Chemical Reactivity of Tributyl Phosphate with Selected Solvent Extraction Reagents

It has recently been shown that Cyanex 272 can react with tributyl phosphate (TBP) to form the corresponding butyl ester species under both commercial and anhydrous operating conditions. The present work found that acidic organic extractants MEHPA, DEHPA, Ionquest 801, Cyanex 302, Cyanex 301, and decanoic acid also react with TBP to form the corresponding butyl ester species and dibutyl phosphate under anhydrous conditions at 65°C, whereas non-acidic reagents Alamine 308, LIX 84, LIX 63, and Acorga M5640 do not. Excluding MEHPA, the rate of ester formation appears inversely correlated with the pKa of the organic acid used.     

Modelling the formation of high aspect CdSe quantum wires: axial-growth versus oriented-attachment mechanisms

Following the recent low temperature synthesis of high quality and single crystal CdSe quantum nanowires, we have used a thermodynamic model to investigate the plausibility of axial-growth and oriented-attachment formation mechanisms. Using surface energies for clean and alkylamine-passivated CdSe surfaces reported elsewhere by Manna et al (2005 J. Phys. Chem. B 109 6183), we have compared equilibrium and metastable shapes of CdSe nanowires as a function of aspect ratio and axial orientation for different degrees of surface passivation. In general, the theoretical results support the oriented-attachment of low aspect quantum dots or nanorods, followed by coalescence to form high aspect [Formula: see text] quantum wires.     

Reconfigurable terminals for mobile communication systems

Mobile phones of the future will be the access terminals to many different types of service. This will mean that they must be able to reconfigure themselves to support the differing service requirements placed upon them. At the root of this ability to reconfigure must be components and architectures that allow such flexibility, and so the key objective of the work programme on terminals within the Virtual Centre of Excellence in Mobile and Personal Communications (Mobile VCE) has been the design, definition and performance evaluation of key components and architectures for future generation reconfigurable terminals     

Numerical technique to correct for weak acid errors in gran function analysis of titration data

Ordinary Gran function analysis of titration data from samples which contain weak acids results in overestimates of strong acid acidity and underestimates of weak acid acidity. A numerical technique is developed which solves a general acid-base model from titration data. The technique is an iterative procedure which adjusts Gran functions for the effect of the weak acid components. The model and the method are validated with simulated titration data and laboratory data from test solutions.     

Tailoring 3D Printed Micro-Structured Carbons for Adsorption

The manufacture of tailored carbon-based adsorbent structures with exceptionally low-pressure drops and improved kinetics using stereolithographic 3D printing is presented. Adsorbent structures are printed from commercial resins with square, circular, and hexagonal cross-sectional microchannels. These structures can reduce energy use by 50–95% compared to conventional carbon-packed beds. The activated 3D printed carbon achieves Brunauer–Emmett–Teller surface areas over 1000 m² g⁻¹ and shows outstanding butane adsorption capacities, over twice the capacity of a commercial carbon and a comparable capacity to phenolic-based carbons. The structures also show excellent uptakes of cyclohexane, up to 0.62 g g⁻¹ in a saturated feed. The introduction of complex axial geometries including spirals and chevrons enable superior adsorption kinetics and premature breakthrough of contaminants at high gas flow rates. These results demonstrate the success of intelligent manufacturing of low-pressure drop, high-capacity micro-structured adsorbents, allowing for the development of gas separation technologies for applications such as greenhouse gas removal and respiratory protection.