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ARS Home » Research » Publications at this Location » Publication #66934

Title: INTERACTING BETWEEN ATRAZINE AND SMECTITE SURFACES

Author
item Laird, David

Submitted to: American Chemical Society Symposium Series
Publication Type: Proceedings
Publication Acceptance Date: 10/2/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Smectites contribute much of the inorganic surface area of soils and therefore have a large potential for influencing the fate of atrazine in soil environments. The sorption capacity of smectites for atrazine varies widely depending on the surface charge density of the smectite, nature of the adsorbed cation, and pH of the equilibrating solution. Under neutral conditions, molecular atrazine is initially sorbed on smectites by a combination of water bridging between electronegative moieties on the atrazine molecule and interlayer cations and hydrophobic bonding between the alkyl-side chains on the atrazine molecule and hydrophobic microsites on the smectite surface. Surface acidity, arising principally from enhanced ionization of solvation water for adsorbed metal cations, catalyzes protonation and hydrolysis of atrazine sorbed on smectite surfaces. The hydrolysis product is protonated hydroxy/keto-atrazine, which may exist in any of 14 different tautomeric forms. Tautomerism and resonance allow protonated hydroxy/keto-atrazine molecules to adapt to the heterogeneous microsites on smectite surfaces which results in strong bonding.