Molecular dynamics (MD) calculations have been performed to determine equilibrium structure and properties of systems modeling supercritical (SC) water and SC aqueous solutions at two states near the critical point using the simple point charge (SPC) potential model of Berendsen et al. for water. Both thermodynamic and dielectric properties from the simulations for pure water are accurate in co...

The cleavage of C-S linkages plays a key role in fuel processing and organic geochemistry. Water is known to affect these processes, and several hypotheses have been proposed, but the mechanism has been elusive. Here we use both experiment and theory to demonstrate that supercritical water reacts with intermediates formed during alkyl sulfide decomposition. During hexyl sulfide decomposition in...

Proposed carbon dioxide sequestration scenarios in sedimentary reservoirs require investigation into the interactions between supercritical carbon dioxide, brines, and the mineral phases found in the basin and overlying caprock. Molecular simulations can help to understand the partitioning of metal cations between aqueous solutions and supercritical carbon dioxide where limited experimental dat...

It is well established that at ambient and supercooled conditions water can be described as a percolating network of H bonds. This work is aimed at identifying, by neutron diffraction experiments combined with computer simulations, a percolation line in supercritical water, where the extension of the H-bond network is in question. It is found that in real supercritical water liquidlike states a...

Supercritical carbon dioxide extraction (scCO2) is chosen to a treatment to remove lignin and to peel off outer cell wall layers to expose S2 layer of aspen wood fibres. The aim is to find an effective and environmentally friendly method to advance the fibrillation of the BCTMP pulp. The effects of the treatment are analysed by using scanning electron microscopy (SEM). The chemicals used togeth...

Drill mud is a fluid which is used in oil extraction industries in order to cool and lubricate the drill bit. Due to containing numerous toxic components, it is considered as a hazardous waste which must be treated before discharging to the environment. Current separation techniques for drill cutting treatment can be categorized into three main categories of physical (dewatering), physiochemica...

We examine the structure of the hydrated Ti(IV) complex under both ambient and supercritical conditions using first-principles molecular dynamics. We find that an unanticipated fivefold coordination of Ti(IV) is favoured under ambient conditions, with rapid interconversions between square pyramidal and trigonal bipyramidal structures. At supercritical conditions the Ti coordination increases fr...

We have used Gibbs ensemble and histogram-reweighting Monte Carlo techniques to obtain the phase behavior of water and aqueous mixtures at high pressures. These calculations are relevant for the design of high-pressure separation processes, such as supercritical fluid extraction and supercritical water oxidation. In particular, we have obtained the phase behavior of several simple point charge ...