مجله فرآیند نو
پیاپی 52 (زمستان 1394)

The concept of mixed matrix membranes (MMMs) comprising rigid particles dispersed in a continuous polymeric matrix was proposed to improve the separation properties of polymeric membranes. In this approach, the good advantages of both polymeric matrix and inorganic fillers combined and a good permeable membrane with high selectivity, chemical stability, mechanical strength and processability can be prepared. In this article, factors affecting the performance of MMMs where reviewed. Also, the types of MMMs by structure, preparations methods were discussed. In addition, types of common inorganic fillers, gas transport mechanism in MMMs, stress and defects in polymer/inorganic interface and the most prevalent models which can predict the performance of MMMs were stated and discussed. Finally, the future directions of researches in this context and potential usages of MMMs where shown.

In this study, equilibrium system of H2O-Pz-CO2 has been modeled using neural networks. In the modeling two networks RBF and MLP were used. Back propagation algorism was used in the learning of the networks. In the RBF network, nonlinear Gaussian function was used as an activation function whereas sigmoid function was used in MLP network. The networks results were evaluated by experimental data presented in the literature. Mean absolute error for RBF and MLP are 4.21 and 4.78 percent, respectively. The results showed that neural networks are suitable tools for decreasing of calculation time and increasing of accuracy in the equilibrium data predictions.

Adsorption process with activated carbon is one of the most common methods for heavy metals removal from various wastewaters. In this study, modeling of of Pb2,Cd2,Ni2 adsorption have been investigated with activated carbon in equilibrium and kinetic states. Langmuir, Freundlich, Redlich-Peterson and Sips isotherms were applied for study of equilibrium in single adsorption systems and multicomponent Langmuir isotherm was selected for equilibrium study in multicomponent adsorption system. All studied isotherms had good prediction for equilibrium of these systems. Pseudo-first order, pseudo second order and film-pore volume diffusion model were applied for investigation of adsorptionkinetics. According to the results, film-pore volume diffusion model based Langmuir isotherm had minimum average relative error. Effective pore volume diffusivity was determined 1.9210-6 cm2.s-1, 1.9010-6 cm2.s-1 and 1.2010-6 cm2.s-1, for Pb2, Cd2 and Ni2, respectively.

Oily wastewaters are generated in many industrial processes, such as petroleum refining, ýpetrochemical and food. These oily wastewaters are mainly in the form of oil-in-water (O/W) ýemulsions. Oil removal requires an understanding of the physical properties and chemical ýcomposition of O/W emulsions. Several properties in the stability of an O/W emulsion should ýbe measured for the selection of the appropriate separation process, specifically, surface ýtension, contact angle, zeta potential and droplet size distribution. Treatment of oily ýwastewaters is performed by a variety of methods and the degree of oil removal depends on ýthe concentration and physical nature of the oil, droplet size and separation techniques. The ýpurpose of this work is to study oil/water system properties, and techniques for removing oil. ýThese techniques include gravity and centrifugal separations, chemical treatment, flotation, ýmembrane processes, evaporation, activated carbon adsorption and biological treatment. At ýlast, treatment costs and hybrid processes will be covered.ý

Several methods have been presented for CO2 capture from the flare of the factories, but these methods are not able to lower the existing atmospheric CO2. Direct air capture of CO2 has to be used for this purpose. In the current research, this process is simulated with the aid of software and the influence of different parameters such as the type and flow of the solvent, the number of the trays of the absorption and desorption towers on the energy consumption and CO2 recovery are studied. The results show that the average CO2 recovery is about 89% and the average energy consumption would be about 8 GJ for each ton of recovered CO2.

Polyvinyl chloride based heterogeneous cation exchange membranes were prepared by solution casting technique. The effect of multi walled carbon nano tubes and also MWCNTs-co-Ag nanolayer composite nanoparticles on electrochemical and antibacterial properties of membranes was studied. The MWCNTs-co-Ag nanolayer composite nanoparticles were prepared by magnetron sputtering method. Scanning optical microscopy images showed uniform particles distribution for the membranes. Also surface modification of MWCNTs by Ag nanolayer caused to more uniformity for the membranes. Results showed that membrane electrochemical properties were improved by using of nanoparticles in membrane matrix. Also the modified membrane containing Multi Walled Carbon Nano Tubes-co-Ag nanolayer showed more suitable electrochemical characteristics and antibacterial property in E-Coli removal compared to others.