Thermal Stability and Water Content Study of Void-Free Electrospun SPEEK/Cloisite Membrane for Direct Methanol Fuel Cell Application

Designing a novel poly (methyl vinyl ether maleic anhydride) based polymeric membrane with enhanced antifouling performance for removal of pentachlorophenol from aqueous solution

In this current study, poly (methyl vinyl ether maleic anhydride) (PMVEAMA), a sustainable additive, was incorporated into poly (ether-ether sulfone) (PEES) polymer to design a novel polymeric hybrid membrane for the efficient filtration of toxic pentachlorophenol (PCP) from an aqueous medium. Hydrophilic additives significantly altered the membrane's morphology, structure, porosity, water content, and flux performance compared to the bare PEES membrane. The influence of PMVEAMA on the structural modification of the synthesized polymer membrane was confirmed by SEM, ATR-FTIR, XRD, AFM, zeta potential and contact angle. Findings revealed that the addition of PMVEAMA to the PEES polymer enhances the porosity (17.7%-28.9%), water content (29.8%-39.8%), and pure water flux (186 Lm^-2h^-1 to 349 Lm^-2h^-1). The effect of PMVEAMA concentration on the PEES membrane exhibited more finger like pores, better porosity and hydrophilicity, reduced surface roughness, fouling and increased permeability. The fouling studies exhibit an improved 57% PCP rejection and permeation flux of 22.3 Lm^-2h^-1 due to the addition of the hydrophilic additive. Surprisingly, the incorporation of PMVEAMA into the bare PEES membrane resulted in a high flux recovery ratio of 73.7%. The antifouling properties and enhanced permeability of the PEES/PMVEAMA membrane indicates its potential application in water purification sectors for the efficient separation of contaminants.

Preparation and characterization of polysulfone-polyurethane membranes for recovery of simulated wastewater from industrial textile processes

Techniques using membranes for the treatment of wastewaters usually promote higher quality of treated water when compared to other processes. Among them, pervaporation has advantages in terms of selectivity in addition to low working pressure, which can prevent clogging problems. Polysulfone and polyurethane have complementary characteristics and are interesting in the context of membranes for industrial applications. In this sense, the aim of this work was to prepare and characterize polysulfone/polyurethane-based membranes and tested them with a simulated wastewater containing the reactive black dye and sodium chloride by pervaporation. In their manufacture, thermal treatment (at 60°C) and photo-radiation treatment (using ultraviolet light) were also applied. The characterizations were performed using different analytical tools. In general, it was possible to verify that all membranes have a dense layer. The thermal analysis allowed to define that the indicated working temperature is below 50°C. With respect to the simulated wastewater treatment, all membranes reached 100% selectivity. Concerning the saline solution, the mean selectivity was around 98.5%. Moreover, the permeate flow values were within the range presented by commercial membranes ranging from 1.6 to 2.4 kg m^-2 h^-1. Although for the photoirradiated membranes the photo-graft reaction has occurred, among all membranes, the blend without any treatment stood out from the others, presenting the highest permeate flow of the simulated wastewater. Finally, the results reveal that these membranes are capable of recovering wastewater from textile processes, in addition to having the potential to remove salts from water through the pervaporation process.Highlights Polysulfone/polyurethane-based membranes were not yet evaluated for wastewater recovery.Modifications in the membrane characteristics promoted variations in the permeate flow.Changes in physical-chemical properties of membrane as a result of a photoinitiation reaction.Removal efficiency achieved was 100% for reactive black dye and 98.5% for sodium chloride.A new way of performing pervaporation on the recovery of aqueous solutions.

Effect of Sulfonation Degree and PVDF Content on the Structure and Transport Properties of SPEEK/PVDF Blend Membranes

Sulfonated poly (ether ether ketone) (SPEEK) with four different sulfonation degrees (SDs) were prepared, and mixed with polyvinylidene fluoride (PVDF) to prepare four series of SPEEK/PVDF blend membranes. The miscibility between SPEEK and PVDF was investigated by observing the micro-morphologies. The miscible blend membranes were found in the SPEEK/PVDF blend membranes in which either SPEEK had relatively low SD or consisted of low content of one component (either SPEEK or PVDF). The PVDF crystallinity was found to decrease in the SPEEK/PVDF membranes that had better blend miscibility. With the increase of PVDF content, all the blend membranes exhibited the decreased proton conductivity and methanol permeability, and the miscible blend membranes decreased more slowly than the immiscible ones.

Performance of Void-Free Electrospun SPEEK/Cloisite as a Function of Degree of Dispersion State on Nanocomposite Proton Exchange Membrane for Direct Methanol Fuel Cell Application

One of the main problems in direct methanol fuel cell (DMFC) application is methanol crossover. In order to solve the problem, an exfoliated void-free electrospun Sulfonated Poly(Ether Ether Ketone) (SPEEK)/cloisite nanocomposite membrane was developed. The membrane was prepared by immersing electrospun SPEEK/cloisite fiber mats onto incomplete solidified SPEEK polymer matrix. A well dispersed and reduction size of cloisite particles that ranges from 0.29⁻0.39 µm was observed by using Scanning Electron Microscopy Analysis (SEM) and Atomic Force Microscope (AFM). The effect of the morphology of the composite membrane in terms of degree of dispersion state of the Cloisite on the membrane performance was discussed. SP/e-spunCL15 with fully exfoliated structure exhibited the highest performance as compared to other tested membranes and Nafion® 115 with current density of 1042.2 mAcm-2 and power density of 1.18 mWcm-2. Improved morphological, dimensional change properties, and performance assigned to well-dispersed cloisite15A induced by the electrospinning technique make the membranes more efficient for direct methanol fuel cell applications.