Semi-clathrate hydrates are members of the class of clathrate compounds. In comparison with clathrate hydrates, where the networks are formed only by H2O molecules, the networks of semi-clathrate hydrates are formed by mixtures of H2O and quaternary ammonium salts (QASs). The addition of QASs to the solution enables to improve the formation of semi-clathrate hydrates at much milder conditions comparing to clathrate hydrates. In this work, we study the phase equilibria of semi-clathrate hydrates of CH4, CO2, and N2gas in an aqueous solution of tetra-n-butyl ammonium fluoride (TBAF). An extension of the Chen–Guo model is proposed as a thermodynamic model. The Peng–Robinson equation of state (PREOS) was applied to calculate the fugacity of the gas phase and in order to determine the water activity in the presence of TBAF, a correlation between the system temperature, the TBAF mass fraction, and the nature of the guest molecules has been used. These equations were solved simultaneously and through optimizing tuning parameters via the Nelder–Mead simplex algorithm. The results are compared to experimental data and good agreement is observed.
Two general and simple models, a group contribution correlation (model I) and an empirical relation (model II), were proposed to predict the solubility of H2S in methylimidazolium based ionic liquids (ILs) over wide range of temperatures (303.15‐363.15 K) and pressures (60.8‐2016.8 kPa). The constants of the suggested functionality relations were found via the Nelder‐Mead simplex algorithm. Both correlations were trained with 407 data points of H2S solubility in 9 methylimidazolium based ILs and tested through 121 H2S solubility data points of 3 different methylimidazolium based ILs to ensure generality. A comprehensive statistical evaluation showed that both suggested correlations are vigorous and have satisfactory error trends. The dataset was subjected to a statistical outlier diagnostic test and the validity of the database was confirmed. In addition, the sensitivity analysis revealed that the experimental data and both models have the same responses toward pressure and temperature, which indicates the reliability of the proposed correlations.
Polyether block amide (PEBA) polymeric layers were prepared on polysulfone (PSf) supports via dip coating. The effects of the coating speed and the solution concentration on the membrane performance were studied. The membranes were characterized by scanning electron microscopy, Fourier transform infrared spectra, and gas permeation. The coating speed was adjusted in the range of 0.32–0.48 cm s−1 at a solution concentration of 3 wt % to obtain suitable membranes so that the CO2 permeance and the CO2/N2 selectivity increased by more than three and ten times, respectively, compared to other speed ranges. Statistical analysis also showed that the effect of the interaction between solution concentration and coating speed is more considerable than the separate effects of both factors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.