Polyphenylsulfone Membrane Research Articles

The potential of pervaporation for separation of acetic acid and water mixtures using polyphenylsulfone membranes

Conventional pervaporation (PV) membranes usually have limited resistance to acetic acid (HAc), particularly in high pressure and temperature conditions, resulting in a cumbersome water-acetic acid separation. When acetic acid is to be recycled in process conditions in a hybrid pervaporation approach, the PV membrane may experience these conditions of high temperatures and pressures. This study explores the potential of dehydrating acetic acid using pervaporation with novel polyphenylsulfone (PPSU) membranes. These membranes were tested for PV dehydration of mixtures of acetic acid–water with 80 and 90 wt.% acetic acid in the temperature range between 30 and 80 °C. In addition to that, an experimental study of membrane stability was performed at high concentration of HAc and high temperatures. It was found that a higher polymer concentration does not necessary yield a better separation factor: PPSU-based membranes with 27.5 wt.% of the polymer (PPSU-27.5) were similar to 30 wt.% (PPSU-30) in terms of overall performance, considering both flux and separation factor. Although the total flux of PPSU-27.5 (∼0.12–0.83 kg/m 2 h) is lower than PPSU-25 (∼0.24–1.48 kg/m 2 h) the average separation factor can be higher than for the PPSU-30 membrane. For example, in 90 wt.% HAc, the separation factor is 8.4 for PPSU-27.5 and 5.7 for PPSU-30. The swelling degree (DS) was found to decrease with feed temperature, while an increase of the selectivity and flux was observed. The activation energy of permeability ( E p ) shows that PPSU membranes have negative E p values. This indicates that the membrane partial permeabilities decrease with increasing temperature. With the enrichment of acetic acid on the feed side of the membrane, the degree of swelling, flux and separation factor all increase. Regarding on the membrane stability tests, the PPSU membranes showed promising results at tested conditions.

Novel polyphenylsulfone membrane for potential use in solvent nanofiltration

In this work, the preparation of nanofiltration flat sheet membranes based on polyphenylsulfone (PPSU) was investigated. A synthesis method based on phase inversion with three different compositions of PPSU (17 wt.%, 21 wt.% and 25 wt.%) in dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP) and a mixture of dimethylformamide (DMF) and NMP was employed. Scanning electron microscopy (SEM) was used to investigate the morphological characteristics and the structure of the membranes, which were found to have a typical asymmetric structure with a dense skin top layer and a porous substructure. The pore size was estimated by measuring the permeation rate of N 2 when different pressures are applied, ranging from 15 nm to 40 nm, depending on the manufacturing method. An increasing amount of macro-voids was observed in the membrane substructure when the polymer concentration is decreased. The performance of the prepared membranes has been tested by the measure of methanol permeability and the rejection of a dissolved dye (Rose Bengal). The methanol permeability decreases with increasing polymer concentration while the rejection of Rose Bengal (RB) increases. In addition, the impact of ethyl acetate, n-hexane, toluene, diethyl ether, iso-propanol and acetone on the membranes was investigated by measuring the flux of methanol and rejection of RB before and after solvent exposure. The membranes were visually stable in most of the solvents except acetone and toluene. The performance of the membranes changed dramatically for ethyl acetate and diethyl ether while iso-propanol had a minor effect and complete stability was observed with n-hexane.

Synthesis and Evaluation of Novel Proton Exchange Membranes Containing the Semisquaric Acid Group

We focus our attention here on semisquaric acid, which is known to show high acidity, as a new proton dissociating group for proton exchange membranes (PEMs). The introduction of a squaric acid group into aromatic polymers was conducted by the reaction of lithiated aromatic polymers and diisopropoxy squarate, followed by treatment with hydrochloric acid. A resulting polyphenylsulfone membrane with the squaric acid group introduced (PPSf-SQ, IEC = 4.1 meq·g(-1) ) showed proton conductivity of 1.0 × 10(-1) S·cm(-1) at 80 °C under 95% relative humidity, which indicates that the semisquaric acid has the potential to become an alternative proton-conducting group for PEMs.

Sulfonated Polyphenylsulfone Membrane for all Vanadium Redox Flow Batteries

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