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Calorimetric investigations on the effect of position of functional groups on surfactant adsorption

Journal Article · · Journal of Colloid and Interface Science; (United States)
;  [1];  [2]
  1. Columbia Univ., New York, NY (United States). Langmuir Center for Colloids and Interfaces
  2. ARCO Exploration and Technology Co., Plano, TX (United States)
The effect of the positions of sulfonate and of methyl groups on the aromatic ring of isomerically pure alkylxylenesulfonates on their adsorption investigated in this study using microcalorimetry and electrokinetic measurements is found to be marked. It was observed that the position of the sulfonate with respect to the alkyl chain is more critical than that of the methyl groups in determining the adsorption behavior. The surfactant with the sulfonate in the para position with respect to the alkyl chain adsorbed more than that with the sulfonate in the meta position. Steric constraint to the packing of the molecules is proposed to be the main reason for the differences in the adsorption of these surfactants. Zeta potential measurements showed no difference in the charge characteristics of the surfactants. Calorimetric results suggest enthalpy to be the main driving force for adsorption at low surfactant concentrations while the adsorption is entropy driven at higher surfactant concentrations.
OSTI ID:
6298499
Journal Information:
Journal of Colloid and Interface Science; (United States), Journal Name: Journal of Colloid and Interface Science; (United States) Vol. 159:2; ISSN 0021-9797; ISSN JCISA5
Country of Publication:
United States
Language:
English