Ebru Kondolot Solak

Separation Characteristics of Dimethylformamide/Water Mixtures through Alginate Membranes by Pervaporation, Vapor Permeation and Vapor Permeation with Temperature Difference Methods

Abstract In this study permeation and separation characteristics of dimethylformamide (DMF)/water mixtures were investigated by pervaporation (PV), vapor permeation (VP), and vapor permeation with temperature difference (TDVP) methods using alginate membranes crosslinked with calcium chloride. The effects of membrane thickness (30–90 µm), feed composition (0–100 wt%), operating temperature (30–50°C) on the permeation rates and separation factors were investigated. The permeation rate was found to be inversely proportional to the membrane thickness whereas separation factor increased as the membrane thickness was increased. It was observed that the permeation rates in VP and TDVP were lower than in PV however the highest separation factors were obtained with TDVP method. Alginate membranes gave permeation rates of 0.97–1.2 kg/m2 h and separation factors of 17–63 depending on the operation conditions and the method. In addition, sorption‐diffusion properties of the alginate membranes were investigated at the operating temperature and the feed composition. It was found that the sorption selectivity was dominant factor for the separating of DMF/water mixtures.

Use of Sodium Alginate-Poly(vinyl pyrrolidone) Membranes for Pervaporation Separation of Acetone/Water Mixtures

Pervaporative separation of acetone from water at a concentration range of 0–100 wt% were studied using sodium alginate (NaAlg)/Poly vinyl pyrrolidone (PVP) membranes. Membranes were prepared in different ratios (w/w) (100/0, 95/5, 90/10, 85/15, 80/20, 75/25) of NaAlg/PVP by crosslinking with CaCl2. Experimental studies were carried out to investigate the effects of the operating temperature, feed composition, and membrane thickness on the pervaporation performance. The optimum operating temperature, membrane thickness, NaAlg/PVP ratio, and feed composition were determined as 40°C, 70 µm, 75/25 (w/w), and 20 wt% acetone, respectively. The effect of PVP content in the membranes was investigated on pervaporation performance. The permeation rate was increased with increasing the PVP content; however, there was no appreciable change about the separation factor. The permeation rate and separation factor values were found to be in the range of 0.304–1.023 kg/m2 h and 16–57, respectively. In addition, the sorption-diffusion properties of the alginate membranes were investigated at the operating temperature and the feed composition. It was found that the sorption selectivity was the dominant factor for the separation of acetone/water mixtures.

Preparation of magnetite-chitosan/methylcellulose nanospheres by entrapment and adsorption techniques for targeting the anti-cancer drug 5-fluorouracil.

In this work, we have formulated novel nanospheres that could be used in the controlled release of the anticancer drug, 5-fluorouracil (5-FU). The nanospheres are composed of magnetite, containing chitosan (CS) and methylcellulose (MC). The drug entrapment was achieved through the encapsulation and adsorption processes. The effects of the preparation conditions, such as magnetite content, CS/MC ratio, crosslinking concentration, exposure time to glutaraldehyde (GA), and the drug/polymer ratio were investigated for both processes. The 5-FU release was found to follow the Fickian mechanism, and the Langmuir isotherm for the nanospheres was achieved through encapsulation and adsorption processes, respectively.

pH-sensitive interpenetrating polymer network microspheres of poly(vinyl alcohol) and carboxymethyl cellulose for controlled release of the nonsteroidal anti-inflammatory drug ketorolac tromethamine

In this study, we aimed to produce pH-sensitive microspheres for the controlled release of the nonsteroidal anti-inflammatory drug, ketorolac tromethamine (KT). For this purpose, an interpenetrating polymer network (IPN) of microspheres of poly(vinyl alcohol) (PVA)/sodium carboxymethyl cellulose (NaCMC) were prepared, based on different formulations using glutaraldehyde (GA) (0.66 M) and hydrochloric acid (HCl) (3%, v/v). The preparation conditions of the microspheres were optimized by considering the percentage of entrapment efficiency and swelling capacity of the microspheres, and their release data. The effects of PVA and NaCMC ratio on the release of KT for over a period of 6 h, at three pH values (1.2, 6.8, and 7.4), have been discussed.