A study of changes in the heat capacity of carbon nanotube-based ionanofluids prepared from a series of imidazolium ionic liquids.

Ionanofluids (INFs), nanoparticles dispersed into a base fluid, e.g. an ionic liquid, are a novel class of alternative heat transfer fluids. Addition of nanoparticles to a base ionic liquid is the prime reason for an enhancement in the thermophysical properties of ionanofluids. However, due to very limited research on ionanofluids, further studies are required to understand changes in the isobaric heat capacity of ionanofluids as a function of size of cations of the base ionic liquid structure and concentration of nanoparticles. Herein, isobaric heat capacity was measured as a function of temperature for the prepared ionanofluid samples from a series of imidazolium ionic liquids and multi walled carbon nanotubes (MWCNTs). Moreover, the influence of the size of cations on the isobaric heat capacity enhancement mechanism and the stability of ionanofluid samples was studied. Furthermore, experimental isobaric heat capacity data were assessed by a novel non-statistical data analysis method named mathematical gnostics (MG). MG marginal analysis was used to evaluate the most probable values from the measured data set. A robust linear regression along a gnostic influence function was also used to find the best fit to correlate the measured data.

Evaluation of a Conceptual Model for Gas-Particle Partitioning of Polycyclic Aromatic Hydrocarbons Using Polyparameter Linear Free Energy Relationships.

A model for gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs) was evaluated using polyparameter linear free energy relationships (ppLFERs) following a multiphase aerosol scenario. The model differentiates between various organic (i.e., liquid water-soluble (WS)/organic soluble (OS) organic matter (OM), and solid/semisolid organic polymers) and inorganic phases of the particulate matter (PM). Dimethyl sulfoxide and polyurethane were assigned as surrogates to simulate absorption into the above-mentioned organic phases, respectively, whereas soot, ammonium sulfate, and ammonium chloride simulated adsorption processes onto PM. The model was tested for gas and PM samples collected from urban and nonurban sites in Europe and the Mediterranean, and the output was compared with those calculated using single-parameter linear free energy relationship (spLFER) models, namely Junge-Pankow, Finizio, and Dachs-Eisenreich. The ppLFER model on average predicted 96 ± 3% of the observed partitioning constants for semivolatile PAHs, fluoranthene, and pyrene, within 1 order of magnitude accuracy with root-mean-square errors (RMSE) of 0.35-0.59 across the sites. This was a substantial improvement compared to Finizio and Dachs-Eisenreich models (37 ± 17 and 46 ± 18% and RMSE of 1.03-1.40 and 0.94-1.36, respectively). The Junge-Pankow model performed better among spLFERs but at the same time showed an overall tendency for overestimating the partitioning constants. The ppLFER model demonstrated the best overall performance without indicating a substantial intersite variability. The ppLFER analysis with the parametrization applied in this study suggests that the absorption into WSOSOM could dominate the overall partitioning process, while adsorption onto salts could be neglected.

Phase behaviour, interactions, and structural studies of (amines+ionic liquids) binary mixtures.

We present a study on the phase equilibrium behaviour of binary mixtures containing two 1-alkyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide-based ionic liquids, [C(n)mim] [NTf(2)] (n=2 and 4), mixed with diethylamine or triethylamine as a function of temperature and composition using different experimental techniques. Based on this work, two systems showing an LCST and one system with a possible hourglass shape are measured. Their phase behaviours are then correlated and predicted by using Flory-Huggins equations and the UNIQUAC method implemented in Aspen. The potential of the COSMO-RS methodology to predict the phase equilibria was also tested for the binary systems studied. However, this methodology is unable to predict the trends obtained experimentally, limiting its use for systems involving amines in ionic liquids. The liquid-state structure of the binary mixture ([C(2)mim] [NTf(2)]+diethylamine) is also investigated by molecular dynamics simulation and neutron diffraction. Finally, the absorption of gaseous ethane by the ([C(2)mim][NTf(2)]+diethylamine) binary mixture is determined and compared with that observed in the pure solvents.