Volumetric and thermochemical properties of ionic surfactants: sodium decanoate and octylamine hydrobromide in water

1980 ◽  
Vol 58 (10) ◽  
pp. 959-969 ◽  
Author(s):  
Rosario De Lisi ◽  
Gérald Perron ◽  
Jacques E. Desnoyers
Keyword(s):  
Sodium Dodecyl ◽  
Heat Capacities ◽  
Published Data ◽  
Similar Data ◽  
Enthalpies Of Dilution ◽  
Sharp Maximum ◽  
Alkyltrimethylammonium Bromides ◽  
Partial Molal Heat Capacities ◽  
Sodium Decanoate ◽  
Separation Model

The heat capacities per unit volume and the densities of sodium decanoate (NaDec) in water were measured as a function of concentration and temperature in the range 0.5 to 45 °C. Similar data were obtained for octylamine hydrobromide at 5 and 15 °C. Enthalpies of dilution of NaDec in water were measured at 25 °C. From these and previously published data the apparent and partial molal heat capacities, expansibilities, volumes, and relative enthalpies were determined as a function of temperature and concentration. The concentration dependence of [Formula: see text] and [Formula: see text], is similar to that of other surfactants such as alkyltrimethylammonium bromides and sodium dodecyl sulfate, but in contrast with the other surfactants, [Formula: see text] goes through a sharp maximum in the micellization region at the lower temperatures. These thermodynamic properties can be analysed with a phase-separation model to give the changes in volume, heat capacity, and enthalpy during micellization as a function of temperature. The limitations of this model are also discussed.

Heat capacities and volumes in aqueous polymer and polymer–surfactant solutions

1987 ◽  
Vol 65 (5) ◽  
pp. 990-995 ◽  
Author(s):  
Gérald Perron ◽  
Josée Francoeur ◽  
Jacques E. Desnoyers ◽  
Jan C. T. Kwak
Keyword(s):  
Thermodynamic Properties ◽  
Chain Length ◽  
Polymer Concentration ◽  
Heat Capacities ◽  
Aqueous Mixtures ◽  
Alkyltrimethylammonium Bromides ◽  
Aqueous Polymer ◽  
Surfactant Interactions ◽  
Polymer Surfactant ◽  
Polymer Interaction

The apparent molar volumes and heat capacities of aqueous mixtures of neutral polymers and ionic surfactants were measured at 25 °C. The polymers chosen were poly(vinylpyrrolidone) (PVP) and poly(ethyleneoxide) (PEO) and the surfactants were the C8, C10, and C12 homologs of sodium alkylsulfates and the C10, C12, and C16 homologs of alkyltrimethylammonium bromides. The polymer–surfactant interactions depend on the nature of both components and on the chain length of the surfactant. The thermodynamic properties of the cationic surfactants are essentially the same in the absence and presence of polymer indicating little surfactant–polymer interaction. On the other hand, the thermodynamic properties of anionic surfactants are shifted, upon the addition of polymers, in the direction of enhanced hydrophobic association. The effect increases with the surfactant chain length and with the polymer concentration. The effect is larger with PVP than with PEO.

scholarly journals The Denominator problem: estimating the size of local populations of men-who-have-sex-with-men and rates of HIV and other STIs in Switzerland

2019 ◽  
Vol 95 (4) ◽  
pp. 285-291 ◽  
Author(s):  
Axel Jeremias Schmidt ◽  
Ekkehardt Altpeter
Keyword(s):  
General Population ◽  
Population Data ◽  
Hiv Prevalence ◽  
Postal Code ◽  
Published Data ◽  
Similar Data ◽  
Online Surveys ◽  
Credible Intervals ◽  
Sex With Men ◽  
Notification Data

ObjectivesThere is no estimate of the current number of men who have sex with men (MSM) in Switzerland, or of their geographical distribution. We aimed to (1) estimate MSM concentration factors and population sizes for 83 Swiss postal code areas (PCA), including the nine largest Swiss cities, and (2) calculate MSM-specific local HIV prevalence and yearly rates of diagnosed HIV, hepatitis C virus (HCV), syphilis and gonorrhoea.MethodsWe triangulated data from general population estimates, MSM online surveys, published data on HIV prevalence and Swiss notification data for HIV and STDs. We compared two different formulae for the estimation of local MSM populations and calculated Bayesian 95%-credible-intervals (CrI) for each PCA.ResultsAcross Switzerland, we estimate the MSM population aged 15–64 at roughly 80 000 men (95% CrI 64 000–96 000). (1) MSM in Switzerland were most concentrated in the five largest cities of Zurich, Geneva, Lausanne, Bern and Basel. (2) We estimate that in 2012, 6300 MSM, or 8.0%, were living with HIV, both diagnosed and undiagnosed and 1700 MSM, or 2.2%, had non-suppressed HIV infection. Between 2010 and 2013, average yearly rates of diagnosed HIV, HCV, syphilis and gonorrhoea were 0.3%, 0.02%, 0.4 % and 0.4 %, respectively.ConclusionsCombining general population data, MSM online surveys and notification data allows the calculation of realistic estimates of local MSM populations and thus proportions of MSM with diagnosed HIV and other STIs, with implications for prevention planning, commissioning of health services and counselling MSM on HIV/STI risk. Our methodology for Switzerland is transferable to other countries with similar data sources.

Heat capacities and enthalpies of dilution of water/AOT/n-heptane microemulsions at 25°C

1992 ◽  
Vol 151 (2) ◽  
pp. 396-401 ◽  
Author(s):  
Fabrizio Goffredi ◽  
Vincenzo Turco Liveri ◽  
Giuseppina Vassallo
Keyword(s):  
Heat Capacities ◽  
Enthalpies Of Dilution

scholarly journals Association of neutral red with micelles and its effect on the pKa

1993 ◽  
Vol 71 (11) ◽  
pp. 1785-1791 ◽  
Author(s):  
Robin K. Dutta ◽  
Subray N. Bhat
Keyword(s):  
Equilibrium Constants ◽  
Sodium Dodecyl ◽  
Surfactant Solution ◽  
Neutral Red ◽  
Association Constants ◽  
Alkyltrimethylammonium Bromides ◽  
Surfactant Solutions ◽  
Constant Ph ◽  
Apparent Association Constants ◽  
Apparent Association

The interactions of neutral red with cationic surfactants, viz., N-hexadecylpyridinium chloride and alkyltrimethylammonium bromides; a nonionic surfactant, viz., Triton X100; and an anionic surfactant, viz., sodium dodecyl sulfate, were investigated spectroscopically. The equilibrium constants for the association of the indicator with the micelles were determined from the apparent association constants at constant pH at 298 K. The effects of the indicator-micelle association on the apparent pKa of the indicator in aqueous surfactant solutions are discussed. It was shown that the apparent pKa of the indicator in cationic surfactant solution can be predicted from knowledge of the indicator-micelle association constant.

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