Purification and Concentration of Nanoparticles Using Diafiltration

The present film was created by the US Army Engineers Research and Development Center in Vicksburg, MS for their Environmental Consequences of Nanomaterials Focus Area. For a step-by-step guide of the method shown here, visit http://acwc.sdp.sirsi.net/client/en_US/search/asset/1045126 Nanoparticle solutions, especially those synthesized in a laboratory, may contain additional solutes associated with synthesis and storage, such as ionic salts, suspension stabilizers, pH buffers, chelating agents, etc. These contaminants can cause instability in the nanoparticle suspensions and otherwise modify suspension behavior in a way not representative of a pure solution. Thus, it is important to purify the nanoparticle suspensions in a way that removes reactants but maintains the particles’ dimensions and properties. Diafiltration is a pressure-driven filtration process that has been shown to effectively and efficiently purify nanoparticle suspensions. This film describes the diafiltration method used in the team’s laboratory for controlling the initial properties of a nanoparticle dispersion. The authors wish to emphasize the importance of utilizing this technique to obtain data about the initial properties of nanoparticle dispersions. It is recommended that the data be obtained prior to endeavoring to understand how different ionic media — such as the media relevant to fate and transport experiments — impact behavior.