Membrane processes in nanoparticle production

With the development of the scanning tunneling microscope, and other high resolution "microscopies", researchers could examine and adapt synthetic processes to control particles on the nanometer scale. Since then there have been an explosion of techniques for fabricating nanoparticles. So called "top-down" synthetic techniques start with large particles and make them smaller via grinding, spraying or pyrolysis while "bottom-up" techniques start with precursors and build up to nanoparticles (NPs) using deposition techniques or self-assembly of molecules. An ideal process for fabricating NPs would be tunable to a specific size or shape, using few industrially-available, nontoxic reagents, and the produced-NPs should be shelf-stable and in a concentrated suspension, with a narrow size distribution. In this work, we provide a summary meta-review of how membranes have been used to produce 100 nm entities and provide observations that membranes could be used to enable rational processes for industrially-friendly, continuous production of NPs. Our meta-review focuses on nano-sized entities created in a suspension versus using the membrane as a potentially "sacrificial" template, thus, we consider three nominal, membrane device operating modes: dispersion, emulsion, and contactor. (C) 2016 Elsevier B.V. All rights reserved.