TY - JOUR

T1 - Adsorption kinetics of heptadecafluoro-1-nonanol: Phase transition and mixed control

AU - Casandra, Alvin

AU - Noskov, Boris A.

AU - Hu, Min-Yu

AU - Lin, Shi-Yow

PY - 2018

Y1 - 2018

N2 - Hypothesis: The adsorption kinetics of heptadecafluoro-1-nonanol (C 9H 2F 17OH) onto a clean air-water interface at low surfactant concentrations (equilibrium surface tension, γ(C) > 65 mN/m) has been reported, and the controlling mechanism was found to be mixed diffusive-kinetic controlled (Kuo et al., JCIS 402 (2013) 131). However, it remains to be determined what the adsorption kinetics are at higher concentrations. Hence, the dynamic surface tension, γ(t) of C 9H 2F 17OH was measured and compared with the theoretical γ(t) curves predicted from phase transition model. Experiments: A video-enhanced pendant bubble tensiometer was used to measure the γ(t) data of aqueous C 9H 2F 17OH solutions at higher concentrations (C > 7.7 × 10 −9 mol/cm 3). A new generalized Frumkin-Langmuir phase transition model was built up to simulate the γ(C) and γ(t) data. Findings: At higher surfactant concentrations, a constant-γ region at 64.8 mN/m was observed for one hundred to a few thousand seconds during the γ(t) relaxation. This constant-γ region implies the existence of a phase transition of the adsorbed surfactant monolayer at air-water interface. The γ(t) data of C 9H 2F 17OH can be simulated perfectly using this mixed-controlled phase transition model with the adsorption rate constants β 1 = 1.0 ± 0.5 and β 2 = 13 ± 4 (10 5 cm 3/mol·s). It is therefore concluded that the adsorption process of C 9H 2F 17OH onto a clean air-water interface is of mixed-control.

AB - Hypothesis: The adsorption kinetics of heptadecafluoro-1-nonanol (C 9H 2F 17OH) onto a clean air-water interface at low surfactant concentrations (equilibrium surface tension, γ(C) > 65 mN/m) has been reported, and the controlling mechanism was found to be mixed diffusive-kinetic controlled (Kuo et al., JCIS 402 (2013) 131). However, it remains to be determined what the adsorption kinetics are at higher concentrations. Hence, the dynamic surface tension, γ(t) of C 9H 2F 17OH was measured and compared with the theoretical γ(t) curves predicted from phase transition model. Experiments: A video-enhanced pendant bubble tensiometer was used to measure the γ(t) data of aqueous C 9H 2F 17OH solutions at higher concentrations (C > 7.7 × 10 −9 mol/cm 3). A new generalized Frumkin-Langmuir phase transition model was built up to simulate the γ(C) and γ(t) data. Findings: At higher surfactant concentrations, a constant-γ region at 64.8 mN/m was observed for one hundred to a few thousand seconds during the γ(t) relaxation. This constant-γ region implies the existence of a phase transition of the adsorbed surfactant monolayer at air-water interface. The γ(t) data of C 9H 2F 17OH can be simulated perfectly using this mixed-controlled phase transition model with the adsorption rate constants β 1 = 1.0 ± 0.5 and β 2 = 13 ± 4 (10 5 cm 3/mol·s). It is therefore concluded that the adsorption process of C 9H 2F 17OH onto a clean air-water interface is of mixed-control.

KW - Adsorption kinetics

KW - Fluorinated surfactant

KW - Mixed-control

KW - Phase transition

KW - Surface tension

KW - AIR/WATER INTERFACE

KW - SOLUBLE SURFACTANTS

KW - 1-DODECANOL

KW - PENDANT DROP DIGITIZATION

KW - MONOLAYERS

KW - AQUEOUS-SOLUTION

KW - DYNAMIC SURFACE-TENSION

KW - EQUILIBRIUM

KW - GEMINI SURFACTANTS

KW - HYDROCARBON

UR - http://www.scopus.com/inward/record.url?scp=85046880459&partnerID=8YFLogxK

U2 - 10.1016/j.jcis.2018.04.096

DO - 10.1016/j.jcis.2018.04.096

M3 - Article

VL - 527

SP - 49

EP - 56

JO - Journal of Colloid and Interface Science

JF - Journal of Colloid and Interface Science

SN - 0021-9797

IS - 1

ER -