Ayça Hasanoğlu

Sorption behavior and preliminary pervaporation results of cross-linked polyvinylalcohol and polydimethylsiloxane membranes prepared for the separation of water-ethylacetate mixtures

Since pervaporation process is the coupling of solution and diffusion mechanisms, a sorption study was carried out with membranes prepared by cross-linking polyvinylalcohol (PVA) and polidimethylsiloxane (PDMS). Tartaric acid (Tac) was used as the cross-linking agent for PVA, and a commercial cross-linking agent was used for PDMS. Sorption experiments were carried out at 30-50°C temperature range in pure water and ethyl acetate using the films prepared. The PVA and PDMS films prepared preferentially sorb water and ethylacetate, respectively. A pervaporation study at 30°C was carried out for pure ethylacetate and pure water, and mixtures of ethylacetate containing 2 and 2.5 wt% water using 100 w m thick PVA membrane. The results indicate that the PVA membrane prepared is extremely selective for water.

Gas-filled membrane absorption: a review of three different applications to describe the mass transfer by means of a unified approach

Abstract This work involves the presentation of a general approach to describe the gas-filled membrane absorption process by analyzing three different applications. Ammonia removal from wastewater was described in a previous work using a resistance-in-series model. In this contribution, this model has been applied to describe the HCN removal from wastewater as well as to characterize the transfer of SO2 from wines to a receiving solution to develop a new method for enhanced quantification of sulfite content. The experimental results of this novel technique for SO2 quantification and its theoretical validation are presented in this study. The analyzed operations are based on hydrophobic hollow fiber contactors, which are used to physically separate two aqueous phases: a feed solution containing a volatile compound and a reactive receiving solution. Mainly removal of three volatile compounds under this configuration was analyzed: NH3, HCN, and SO2. By this way, a unified description based on a resistance-in...

DESORPTION OF ETHYL ACETATE-WATER MIXTURE BY USING CROSS-LINKED POLY(VINYLALCOHOL) MEMBRANE AND COMPARISON OF RESULTS WITH PERVAPORATION

In this study using poly(vinylalcohol) (PVOH) membranes cross-linked with tartaric acid (Tac) desorption experiments were performed for selected concentrations of binary ethyl acetate (EtAc)-water mixture at temperatures of 30°, 40°, and 50°C to determine sorption of components. Sorption values measured were compared with those estimated by the Flory-Huggins approach. Additionally, desorption results were compared with pervaporation results of another study in terms of solution-diffusion theory, and the effect of thermodynamic interactions on selective transport of the binary mixture and membrane system was investigated. The results obtained show that selective transport of EtAc-water mixture was influenced by increasing temperature and water content in the feed. It is shown that preferential sorption is more effective for pervaporation selectivity than diffusion selectivity.

Investigation of sorption characteristics of polymeric membranes containing ionic liquids for n-butanol recovery from aqueous streams

AbstractIonic liquid–polydimethylsiloxane (IL–PDMS) blending membranes were prepared to separate n-butanol from aqueous mixtures. The ionic liquids (ILs) used were [hmim][PF6] (1-hexyl-3-methylimidazolium hexafluorophosphate), [bmim][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate), and [bmim][TF2N] (1-Butyl-3-methylimidazolium bistrifluoromethylsulfonylimide). Sorption experiments were carried out to define the sorption and separation capacity of the blending membranes using aqueous butanol solutions in the range of 1–5% (wt), and also sole solvents of butanol and water. The desorption experiments allowed to determine the selectivity of the membranes as the liquid composition inside the membrane could be obtained with the desorption step. The results obtained by IL–PDMS blends were compared with the results obtained by unblended PDMS membranes to show the effect of the IL in the PDMS matrix. [Hmim][PF6]–PDMS-blended membranes showed lower selectivity. The addition of [bmim][PF6] to PDMS enhanced the ...