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Comparison of Photon Correlation Spectroscopy With Photosedimentation Analysis for the Determination of Aqueous Colloid Size Distributions
Author(s) -
Rees Terry F.
Publication year - 1990
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr026i011p02777
Subject(s) - colloid , brownian motion , dispersity , particle size distribution , particle size , fluorescence correlation spectroscopy , analytical chemistry (journal) , diffusion , dynamic light scattering , materials science , chemistry , optics , physics , nanoparticle , mathematics , chromatography , nanotechnology , thermodynamics , statistics , fluorescence , polymer chemistry
Colloidal materials, dispersed phases with dimensions between 0.001 and 1 μm, are potential transport media for a variety of contaminants in surface and ground water. Characterization of these colloids, and identification of the parameters that control their movement, are necessary before transport simulations can be attempted. Two techniques that can be used to determine the particle‐size distribution of colloidal materials suspended in natural waters are compared. Photon correlation Spectroscopy (PCS) utilizes the Doppler frequency shift of photons scattered off particles undergoing Brownian motion to determine the size of colloids suspended in water. Photosedimentation analysis (PSA) measures the time‐dependent change in optical density of a suspension of colloidal particles undergoing centrifugation. A description of both techniques, important underlying assumptions, and limitations are given. Results for a series of river water samples show that the colloid‐size distribution means are statistically identical as determined by both techniques. This also is true of the mass median diameter (MMD), even though MMD values determined by PSA are consistently smaller than those determined by PCS. Because of this small negative bias, the skew parameters for the distributions are generally smaller for the PCS‐determined distributions than for the PSA‐determined distributions. Smaller polydispersity indices for the distributions are also determined by PCS.