Enthalpy-entropy compensation and order in alkane and aqueous systems

Patterson, Donald; Barbe, M.

doi:10.1021/j100562a026

Cited by 41 publications

(8 citation statements)

References 2 publications

(2 reference statements)

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“…This kind of enthalpy-entropy compensation has been observed before for ion exchange reactions and also for many other reactions (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44).…”

Section: Resultssupporting

confidence: 72%

Clay chemistry: Investigation of thermodynamics of ion exchange reactions by titration calorimetry

Ewin¹,

Erno²,

Hepler³

1981

Can. J. Chem.

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We have built a titration calorimeter that is suitable for measurements on colloidal suspensions as well as more conventional chemical reactions in solution. This calorimeter has been used for investigation of a number of ion exchange reactions involving kaolinite and montmorillonite clays. Results of these measurements have led to cation exchange capacities, to enthalpies of ion exchange reactions, and also to equilibrium constants for some of these same reactions. These calorimetrically determined cation exchange capacities and equilibrium constants agree well with corresponding quantities obtained by way of conventional methods based on chemical analyses. It has been demonstrated that titration calorimetry is a useful and convenient method for investigation of ion exchange in clays.

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“…This kind of enthalpy-entropy compensation has been observed before for ion exchange reactions and also for many other reactions (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44).…”

Section: Resultssupporting

confidence: 72%

Clay chemistry: Investigation of thermodynamics of ion exchange reactions by titration calorimetry

Ewin¹,

Erno²,

Hepler³

1981

Can. J. Chem.

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“…At 60 °C the entropy has decreased, but the (exothermic) enthalpy renders the standard Gibbs energies virtually temperature independent. This is another example of enthalpy entropy compensation which is characteristic for hydrophobic bonding and which has also been found for the solubility of alkanes in aqueous solution[182,183]. imply that about % of the CEC is due to the plate surfaces.…”

mentioning

confidence: 61%

Surfactant adsorption to soil components and soils

Ishiguro

Koopal

2016

Advances in Colloid and Interface Science

100

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Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on water/air interfaces, the latter gives an impression of surfactant adsorption to a hydrophobic surface and illustrates the importance of the CMC for the adsorption process. Then attention is paid to the most important types of soil particles: humic and fulvic acids, silica, metal oxides and layered aluminosilicates. Information is provided on their structure, surface properties and primary (proton) charge characteristics, which are all important for surfactant binding. Subsequently, the adsorption of different types of surfactants on these individual soil components is discussed in detail, based on mainly experimental results and considering the specific (chemical) and electrostatic interactions, with hydrophobic attraction as an important component of the specific interactions. Adsorption models that can describe the features semi-quantitatively are briefly discussed. In the last part of the paper some trends of surfactant adsorption on soils are briefly discussed together with some complications that may occur and finally the consequences of surfactant adsorption for soil colloidal stability and permeability are considered. When we seek to understand the fate of surfactants in soil and aqueous environments, the hydrophobicity and charge density of the soil or soil particles, must be considered together with the structure, hydrophobicity and charge of the surfactants, because these factors affect the adsorption. The pH and ionic strength are important parameters with respect to the charge density of the particles. As surfactant adsorption influences soil structure and permeability, insight in surfactant adsorption to soil particles is useful for good soil management.

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“…Water structuring was considered to provide a large, negative contribution to the entropy for the transfer of hydrocarbons to bulk water − Since the free energy of water structuring is negative, it is concluded that water structuring around the hydrophobic molecule increases its stability in water. An interpretation in terms of water structuring presumes that the temperature dependence of the poly(ethylene oxide)−water interaction is dominated by the postulated water structuring occurring in the vicinity of hydrophobic molecules, and thus an increase in adsorption with temperature corresponds to a decrease in water structuring.…”

Section: Discussionmentioning

confidence: 99%

Comparative Study of the Adsorption of Nonionic Surfactants: Triton X-100 and C₁₂E₇ on Polystyrene Latex Particles Using Dynamic Light Scattering and Adsorption Isotherm Measurements

Zhao

Brown

1996

J. Phys. Chem.

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The adsorption of the nonionic surfactants Triton X-100 and C12E7 on predominantly hydrophobic polystyrene latex particles has been examined as a function of surfactant concentration by measuring the hydrodynamic radius by dynamic light scattering and adsorption isotherms by a surface tension technique. The adsorption behavior of these materials differs significantly and is related to the structures of the surfactant “tails”. Adsorption of TX-100 most probably occurs in an approximately perpendicular geometry with contact between its methyl end groups and the partially extended polymer chains at the latex surface and is accompanied by association between the aromatic nuclei of the adsorbed surfactant molecules. The latter leads to cooperative adsorption and an S-type isotherm. The perpendicular adsorption mode leads to expansion of the polymer chains for steric reasons, giving a pronounced increase in the hydrodynamic radius in the initial adsorption stage. There is a larger adsorbed amount of TX-100 compared with the C12E7. C12E7 has a straight dodecyl chain and an extended molecular conformation. This favors bridging of neighboring polymer chains through interactions both between the alkyl tails and the polymer chains and between the POE chain and the terminal sulfate groups. Bridging leads to aggregation of the polymer chains and reflects the strong interaction between C12E7 and the polymer chain which gives an L-type adsorption isotherm. The adsorption isotherm is two-stepped in TX-100/latex solutions but is single-stepped for C12E7/latex suspensions, except in 100 mM added NaBr and at 35 °C. The characteristic types of adsorption isotherms observed with the two surfactants remain unchanged on altering other parameters, for example, the ionic strength or the temperature. NaBr augments C12E7 adsorption partly owing to salting-out of water from the hydration shell of the POE chain. On the other hand, TX-100 adsorption in 100 mM NaBr is complicated by competition between adsorption and micellization in aqueous solution since there is a pronounced tendency for TX-100 to aggregate in bulk solution at higher ionic strengths. Enhanced adsorption of both surfactants occurs on increasing the temperature, owing to a decrease in surfactant solubility in aqueous solution deriving from a combination of changes in the POE chain conformation and a reduction in the amount of structured water around the surfactant head group.

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Enthalpy-entropy compensation and order in alkane and aqueous systems

Cited by 41 publications

References 2 publications

Clay chemistry: Investigation of thermodynamics of ion exchange reactions by titration calorimetry

Clay chemistry: Investigation of thermodynamics of ion exchange reactions by titration calorimetry

Surfactant adsorption to soil components and soils

Comparative Study of the Adsorption of Nonionic Surfactants: Triton X-100 and C₁₂E₇ on Polystyrene Latex Particles Using Dynamic Light Scattering and Adsorption Isotherm Measurements

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Enthalpy-entropy compensation and order in alkane and aqueous systems

Cited by 41 publications

References 2 publications

Clay chemistry: Investigation of thermodynamics of ion exchange reactions by titration calorimetry

Clay chemistry: Investigation of thermodynamics of ion exchange reactions by titration calorimetry

Surfactant adsorption to soil components and soils

Comparative Study of the Adsorption of Nonionic Surfactants: Triton X-100 and C12E7 on Polystyrene Latex Particles Using Dynamic Light Scattering and Adsorption Isotherm Measurements

Contact Info

Product

Resources

About

Comparative Study of the Adsorption of Nonionic Surfactants: Triton X-100 and C₁₂E₇ on Polystyrene Latex Particles Using Dynamic Light Scattering and Adsorption Isotherm Measurements