Viscosity and Surface Tension of Benzene at Saturation Conditions from Surface Light Scattering

In the present study, the liquid viscosity and surface tension of benzene was determined at saturation conditions from surface light scattering (SLS) experiments between (283 and 393) K. Based on the application of the hydrodynamic theory for surface fluctuations at the vapor–liquid phase boundary which was successfully validated by the measurements, a simultaneous determination of liquid viscosity and surface tension with average relative expanded uncertainties (k = 2) of (1.0 and 0.8)% was achieved. Agreement between the measurement data and reference values available in the literature was found for the viscosity and in general also for the surface tension, where benzene constitutes a recommended reference material of relatively moderate surface tension values. All these findings demonstrate for a repeated time that SLS is a suitable method for the investigation of fluids including reference fluids such as benzene, which enables a sound representation of its surface tension, presumably as a result of a rather random molecular orientation at the surface. Overall, the experimental results from this work could contribute to an improved data situation for benzene, in particular with respect to providing viscosities and surface tensions at true saturation conditions.

Activity modelling of the solid–liquid equilibrium of deep eutectic solvents

Compared to conventional solvents used in the chemical industry, deep eutectic solvents (DESs) are considered as promising potentially sustainable solvents. DESs are binary mixtures and the resulting liquid mixture is characterized by a large melting point depression with respect to the melting temperatures of its constituents. The relative melting point depression becomes larger as the two components have stronger attractive interactions, resulting in non-ideal behavior. The compositional range over which such binary mixtures are liquids is set by the location of the solid–liquid phase boundary. Here we present experimental phase diagrams of various recent and new DESs that vary in the degree of non-ideality. We investigate whether thermodynamic models are able to describe the solid–liquid equilibria and focus on relating the parameters of these models to the non-ideal behavior, including asymmetric behavior of the activity coefficients. It is shown that the orthogonal Redlich–Kister-like polynomial (OP) expansion, including an additional first order term, provides an accurate description. This theory can be considered as an extension of regular solution theory and enables physical interpretation of the fit parameters.

Carbon Capture From Natural Gas via Polymeric Membranes

Polymeric membrane is a promising energy and an active alternative for conventional CO2 absorption column. The type of absorption liquid and operating parameters plays an efficient role in the ultimate absorption/stripping performance using gas-liquid membrane contactor. The gas flow rate has a significant effect on CO2 absorption performance; by contrast, it has no effect on stripping performance. Further, the CO2 absorption performance in membrane contactor could be enhanced by high liquid flow rates. The gas-liquid contact time was a key factor in enhancing the stripping flux at low temperature while liquid phase boundary layer thickness and associated mass transfer resistance is important at elevated temperature. By controlling the liquid phase velocity and the length of module at low temperature, better stripping performance can be achieved. The effect of liquid temperature on absorption performance in gas-liquid is not straightforward, since the liquid temperature cooperatively influences several factors.

Carbon Capture From Natural Gas via Polymeric Membranes

Polymeric membrane is a promising energy effective and an active alternative for conventional CO2 absorption column. The type of absorption liquid and operating parameters plays an efficient role in the ultimate absorption/stripping performance using gas-liquid membrane contactor. The gas flow rate has a significant effect on CO2 absorption performance, by contrast, it has no effect on stripping performance. Further the CO2 absorption performance in membrane contactor could be enhanced by high liquid flow rates. Because the gas–liquid contact time was a key factor to enhance the stripping flux at low temperature while liquid phase boundary layer thickness and associated mass transfer resistance is important at elevated temperature. So by controlling the liquid phase velocity and the length of module at low temperature better stripping performance can be achieved. The effect of liquid temperature on absorption performance in gas-liquid is not straightforward, since the liquid temperature cooperatively influence several factors.

Probing Phase Transitions with Supersonic Beams – A Joint Experimental and Theoretical Study

Pulsed, supersonic beams of propane have been investigated by mass-resolved time-of-flight measurements as a function of source pressure, covering sub- and supercritical expansion conditions. The experimental observation of a pronounced change in the terminal flow velocity is explained in terms of a thermodynamic model that is capable of describing the expansion of gases, liquids, and supercritical fluids; in particular, it allows the treatment of the vapor-liquid phase boundary and the critical point. Its major prediction is a distinct pressure dependence of the mean terminal flow velocity that is caused by condensation both in the stagnation reservoir and during the jet expansion. The agreement with experimental data is excellent.

Rate and Mechanism of Reduction-Dissolution of Chromite in Liquid Slags

The dissolution of chromite from the Bushveld Complex of South Africa in liquid slags was studied in the temperature range 1550° to 1665°C under argon gas. The slag compositions were similar to those of ferrochromium production and stainless steel making. Empirical relations between the slag composition and the dissolution of chromite were established through the use of a statistical model. The dissolution process was investigated by using the rotating cylinder technique and measured by the chemical analysis of the samples taken from the melt and the SEM-EDAX analysis of the reacted chromite cylinder samples. The chromite grains were depleted in iron and chromium as the dissolution progressed, leaving behind an alumina and magnesia rich spinel. The experimental data was evaluated by using kinetic models and mass transfer coefficients of chromium, iron and oxygen ions through the phase boundary between the solid chromite cylinder and the liquid slag were determined.The dissolution of chromite in liquid slags increases with increasing stirring rate. SEM-EDAX studies on the reacted chromite cylinders showed that coring took place within the chromite grains subjected to dissolution for sufficient length of time. Chromium and iron concentrations in the chromite were decreasing from the centre towards the surface of the grains while aluminum and magnesium contents were increasing at the edges compared to the centre of the chromite grains. Furthermore, the slag rich in alumina and magnesia diffuses in bulk into the chromite with a net result of increase in the concentration of these elements.The rate of dissolution of chromite in liquid slags was found to be controlled by the mass transfer of oxygen ions (O2−) through the liquid phase boundary between the solid chromite and the liquid slag. The activation energy for the mass transfer of O2− ions was calculated as 30.61 kCal/mol (128.07 kJ/mol).