Preparation and Performance of PET-Braid-Reinforced Poly(vinylidene fluoride)/Graphene Hollow-Fiber Membranes

Natural and recycled materials for sustainable membrane modification: Recent trends and prospects

Despite water being critical for human survival, its uneven distribution, and exposure to countless sources of pollution make water shortages increasingly urgent. Membrane technology offers an efficient solution for alleviating the water shortage impact. The selectivity and permeability of membranes can be improved by incorporating additives of different nature and size scales. However, with the vast debate about the environmental and economic feasibility of the common nanoscale materials in water treatment applications, we can infer that there is a long way before the first industrial nanocomposite membrane is commercialized. This stumbling block has motivated the scientific community to search for alternative modification routes and/or materials with sustainable features. Herein, we present a pragmatic review merging the concept of sustainability, nanotechnology, and membrane technology through the application of natural additives (e.g., Clays, Arabic Gum, zeolite, lignin, Aquaporin), recycled additives (e.g., Biochar, fly ash), and recycled waste (e.g., Polyethylene Terephthalate, recycled polystyrene) for polymeric membrane synthesis and modification. Imparted features on polymeric membranes, induced by the presence of sustainable natural and waste-based materials, are scrutinized. In addition, the strategies harnessed to eliminate the hurdles associated with the application of these nano and micro size additives for composite membranes modification are elaborated. The expanding research efforts devoted recently to membrane sustainability and the prospects for these materials are discussed. The findings of the investigations reported in this work indicate that the application of natural and waste-based additives for composite membrane fabrication/modification is a nascent research area that deserves the attention of both research and industry.

Challenges, Opportunities and Future Directions of Membrane Technology for Natural Gas Purification: A Critical Review

Natural gas is an important and fast-growing energy resource in the world and its purification is important in order to reduce environmental hazards and to meet the required quality standards set down by notable pipeline transmission, as well as distribution companies. Therefore, membrane technology has received great attention as it is considered an attractive option for the purification of natural gas in order to remove impurities such as carbon dioxide (CO₂) and hydrogen sulphide (H₂S) to meet the usage and transportation requirements. It is also recognized as an appealing alternative to other natural gas purification technologies such as adsorption and cryogenic processes due to its low cost, low energy requirement, easy membrane fabrication process and less requirement for supervision. During the past few decades, membrane-based gas separation technology employing hollow fibers (HF) has emerged as a leading technology and underwent rapid growth. Moreover, hollow fiber (HF) membranes have many advantages including high specific surface area, fewer requirements for maintenance and pre-treatment. However, applications of hollow fiber membranes are sometimes restricted by problems related to their low tensile strength as they are likely to get damaged in high-pressure applications. In this context, braid reinforced hollow fiber membranes offer a solution to this problem and can enhance the mechanical strength and lifespan of hollow fiber membranes. The present review includes a discussion about different materials used to fabricate gas separation membranes such as inorganic, organic and mixed matrix membranes (MMM). This review also includes a discussion about braid reinforced hollow fiber (BRHF) membranes and their ability to be used in natural gas purification as they can tackle high feed pressure and aggressive feeds without getting damaged or broken. A BRHF membrane possesses high tensile strength as compared to a self-supported membrane and if there is good interfacial bonding between the braid and the separation layer, high tensile strength, i.e., upto 170Mpa can be achieved, and due to these factors, it is expected that BRHF membranes could give promising results when used for the purification of natural gas.

Effective Parameters on Fabrication and Modification of Braid Hollow Fiber Membranes: A Review

Hollow fiber membranes (HFMs) possess desired properties such as high surface area, desirable filtration efficiency, high packing density relative to other configurations. Nevertheless, they are often possible to break or damage during the high-pressure cleaning and aeration process. Recently, using the braid reinforcing as support is recommended to improve the mechanical strength of HFMs. The braid hollow fiber membrane (BHFM) is capable apply under higher pressure conditions. This review investigates the fabrication parameters and the methods for the improvement of BHFM performance.

Fabrication and characterization of polysulfone reinforced hollow fibre membrane

In this study, reinforced hollow fibre membranes were fabricated using different molecular weights of polyvinylidene prolidone (PVP Mw: 10, 40 and 360 kDa) and different take-up speeds (1, 2, 2.6 and 3.5 m/min). Prepared reinforced hollow fibre membranes were characterized in terms of permeability; surface morphology and hydrophilicity; pore size distribution; bovine serum albumin (BSA) rejection and flux recovery ratio. Optimum permeability and BSA rejection were obtained when PVP molecular weight was 40 kDa. After PVP molecular weight determination, advancing speed was changed and it was seen that increasing advancing speed ended up with decreased membrane wall thickness; however, decreased wall thickness increased the probability of irreversible fouling.

Waterproof breathable layers - A review

Waterproof breathable layers (WPBLs) can be classified into two large groups of hydrophilic nonporous and hydrophobic porous layers. These layers (e.g., fabrics, films, membranes, and meshes) can be produced by various continuous and non-continuous processes such as coating, laminating, film stretching, casting, etc. The most common methods for production, characterization, and testing of WPBLs are presented and discussed in light of recent publications. The materials with high level of waterproofness and breathability are often used in outerwear for winter sports, sailing apparel, raincoats, military/police jackets, backpacks, tents, cargo raps, footwear and etc. WPBLs can also be used for other specialized applications such as membrane distillation, oil-water filtration, and wound dressing. These applications are discussed by presenting several good examples. The main challenge in the production of these layers is to compromise between waterproofness and breathability with opposing nature. The related research gaps, challenges, and future outlook are highlighted to shed more light on the topic.

Graphene-Coated Poly(ethylene terephthalate) Nonwoven Hollow Tube for Continuous and Highly Effective Oil Collection from the Water Surface

Graphene (GE) has attracted significant attention on account of its unique structure and superior performance, arousing a new research field for materials science. Herein, a novel GE-coated poly(ethylene terephthalate) nonwoven (PGNW) hollow tube (PGNW-T) was fabricated for continuous and highly effective oil collection from the water surface. The PGNW was prepared via a dip-spray coating method, which possessed superhydrophobicity-superoleophilicity and could absorb a variety of oils or organic solvents with the absorption capacity (Q) value of 18-34 times its own weight. Then, PGNW-T was obtained through winding the PGNW on the surface of a porous polypropylene hollow tube. As-prepared PGNW-T was competent for dynamic oil collection with high flux (18 799.94 L/m2 h), outstanding separation efficiency (97.14%), and excellent recyclability (>96% after 10 cycles) from the oil/water mixture. In particular, a miniature device based on as-prepared PGNW-T was developed for continuous thin oil film collection, which could dynamically "catch up" floated oils or organic solvents from the water surface. Finally, our strategy is extremely facile to scale up, showing its huge potential application in practical oil-spill remediation.

In situ reduced graphene oxide-based polyurethane sponge hollow tube for continuous oil removal from water surface

Graphene oxide (GO) was prepared by using the natural graphite as raw materials via the modified Hummers' method and ultrasonic stripping method. GO was reduced online after its anchoring on the surface of polyurethane sponges by a dip-coating method, then in situ reduced graphene oxide-based polyurethane (IRGOPU) sponges were fabricated. The characterizations of IRGOPU sponges were investigated using Field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and contact angle measurement. The IRGOPU sponges had an adsorption capacity for a broad range of oils up to 21.7 ~ 55 g/g. A simulation experiment of large-scale oil spill using a simple IRGOPU sponge hollow tube component was designed. The process of continuous oil removal from water surface was quick and effective, and the oil/water separation efficiency could be up to 99.6%. The results indicated that the IRGOPU sponge hollow tube may be an optimum candidate for the oil/water separation of large-scale oil spill.

Study on the structural design and performance of novel braid-reinforced and thermostable poly(m-phenylene isophthalamide) hollow fiber membranes

Novel braid-reinforced (BR) PMIA hollow fiber membranes showing excellent mechanical property and thermal stability were fabricated.