Significance of kinetics for sorption on inorganic colloids: Modeling and experiment interpretation issues
2002 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 36, no 24, 5369-5375 p.Article in journal (Refereed) Published
A two-site kinetic model for solute sorption on inorganic colloids is developed. The model quantifies linear first-order sorption on two types of sites (fast and slow) characterized by two pairs of rates (forward and reverse). We use the model to explore data requirements for long-term predictive calculations of colloid-facilitated transport and to evaluate laboratory kinetic sorption data of Lu et al.. Five batch sorption data sets are considered with plutonium as the tracer and montmorillonite, hematite, silica, and smectite as colloids. Using asymptotic results applicable on the time stale of limited duration experiments, a robust estimation procedure is developed for the fast-site partitioning coefficient K-c and the slow forward rate alpha. The estimated range of K-c is 1.1-76 L/g, and the range for a is 0.0017-0.02 1/h. The fast reverse rate k(r) is estimated in the range 0.012-0.1 1/h. Comparison of one-site and two-site sorption interpretations reveals the difficulty in, discriminating between the two models for montmorillonite and to a lesser extent for hematite. For silica and smectite, the two-site model clearly provides a better representation of the data as compared with a single site model. Kinetic data for silica are available for different colloid concentrations (0.2 g/L and 1 g/L). For the range of experimental conditions considered, a. appears to be independent of colloid concentration.
Place, publisher, year, edition, pages
2002. Vol. 36, no 24, 5369-5375 p.
transport, plutonium, aquifer, nevada
IdentifiersURN: urn:nbn:se:kth:diva-22122DOI: 10.1021/es025718oISI: 000179833400013OAI: oai:DiVA.org:kth-22122DiVA: diva2:340820
QC 201005252010-08-102010-08-10Bibliographically approved