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Review: membrane materials for the removal of water from industrial solvents by pervaporation and vapor permeation
Citation:
Vane, L. Review: membrane materials for the removal of water from industrial solvents by pervaporation and vapor permeation. Journal of Chemical Technology and Biotechnology. John Wiley and Sons, LTD, , Uk, 94(2):343-365, (2019).
Impact/Purpose:
Organic solvents serve a variety of functions in the manufacture of chemicals and materials in the worldwide economy. The production, use, and disposal of industrial solvents result in emissions that potentially impact human health and the environment. These impacts can be reduced through the recovery and reuse of the solvents. The EPA’s 2015 Definition of Solid Waste Rule encouraged the reuse/re-processing of 18 higher-value hazardous spent solvents used in the pharmaceuticals, paints and coatings, plastics and resins, and basic organic chemicals industrial sectors. The technical challenge to solvent reuse is the application of separation technologies to recover those solvents from mixtures with other processing materials and to purify them to meet quality specifications. Water can be a problematic contaminant because it forms difficult-to-separate “azeotropic” mixtures with most of the 18 solvents identified in the Definition of Solid Waste Rule. This article is a review of materials that can remove water from industrially-important solvents, with an emphasis on two emerging membrane-based separation technologies: pervaporation and vapor permeation. Although these are considered emerging technologies, a relatively robust and varied industry has developed to provide pervaporation/vapor permeation membranes and systems. Membranes made from at least seven water-selective materials are commercially available for this application. Thus, industries now have a useful and available means to dry water-loving solvents that are not easily dried with conventional separation technologies. States and EPA Regions providing technical support for solvent reclamation efforts can include pervaporation/vapor permeation in their consultations. This review contributes to an SHC 3.63.2 FY18 deliverable.
Description:
Organic solvents are widely used in a variety of industrial sectors. Reclaiming and reusing the solvents may be the most economically and environmentally beneficial option for managing spent solvents. Purifying the solvents to meet reuse specifications can be challenging. For hydrophilic solvents, water must be removed prior to reuse, yet many hydrophilic solvents form hard‐to‐separate azeotropic mixtures with water. Such mixtures make separation processes energy‐intensive and cause economic challenges. The membrane processes pervaporation (PV) and vapor permeation (VP) can be less energy‐intensive than distillation‐based processes and have proven to be very effective in removing water from azeotropic mixtures. In PV/VP, separation is based on the solution–diffusion interaction between the dense permselective layer of the membrane and the solvent/water mixture. This review provides a state‐of‐the‐science analysis of materials used as the selective layer(s) of PV/VP membranes in removing water from organic solvents. A variety of membrane materials, such as polymeric, inorganic, mixed matrix, and hybrid, have been reported in the literature. A small subset of these is commercially available and highlighted here: poly (vinyl alcohol), polyimides, amorphous perfluoro polymers, NaA zeolites, chabazite zeolites, T‐type zeolites, and hybrid silicas. The typical performance characteristics and operating limits of these membranes are discussed. Solvents targeted by the United States Environmental Protection Agency for reclamation are emphasized and ten common solvents are chosen for analysis: acetonitrile, 1‐butanol, N,N‐dimethyl formamide, ethanol, methanol, methyl isobutyl ketone, methyl tert‐butyl ether, tetrahydrofuran, acetone, and 2‐propanol. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.
URLs/Downloads:
Free access through PubMed Central
https://www.onlinelibrary.wiley.com/doi/10.1002/jctb.5839