The effect of structural modifications on the solution and interfacial properties of straight and branched aliphatic alcohols: the role of hydrophobic effects.

The effect of structural modifications, such as branching of the hydrocarbon chain on the solution and interfacial properties of short-chain aliphatic alcohols has been investigated. Surface tension measurements have been used to study the adsorption of the alcohols at the aqueous solution/air interface from water/alcohol mixtures, and to determine the aqueous solubilities of the alcohols. The related process of the partitioning behaviour of the alcohols between two immiscible phases has also been studied.

Effect of the degree of dissociation of molecules in a monolayer at an air/water interface on the force between the monolayer and a like-charged particle in the subphase.

We used the monolayer particle interaction apparatus to measure the force between a monolayer of stearic acid or octadecanol at the air/water interface and a colloidal silica sphere. The silica sphere approached the monolayer from the aqueous subphase. The aim was to analyze how the magnitude of the charge of a deformable interface affects the interaction between that interface and a like-charged hard particle.

The isoelectric point/point-of zero-charge of interfaces formed by aqueous solutions and nonpolar solids, liquids, and gases.

From our previous work on the role of the electrostatic field strength in controlling the pH of the iso-electric point (iep)/point-of-zero-charge (pzc) of polar solids we have extended the analysis to predict that the pH of the iep/pzc of a nonpolar solid, liquid or gas-aqueous interface should occur at pH 1.0-3.0, dependent on the value assigned to water molecules or clusters at the interface.

Particulate hematite diffusion in sodium polyacrylate solutions. The effect of ionic strength.

The diffusion coefficients of hematite particles in polyelectrolyte solution have been investigated using dynamic light scattering. Two apparent diffusion coefficients, a fast and a slow diffusional mode, are observed for the hematite particles in high-molecular-weight sodium polyacrylate solution at pH 10.5.

PAA/PEO comb polymer effects on rheological properties and inter-particle forces in aqueous silica suspensions.

The effects of a poly(acrylic acid) (PAA)-poly(ethylene) (PEO) comb polymer dispersant on the rheological properties and inter-particle forces in aqueous silica suspensions have been studied under varying pH conditions. The comb polymer was found to adsorb more strongly under acidic than basic conditions, indicating that the PAA backbone of the copolymer preferentially adsorbs onto silica surfaces with the PEO "teeth" extending out from the surface into the solution. In the presence of low concentrations of copolymer, the silica suspensions were stable due to electrostatic repulsions between the silica surfaces.

Electrical double layer interactions between dissimilar oxide surfaces with charge regulation and Stern-Grahame layers.

Models of surfaces with intrinsic ionisable amphoteric surface sites governed by the dissociation of acid-base potential determining ion species together with the capacity for the adsorption of anion and cations of the supporting electrolyte are required to describe both the results of electrokinetic and titration measurements of inorganic oxides. The Gouy-Chapman-Stern-Grahame (CGSG) model is one such model that has been widely used in the literature. The electrical double layer interaction between two dissimilar CGSG surfaces has been studied by Usui recently [S.

Adsorption of organic matter at mineral/water interfaces. 6. Effect of inner-sphere versus outer-sphere adsorption on colloidal stability.

The effects of the adsorption modes of several low molecular weight (LMW) organic anions (maleate, oxalate, and citrate) on the colloidal stability of corundum-water suspensions have been examined using electrokinetic and shear yield stress (tau(y)) measurements over a broad range of pH conditions and LMW organic anion concentrations. Consistent with previous studies, increasing concentrations of maleate, oxalate, and citrate progressively shift the electrokinetic isoelectric point and pH of the maximum shear yield stress (tau(y,max)) to more acidic conditions. Due to its predominant electrostatic driving force for adsorption, outer-spherically adsorbed maleate possesses a very limited ability to charge reverse the corundum-water interface or bind to the negatively charged corundum surface.

The Adsorption of Dodecyltrimethylammonium Bromide on Mica in Aqueous Solution Studied by X-Ray Diffraction and Atomic Force Microscopy.

The adsorption of dodecyltrimethylammonium bromide (DTAB) onto natural muscovite mica and a synthetic expandable mica (EM) in aqueous solution has been investigated using both microscopic and macroscopic surface characterization techniques. The electrokinetic properties of the surfaces were monitored as a function of the concentration of DTAB using atomic force microscopy and microelectrophoresis. The adsorption isotherm of DTAB on EM was measured up to a solution concentration just below the critical micelle concentration of the surfactant.