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This study focuses on the effect of a silicon rubber coating technique on the hollow fiber membrane contactor for the purpose of CO2 removal. The polymer and the coating agent used were polyetherimide (PEI) and polydimethylsiloxane (PDMS) respectively. The hollow fibers were fabricated via a simple wet spinning technique. The surfaces of the hollow fibers were coated by means of PDMS dissolved in n-hexane applying different protocols. The membranes were characterized applying: gas permeation test (GPT) via pure helium, critical entry pressure of water (CEPw), contact angle and Gas absorption test. Based on the observations, the coating technique resulted in drastic changes in the contact angle and CEPw of the coated membranes for the inside and outside coated hollow fiber membranes in common. Disregarding the method of coating and even the polymer concentration, the contact angle have enhanced dramatically. A slight decrease in CO2 absorption flux for the other cases was outweighed by substantial enhancement in the membrane wetting resistant due to high contact angle and CEPw. This observations showed the high influence of the silicon rubber layer on the CO2 gas absorption, which emphasis the role of this key-parameter in controlling the final membrane contactor performance.
Date: 11/21/2015       (visite count : 1386)

Liquid-gas separators are applicable in many applications and in some cases, use of them are obligatory. For instance, the use of separators in two-phase flows in the suction line of pumps and compressors is necesary. Separators are also used to enhance the required fluid condition, to boost the measurement accuracy and to split the two phases. With regard to the wide spread need of liquid-gas separators and different process requirements, like droplet diameter, desired pressure drop, efficiency, available space and applicability, different models have been designed based on their operating conditions and each one is suggested for a specific situation. Evidently, for proper and optimum use of these separators, a precise investigation of different models of separators is required. As a result, in this study the structure and separating mechanism of conventional technologies in industry have been investigated. Together with a move to the recently suggested technologies which were designed with regard to the better fit the different process conditions have been introduced. Consequently, by taking these parameters into account, an approach to the selection of appropriate separator is suggested for each specific application.
Date: 11/21/2015       (visite count : 1886)

In this research, an effective biosorption, in the form of fine powder, was prepared from Low-cost leaves of pistachio tree for removing methylene blue from aqueous solution. The effects of pH, contact time, adsorbent dosage on the sorption capacity at 30ºC were investigated in batch study. The analysis of residual methylene blue of solution was determined by UV-visible spectrophotometer. It is found that the MB adsorption is greatly dependent on the pH of the solution, adsorption is increased with increasing pH to 5 and then it reached to constant value in higher pH. The obtained adsorption isotherms fitted well into both the Freundlich and Langmuir isotherms. Maximum monolayer adsorption capacity was found at 122 mg MB per g modified pistachio leaves. The result of adsorption kinetics shows that the pseudo-second order kinetic model provided a good correlation in compare to the pseudo-first order model.
Date: 11/21/2015       (visite count : 1853)

In this research, membrane contactor based CO2 stripping experiments were conducted using loaded CO2 monoethanolamine (MEA) solution as an absorbent while N2 gas was used as a stripping gas. Process asymmetric polyetherimide hollow fiber membranes using ethanol (2 wt%) as non-solvent additive in the polymer dope via phase inversion method were fabricated. Aqueous solution of 1-methyl-2-pyrrolidine (NMP) (90%) was applied as a bore fluid and water(10%) was used as the external coagulant. Gas permeation test was conducted using Nitrogen. Fabricated membranes were characterized in terms of pore size, critical water entry pressure and collapsing pressure. The performance of fabricated membranes for carbon dioxide stripping from monoethanolamine solution using a gas - liquid membrane contactor system was studied. The results showed that carbon dioxide stripping flux increased by increasing liquid velocity. Also, enhancement of stripping flux by increasing gas velocity was negligible.
Date: 11/21/2015       (visite count : 1821)

An experimental study on the removal of Cr(VI) through a supported liquid membrane (SLM) using a mixture Methyltrialkylammonium chloride (Aliquat 336), Tributyl phosphate (TBP) and kerosene as the liquid membrane (LM) was performed. Parameters affecting the extraction of Cr(VI) such as the Carrier/Solvent ratio in the liquid membrane phase and the Stirring rate of both feed and stripping phases were analyzed. Nevertheless, other factors such as the TBP/Aliquat ratio, solute concentration of feed, HCl concentration, stripping phase concentration and contact time were regarded in a constant level. Optimal experimental conditions for Cr(VI) removal (permeability of 2.565×10−5) were obtained after a 7 h separation with the Carrier/Solvent ratio of 0.5, the stirring rate of 500 min-1, the TBP/Aliquat 336 of 0.2, initial Cr(VI) concentration of 50mgL-1, HCl concentration of 0.05 mol L−1, NaOH concentration of 0.1 mol L−1.
Date: 11/21/2015       (visite count : 1778)

In the current research, purification of produced biodiesel was carried out using Polymeric membranes based on poly ether sulfone and poly phenylene ether ether sulfone. The effect of polymer type used in the body of polymeric membranes on separation characteristic of membranes was studied. The biodiesel was produced from waste cooking oils by trans-esterification method. Three Polymeric membranes containing 16 %wt poly ether sulfone and 13, 14 %wt poly phenylene ether ether sulfone were prepared by casting technique and phase inversion method. The results of the biodiesel purifying test, including flux through the membrane, separation efficiency and SEM images revealed The prepared Polymeric membrane containing 13 %wt poly phenylene ether ether sulfone showed more suitable performance compared to other Polymeric membranes.
Date: 11/21/2015       (visite count : 1540)

poly (styrene-co-divinylbenzene) with high amounts of cross-linker (DVB) and diverse proportions of diluent agent (porogen) are synthesized according to the methodology of the suspension polymerization technique. Also it was functionalized by sulfuric acid. The applicability of poly(styrene-co-divinyl benzene) beads to separation and concentration of Ni(II) is discussed. In separation of Ni(II) from aqueous solution the effect of contact time for poly(styrene-co-divinyl benzene) beads before and after functionalization are discussed. To measure the ion concentration in the solution used the UV–vis spectrophotometer. It was found that the optimal conditions for Ni(II) separation from aqueous solution for poly (styrene-co-divinylbenzene) is 180 minute while after functionalization is 5 minute. So that with functionalization, therefore separation of Nickel ions by ion exchange, adsorption process as well as improved
Date: 11/18/2015       (visite count : 1683)

Carbon dioxide (CO2) is one of the responsible gases for the increase of the greenhouse effects. CO2 concentration has been drastically increased in the last decades mainly due to the increase of anthropogenic emissions. Biological fixation of CO2 using microalgae is currently considered as a remarkable and promising technology. In this paper, a photobioreactor integrated with hydrophobic microporous polyethylene hollow fiber membrane was constructed to remove CO2 from air using a photosynthetic microalgae Dunaliella Salina. The main objective of this work was to maximize the biomass productivity (Pbiomass) at different aeration flow rates and circulation rates of culture fluid including 0.1 and 0.2 vvm and 500 and 1000 ml/h, respectively. Obtained results showed that the maximum Pbiomass (0.59 g/L/day) was obtained at minimum aeration flow rate (0.1 vvm) and at maximum circulation rate of culture fluid (1000 ml/h). In comparison with conventional bubble column, results were promising.
Date: 11/18/2015       (visite count : 1666)

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