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Title: Adsorption of counter ions to a stearate monolayer spread at the water-air interface: A synchrotron x-ray study

Technical Report ·
DOI:https://doi.org/10.2172/5852880· OSTI ID:5852880
; ;  [1];  [2];  [3];  [4]
  1. Argonne National Lab., IL (USA)
  2. Brooklyn Coll., NY (USA). Dept. of Physics
  3. West Virginia Univ., Morgantown, WV (USA)
  4. Minnesota Univ., Minneapolis, MN (USA)

The Near Total External Fluorescence (NTEF) technique was used to measure in-situ the adsorption of a metal ion from a subphase solution to the liquid-air interface, induced by a surfactant monolayer on the interface. For a monolayer formed by spreading stearic acid (a surfactant material) on a 10{sup {minus}3} mole/l solution of MnCl{sub 2}, the ratio of Mn ions segregated to the interface to the number of stearate molecules on the surface was determined to be approximately 0.6 {plus minus} 0.2. SEXAFS experiments revealed local order of the Mn ions at the surface at the condensed phase but no order showed up in the expanded phase. We explain these findings using a self consistent Poisson-Boltzman calculation of a partially ionized monolayer. Our model also explains earlier reports of adsorption of metal ions to the liquid/monolayer interface. 19 refs., 3 figs.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE; USDOE, Washington, DC (USA)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
5852880
Report Number(s):
ANL/PP-65479; ON: DE91011124
Country of Publication:
United States
Language:
English