Dynamic Light Scattering experiments revealed a highly uniform dispersion of the particles with sizes in the range of 4 nm. The doped nanoparticles are found to retain “rubbery” properties of natural rubber and therefore these can be rightly termed as Rubber Nano particles. The development of nanoparticles of rubber assumes great significance in that it would lead to hitherto unknown applications for natural rubber in micro applications‐like sensors, and optoelectronics devices to macro applications such as compatible reinforcing fillers for elastomers and plastics to replace conventional fillers like carbon particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Eggshell reinforced biocomposite—An advanced “green” alternative structural material

The need for bio‐based polymers as substitutes to recalcitrant petroleum sourced plastics is ever growing, because of increase in demand globally. Eggshell nanopowder (ENP) prepared using mechanical attrition and ultrasound irradiation was used to infuse a bio‐based polymer [Super Sap 100/1000 epoxy (SSE)] for possible enhancement of its mechanical properties. The ENP, neat SSE and SSE/ENP composites were characterized using X‐ray Diffraction, Transmission Electron Microscopy (TEM), Energy dispersive spectroscopy (EDS), Scanning Electron Microscopy, Thermogravimetic Analysis (TGA), Dynamic Mechanical Analysis (DMA), Thermomechanical Analysis (TMA) and flexure analysis. TEM and EDS analysis showed evidence of ENP in the SSE matrix whiles DMA and TMA analysis revealed significant improvements (7–22%) in the storage moduli and (3–17%) in coefficient of thermal expansion (CTE) respectively. Also, major delay in 5% decomposition temperatures and increases in char yields were observed in TGA analysis. The flexure strength, modulus, and toughness significantly improved by 6–31%, 11–37%, and 10–36%, respectively. Microstructure of fractured surfaces showed deflected crack paths which contributed to improve toughness. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43124.