Experimental and theoretical investigation of molecular diffusion coefficient of propylene in NMP

In this study, the absorption of propylene in N-methyl pyrolidone (NMP) was experimentally performed at three different temperatures (276.15, 293.15, and 328.15 K) using the pressure decay method and as a result, the equilibrium data, Henry's law constants, and kinetic data were reported. It was shown that the solubility and diffusivity are two important factors affecting the kinetic behavior of the system. This absorption system was mathematically modeled using Fick's second law accompanied by a time dependent boundary condition. An analytical method followed by numerical optimization was used to estimate the diffusion coefficient of propylene in NMP at different operating temperatures. The results demonstrated that the calculated diffusion coefficient obeys an Arrhenius type model. The resulting mathematical model was applied to calculate the number of absorbed moles of the gas. It shows a deviation of about 10% in comparison with the experimental measurements. Furthermore, the time dependent concentration profile along the liquid depth was also predicted.     

Supported liquid membrane separation of propylene-propane mixtures using a metal ion carrier

Experimental results for the separation of propylene from a propylene/propane mixture using facilitated transport membrane system with silver nitrate as carrier are presented. The equilibrium constant of the reaction between propylene and silver ion (Ag⁺) at different operating conditions was determined, experimentally. For a 50:50 (vol.%) propylene-propane mixture, at feed pressure of 50-120 kPa, the separation performance of a facilitated transport membrane system was evaluated. It was observed that increasing carrier concentration and trans-membrane pressure, separation factor was increased. At feed pressure of 120 kPa and the carrier concentration of 20 wt.%, a separation factor of 270 was obtained.     

Analytical approximate solution of competitive facilitated transport of acid gases through liquid membranes

An analytical approximate solution for the competitive facilitation factor of components A and E across a liquid membrane is developed in the case of instantaneous reactions inside the liquid membranes. This analytical solution solves the dimensionless, nonlinear diffusion-reaction transport problem governing the competitive facilitated transport of two gaseous components through liquid membranes. Prediction of the facilitation factors has been obtained for the equilibrium chemical reaction regime, considering the unequal complexes diffusivities and cases of zero and nonzero permeate side solute concentrations. This mathematical solution leads to analytical expressions for the concentration profiles of the species across the liquid membrane. In comparison with the present numerical solution and also numerical calculations and experimental data from the open literature, the difference between the analytical predictions and those obtained from the numerical solution were found to be in well agreement.     

Water and mercaptan adsorption on 13X zeolite in natural gas purification process

The aim of this work is to model the adsorption process used for mercaptan and water removal from natural gas. Three fixed beds containing Zeolite molecular sieve type 13X, are used in this plant. In this operation, two beds are in process for adsorption purposes and the other one is regenerated simultaneously. This system is also operated under isothermal condition. In modeling of this process, rate of adsorption is approximated by linear driving force (LDF) expression, and the extended Langmuir isotherm is used to describe adsorption equilibrium. The set of partial differential equations of dynamic model is solved by Crank-Nicolson method. The effect of equations of state is also studied and the best equation fitting the industrial data is selected. Also, concentration profile is presented versus bed length at various times. The influences of pressure, inlet concentration and bed height on the breakthrough time are also investigated.     

Effect of sintering temperature on the microstructure,roughness and electrochemical impedance of electrophoretically deposited YSZ electrolyte for SOFCs

In the present work, the microstructures of YSZ electrolyte films, which were sintered at various temperatures in the range of 1300–1600 °C, were investigated. First, a suitable and uniform film was deposited on the surface of NiO–YSZ composite by EPD. After the consequence sintering, the surfaces of deposited YSZ films were observed by SEM. In addition, other characteristics of the YSZ electrolyte films such as surface roughness and morphology of the sintered films were investigated by AFM. The ability of ionic transfer and permeability of the YSZ electrolyte was examined by electrochemical impedance spectroscopy at different temperatures. It seems that the YSZ electrolyte sintered at 1400 °C was appropriate for SOFCs applications, because this film had the minimum impedance, minimum roughness and the maximum conductivity. Furthermore, the temperature of 1400 °C was the minimum temperature in which a dense film of YSZ was formed uniformly on the surface of anode and coated it completely.     

Bleaching of Olive Oil by Membrane Filtration

In this study the application of membrane processes for olive oil bleaching is investigated. Olive oil is treated by adding 0.7 wt% of bleaching earth, 0.3 wt% of activated charcoal, and 5% wt% of sodium dodecyl sulfate solution (0.05 m ) and then charged into the membrane cell. Operating conditions including pressure ((2?4) × 10⁵ Pa), temperature (25–45 °C), and stirring rate (100–300 rpm) are optimized. Physico‐chemical properties of membrane bleached oil are evaluated and compared with crude and industrially bleached olive oil. Results show that the filtration conditions for the optimized point are as follows: pressure = 3.7 bar (3.7×10⁵ Pa), temperature = 36.5 °C, and stirring rate = 300 rpm. Under optimum conditions, the amounts of carotenoid and chlorophyll contents are decreased (71.3% and 40.42%, respectively). Acidic and thiobarbituric acid values reduction in membrane‐processed oil (12.42% and 14.46%, respectively) are more than the industrial one. Also, some bioactive compounds such as sterols and phenolic compounds are increased in the membrane‐filtered sample (23.13% and 57.12%, respectively). Practical Applications: Olive oil bleaching is an important step along the refining process. Pigments and minor impurities that reduce olive oil stability are removed in this step. Given the disadvantages of conventional bleaching, alternative methods are introduced. In this study, the effect of membrane filtration on olive oil color is studied. Because of the mild operating conditions, the reduction of clay percentage, as well as the increase of bioactive compounds in optimum conditions, this method has the potential to be a good alternative to conventional bleaching processes.     

A Review on the Role of Non-Coding RNAs in the Pathogenesis of Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune condition related to autoantibodies against certain proteins in the postsynaptic membranes in the neuromuscular junction. This disorder has a multifactorial inheritance. The connection between environmental and genetic factors can be established by epigenetic factors, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). XLOC_003810, SNHG16, IFNG-AS1, and MALAT-1 are among the lncRNAs with a possible role in the pathoetiology of MG. Moreover, miR-150-5p, miR-155, miR-146a-5p, miR-20b, miR-21-5p, miR-126, let-7a-5p, and let-7f-5p are among miRNAs whose roles in the pathogenesis of MG has been assessed. In the current review, we summarize the impact of miRNAs and lncRNAs in the development or progression of MG.     

Application of Dispersive Liquid–Liquid Micro-extraction Using Mean Centering of Ratio Spectra Method for Trace Determination of Mercury in Food and Environmental Samples

In the present study, dispersive liquid–liquid micro-extraction has been applied for trace extraction and determination of mercury (Hg) ions in environmental samples. The mean centering of ratio spectra method was used to optimize the experimental parameters affecting the extraction of Hg. The factors influencing the extraction procedure such as type and volume of extracting and disperser solvent, concentration of chelating reagent, pH, salt effect, and centrifuge time were investigated and optimized. Under the optimized conditions, the limit of detection of the method was 0.15 μg l^?1 and enrichment factor was 39. The calibration curve was linear in the range of 0.5–100 μg l^?1 with a correlation of determination (R ²) of 0.998. The relative standard deviation for determination of 40 μg l^?1 of Hg(II) was 2.6 % (n?=?5). The proposed method was applied for the determination of Hg in pine leaf, sea and river fish, sand, and water samples as indicators of environmental pollution and cigarette with satisfactory analytical results. In comparison with other methods, the proposed method is very simple, easy, rapid, and sensitive for determination of Hg at trace levels in complex matrices.     

News media attention in Climate Action: latent topics and open access

Scientometrics - In this study we investigated whether open access could assist the broader dissemination of scientific research in Climate Action (Sustainable Development Goal 13) via news...