| 1. |
- Kanai, M, et al.
(författare)
-
- 2023
-
swepub:Mat__t
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Alexandrova, L, et al.
(författare)
-
Confirmation of the heterocoagulation theory of flotation
- 1999
-
Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 15, s. 7464-7471
-
Tidskriftsartikel (refereegranskat)abstract
- To model the flotation process, we have used the microscopic method developed by Scheludko to study the stability of an aqueous thin film containing tetradecyltrimethylammonium bromide ( C14TAB ) between an air bubble and a silica substrate. Experiments were performed at a range of C14TAB concentrations and pH values. Spontaneous rupture of the thin aqueous film was interpretated in terms of heterocoagulation resulting from the preferential adsorption of relatively low surfactant concentrations at the vapour/solution interface causing a net positive charge while the solution/silica interface remained negatively charged. In addition, during the the three-phase-contact (TPC) expansion or de-wetting step following film rupture, the movement of TPC across the silica substrate leads to transfer of amine from the vapour/solution interface to the vapour/silica. This process resembles a Langmuir-Blodgett deposition process and emphasized the importance of the solution/vapour interface in the de-wetting process.
|
|
| 5. |
- Ardebrant, H, et al.
(författare)
-
Surface acidity/basicity of road stone aggregates by adsorption from non-aqueous solutions
- 1991
-
Ingår i: Colloids and Surfaces. - 0166-6622 .- 1873-4340. ; 53, s. 101-116
-
Tidskriftsartikel (refereegranskat)abstract
- The surface of several road stone aggregates were characterized by the adsorption of organic probe molecules (with acidic and basic functional groups) from cyclohexane. The results show differences in the adsorption affinity and adsorption capacity of the molecules for the different mineral surfaces. In most cases it was found convenient to represent the data by a Langmuir-Freundlich type of isotherm, which defines a quasi-Gaussian energy distribution around a peak value. From the theory a range of adsorption free energies and surface coverages (site densities) were calculated, and the heterogenity of the surfaces evaluated. Generally the interaction strengths were rationalized in terms of Lewis acid-base theory.
|
|
| 6. |
- Ardebrant, H, et al.
(författare)
-
Wetting studies on silicate minerals and rocks used in bituminous highways
- 1991
-
Ingår i: Colloids and Surfaces. - 0166-6622 .- 1873-4340. ; 58, s. 111-130
-
Tidskriftsartikel (refereegranskat)abstract
- A study has been made on the wetting characteristics of quartz and several other silicate minerals and road stones used in bituminous roads. From contact angle measurements using the "two-liquid phase" method the nondispersive interaction energy between the mineral or road stone and water (I_S(p;sw)) with and without heat treatment was obtained. The results indicate a wide range of I_S(p;sw)-values, which appear to depend on the chemical composition of the aggregate. It was also suggested that the result may be related to the degree of contamination. From these studies it also appears that I_S(p;sw) is a useful parameter defining the vulnerability of stripping.
|
|
| 7. |
- Beneventi, D, et al.
(författare)
-
Surface rheology and foaming properties of sodium oleate and C12(EO)6 aqueous solutions
- 2003
-
Ingår i: Journal of Colloid and Interface Science. - 0021-9797 .- 1095-7103. ; 268, s. 221-229
-
Tidskriftsartikel (refereegranskat)abstract
- The dynamic surface tension (DST) and the surface viscoelastic modulus of sodium oleate aqueous solutions at different concentrations were measured using an image analysis tensiometer based on the oscillating bubble technique. The diffusion coefficient of oleate moieties was calculated from DST measurements and the surface viscoelastic modulus using the Langmuir–Szyszkowski and the diffusion-controlled adsorption models. The viscoelastic moduli obtained from model calculations were compared with the corresponding experimental values. The diffusion coefficient of C12(EO)6 in water and the parameters of the Langmuir–Szyszkowski adsorption isotherm were taken from the literature and used to calculate the surface viscoelastic modulus of its aqueous solutions at different concentrations. The foaming properties of both C12(EO)6 and sodium oleate solutions, viz., the foam conductance and the water volume fraction in the foam, were measured using a commercial Foamscan device. Foaming experiments with C12(EO)6 and sodium oleate solutions were carried out either under static conditions; i.e., the foam conductance and the water volume fraction were measured as a function of time after the generation of a fixed volume of foam, or under dynamic conditions; i.e., the foam conductance and the water volume fraction were measured during foam formation. The variations in the foam permeability as a function of surfactant concentration were related to the viscoelastic properties of the air/water interface and to the presence of micelles in the foam films. With foams in which the water volume fraction was higher than 0.05, the foam electrical conduction could be described using a simple parallel resistor model and their conductance measurements were related to the foam water volume fraction. The results related to water drainage under static conditions were used to interpret water drainage under dynamic conditions. Preliminary conjectures on the influence of foam permeability and water volume fraction on the yield of the flotation deinking process were drawn from these results.
|
|
| 8. |
|
|
| 9. |
- Djuve, J, et al.
(författare)
-
Foaming and dynamic surface tension of aqueous polymer/surfactants solutions 1: ethyl(hydroxyethyl) cellulose and sodium dodecyl sulphate
- 2001
-
Ingår i: Colloids and Surfaces A. - 0927-7757 .- 1873-4359. ; 186, s. 189-202
-
Tidskriftsartikel (refereegranskat)abstract
- Foaming (in a column) and dynamic surface tension behaviour of aqueous solutions of sodium dodecyl sulphate (SDS), and ethyl (hydroxy ethyl) cellulose/ sodium dodecyl sulphate (EHEC/SDS) mixtures was determined. The results indicated a synergism in foaming and surface activity for the EHEC/SDS mixtures over a specific concentration range. For the SDS solution, the maximum value in Marangoni Elasticity (EM max), as determined from dynamic surface tension data, was reached within a surface age of 0.05s and it could be suggested that in this case EM max was relevant to foam stability. However, for the EHEC (non-foaming solutions), EM max was reached after longer surface ageing periods (0.05-0.1 s). For the EHEC/SDS solutions, EM max occurred over a range of surface ageing periods depending on the polymer/surfactant ratio and no correlation was obtained between EM max and foaming. The EM max time lag for the polymer and polymer/surfactant mixtures was explained by the slower diffusion from solution to the new surface. For the EHEC/SDS, the enhanced the foaming behaviour was explained by the adsorption of surface active polymer/surfactant (clusters) species at the air/solution interface. It was suggested that this could lead to coherent (gelatinous) interfacial layers in the thin film lamella which reduce drainage from the central fluid.
|
|
| 10. |
- Djuve, J, et al.
(författare)
-
Templating of ethyl(hydroxyethyl) cellulose on graphite by surfactant-polymer interactions
- 2002
-
Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 18, s. 2673-2677
-
Tidskriftsartikel (refereegranskat)abstract
- Ordered, templated, thin films of ethyl(hydroxyethyl)cellulose (EHEC) were produced on a freshly cleaved crystalline graphite surface by exploiting the nature of sodium dodecyl sulfate adsorption (SDS) and its interaction with EHEC. The films were prepared by exposing the graphite surface to a dilute aqueous solution containing EHEC-SDS mixtures, followed by rinsing to remove the SDS and drying. The structure of the remaining EHEC film at the graphite-air interface was investigated by atomic force microscopy and compared with images of SDS and EHEC polymer on adsorbed graphite obtained in separate experiments. The results showed that polymer networks were formed from the EHEC-SDS mixture (after rinsing out the SDS), which were predominately aligned in one of three preferential directions separated by 60°, presumably as a result of templating by coadsorbed SDS. In addition, the alignment of the EHEC polymer and spacing between the polymer strands was found to be a function of surfactant concentration. Films formed from a solution containing EHEC (10 ppm) and SDS solution (5 mM) after removal of the SDS by washing formed "tight", highly aligned networks. At the same EHEC concentration and 20 mM SDS, a more "open" structure was formed. The results provide valuable insights into the interaction and organization of SDS and EHEC at a crystalline hydrophobic surface.
|
|
