Gülsen Asman

Characteristics of Permeation and Separation for Acetic Acid–Water Mixtures Through Poly(Vinyl Alcohol) Membranes Modified with Poly(Acrylic Acid)

The pervaporation separation of acetic acid–water mixtures was carried out over the full range of compositions at temperatures varying from 30° to 55°C using poly(vinyl alcohol) (PVA) membranes modified with poly(acrylic acid) (PAA). The best condition for the preparation of the membranes was found as PVA/PAA ratio as 75/25 (v/v). Effects of membrane thickness, operation temperature, feed composition on the permeation flux, and separation factor were investigated. PVA/PAA membranes gave separation factors of 34 to 3548 permeation rates of 0.03 to 0.60 kg/m2 h, depending on the operation temperature and feed mixture composition. The temperature dependence of permeation rate for binary mixtures was expressed by the Arrhenius type relation and activation energy of 17.62 kcal/mol was calculated for the permeation.

Separation of Acetic Acid‐Water Mixtures through Poly(Vinyl Alcohol)/Poly(Acrylic Acid) Alloy Membranes by Using Evapomeation and Temperature Difference Evapomeation Methods

Abstract Separation of acetic acid‐water mixtures by using evapomeation (EV) method were carried out over the full range of compositions at temperatures varying from 30 to 55°C using poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) (75/25) (v/v) alloy membranes. PVA/PAA membranes gave separation factors of 110–5711 and permeation rates of 2.3×10−4–1.53×10−1 kg/m2h, depending on the operation temperature and feed mixture composition. The temperature dependence of the permeation in EV was expressed by the Arrhenius type expression and the activation energy was calculated as 9.15 kcal/mol. More efficient EV technique, which is called temperature difference evapomeation method (TDEV) was also applied to PVA/PAA membranes to separate acetic acid‐water mixtures; high permeation rates (1.7×10−3–3.0×10−1 kg/m2h) and separation factors (1335–8924) were obtained for each of the studied feed compositions. Azeotropic mixture of acetic acid and water was also separated by TDEV method with a separation factor of 297 and permeation rate of 1.50×10−1 kg/m2h.

Use of Poly(methyl methacrylate-co-methacrylic acid) Membranes in the Ultrafiltration of Aqueous Fe3+ Solutions by Complexing with Poly(vinyl pyrrolidone) and Dextran

Abstract In this study water soluble complexible polymers, poly(vinyl pyrrolidone) (PVP) and dextran, were used for the ultrafiltration (UF) of aqueous Fe+3 solutions by using poly(methyl methacrylate-co-methacrylic acid) (PMMA-co-MA) membranes. Effects of polymer concentration and pH on the volume collected in the filtration of Fe+3 solutions and percent retentions (R%) were examined. It was determined that increase in polymer concentration decreased the permeability of PMMA-co-MA membrane and pH increased the retention of Fe3+ solutions. R% for Fe3+ solutions were obtained as 62% and 48% with PVP and dextran respectively at pH 3.0, for a filtration period of 80 minutes and retention for Fe3+ solution without using any complex forming polymer was found as 14%. Membranes were characterized by AFM analysis and contact angle measurements.

Effect of Membrane Preparation Methods on the Release of Theophylline through CA Membranes at In-Vitro Conditions

In this study the effect of the membrane preparation methods on the release of theophylline through cellulose acetate (CA) membranes was studied at in vitro conditions. CA/acetone binary and CA/acetone/water ternary systems were used as casting solutions and poly(ethylene glycol) (PEG) was used as the pore forming, plasticizing agent in the study. Membranes were characterized by FTIR, SEM, and DSC analysis. It was determined that pH, temperature and drug concentration affected the release of theophylline. A decrease in pH, increase in temperature and drug concentration increased the permeated amount of theophylline through the membranes. In addition, receiver solution circulation at a capillary blood rate increased the permeation of theophylline. As a result of the study, it was concluded that the release of theophylline could be controlled for a prolonged period of time and modified CA membranes prepared in the study could be as an advisable membrane material for potential release of theophylline at transdermal conditions.