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Practical Kedem-Katchalsky equations and their modification

100%
Jarzyńska M.
Open Physics
|
2007
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vol. 5
|
issue 4
586-598
EN
The research problem presented in this work concerns modification of the Kedem-Katchalsky (K-K) equation for volume flow (J v) through system (h|M|l), consisting of a membrane M and boundary layers h and l. Such boundary layers appear in the vicinity of the membrane on both sides due to the lack of mixing of solutions. This paper also includes the derivation of the equation for volume flow (J vr) dissipated on concentration boundary layers h and l. The derivation of these equations concerns the case in which the substance transport through the membrane is generated by the osmotic pressure gradient $$\Delta \dot \prod $$ . On the basis of the equations for the volume flows (J v) and (J vr), some calculations for a nephrophane membrane, used in medicine, and for aqueous glucose solutions have been carried out. In order to test the equations for (J v) and (J vr), we have also carried out calculations for the volume flow (J′ v) that is transferred through the membrane in the case of mixed solutions on both sides of the membrane. This volume flux has been calculated on the basis of the original (K-K) equation. The results are presented in Fig. 2.
2
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Carbon Black Loaded Composite Poly(Dimethyl Siloxane) Membrane Preparation and Application for Hazardous Chemical Removal from Water

64%
Nigiz F., Unlu D., Hilmioglu N.
Acta Physica Polonica A
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2017
|
vol. 132
|
issue 3
693-696
EN
Industrial waste-water contains hundreds of hazardous chemical components such as volatile organic compounds. Several of the chemicals, such as acetone, are soluble in water. These chemicals pose a threat to the human health and ecosystem. The governments are interested in decreasing the concentration of these chemicals in waste-water by making environmental regulations. Most of the chemical industries have their own waste-water treatment units. These units can separate impurities down to ppm level. After that point, more complicated and costly methods are required. Alternatively, membrane separation methods, such as pervaporation can be used for selective separations of the volatile organic compounds. Pervaporative separation system is defined as environmentally friendly, cost effective process to separate azeotropic and water soluble mixtures. The membrane is the main constituent of the pervaporation and the performance of the separation is directly affected by the membrane selection. In this study, carbon black loaded poly(dimethyl siloxane) mixed matrix membrane was prepared to separate acetone from water by pervaporation. Thermal gravimetric analysis was applied to determine the thermal behavior of the membrane. Inorganic distribution was monitored by means of polarized electron microscopy. Contact angle measurement was applied to determine the effect of filler incorporation on the polymer hydrophobicity. Effect of temperature and feed molar ratio on acetone selectivity and flux were determined.
3
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Biodiesel from Oleic Acid by Green Catalyst "Catalytic Membrane": a Solution to Global Warming Problems

64%
Unlu D., Nigiz F., Hilmioglu N.
Acta Physica Polonica A
|
2017
|
vol. 132
|
issue 3
689-692
EN
In recent years biodiesel is receiving more attention as a sustainable alternative to fossil fuel. Biodiesel has lower exhaust emissions and toxicity compared to petroleum diesel fuel. In this study, biodiesel is produced from the oleic acid esterification process. We try to develop an efficient heterogeneous catalyst for biodiesel synthesis. A catalytic membrane carboxymethyl cellulose with sulfosuccinic acid has been prepared for using as catalyst. Carboxymethyl cellulose is a natural and biodegradable polymer and it has the advantage of green catalysis. Sulfosuccinic acid is a homogeneous catalyst. To overcome the disadvantages of the homogenous catalyst, sulfosuccinic acid is used together with polymeric membranes. The effects of the ethanol/oleic acid molar ratio, the reaction temperature, the sulfosuccinic acid concentration and the stirring speed were investigated to find out the optimum reaction conditions. The catalytic stability of the catalytic membrane is also studied. The optimum conditions for the reaction were found to be 65°C, catalytic membrane with 6 mmol of sulfosuccinic acid, 9:1 ethanol to oleic acid molar ratio and 600 rpm stirring speed. The oleic acid conversion using the catalytic membrane was 85% under these conditions after 6 h. Our findings show that carboxymethyl cellulose membrane with sulfosuccinic acid groups is a suitable catalyst for esterification.
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