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Published November 1994 | metadata_only
Journal Article

Sorption of Perylene on a Nonporous Inorganic Silica Surface: Effects of Aqueous Chemistry on Sorption Rates


The influence of solution chemistry on the initial rate of perylene adsorption to a nonporous inorganic silica surface was investigated. Fluorescence was utilized to monitor the loss of perylene from aqueous solution. At constant ionic strength, the initial rate of adsorption decreased with increasing pH for all background electrolyte compositions. The observed adsorption rates were correlated with the aqueous activity coefficient (γ_i^W) of perylene and the surface speciation of silica. At low pH, the rate of perylene adsorption appeared to depend solely on its γ_i^W. At neutral to high pH, binding of cations at the silica surface became increasingly important in determining adsorption rates. Binding of Na^+ at the silica surface decreased the rate of perylene adsorption, whereas binding of Ca^(2+) at the surface increased the adsorption rate. The reasons for this difference are not presently known, but may relate to the structure of water at the solution-silica surface when different cations are Dresent in the interfacial region.

Additional Information

© 1994 American Chemical Society. Received for review March 14, 1994. Revised manuscript received August 4, 1994. Accepted August 5, 1994. We gratefully acknowledge Deb Backhus, Steve Eisenreich, and Phil Gschwend for their helpful discussions, Elizabeth Carraway for the nonlinear least-squares curve-fitting program used to analyze fluorescence data, and the three reviewers for their constructive comments. This work was supported by grants from the Andrew W. Mellon Foundation, William and Flora Hewlett Foundation, Smith and Louise Lee Memorial Endowment, San Francisco Foundation (Switzer Foundation Environmental Fellowship), and the American Water Works Association (Larson Aquatic Research Support Ph.D. Scholarship). Elements of this paper were presented at the Symposium on Physical-Chemical Processes Controlling Contaminant Mobility in Aquatic Environments at the 207th American Chemical Society Meeting in San Diego, CA, March 13-18, 1994.

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August 20, 2023
August 20, 2023