Hydrophilically surface-modified and crosslinked polybenzimidazole membranes for pervaporation dehydration on tetrahydrofuran aqueous solutions

State-of-the-Art Organic- and Inorganic-Based Hollow Fiber Membranes in Liquid and Gas Applications: Looking Back and Beyond

The aggravation of environmental problems such as water scarcity and air pollution has called upon the need for a sustainable solution globally. Membrane technology, owing to its simplicity, sustainability, and cost-effectiveness, has emerged as one of the favorable technologies for water and air purification. Among all of the membrane configurations, hollow fiber membranes hold promise due to their outstanding packing density and ease of module assembly. Herein, this review systematically outlines the fundamentals of hollow fiber membranes, which comprise the structural analyses and phase inversion mechanism. Furthermore, illustrations of the latest advances in the fabrication of organic, inorganic, and composite hollow fiber membranes are presented. Key findings on the utilization of hollow fiber membranes in microfiltration (MF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), pervaporation, gas and vapor separation, membrane distillation, and membrane contactor are also reported. Moreover, the applications in nuclear waste treatment and biomedical fields such as hemodialysis and drug delivery are emphasized. Subsequently, the emerging R&D areas, precisely on green fabrication and modification techniques as well as sustainable materials for hollow fiber membranes, are highlighted. Last but not least, this review offers invigorating perspectives on the future directions for the design of next-generation hollow fiber membranes for various applications. As such, the comprehensive and critical insights gained in this review are anticipated to provide a new research doorway to stimulate the future development and optimization of hollow fiber membranes.

Pervaporation as a Successful Tool in the Treatment of Industrial Liquid Mixtures

Pervaporation is one of the most active topics in membrane research, and it has time and again proven to be an essential component for chemical separation. It has been employed in the removal of impurities from raw materials, separation of products and by-products after reaction, and separation of pollutants from water. Given the global problem of water pollution, this approach is efficient in removing hazardous substances from water bodies. Conventional processes are based on thermodynamic equilibria involving a phase transition such as distillation and liquid-liquid extraction. These techniques have a relatively low efficacy and nowadays they are not recommended because it is not sustainable in terms of energy consumption and/or waste generation. Pervaporation emerged in the 1980s and is now becoming a popular membrane separation technology because of its intrinsic features such as low energy requirements, cheap separation costs, and good quality product output. The focus of this review is on current developments in pervaporation, mass transport in membranes, material selection, fabrication and characterization techniques, and applications of various membranes in the separation of chemicals from water.

Mixed matrix membranes (MMMs) for ethanol purification through pervaporation: current state of the art

Over the last few decades, different polymers have been employed as materials in membrane preparation for pervaporation (PV) application, which are currently used in the preparation of mixed matrix membranes (MMMs) for ethanol recovery and ethanol dehydration. The ethanol-water and water-ethanol mixtures are, in fact, the most studied PV systems since the bioethanol production is strongly increasing its demand. The present review focuses on the current state of the art and future trends on ethanol purification by using MMMs in PV. A particular emphasis will, therefore, be placed on the enhancement of specific components transport and selectivity through the incorporation of inorganic materials into polymeric membranes, mentioning key principles on suitable filler selection for a synergistic effect toward such separations. In addition, the following topics will be discussed: (i) the generalities of PV, including the theoretical aspects and its role in separation; (ii) a general overview of the methodologies for the preparation of MMMs; and (iii) the most recent findings based on MMMs for both ethanol recovery and ethanol dehydration for better evolution in the field. From the last decade of literature inputs, the poly(vinyl alcohol) has been the most used polymeric matrix targeting ethanol dehydration, while the zeolites have been the most used embedded materials. Today, the latest developments on MMM preparation declare that the future efforts will be directed to the chemical modification of polymeric materials as well as the incorporation of novel fillers or enhancing the existing ones through chemical modification.

Self-healing polymeric materials for membrane separation: an example of a polybenzimidazole-based membrane for pervaporation dehydration on isopropanol aqueous solution

The demonstration of a self-healing material based separation membrane for pervaporation dehydration on liquid–liquid mixtures.