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The adsorption kinetics of a fluorinated surfactant--heptadecafluoro-1-nonanol.

Research paper by Chang-Cheng CC Kuo, Boris A BA Noskov, Yu-Ching YC Liao, Shi-Yow SY Lin

Indexed on: 11 May '13Published on: 11 May '13Published in: Journal of Colloid and Interface Science



Abstract

The adsorption kinetics of heptadecafluoro-1-nonanol (C8F17CH2OH) onto a clean air-water interface were studied. Video-enhanced pendant (emerging) bubble tensiometry was employed to measure the equation of state and the dynamic/equilibrium surface tensions. Relaxation profiles of the surface tension for heptadecafluoro-1-nonanol molecules absorbing onto a freshly created air-water interface were obtained and simulated from theory. The adsorption of the fluoroalcohol C8F17CH2OH was found to be cooperative from the comparison of the equilibrium surface tension data at γ(C)>65 mN/m to the prediction of the Frumkin model. The comparison was made for the entire relaxation period of the tension data and the model predictions. The controlling mechanism of the adsorption process was found to be mixed diffusive-kinetic control. Values of the adsorption/desorption rate constants of C8F17CH2OH were estimated from these dynamic surface tension profiles with a diffusivity of 5.93×10(-6) cm(2)/s, which was evaluated from the Wilke-Chang equation for C8F17CH2OH.