Investigation of Conventional Membrane and Tangential Flow Ultrafiltration Artifacts and Their Application to the Characterization of Freshwater Colloids

Artifacts associated with the fractionation of colloids in a freshwater sample were investigated for conventional membrane filtration (0.45 μm cutoff), and two tangential flow ultrafiltration cartridges (0.1 μm cutoff and 3000 MW cutoff). Membrane clogging during conventional filtration removed some...

Full description

Saved in:
Bibliographic Details
Published in:Environmental science & technology 2004-12, Vol.38 (24), p.6817-6823
Main Authors: Morrison, Matthew A, Benoit, Gaboury
Format: Article
Language:English
Subjects:
Analysis methods
Applied sciences
Colloids - analysis
Earth sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
Engineering geology
Environmental Monitoring - standards
Environmental science
Exact sciences and technology
Filtration
Fresh water
Membrane filters
Membranes
Membranes, Artificial
Natural water pollution
Particle Size
Pollution
Samples
Sensitivity and Specificity
Water Movements
Water Pollutants - analysis
Water treatment and pollution
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Artifacts associated with the fractionation of colloids in a freshwater sample were investigated for conventional membrane filtration (0.45 μm cutoff), and two tangential flow ultrafiltration cartridges (0.1 μm cutoff and 3000 MW cutoff). Membrane clogging during conventional filtration removed some colloids smaller than 0.1 μm in diameter, much smaller than the nominal size of the filter. For certain constituents (e.g., Fe), filter clogging had a significant effect on filtrate concentrations, while artifacts associated with tangential flow ultrafiltration using a 0.1 μm cutoff were minimal. Artifacts occurred during tangential flow ultrafiltration with a 3000 MW cutoff, but did not deviate from predicted changes in concentration based on a standard permeation model. Comparison of filtrate concentrations for membrane filtration (at 1.0 and 0.45 μm) and tangential flow ultrafiltration (at 0.1 μm) for a large number of samples from Connecticut rivers shows that significant and consistent differences exist between their separation characteristics. Results for organic carbon, Fe, Mn, Al, Cu, and Pb demonstrate the magnitude of the effects of the fractionation technique on filtrate element concentration, show variability by element and flow condition, and highlight the importance of larger colloids to freshwater metal speciation. One implication of the research is that tangential flow ultrafiltration with large size cutoff membranes (e.g., ∼0.1 μm) may be superior to conventional filtration with filters in the same size discrimination range, and potentially more appropriate for the fractionation of natural water samples.
ISSN:0013-936X
1520-5851
DOI:10.1021/es049710l