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Volumn 113, Issue 51, 2009, Pages 14131-14140

HCl uptake through films of pentanoic acid and pentanoic acid/hexanol mixtures at the surface of sulfuric acid

Author keywords

[No Author keywords available]

Indexed keywords

ALKYL CHAIN; COOH GROUP; HEXANOL; MAXIMUM PACKING; MIXED FILMS; MOLECULAR BEAM SCATTERING; PENTANOIC ACID; SURFACE ACTIVE; SURFACE COVERAGES; SURFACE OH GROUP; SURFACE TENSION MEASUREMENTS; TWO-STEP MODEL;

EID: 73349097239     PISSN: 10895639     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp9072119     Document Type: Article
Times cited : (16)

References (69)
  • 14
    • 0142216366 scopus 로고    scopus 로고
    • 5 Hydrolysis on Sub-Micron Organic Aerosols. In. Phys. Chem. Chem. Phys. 2003, 5, 4593.
    • 5 Hydrolysis on Sub-Micron Organic Aerosols. In. Phys. Chem. Chem. Phys. 2003, 5, 4593.
  • 25
    • 73349100096 scopus 로고    scopus 로고
    • For reviews of earlier studies, see refs 1, 2, 4, 42, and 55
    • For reviews of earlier studies, see refs 1, 2, 4, 42, and 55.
  • 31
    • 73349101953 scopus 로고    scopus 로고
    • rms ≈ 60 Å. See also ref 26.
    • rms ≈ 60 Å. See also ref 26.
  • 38
    • 0000701055 scopus 로고    scopus 로고
    • M. Massucci, M.; Clegg, S. L.; Brimblecombe, P. J. Phys. Chem. A 1999, 103, 4209 Calculations from the aerosol inorganics model at http://mae.ucdavis.edu/wexler/aim.
    • M. Massucci, M.; Clegg, S. L.; Brimblecombe, P. J. Phys. Chem. A 1999, 103, 4209 Calculations from the aerosol inorganics model at http://mae.ucdavis.edu/wexler/aim.
  • 46
    • 73349138345 scopus 로고    scopus 로고
    • Equation 1 assumes constant activity coefficients over the 0-0.2 M addition of PA, We verified this assumption at 213 K by showing that the pentanoic acid evaporation signal is linear with bulk PA concentration up to 0.2 M. The evaporation signal is well fit by a Maxwell-Boltzmann distribution at 213 K at each concentration. These observations also imply that there is no barrier to PA evaporation itself by the PA film.
    • Equation 1 assumes constant activity coefficients over the 0-0.2 M addition of PA, We verified this assumption at 213 K by showing that the pentanoic acid evaporation signal is linear with bulk PA concentration up to 0.2 M. The evaporation signal is well fit by a Maxwell-Boltzmann distribution at 213 K at each concentration. These observations also imply that there is no barrier to PA evaporation itself by the PA film.
  • 47
    • 73349094464 scopus 로고    scopus 로고
    • For monolayer segregation, Γ ≈ csurf+ n2D (1, Γ Asurfactant, where Asurfactant ≈2 × 10-15 cm2 is the surface area of the surfactant molecule and n2D is the monolayer concentration of the surfactant that would be found in the absence of segregation. It is given by n2D ≈ c surfactant/cwateAwater, cacid Aacid, where c refers to the bulk-phase concentration. For 0.2 M PA in 68 wt, D2SO4, Γ, 2.5 × 1014 cm-2, cwater, 29 M, cacid, 11.5 M, Awater, 10 -15 cm-2, Aacid, 2 × 10 -15 cm-2, we find that n2D, 4 × 1012 cm-2
    • surf = 1.008Γ.
  • 48
    • 40549126287 scopus 로고    scopus 로고
    • See also eq A.4 of: DeZwaan, J. L.; Brastad, S. M.; Nathanson, G. M. J. Phys. Chem. C 2007, 112, 3008.
    • See also eq A.4 of: DeZwaan, J. L.; Brastad, S. M.; Nathanson, G. M. J. Phys. Chem. C 2007, 112, 3008.
  • 52
    • 73349099442 scopus 로고    scopus 로고
    • The minimum surface area of normal C3-C10 alcohols is given in ref 48 as 20.7 Å2. The minimum surface area of normal carboxylic acids given in refs 49 and 51 is 22.6 Å2 and is larger due to the greater size of COOH than OH. We use the one significant figure value of 20 Å2 (or 5 times; 1014 cm -2) as a reference state for both hexanol and pentanoic acid in order to use a single gauge of the maximum possible chain-chain packing
    • -2) as a reference state for both hexanol and pentanoic acid in order to use a single gauge of the maximum possible chain-chain packing.
  • 55
    • 0032463094 scopus 로고    scopus 로고
    • When the acid is exposed to HCl for a time texp, the fraction of HCl molecules remaining in solution as HCl/Cl-is given by the time average of the uptake coefficient γ (t, where 〈γ (t exp) 〉, 1/t exp, ∫texp0γ (t) dt, α (τ/texp, erfc (texp/τ) 1/2et/τ, 2/π) 1/2 (t exp/τ) 1/2-1, For τ, 130 μs, t exp, 0.27 s, and α, 0.46, the equation predicts 〈γ〉, 0.011. See: Robinson, G. N, Worsnop, D. R, Jayne, J. T, Kolb, C. E, Swartz, E, Davidovits, P. J. Geophys. Res. Atmos. 1998, 103, 25371
    • exp = 0.27 s, and α = 0.46, the equation predicts 〈γ〉 = 0.011. See: Robinson, G. N.; Worsnop, D. R.; Jayne, J. T.; Kolb, C. E.; Swartz, E.; Davidovits, P. J. Geophys. Res. Atmos. 1998, 103, 25371.
  • 56
    • 73349131175 scopus 로고    scopus 로고
    • exch values was found to be uniform for all surfactant concentrations.
    • exch values was found to be uniform for all surfactant concentrations.
  • 61
    • 73349143704 scopus 로고    scopus 로고
    • We note that eq 6 generates an identical fit for negative values of a and b, namely, a, b/f;exch (bare) and b, afexch (bare, In this picture, the alkyl chains enhance entry and the headgroups impede it. This scenario might apply to (1) polarizable gas molecules that dissolve well in the hydrocarbon chains and (2) headgroups that bind strongly to water, reducing the effective number of interfacial protonation sites. We do not believe that this situation pertains to HCl because HCl entry through butanol and hexanol films at the same surface concentration is significantly lower for hexanol than for butanol. This comparison implies that, at fixed headgroup concentration, longer chains reduce HCl entry, in accord with a model in which the chains impede HCl transport. We also note that the second term in eq 6 may also be expressed as f exch bare, 1-csurf/cmax, b
    • max, which takes into account the loss of free acid surface as the surfactant molecules take up space. The trends among the b and b" values remain the same.
  • 67
    • 73349119738 scopus 로고    scopus 로고
    • The immiscible domain model requires knowledge of the surface densities of hexanol and PA in each domain. This information is not available; we know only the number of hexanol and PA molecules over the total area but not the area fractions of the domains. To make progress, we assume that the surface densities are the same and thus equal to csurf total, 2.4 x 1014 cm-2
    • -2.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.