Enhanced water permeation through sodium alginate membranes by incorporating graphene oxides

Preparation and characterization of anti-fouling PVDF membrane modified by chitin

Poly(vinylidene fluoride) (PVDF)/chitin (CH) blend membranes were prepared via the method of immersion-precipitation phase transformation with the solvent system N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl) as solvent and water as coagulant. The effect of CH on membrane structure and performance was investigated. Owing to the strong hydrophilicity, CH chains enriched on the blend membrane surface and improved the hydrophilicity of the membrane. The addition of CH also led to the formation of finger-like pores and the increase of pore size and porosity. The flux and the flux recovery ratio (FRR) of the blend membrane were higher than that of pure PVDF membrane. The fouling resistance of the blend membrane was lower than that of PVDF original membrane. In a word, the addition of CH to PVDF membrane improved the hydrophilicity and the anti-fouling ability of PVDF membrane.

Hybrid membrane biomaterials from self-assembly in polysaccharide and peptide amphiphile mixtures: controllable structural and mechanical properties and antimicrobial activity

Macroscopic capsules, with tunable properties based on hierarchical self-assembly on multiple lengthscales, are prepared from the co-operative self-assembly of polysaccharide and peptide amphiphiles.

A physically cross-linked self-healable double-network polymer hydrogel as a framework for nanomaterial

Physically cross-linked double-network hydrogels with different first networks act as a framework for graphene.

Enhanced Stability of Laminated Graphene Oxide Membranes for Nanofiltration via Interstitial Amide Bonding

Laminated graphene oxide (GO) has promising use as a membrane because of its high permeance, chemical and mechanical stability, as well as the molecular sieving effect of its interlayers. However, the hydrophilic surface of GO, which is highly decorated with oxygen groups, easily induces delamination of stacked GO films in aqueous media, thereby limiting the practical application. To stabilize GO films in aqueous media, we functionalized a polymer support with branched polyethylene-imine (BPEI). BPEI adsorbed intercalated into the stacked GO sheets via diffusion during filtration. The GO/BPEI membrane obtained exhibits high stability during sonication (>1 h duration, 40 kHz frequency) in water within a broad pH range (2-12). In contrast, the GO film spontaneously delaminated upon sonication. Furthermore, BPEI treatment did not affect the filtration performance of the GO film, as evidenced by the high rejection rates (>90%) for the dye molecules methylene blue, rose bengal, and brilliant blue and by their permeation rates of ca. 124, 34.8, 12.2, and 5.1%, respectively, relative to those of a typical GO membrane.

Incorporating Zwitterionic Graphene Oxides into Sodium Alginate Membrane for Efficient Water/Alcohol Separation

For the selective water-permeation across dense membrane, constructing continuous pathways with high-density ionic groups are of critical significance for the preferential sorption and diffusion of water molecules. In this study, zwitterionic graphene oxides (PSBMA@GO) nanosheets were prepared and incorporated into sodium alginate (SA) membrane for efficient water permeation and water/alcohol separation. The two-dimensional GO provides continuous pathway, while the high-density zwitterionic groups on GO confer electrostatic interaction sites with water molecules, leading to high water affinity and ethanol repellency. The simultaneous optimization of the physical and chemical structures of water transport pathway on zwitterionic GO surface endows the membrane with high-efficiency water permeation. Using dehydration of water/alcohol mixture as the model system, the nanohybrid membranes incorporating PSBMA@GO exhibit much higher separation performance than the SA membrane and the nanohybrid membrane utilizing unmodified GO as filler (with the optimal permeation flux of 2140 g m(-2) h(-1), and separation factor of 1370). The study indicates the great application potential of zwitterionic graphene materials in dense water-permeation membranes and provides a facile approach to constructing efficient water transport pathway in membrane.

Pervaporation dehydration of an acetone/water mixture by hybrid membranes incorporated with sulfonated carbon molecular sieves

Sulfonated carbon molecular sieves (SCMS) were incorporated into a chitosan (CS) matrix. The sulfonic acid groups hydrophilic sites can preferentially interact with water, while the ordered channels facilitate water transport.

Hierarchical alginate biopolymer papers produced via lanthanide ion coordination

A layered alginate-based biopolymer paper with a hierarchical structure and excellent mechanical properties was prepared via lanthanide ions coordination.

Enhancing the permeation selectivity of sodium alginate membrane by incorporating attapulgite nanorods for ethanol dehydration

Hydrophilic AT nanorods with selective channels were applied to fabricate hybrid membranes with high permeation selectivity for ethanol dehydration.

Graphene oxide/polysulfone hollow fiber mixed matrix membranes for gas separation

The application of graphene oxide as a nano-filler in polysulfone asymmetric hollow fiber mixed matrix membranes for CO₂ removal.

Graphene-based membranes

Graphene is a well-known two-dimensional material that exhibits preeminent electrical, mechanical and thermal properties owing to its unique one-atom-thick structure. Graphene and its derivatives (e.g., graphene oxide) have become emerging nano-building blocks for separation membranes featuring distinct laminar structures and tunable physicochemical properties. Extraordinary molecular separation properties for purifying water and gases have been demonstrated by graphene-based membranes, which have attracted a huge surge of interest during the past few years. This tutorial review aims to present the latest groundbreaking advances in both the theoretical and experimental chemical science and engineering of graphene-based membranes, including their design, fabrication and application. Special attention will be given to the progresses in processing graphene and its derivatives into separation membranes with three distinct forms: a porous graphene layer, assembled graphene laminates and graphene-based composites. Moreover, critical views on separation mechanisms within graphene-based membranes will be provided based on discussing the effect of inter-layer nanochannels, defects/pores and functional groups on molecular transport. Furthermore, the separation performance of graphene-based membranes applied in pressure filtration, pervaporation and gas separation will be summarized. This article is expected to provide a compact source of relevant and timely information and will be of great interest to all chemists, physicists, materials scientists, engineers and students entering or already working in the field of graphene-based membranes and functional films.

Recent Advances in Nanocomposite Materials of Graphene Derivatives with Polysaccharides

This review article presents the recent advances in syntheses and applications of nanocomposites consisting of graphene derivatives with various polysaccharides. Graphene has recently attracted much interest in the materials field due to its unique 2D structure and outstanding properties. To follow, the physical and mechanical properties of graphene are then introduced. However it was observed that the synthesis of graphene-based nanocomposites had become one of the most important research frontiers in the application of graphene. Therefore, this review also summarizes the recent advances in the synthesis of graphene nanocomposites with polysaccharides, which are abundant in nature and are easily synthesized bio-based polymers. Polysaccharides can be classified in various ways such as cellulose, chitosan, starch, and alginates, each group with unique and different properties. Alginates are considered to be ideal for the preparation of nanocomposites with graphene derivatives due to their environmental-friendly potential. The characteristics of such nanocomposites are discussed here and are compared with regard to their mechanical properties and their various applications.