A Bibliometric Study on Biomimetic and Bioinspired Membranes for Water Filtration

Insights into the biological channels and synthetic pore-forming assemblies have elucidated many fundamental aspects of selective water and solute transport over the last few decades. This has led to the development of novel technologies with unique selectivity and permeability. In terms of membrane separation technology, this development has proceeded by adapting either of two approaches: (i) one where biological channel proteins are reconstituted in suitable materials mimicking the biological bilayer membrane and (ii) one where selective transport is mimicked in synthetic structures. The development of water filtration membranes in the former approach takes advantage of aquaporin proteins as representative building blocks and that of carbon nanotubes and molecular pore-forming assemblies in the latter approach. The first approach is often referred to as the field dominated by biomimetic membranes and the latter referred to as artificial water channels. In this study, a bibliometric analysis was conducted to investigate trends in these two areas based on growing publication trends, peer-reviewed journal selection, countries, institutions, authors and collaborative networks. A total of 3199 records available from Scopus between 1962 and 2021 were extracted and analysed. The results showed strong international collaborations and highlighted leading researchers and hubs of excellence in these two areas. This is very timely considering that the UN climate change conference (COP26) in Glasgow, UK later this year will bring focus to the global need for water treatment technologies. This work can serve as a quick reference for early-career researchers and industries working in the area of membrane development for water purification/filtration

Biomimetic aquaporin membranes coming of age

Membrane processes have been widely used for water purification because of their high stability, efficiency, low energy requirement and ease of operation. Traditional desalting membranes are mostly dense polymeric films with a "trade off" effect between permeability and selectivity. Biological membranes, on the other hand, can perform transport in some cases with exceptional flux and rejection properties. In particular the discovery of selective water channel proteins - aquaporins - has prompted interest in using these proteins as building blocks for new types of membranes. The major challenge in developing an aquaporin-based membrane technology stems from the fact that the aquaporin protein spans a membrane only a few nanometers thick. Such ultrathin membranes will not be able to withstand any substantial pressures, nor being industrially scalable without supporting structures. Incorporating aquaporin proteins into compatible materials, while ensuring membrane performance, scalability, and cost-effective production, is crucial for a successful technology development. Since the first suggestions for using aquaporins in membrane technology appeared around ten years ago, two main approaches have been suggested based on planar membranes and vesicles respectively. Here we summarize the essentials of aquaporin protein function and review the latest progress in this fascinating area of membrane research and development

Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

© 2017 Elsevier B.V. Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after cleaning with NaOCl and Alconox. Changes in the membrane structure and increased hydrophilicity in the surrounding areas of the aquaporin may be accountable for the increase in water permeability. The membrane shows stable salt rejection up to 99% after all cleaning agents were tested. A 15-day experiment with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane exhibits chemical resistance for most agents used in membrane cleaning procedures, maintaining a stable flux and high salt rejection

Enhanced performance of a biomimetic membrane for Na2CO3 crystallization in the scenario of CO2 capture

Membrane assisted crystallization (MACr) offers an innovative platform for crystallizing Na2CO3, allowing its reuse after CO2 capture from flue gases by an alkaline solution (i.e., NaOH). In this study, the biomimetic aquaporin Inside™ membrane AIM60 was employed to enhance water removal, facilitating Na2CO3 crystallization. The water channel in the active layer, comprising aquaporin proteins, and the strong wettability of membrane substrate assist a better performance. For instance, the water flux of AIM60 membrane for concentrating a 1.89molL-1 Na2CO3 solution (osmotic pressure of 94.8bar) in forward osmosis (FO) mode was 6.62Lm-2h-1 and 3.25Lm-2h-1 in pressure retarded osmosis (PRO) mode when a 5.13molL-1 NaCl solution (osmotic pressure of 304.9bar) was employed as the draw solution. This demonstrates that the AIM60 FO membrane outperformed the previously reported dense reverse osmosis membrane (0.21Lm-2h-1 in FO mode and 0.16Lm-2h-1 in PRO mode) and a porous hydrophobic hollow fiber membrane (0.08Lm-2h-1) under the same operating conditions.Crystallization utilizing the AIM60 membrane in an osmotic crystallizer was achieved without noticeable membrane scaling or degradation. Furthermore, a proper control of the supersaturation level induces crystallization of Na2CO3·10H2O crystals with a purity of 99.94%. Hence, the aquaporin Inside™ FO membrane may be a promising alternative to existing methods for Na2CO3 crystallization for its application in a CO2 capture scenario

Desalination by biomimetic aquaporin membranes: Review of status and prospects

Based on their unique combination of offering high water permeability and high solute rejection aquaporin proteins have attracted considerable interest over the last years as functional building blocks of biomimetic membranes for water desalination and reuse. The purpose of this review is to provide an overview of the properties of aquaporins, their preparation and characterization. We discuss the challenges in exploiting the remarkable properties of aquaporin proteins for membrane separation processes and we present various attempts to construct aquaporin in membranes for desalination; including an overview of our own recent developments in aquaporin-based membranes. Finally we outline future prospects of aquaporin based biomimetic membrane for desalination and water reuse. © 2012 Elsevier B.V.link_to_subscribed_fulltex

Lipid Directed Intrinsic Membrane Protein Segregation

We demonstrate a new approach for direct reconstitution of membrane proteins during giant vesicle formation. We show that it is straightforward to create a tissue-like giant vesicle film swelled with membrane protein using aquaporin SoPIP2;1 as an illustration. These vesicles can also be easily harvested for individual study. By controlling the lipid composition we are able to direct the aquaporin into specific immiscible liquid domains in giant vesicles. The oligomeric alpha-helical protein co-segregates with the cholesterol-poor domains in phase separating ternary mixtures