Removal of Metal Oxide Nanoparticles from Aqueous Suspensions

Abstract

Abstract An experimental investigation was carried out to assess the removal efficiency of metal oxide nanoparticles from aqueous suspensions via sedimentation and the added benefit of membrane filtration. The study was conducted with aqueous suspensions of TiO2, ZnO, and CeO2 nanoparticles (NPs) of primary size of 10 nm–21 nm. The removal of NPs by gravitational settling was carried out with suspensions that were pretreated via pH adjustment and coagulant addition in order to increase the agglomerate size. Removal efficiencies were as high as 72.3–98.6% for the studied NPs with subsequent ultrafiltration of the remaining suspensions (post sedimentation) enabling essentially complete NP removal. Keywords: coagulationnanoparticlespH adjustmentultrafiltration ACKNOWLEDGEMENTS This work was supported, in part, by the UCLA Water Technology Research Center and the California Department of Water Resources. The authors also acknowledge discussions with Arturo Keller and the help of Bradley Cardinale who provided mesocosm wastewater samples, both from the University of California, Santa Barbara. The presented work was also supported, in part, by the National Science Foundation and the Environmental Protection Agency under Cooperative Agreement Number DBI-0830117. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the Environmental Protection Agency. This work has not been subjected to EPA review and no official endorsement should be inferred. Notes a Coagulant dose of 2 mg/L. Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lsst.