David W. Rooney

An investigation of the radiochemical stability of ionic liquids

Ionic liquids have been considered for their potential applications within the nuclear fuel cycle. If ionic liquids are to be successful in their application as solvents for highly radioactive materials in any future process, there will be a requirement for them to be robust to high radiation doses. A preliminary assessment of the radiation stability of 1,3-dialkylimidazolium cation based ionic liquids containing nitrate and chloride anions has been performed. The results of radiolysis studies are reported, in which the samples were exposed to alpha radiation from a tandem Van der Graaff generator, beta radiation from a linear accelerator and gamma radiation from cobalt 60 sources. These results suggest that their stability is similar to that of benzene and that they are much more stable than mixtures of tributylphosphate and odourless kerosene under similar irradiation conditions. The radiolysis of 1,3-dialkylimidazolium cation based ionic liquids reflects their combination nof the properties of a salt, an alkane and an aromatic. They appear to be relatively radiation resistant and there is certainly no major decomposition of the organic component.

Thermophysical properties of ionic liquids

Low melting point salts which are often classified as ionic liquids have received significant attention from research groups and industry for a range of novel applications. Many of these require a thorough knowledge of the thermophysical properties of the pure fluids and their mixtures. Despite this need, the necessary experimental data for many properties is scarce and often inconsistent between the various sources. By using accurate data, predictive physical models can be developed which are highly useful and some would consider essential if ionic liquids are to realize their full potential. This is particularly true if one can use them to design new ionic liquids which maximize key desired attributes. Therefore there is a growing interest in the ability to predict the physical properties and behavior of ionic liquids from simple structural information either by using group contribution methods or directly from computer simulations where recent advances in computational techniques are providing insight into physical processes within these fluids. Given the importance of these properties this review will discuss the recent advances in our understanding, prediction and correlation of selected ionic liquid physical properties.

Marked enantioselectivity enhancements for Diels–Alder reactions in ionic liquids catalysed by platinum diphosphine complexes

Asymmetric Diels–Alder reactions using platinum complexes of BINAP, or of conformationally flexible NUPHOS-type diphosphines, have been compared in dichloromethane and selected ionic liquids. Significant enhancements in the enantioselectivity (Δee n ≈ 20%), as well as reaction rate, were achieved in ionic liquids compared with the organic media.

Particle and droplet trajectories in a non-linear electrical field

Abstract In this paper we describe a new approach in which finite element analysis is applied to predict charged particle trajectories in a liquid continuum across which a non-linear electrical field is applied. The equations of motion and equations describing the distribution of the electrical field in the entire contactor are solved simultaneously and thus yield the trajectories of individual particles emerging from a single charged nozzle. The predictions are compared with experimentally determined trajectories and good agreement is demonstrated. The work is regarded as a starting point for the quantitative description of charged droplet motion in a liquid–liquid contactor and the associated prediction of droplet hold-up and mass transfer using a similar approach.

The energetics of tetrahydrocarbazole aromatization over Pd(111): A computational analysis

The carbazole moiety is a component of many important pharmaceuticals including anticancer and anti-HIV agents and is commonly utilized in the production of modern polymeric materials with novel photophysical and electronic properties. Simple carbazoles are generally produced via the aromatization of the respective tetrahydrocarbazole (THCZ). In this work, density functional theory calculations are used to model the reaction pathway of tetrahydrocarbazole aromatization over Pd(111). The geometry of each of the intermediate surface species has been determined and how each structure interacts with the metal surface addressed. The reaction energies and barriers of each of the elementary surface reactions have also been calculated, and a detailed analysis of the energetic trends performed. Our calculations have shown that the surface intermediates remain fixed to the surface via the aromatic ring in a manner similar to that of THCZ. Moreover, the aliphatic ring becomes progressively more planer with the dissociation of each subsequent hydrogen atom. Analysis of the reaction energy profile has revealed that the trend in reaction barriers is determined by the two factors: (i) the strength of the dissociating ring-H bond and (ii) the subsequent gain in energy due to the geometric relaxation of the aliphatic ring.

A finite element model of enzymatically catalyzed hydrolysis in an electrostatic spray reactor

Abstract The overall goal of the work was to determine the effect of the electrically driven hydrodynamics on transport processes and the reaction rate at the interface. The theoretical approach adopted here was based upon the fundamental relationships governing the electrical field, the equations of motion for both continuous and dispersed phases (with mutual coupling) and most importantly, the mass transfer between the phases with the accompanying enzymatic reaction. Michaelis–Menten kinetics were used for evaluating the reaction rate and its inter-relationship with the mass transport at the interface. A new algorithm was implemented using original FEM software involving the Lagrangian approach for both the particle/droplet tracking on one hand, and for the convection-dominated transport equations involving the cloud model on the other. The latter was further developed to account for the mass transport between the continuous and the dispersed phases. The model was verified using our own experimental data.