Environ. Sci. Technol. 2010, 44, 4383
2009, Volume 43, Pages 8573–8579 Huilian Ma, Julien Pedel, Paul Fife, and William P. Johnson*: Hemispheres-in-Cell Geometry to Predict Colloid Deposition in Porous Media The correct hemispheres in cell-based correlation equation for the collector efficiency (η) under favorable conditions (in the absence of repulsive energy barriers to deposition) is as follows: -0.66 0.052 η ≈ γ2[2.3As1/3NR-0.028NPE NA + 0.55AsNR1.8NA0.15 0.053 0.053 + 0.2NR-0.047NG1.1NPE NA ]
(E1)
We emphasize here that the above equation (eq E1) should replace any previously published hemisphere in cell-based correlation equations (i.e., Equation 3 in ref 1, or eq 6 in ref 2), shown again below (eq E2) for estimation of η under favorable conditions. -0.65 0.052 η ≈ γ2[2.3As1/3NR-0.08NPE NA + 0.55AsNR1.8NA0.15 0.053 + 0.2NR-0.1NG1.1NA0.053NPE ]
(E2)
The differences between the correct (eq E1) and previously published (eq E2) correlation equations are in the exponents for parameter NR in the first and third terms in the brackets of both equations (note, the slight differences in the exponents of NPE in the first terms from both equations are due to decimal digit omission). All data presented in refs 1 and 2 reflect the correct correlation equation (i.e., eq E1). Values of η from eq E2 are slightly larger than those from the correct equation (eq E1), typically within a factor of 1.2-1.6 depending upon parameter conditions used (e.g., colloid size, porosity).
Literature Cited (1) Ma, H.; Pedel, J.; Fife, P.; Johnson, W. P. Hemispheres-in-cell geometry to predict colloid deposition in porous media. Environ. Sci. Technol. 2009, 43, 22, 8573-8579, DOI 10.1021/es901242b. (2) Ma, H.; Johnson, W. P. Colloid retention in porous media of various porosities: Predictions by the hemispheres-in-cell model. Langmuir 2010, 26, (3), 1680-1687, DOI 10.1021/la902657v.
ES1009373 10.1021/es1009373 Published on Web 04/19/2010
10.1021/es1009373
2010 American Chemical Society
Published on Web 04/19/2010
VOL. 44, NO. 11, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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