Acrylate Membrane Research Articles

The Development and Evaluation of PFSA‐Free Polyacrylonitrile‐co‐Methyl Acrylate (PAN‐MA) Nanofiber Membranes for its Potential Application as a Proton Exchange Membrane in Fuel Cells

AbstractThe significance of hydrogen energy has grown considerably due to climate change and the depletion of fossil fuels. PEM fuel cells are the key hydrogen technologies. Commercial membranes based on perfluorosulfonic acid (PFSA) with a polymer structure containing fluorine are currently available. However, it has been determined that certain perfluorosulfonic acids (PFSAs) are hazardous, persistent, and bioaccumulative. Advancements in hydrogen technology rely on effective, inexpensive, and perfluorocarbon‐free membranes, specifically proton exchange membranes (PEMs). In this research, a PFSA‐free polyacrylonitrile‐co‐methyl acrylate (PAN‐MA) membrane doped with phosphoric acid is prepared using the electrospinning method and then characterized by SEM, FE‐SEM, XRD, FTIR, TGA, DMA, and EIS. The DMA analysis reveals that the storage modulus of the doped membrane increases from 0.98 to 5.66 MPa at 80 °C. The nanofiber composite membrane, with a thickness of 181 µm, exhibits the highest proton conductivity of 0.306 S m−1 at 20 °C, 1.76 times higher than that of the Nafion 212 membrane. The Nafion 212 membrane has an ionic conductivity of 0.173 S m−1 under the same conditions. These results indicate that the prepared nanofiber membranes are promising materials for evaluating fuel cell applications.

Formation of Microporous Poly Acrylonitrile-Co-Methyl Acrylate Membrane via Thermally Induced Phase Separation for Immiscible Oil/Water Separation.

An interconnected sponge structure and porous surface poly (acrylonitrile-co-methyl acrylate) (P(AN-MA)) microfiltration membranes (MF) were fabricated via thermally induced phase separation (TIPS) by using caprolactam (CPL), and acetamide (AC) as the mixed diluent. When the ternary system was composed of 15 wt.% P(AN-MA), 90 wt.% CPL, and 10 wt.% AC and formed in a 25 °C air bath, the membrane exhibited the highest water flux of 8107 L/m2·h. The P(AN-MA) membrane contained hydrophobic groups (-COOCH3) and hydrophilic groups (-CN), leading it to exhibit oleophobic properties underwater and hydrophobic properties in oil. The membrane demonstrates efficient separation of immiscible oil/water mixtures. The pure water flux of the petroleum ether/water mixture measured 870 L/m2·h, and the pure oil flux of the petroleum tetrachloride/water mixture measured 1230 L/m2·h under the influence of gravity. Additionally, the recovery efficiency of diluents through recrystallization was 85.3%, significantly reducing potential pollution and production costs.

Oleophilic to oleophobic wettability switching of isoporous through-hole membranes by surface structure control for low-voltage electrowetting-based oil-water separation

Wettability control is a critical element in oil-water mixture separation, which is usually implemented by complicated chemical treatment steps such as grafting, coating or chemical deposition. The chemically treated surfaces may degrade both chemically and physically upon repeated use and exposure to harsh conditions. Therefore, facile control of wettability of separation membrane, without applying any chemical treatment steps, is highly demanding. In this work, we have demonstrated wettability switching, from oleophilic to oleophobic, of soft-lithographically fabricated isoporous through-hole membranes by structure control only, while maintaining their intrinsic hydrophobicity. Applied voltage converts the water wettability from hydrophobic to hydrophilic by electrowetting phenomenon, without affecting oleophobicity; this hydrophilic/oleophobic combination has enabled successful oil-water separation. Soft lithographic fabrication of isoprous membranes has enabled easy variation of pore size, ranging from tens of microns down to sub-micron scale in diameter, so that those membranes can be applied for both stratified and emulsified oil-water mixture separation. Based on these properties, stratified and emulsified (both oil-in-water and water-in-oil) oil-water mixtures could be separated in high efficiency (or selectivity) (>99%) and relatively high flux (200–1500 Lm -2 h -1 for stratified and 250–1000 Lm -2 h -1 for emulsified mixtures, respectively). Furthermore, the membranes showed excellent durability by maintaining its hydrophobic/oleophobic wettability even after exposure to chemicals and high temperature, thanks to the thermoset nature of polyurethane acrylate (PUA) membrane material. Wettability switching by structure control only, without complicated chemical processing steps, may find widespread applications in various fields. • Isoporous through-hole membranes having various pore sizes by soft lithography. • Oil wettability switching from oleophilic to oleophobic by structure control only. • Water wettability switching by low-voltage electrowetting phenomenon. • High flux and efficiency separation of both layered and emulsified mixtures. • Robust membranes to harsh conditions such as high T and acidic/basic chemicals.

Green production of bio-ethanol from cellulosic fiber waste and its separation using polyacrylonitrile-co-poly methyl acrylate membrane

The world is currently suffering substantially from the over-use of fossil fuels and worsening global climate change. The recycling and conversion of various types of biomass wastes for production of bio-ethanol have recently received increasing interest around the world to overcome the upcoming fuel shortage. In this work, the cellulosic fibers from textile industry wastes were used as biomass resource for liberation of glucose units. The cellulosic fibers were treated by some acids or alkali reagents followed by application of ultrasonic waves or autoclaving or microwave radiation as green technologies for improving hydrolysis rate. The cellulase enzyme from Trichoderma reesei was later applied to increase the concentration of glucose yield to reach 1133.33 mg/dl. Glucose units were then fermented by yeast isolate that was identified by amplification and sequencing of 18S rRNA as Pichia kluyveri (accession number MF184994). The parameters of pH, temperature, inoculum size, and aerobic/anaerobic conditions were optimized revealing that cultivation of 10% of the yeast isolate at pH 5 and 25 °C under anaerobic conditions are the ideal parameters for higher bio-ethanol production rates (33.9%). The produced bio-ethanol compared with standard 25% ethanol was separated by using amicon cell ultra-filtration that contains poly acrylonitrile co methyl acrylate membrane at different nitrogen pressures. The membrane was characterized by SEM, FTIR, Raman spectroscopy, TGA, IEC, and tensile strength measurement. The hydrophilicity/hydrophobicity of the prepared membrane was investigated using contact angle and water/ethanol uptake. Finally, the prepared polymeric membrane integrated amicon cell succeeded to increase the prepared ethanol concentration from 194.25 to 478.74 mg/ml which approximately elevated from 25 to 61.6%. On the other hand, the bio-ethanol concentration was increased from 256.41 to 540.82 mg/ml which approximately elevated from 33.9 to 69.6%. The obtaining bioethanol concentration is considered cost efficient, where the combined fermentation and separation processes succeeded to convert one ton of cellulosic fiber wastes into 105 l of bioethanol with approximate estimation cost of 103.9$ per liter through lab scale study.

Synthesis and characterization of nano‐modified permeability membrane

Novel high‐flux and fouling‐resistant pervaporation membranes were synthesized. The nano‐SiO2/polyurethane acrylate (NPUSA) membrane was prepared by 2,4‐toluene diisocyanate, hydroxy alkyl silicone oil (Tech‐2120), and hydroxyethyl acrylate and cross‐linked with the monomer pentaerythritol triacrylate (PETA) by UV curing technology. Nano‐SiO2, which has a large amount of hydroxyl groups that can make a reaction with the isocyanato (NCO), was used as a cross‐linking agent as well as an inorganic silicone precursor to generate an inorganic network. An inorganic organosiloxane network (SiOSi) was generated in the membrane by the electrophilic addition of carbamate between hydroxyl groups and isocyanato. The impact of nano‐SiO2 to NPUSA membrane was investigated using Fourier transform infrared spectrometer (FTIR), gel permeation chromatography, thermal gravimetric analysis, and atomic force microscopy (AFM). FTIR analysis confirmed the presence of the SiOSi network in the membrane, and AFM analysis confirmed the homogeneous distribution of this network throughout the membrane. The performance of NPUSA/PETA membrane was also compared with the commercially available membranes poly(vinyl alcohol)/poly(acrylonitrile) and polydimethylsiloxane and was found to be more resistant to compaction and with better permeability. Copyright © 2015 John Wiley & Sons, Ltd.

Multifunctional thiols as additives in UV-cured PEG-diacrylate membranes for CO 2 separation

The utility of incorporating only 20 mol% of multifunctional thiols into UV-cured poly(ethyleneglycol)diacrylate (PEGDA) membranes for CO 2 separation is presented. Five different multifunctional thiols were investigated, spanning a range of functionalities from 2 to 4 and also different rigidities. All thiol-modified networks exhibited lower modulus values according to both small-strain and large-strain mechanical testing. This decrease in modulus was primarily attributed to a decrease in crosslink density via the step-growth thiol–acrylate reaction. Decreased crosslink density was more pronounced for dithiol additives which formed a “train-like” topology of connected PEGDA segments. Because of this more linear topology, dithiol-modified networks exhibited increases in gas permeability and strain at break. CO 2 selectivity of each thiol-modified network was nearly comparable to the unmodified PEGDA network. Each network rapidly reached 100% conversion under a nitrogen atmosphere. However in air, the pure acrylate network reached negligible conversion while the networks modified with tri and tetrathiols reached noticeably higher conversions. Outdoor sunlight curing revealed that all thiol-modified networks were tack-free after only several minutes depending on thiol functionality. In contrast, the pure acrylate membrane remained tacky and uncured on the surface indefinitely. This study emphasizes the importance of thiol monomer selection in diminishing oxygen inhibition in UV-initiated acrylate polymerization as well as marked improvement in permeability for this specific PEGDA network via the incorporation of dithiols.

Influence of the Monomer Mixture Composition on Acrylate Membrane Properties

Macroporous membranes were prepared by bulk radical polymerization. The effect of the addition of a third monomer on membrane permeability and porosity was investigated. It was established that there is a correlation between the initial composition of the monomer mixture and porosity properties (permeability) of the prepared membranes. The use of methyl acrylate and hexyl acrylate as the third monomer enhances the specific surface area and membrane flexibility. On the other hand, increase of the third monomer content decreases the porosity and, hence, the water permeability of the membranes.

Concentration of foot-and-mouth disease virus by ultrafiltration

Stirred cell, flat sheet and spiral configurations were used to concentrate foot-and-mouth disease virus fermentation broth. The initial screening was carried out in a stirred cell using 50–300 k MWCO ultrafiltration membranes made of different polymers. Acrylate membrane showed highest recovery. No significant effect of MWCO and polymer material was observed on operating fluxes. Flat sheet configuration studies indicated as the CFR increases the recovery increased. No significant change was observed in operating fluxes over seven successive concentration and cleaning cycles. 97% recovery was obtained with the spiral module. Negligible effect on operating fluxes was observed over six successive cycles. A ∼30% saving in process time was observed in comparison with the conventional sedimentation process.

Photolithographically patternable nitrate-sensitive acrylate-based membrane

A photocurable acrylate matrix nitrate-sensitive membrane containing 2-nitrophenyl n-octyl ether as mediator and tetraalkylammonium nitrate as an active compound is described. The photocuring was achieved by the use of photoinitiators containing diaryliodonium chloride. This acrylate membrane is patternable via a photolithographic process with a only slight loss of electrochemical characteristics.

Coimmobilization of enzymes and whole cells

A survey on coimmobilization of enzymes and whole cells is given. Coentrapment in polymeric matrices and direct enzyme coupling to cells are shown. As an example of an aerobic system cells of Gluconobacter oxydans and mould catalase were coentrapped in alginate beads which were additionally surrounded with an acrylate membrane. Application of this system for gluconate formation from glucose and hydrogen peroxide led to an eight times increased reaction rate as compared with conventionally aerated fermentation. Yeast cells with s‐glucosidase directly coupled thereto were enabled to ferment cellobiose in a packed bed reactor. The feasibility of coimmobilized systems is discussed.