جستجوی مقالات مرتبط با کلیدواژه « حلالیت » در نشریات گروه « فنی و مهندسی »

As the oil is extracted from reservoir starts, the pressure of the reservoir decreases. Hence, the well needs to use methods of increased harvesting. The method of increasing harvesting through the injection of CO2 gas is a well-known technology, and this method has been economically justified. For this goal, to maximize recovery, sometimes the combination of two methods of water and gas injection, known as the WAG method, is used. Furthermore, in the mixed state, CO2 causes the viscosity of crude oil to decrease. Reduction in viscosity facilitated the flow of oil into production wells. Additionally, the tank pressure rose due to unmixed CO2. The quantity of oil extracted rises as a result of the interaction of these variables. In this research study, the effect of additives was studied and investigated in different conditions, and parameters include type of additive, additive concentration, process pressure, and temperature, and the effects of these parameters on kinetics and the solubility of CO2 were investigated. The inhibitory effect of tetrabutylammonium hydroxide was very effective in preventing the formation of CO2 gas hydrate compared to the pure system. For this purpose, Design Expert software was used to design the experiment. In addition, the presence of TMAH salt extends the induction time of hydrate formation, and the system with the highest concentration of this addition has the most optimal increase in induction time, according to the statistical analysis of the parameters impacting the induction time of hydrate formation.

 Low solubility of pharmaceutical compounds leads to increasing the required drug dosage and their side effects as well as reducing their therapeutic efficiency. Producing pharmaceutical micro/nanoparticles with homogenous morphology and narrow size distribution is one of the confirmed approaches for their solubility enhancement. So, selection and designing an appropriate method for this purpose is one of the most important research fields of pharmaceutical industries. Over the past three decades, supercritical carbon dioxide (sc-CO2) based methods as a clean and green technologies have been received much attention in various fields of pharmaceutical industries. However, in order to design and development of these methods for producing micro/nanoparticles, determination of the compounds solubility in sc-CO2 is essential.

 In this research, well known empirical models (Adachi and Lu, Ch and Madras, Hozahzbr et al., Bian et al., Mendez-Santiago-Teja), as well as the artificial neural network model were applied for prediction the solubility of six anticancer drugs (Aprepitant, 5-Fluorouracil, Imatinib mesylate, Capecitabine, Letrozole, Docetaxel) in sc-CO2.  In order to evaluate the accuracy of these models, a comparison was made between the calculated solubility values and the available experimental data, based on several statistical criteria, such as the average absolute relative deviation (AARD%), adjusted correlation coefficient (Radj) and F-value.

According to obtained results, Adachi and Lu model with AARD% value of 12.12% and Radj value of 0.97 provided acceptable results for solubility of mentioned drugs in sc-CO2. Also, in comparison between empirical and artificial neural network models, the latter one with AARD% value of 1.65% and Radj value of 0.9960 was appointed as the most appropriate model for correlation of drugs solubility data.

In this study, the solubility of methane in pure diethylene glycol, pure water and in the aqueous solution of diethylene glycol has been investigated. The effects of pressure, temperature and mixture concentration on the solubility of methane in the aqueous phase were studied. Design Expert software has been used to reduce and optimize the number of experiments and investigate the effect of different parameters on the solubility data. Kricheveky’s model was used to predict the Henry’s constant of pure water and DEG. The model parameters have been extracted at different temperatures and pressures. In order to estimate the solubility of methane in the mixture from the pure data, O’Connell’s model has been applied. The model parameter has been evaluated using Margules equation. Results showed that the proposed model has good capability to predict the solubility in the mixture.

Determining the solubility of gases in solvents and considering non-ideality at different operating conditions are essential to design a cost-effective and energy-efficient absorption process. In this study, using a pressure decaying set-up, the solubility of pure ethane in N-methyl-2-pyrrolidone (NMP) was measured at different temperatures (278.15, 298.15, and 328.15 K) and pressures up to 14 bar, and kinetic and equilibrium results were obtained. Accordingly, the values of Henry’s law constants and also the heat of absorption were calculated at various temperatures. Then, thermodynamic modeling was accomplished by applying the Peng Robinson equation of state (PR-EOS) and the Wilson activity coefficient model, and the binary interaction parameters for this system were estimated. By the thermodynamic modeling, positive deviation from ideal behavior is apparently observed for this system. Due to low absolute average deviation of less than 12.3%, the correlated thermodynamic model is able to predict the ethane solubility in NMP with a reliable accuracy.

In this research, with evaluation of the solubility of cyclotetramethylene tetranitramine (HMX) explosive in different concentrations of water- methyl ethyl ketone (MEK) solvent, at a temperature range of 40-70 °C, the solubility and some thermodynamic parameters such as enthalpy of dissolution and mixing were calculated. Thereafter, in order to increase the capacity of the crystallization process, the effect of digestion of HMX in evaporative crystallization procedure on the morphology and polymorph conversion of crude HMX was investigated using electron microscopy, X-ray diffraction (XRD) and Raman spectroscopy. Then, two quantitative methods based on the XRD and Raman spectroscopy were developed for the determination of -HMX in  -type samples. The results showed that with the mentioned methods, -polymorph can be determined in the linear dynamic range of 0.32-5.25 wt. % in  -HMX. Also, the crystallization studies in MEK using digestion and evaporative crystallization showed complete conversion of crude HMX polymorphs to  -type, along with significant increasing in the crystallization capacity.

Prediction of solubilities of industrial solid compounds in supercritical carbon dioxide (SC-CO2) have been a challenge since the last two decades. In this study, the Peng-RobinsonStryjek-Vera equation of state (PRSV EoS) and the SoaveRedlich-Kwong equation of state (SRK EoS) were applied to estimate the solubilities of 10 common solid compounds in supercritical carbon dioxide. Simulation results showed that the PRSV EoS had good agreement with experimental data. Both EoS needed binary interaction parameter for prediction of phase behavior of solid-supercritical. In addition, with use of genetic algorithm, parameter for solid compounds and SCCO2 were calculated. Due to the lack of comprehensive correlations for prediction of solubilities of CO2 solids, in this work a correlation to predict the solubility of solid in SCCO2 was proposed. The main advantage of this correlation is its simplicity and having only two inputs, namely temperature and pressure. Minimum value of the average absolute percent deviation (AAPD) was for PRSV EoS and carbon dioxidenaphthalene system (2.77%) and maximum value of this parameter was for SRK EoS and carbon dioxide- anthracene system (19.38%).

This paper presents governing equations of the processes affecting oil and gas condensate slicks involving spreading، evaporation، dissolution، and vertical dispersion، which are important for numerical models of oil spill. These equations are used for crude oil، light oil، and gas condensate spill accidents according to their physical and chemical conditions and atmospheric conditions of the sea between Khark Island and Busher port and Assalouyeh marine region in the winter and summer. The evaporation of gas condensate is 42. 17% at a temperature of 24. 9 °C in the winter while it is 62. 24% at a temperature of 38. 4 °C in the summer after 48 hours. Moreover، the dissolution of gas condensate is 0. 0385% after 48 hours in the summer. The results also show that the evaporation of oil is 39. 74% at a temperature of 20 °C in the winter while it is 62. 025% at a temperature of 35. 5 °C after 48 hours in the summer. Additionally، the dissolution of oil is 0. 0537% after 120 hours in the summer. The results were compared with results of other studies which show good agreement.

The gas injection such as CO2 injection is widely used for enhanced oil recovery (EOR). Moreover,in underground besieging of CO2 to decrease greenhouse gases or in the injection of CO2 to theunderground brine, we face the solubility of this gas in the aqueous salt solutions, so studying thesolubility of CO2 in aqueous salt solutions in the wide range of concentrations, pressures, temperaturesand different electrolytes is very important.In this article, the electrolyte cubic square-well (ECSW) equation of state of Haghtalab and Mazloumi,Fluid Phase equilibrium, is used for investigating the solubility of CO2 in aqueous binary solutionsof the different salts such as NaCl, KCl, Na2SO4, MgSO4, MgCl2 and CaCl2. The results demonstratethat the ECSW equation is able to obtain the solubility data of ternary aqueous salt electrolyte systems especially NaCl in pressures up to 400 bar with very good accuracy.

Experimental solubility data for H2S in aqueous solutions of N-methyldiethanolamine (MDEA), diethanolamine (DEA), diisopropanolamine (DIPA) and monothanolamine (MEA) have been measured at various temperatures (40, 55 and 70 oC) and partial pressures of H2S ranging from 20 to 2000 kPa. Solubility data were obtained in a 250 mL autoclave and analyzed by chemical methods. The autoclave was equipped with a pressure transmitter with an accuracy of +/- 0.01 psi and temperature indicator and controller with an accuracy of +/- 1 oC. The compositions of liquid phase were analyzed by gas chromatography using a flame ionization detector (FID). All experiments were carried out in triplicate. Solubility data were correlated by M-KE (modified Kent-Eisenberg) model and equilibrium constant of alaknolamine protonation reaction was expressed by correlation in terms of temperature, H2S partial pressure (or loading) and alkanolamine concentration. In all cases, it was found that the models were able to give a relatively good H2S loading over a wide range of operating conditions.Therefore, the M-KE model may easily predict the solubility of acid gases in alkanolamine aqueous solutions. Average Absolute Deviation (AAD) for modeling of these alkanolamines by M-KE method are 1.75, 1.92, 2.48 and 1.27 for DIPA, DEA, MDEA and MEA aqueous solutions, respectively.

The critical properties of a solute are required for modeling of the solubility by the equation of state. For many compounds, the critical properties are not available. So, group contribution method is utilized as a common method to estimate these properties. But, it leads to the consecutive errors in calculations of the solubility modeling. In this study, Soave-Redlish-Kowang (SRK) and Peng-Robinson equation of states with Huran-Vidal mixing rules were used for modeling of the solubility. A new method for evaluating of C2 (Huran-Vidal mixing rule parameter) is recommended as a function of temperature and pressure. For solubility modeling by semi-empirical correlation, the new forms of Chrastil and Mendez equations were used. Finally, the modeling of solubility for 20 compounds by these methods has been investigated. Results show that the AARD% for the models with semi-empirical equations (Charstil, Aguilera, Gordillo, Mendez, modified Charstil and modified Mendez) are 12.07, 11.71, 34.89, 19.89, 11.17 and 15.70 respectively; and for SRK, PR EOS are 14, 19.85 respectively.

Cu-Cr alloys with high electrical and thermal conductivity, high strength and good resistance to fatigue and corrosion, as well as good ductility have many applications in industry. These alloys are capable of being age-hardened. As Cr- content in solution before aging increases, their strength increases since more fine particles can be produced in the matrix during ageing stage of hardening. Therefore intensive works have been done to increase Cr solubility in Cu especially by rapid solidification of molten copper containing chromium. In the present work attempts have been done to introduce a method for production of Cu-Cr alloy with acceptable Cr-content with reasonable cost. Results show that maximum solubility of Cr in Cu matrix about 1.12 wt.% can be achieved.

The solubilization of a monoazo disperse dye based on naphthalimide containing an ester group in the presence of DTAB and two gemini cationic surfactants was investigated. The results showed that the solubilization power of gemini surfactants micelles was greater than that of conventional surfactant micelles (DTAB) for this dye. The nature of the visible absorption spectra in aqueous surfactant solutions above CMC was very similar to those in the ethanol solution. The solubilization power is strongly dependent on the surfactant structure and nature of micelles. The absorption of used disperse dye intopolyester fabrics in the presence of cationic surfactants increased in the order of DTAB>12-4-12>14-414, once again confirming the higher solubilization power for gemini surfactants even at elevated temperatures. J. Color Sci. Tech. 4(2010), 55-64 © Institute for Color Science and Technology.

The peng robinson equation of state was used for calculation of solubility of alpha pinene (one of the important component of rosemary essence) in supercritical carbon dioxide.The binary interaction parameters for the equation of state are calculated for temperature range (40 to 45 C) and pressure up to 12 MPa. There was a good agreement between experimental data and calculated solubilities.