Ion Exchange Membranes for Electrodialysis: A Comprehensive Review of Recent Advances

Electrodialysis related processes are effectively applied in desalination of sea and brackish water, waste water treatment, chemical process industry, and food and pharmaceutical industry. In this process, fundamental component is the ion exchange membrane (IEM), which allows the selective transport of ions. The evolvement of an IEM not only makes the process cleaner and energy-efficient but also recovers useful effluents that are now going to wastes. However ion-exchange membranes with better selectivity, less electrical resistance, good chemical, mechanical and thermal stability are appropriate for these processes. For the development of new IEMs, a lot of tactics have been applied in the last two decades. The intention of this paper is to briefly review synthetic aspects in the development of new ion-exchange membranes and their applications for electrodialysis related processes

Aliphatic anion exchange ionomers with long spacers and no ether links by Ziegler–Natta polymerization: properties and alkaline stability

In this work we report the synthesis of poly(vinylbenzylchloride-co-hexene) copolymer grafted with N,N-dimethylhexylammonium groups to study the effect of an aliphatic backbone without ether linkage on the ionomer properties. The copolymerization was achieved by the Ziegler– Natta method, employing the complex ZrCl4 (THF)2 as a catalyst. A certain degree of crosslinking with N,N,N0,N0-tetramethylethylenediamine (TEMED) was introduced with the aim of avoiding excessive swelling in water. The resulting anion exchange polymers were characterized by 1H-NMR, FTIR, TGA, and ion exchange capacity (IEC) measurements. The ionomers showed good alkaline stability; after 72 h of treatment in 2MKOH at 80 C the remaining IEC of 76% confirms that ionomers without ether bonds are less sensitive to a SN2 attack and suggests the possibility of their use as a binder in a fuel cell electrode formulation. The ionomers were also blended with polyvinyl alcohol (PVA) and crosslinked with glutaraldehyde. The water uptake of the blend membranes was around 110% at 25 C. The ionic conductivity at 25 C in the OH form was 29.5 mS/cm

Seven Years of Membranes: Feature Paper 2017

For the last seven years, Membranes has provided an outstanding platform for the publication of articles at the forefront of research in the areas of membrane fabrication, characterization and application. This Special Issue, entitled “Seven Years of Membranes: Feature Paper 2017,” celebrates this achievement. The articles included in this Special Issue, written by prominent researchers in the field, provide an authoritative and up-to-date account of the advances in membrane science and technology. They describe new methods for the fabrication of organic, inorganic and mixed matrix membranes and their utilization in improving the efficiency of membrane-based separation processes, such as membrane distillation, nanofiltration, ultrafiltration, reverse osmosis, and gas permeation. A number of articles are focused on water treatment, which, because of its significance to sustainable development, is one of the main areas of membrane research and application. These articles report novel techniques for the clean-up of contaminated waters, and the desalination of industrial effluents, brackish water and seawater

Acrylic polyampholyte solutions for protein separations

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1994.Includes bibliographical references.by Costas S. Patrickios.Ph.D

THE STUDY OF CHEMICAL INDUCED POLYOLEFIN-BASED ION EXCHANGE MEMBRANE FOR ELECTRODIALYSIS APPLICATION

High-performance ion exchange membranes with high ion exchange capacity (IEC), excellent mechanical properties, lower membrane resistance and superior ions conductivity were developed with chemical-induced polymerization in this work. Through a series of synthesizing experiments, structure characterization and properties testing for polyolefin-based cation exchange membrane (CEM) and anion exchange membrane (AEM), LDPE proved to be an optimized backbone material. The CEM with 57.5% styrene, 38.4% LDPE, 3% crosslinking degree and 1% initiator addition yield the highest IEC value (1.72 mol/g) and moderate burst strength. The 10% addition of styrene was found to enhance IEC of 57% to AEM. However, continually increase styrene leaded lower IEC due to the decreasing grafting degree of vinyl benzene chloride (VBC) on polyethylene. The influence of fillers, such as surface-modified glass fiber (GF) and functionalized graphene oxides (GO), on thermal, mechanical and electrochemical properties of ion exchange membrane were investigated in this work by dynamic mechanical analysis, IEC and field emission scanning electron microscopes (FE-SEM), fourier-transform infrared spectroscopy (FT-IR) and electrochemical impedance spectroscopy. The addition of modified GF increases tensile strength, tensile modulus, storage modulus and interfacial adhesion of GF/CEM composite but degraded the strains. The composite with [3-(Methacryloxy) propyl] trimethoxy silane (3-MPS) modified GF obtained superior mechanical properties and interfacial adhesion, whereas the modified effect of triethoxyvinylsilane (TES) was inconspicuous. The addition of unmodified GF even had negative effects on GF/CEM mechanical properties. The FE-SEM showed that the GF treated by 3-MPS and poly(propylene-graft-maleic anhydride) (PP-g-MA) have better compatibility with the CEM matrix than 1,6 bis and TES treated GF. The FT-IR verified the strengthening effects from modified GF were attributed to the formation of Si-O-Si and Si-O-C bonds. The additions of modified GF in CEM positively influence water uptake ability but negatively on IEC. This section provided a way of strengthening GF/CEM composite. The CEM doped with functionalized graphene oxides was verified to be significantly improved in IEC (21% higher) and membrane conductivity (326.7% higher) compare to the pristine CEM. The results also suggested that the improved effects of dual-functionalized GO on CEM properties are superior to the single functionalized GO. The coexistence of -PO3H, -SO3H in GO resulted in CEM possessed 7.8% higher IEC, 77.29% higher membrane conductivity and 43.56% lower activation energy than that with single functionalized GO. This work provides a new strategy for the design of high-performance IEM with excellent mechanical property, high IEC, high conductivity and low membrane resistance for application

Ionic Conductive Polymers for Electrochemical Devices

Increasing levels of pollution and climate change are pushing the scientific community towards more sustainable solutions for the conversion and storage of energy. This book is dedicated to ionic conductive polymers, fundamental components of devices such as fuel cells (FCs), redox flow batteries (RFBs), and electrolyzers that can help to significantly decrease the amount of greenhouse gases emission. The book focuses on commercial polymers such as Nafion, a benchmark for proton-conducting membranes, acid doped polybenzimidazole (PBI), or blended membranes containing hyperbranched poly(arylene ether sulfone (PAES)/Linear poly(phenylene oxide) (PPO) as anion exchange membranes (AEMs). Promising and low-cost sulfonated aromatic polymers (SAP), or solid polymer blend electrolytes (SPBEs) based on natural chitosan (CS) and methylcellulose (MC). This book is also reports some strategies to enhance mechanical stability, such as cross-linking (XL), or several techniques, including classical casting methods or electrospinning (ES). I am confident that this book will serve to further stimulate advances in this research area, in both the sectors of membranes and catalysts, the first is essential for the long-term functioning of the system, and the second for a drastic reduction in costs, especially in fuel cells

Biomimetic hybrid membranes: incorporation of transport proteins/peptides into polymer supports

Molecular sensing, water purification and desalination, drug delivery, and DNA sequencing are some striking applications of biomimetic hybrid membranes. These devices take advantage of biomolecules, which have gained excellence in their specificity and efficiency during billions of years, and of artificial materials that load the purified biological molecules and provide technological properties, such as robustness, scalability, and suitable nanofeatures to confine the biomolecules. Recent methodological advances allow more precise control of polymer membranes that support the biomacromolecules, and are expected to improve the design of the next generation of membranes as well as their applicability. In the first section of this review we explain the biological relevance of membranes, membrane proteins, and the classification used for the latter. After this, we critically analyse the different approaches employed for the production of highly selective hybrid membranes, focusing on novel materials made of self-assembled block copolymers and nanostructured polymers. Finally, a summary of the advantages and disadvantages of the different methodologies is presented and the main characteristics of biomimetic hybrid membranes are highlightedPeer ReviewedPostprint (author's final draft