Advances in biopolymer-based membrane preparation and applications

Porous polymeric membranes have emerged as the core technology in the field of separation. But some challenges remain for several methods used for membrane fabrication, suggesting the need for a critical review of the literature. We present here an overview on porous polymeric membrane preparation and characterization for two commonly used polymers: polysulfone and poly (vinylidene fluoride). Five different methods for membrane fabrication are introduced: non-solvent induced phase separation, vapor-induced phase separation, electrospinning, track etching and sintering. The key factors of each method are discussed, including the solvent and non-solvent system type and composition, the polymer solution composition and concentration, the processing parameters, and the ambient conditions. To evaluate these methods, a brief description on membrane characterization is given related to morphology and performance. One objective of this review is to present the basics for selecting an appropriate method and membrane fabrication systems with appropriate processing conditions to produce membranes with the desired morphology, performance and stability, as well as to select the best methods to determine these properties.

A Review on Porous Polymeric Membrane Preparation. Part I: Production Techniques with Polysulfone and Poly (Vinylidene Fluoride).

The role of carbon nanotube (CNT) as filler in a membrane matrix became popular recently. CNT is believed to solve the trade-off issue between permeability and selectivity, and also fouling problems in membrane filtration applications. Their fullerene form is a key point to provide a higher pore size on membrane surface as well as empty space called porosity in membrane structures. However, the hydrophobicity characteristic of CNT has made it difficult to distribute and it tends to agglomerate with each other which leads to a decrease in the dispersion ability in a solvent and, in the same way, a decline in the compatibility of a membrane structure. Functionalization of CNT is expected to solve those problems. Moreover, membrane hydrophilicity, which is provided by the existence of hydrophilic functionalized CNT, is aimed to achieve the anti trade-off between permeability and selectivity based on a electrostatic repulsion concept. By an electrostatic repulsion process, a pollutant will be repelled from attaching to a membrane surface while water will be strongly attracted and be transported through the membrane. Therefore, various approaches have been investigated to functionalize CNT for achieving a high dispersion of CNT as well as high compatibility between CNT and a polymer matrix which lead to improvement of modified membrane properties and performances. This paper reviews the progress of CNT functionalization applied in membrane filtration during the years 2006 up to 2016. The influence of functionalized CNT in improving membrane properties as well as membrane performances is specifically highlighted.

/pdf/functionalized-carbon-nanotube-cnt-membrane-progress-and-51t2l52ihg.pdf

Functionalized carbon nanotube (CNT) membrane: progress and challenges

Membrane filtration and absorption strategies based on superwetting surfaces for oil–water separation have regained tremendous attention due to their being low cost, highly efficient and environmentally friendly. Besides the usual superhydrophobic, superhydrophilic/underwater superoleophobic and dual superlyophobic surfaces, very novel and unprecedented surfaces with special extreme wetting behavior have been widely used in oil–water separation. In this review, novel surfaces with extreme wetting behavior for oil-water separation reported over the past three years including superhydrophilic–superoleophobic, superamphiphobic, superhydrophilic-underoil superhydrophilic, underoil superhydrophobic-underwater superoleophobic and liquid-infused surfaces, as well as oil–water separation mechanisms, separation approaches and design principles for obtaining novel superwetting membranes, are systematically summarized. The most common problems in the process of oil–water separation-membrane pollution and solutions are discussed. In addition, the selection of substrates, the swelling of hydrophilic membranes and the wettability conversion of intelligent response membranes are analyzed. The current trends, challenges and future research opportunities are also proposed, providing a road map for the future development of high-efficiency oil–water separation technology.

Designing novel superwetting surfaces for high-efficiency oil–water separation: design principles, opportunities, trends and challenges

Polymers are materials widely used in biomedical science because of their biocompatibility, and good mechanical properties (which, in some cases, are similar to those of human tissues); however, these materials are, in general, chemically and biologically inert. Surface characteristics, such as topography (at the macro-, micro, and nanoscale), surface chemistry, surface energy, charge or wettability are interrelated properties, and they cooperatively influence the biological performance of materials when used for biomedical applications. They regulate the biological response at the implant/tissue interface (e.g., influencing the cell adhesion, cell orientation, cell motility, etc.). Several surface processing techniques have been explored to modulate these properties for biomedical applications. Despite their potentials, these methods have limitations that prevent their applicability. In this regard, laser-based methods, in particular laser surface texturing (LST), can be an interesting alternative. Different works have showed the potentiality of this technique to control the surface properties of biomedical polymers and enhance their biological performance; however, more research is needed to obtain the desired biological response. This work provides a general overview of the basics and applications of LST for the surface modification of polymers currently used in the clinical practice (e.g. PEEK, UHMWPE, PP, etc.). The modification of roughness, wettability, and their impact on the biological response is addressed to offer new insights on the surface modification of biomedical polymers.

/pdf/laser-surface-texturing-of-polymers-for-biomedical-2c5bfoubag.pdf

Laser surface texturing of polymers for biomedical applications

Abstract Polypropylene (PP) is one of the most used polymers for microporous membrane fabrication due to its good thermal stability, chemical resistance, mechanical strength, and low cost. There have been numerous studies reporting the developments and applications of PP membranes. However, PP membrane with high performance is still a challenge. Thus, this article presents a comprehensive overview of the advances in the preparation, modification and application of PP membrane. The preparation methods of PP membrane are firstly reviewed, followed by the modification approaches of PP membrane. The modifications includes hydrophilic and superhydrophobic modification so that the PP membranes become more suitable to be applied either in aqueous applications or in non-aqueous ones. The fouling resistant of hydrophilized PP membrane and the wetting resistant of superhydrophobized PP membrane are then reviewed. Finally, special attention is given to the various potential applications and industrial outlook of the PP membranes.

Advances in preparation, modification, and application of polypropylene membrane

Abstract Superhydrophobic membrane that is highly resistant to wetting by aqueous solution has gained great attention because of its potential to be applied in many emerging membrane processes such as membrane gas absorption (MGA) and membrane distillation (MD). Numerous approaches have been proposed to obtain membranes with superhydrophobic surface from materials with various degrees of hydrophobicity. This paper then reviews the progress in superhydrophobic membrane preparation and its separation properties. A brief description of superhydrophobicity is firstly presented. Preparation methods of the superhydrophobic membrane are subsequently reviewed, including direct processing method and surface modification of the existing membrane. Finally, the separation properties and challenges of superhydrophobic membranes are discussed. This article could provide an insight for further development of superhydrophobic membrane.

Sofiatun Anisah

Papers

Advances in preparation, modification, and application of polypropylene membrane

Superhydrophobic membrane: progress in preparation and its separation properties

Preparation, characterization, and evaluation of TiO2-ZrO2 nanofiltration membranes fired at different temperatures

Al2O3 nanofiltration membranes fabricated from nanofiber sols: Preparation, characterization, and performance

Hydrothermal stability and permeation properties of TiO2-ZrO2 (5/5) nanofiltration membranes at high temperatures