Use of filtration techniques to study environmental fate of engineered metallic nanoparticles: Factors affecting filter performance.
We examined the filtration of aqueous suspensions of negatively charged (citrate-stabilized) Ag (14.5±1.1nm) and positively charged CeO2(7.3±1.4nm) engineered nanoparticles (ENPs) via different filtration techniques such as paper filtration, micro- and ultrafiltration, and evaluated the impact of initial concentration, matrix composition, and filter type and (pre-)treatment, on nanoparticle retention. Solutions of Ag+and Ce3+ions were tested in the same way. Significant retention of nanoparticles was observed even for filters having considerably larger pore sizes than the ENPs size. Retention also seemingly increased with decreasing initial concentration, but generally decreased upon preconditioning of the paper or membrane filters with diluted nitric acid or 0.1M Cu(NO3)2, respectively. In ultrapure water, retention appeared to depend more on particle characteristics than on a membrane type. However, in 2mM KNO3, NaCl, or CaCl2, more significant differences in recovery were observed between different membrane materials. Additionally, background electrolytes might reduce nanoparticle or ionic retention, but could also affect their (colloidal) stability, e.g., resulting in enhanced retention of Ag ENPs and Ag+ions in chloride-containing matrices. Results from centrifugal ultrafiltration recommend using 10kDa filters for nanoparticle removal from the solution, and suggest these filters might potentially be suitable to differentiate between (nano)particulate and dissolved species.
Laboratory of Analytical Chemistry and Applied Ecochemistry, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium. Electronic address: frederik.vankoetsem@gmail.com.
Frederik
F
Van Koetsem
Laboratory of Analytical Chemistry and Applied Ecochemistry, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium.
Simon
S
Verstraete
Department of Materials Science and Engineering, Ghent University, Technologiepark 903, Zwijnaarde, Belgium.
Elien
E
Wallaert
Department of Materials Science and Engineering, Ghent University, Technologiepark 903, Zwijnaarde, Belgium.
Kim
K
Verbeken
Particle and Interfacial Technology Group, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium.
Paul
P
Van der Meeren
Soil- and Groundwater-Management, Institute for Soil Engineering, Water and Wastewater Management, University of Wuppertal, Pauluskirchstraße 7, Wuppertal, Germany.
Jörg
J
Rinklebe
Laboratory of Analytical Chemistry and Applied Ecochemistry, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium. Electronic address: Gijs.DuLaing@UGent.be.
Gijs
G
Du Laing
Cerium dioxide; Filtration; Nanoparticles; Retention; Silver