جستجوی مقالات مرتبط با کلیدواژه "phase diagram" در نشریات گروه "شیمی"

Solubility and micelle formation of cetyltrimethylammonium bromide CTAB andcetylpyridinium chloride CPC surfactants in aqueous solution have been studied bytensiometry, conductometry, and dynamic light scattering (DLS) in vicinity ofKrafft point. Parameters such as the critical micelle concentration (cmc), Kraffttemperature (Tk), average micelle aggregation number (n) and phase diagram ofsurfactants in water were determined and thermodynamic micellization process wasdiscussed in light of enthalpy and entropy contributions. It is shown that unlikeCTAB surfactants which exhibit incubation time independent micellar behavior,CPC surfactants show two solubility curves around Krafft temperature leading tocomplex temperature conductivity concentration plots. The change of solubility andcmc with temperature were investigated according to the mass actionthermodynamic model and permit to extract free energies of micelles formation andto draw partial phase diagram for each surfactant. Dynamic light scatteringtechniques shows that according to the incubation conditions, different populationof micelles can be released in the vicinity of Krafft temperature.

The salt needs are getting bigger from year to year, and also the quality of the salt. Therefore, further research is needed to improve the results of previous studies. It also determines the best conditions for separating each component at the time of deposition. The research procedure is the correlation method between the number of ions and specific gravity at temperatures of 40, 65, and 100ºC. The first method is the process of producing salt from Madura seawater with temperature and density settings. From various pictures and tables in the first method, it can be seen at temperatures of 40, 65, and 100 oC, it shows that NaCl has increased before increasing by 25 oBe even after 29 oBe. After that, it shows the degree of decrease at the final 65oC, namely at 25oBe (56.98) and decreases at 29oBe (56.89). However, it can be attempted so that NaCl can be obtained in large quantities at 25-29oBe, with CaSO4 and MgSO4 to a minimum.

In this study, the liquid-liquid equilibrium (LLE) in the aqueous two-phase system (ATPS) formed by polyethylene glycol (PEG1500 and PEG6000) and magnesium sulfate is investigated. The experimental measurements were performed at temperature of 298.15 K and pH values of 3.60, 5.00, 6.67. Densities and refractive indices of the mixtures were first measured to obtain the compositions from the plotted tie lines. The effects of pH and molecular mass of polymers on the binodal curve, tie lines length (TLL) and slope of tie line (STL) have been examined. It was found the pH values and molecular weight rise the heterogeneous region for each system. The binodal curve was fitted to the Merchuk and the Pirdashti equations. The Othmer-Tobias as well as the Bancroft equations were subsequently selected to correlate the compositions of the tie lines at equilibrium where the fitted parameters are derived. In addition, the Guan’s equation was utilized to correlate the experimental binodal curves. Finally, the effectively excluded volume (EEV) was determined and the values were found to increase with pH.

The study obtained the Liquid – Liquid Equilibrium (LLE) for Aqueous Two-Phase Systems (ATPSs) containing poly (vinyl pyrrolidone) (PVP) (10000, 24000, and 40000) and zinc sulfate at 298.15 K. The phase area is expanded according to the increased molecular weight of the polymer. Density and refractive indices were employed as the physical properties for obtaining phase composition and end of tie-line evaluations. The effect of molecular weight is discussed in relation to binodal curve, Tie-Line Length (TLL), and Slope of Tie Line (STL) determinations. Following the increase in polymer molecular weight value, the TLL increased and STL slightly decreased. Accordingly, Pirdashti’s equation was used to correlate binodal curve evaluations of these systems. Furthermore, tie-line data points were correlated by Othmer-Tobias, Hand, and Bancroft equations. Finally, the study determined the Effective Excluded Volume (EEV) of salt into the PVP aqueous solution.

Constructing phase diagram and its subsequent quality lines for lean gas condensate reservoirs is always crucial and challenging topic in reservoir fluid studies. Due to small amounts of liquid drop-outs in lean gas condensates at reservoir conditions, full experimental tracking of phase diagram and its relevant quality lines is almost impossible for lean gas condensates. On the other hand, EOS models of reservoir fluid characterization softwares are always unable to estimate condensed liquid drop-outs at different pressures and temperatures precisely. This study aims to present a commingled experimental-simulation method which was designed to pinpoint and keep track full phase diagram with correspondent quality lines for a lean gas condensate fluid.