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Interfacial properties, mineral

The recovery of petroleum from sandstone and the release of kerogen from oil shale and tar sands both depend strongly on the microstmcture and surface properties of these porous media. The interfacial properties of complex liquid agents—mixtures of polymers and surfactants—are critical to viscosity control in tertiary oil recovery and to the comminution of minerals and coal. The corrosion and wear of mechanical parts are influenced by the composition and stmcture of metal surfaces, as well as by the interaction of lubricants with these surfaces. Microstmcture and surface properties are vitally important to both the performance of electrodes in electrochemical processes and the effectiveness of catalysts. Advances in synthetic chemistry are opening the door to the design of zeolites and layered compounds with tightly specified properties to provide the desired catalytic activity and separation selectivity. [Pg.169]

Experimental studies of the thermodynamic, spectroscopic and transport properties of mineral/water interfaces have been extensive, albeit conflicting at times (4-10). Ambiguous terms such as "hydration forces", "hydrophobic interactions", and "structured water" have arisen to describe interfacial properties which have been difficult to quantify and explain. A detailed statistical-mechanical description of the forces, energies and properties of water at mineral surfaces is clearly desirable. [Pg.21]

Clay minerals have a permanent negative charge due to isomorphous substitutions or vacancies in their structure. This charge can vary from zero to >200cmol kg" (centimoles/kg) and must be balanced by cations (counter-ions) at or near the mineral surface (Table 5.1), which greatly affect the interfacial properties. Low counter-ion charge, low electrolyte concentration, or high dielectric constant of the solvent lead to an increase in interparticle electrostatic repulsion forces, which in turn stabilize colloidal suspensions. An opposite situation supports interparticle... [Pg.93]

Surface or Interfacial Properties which are Considered Directly Responsible for Performance of Various Unit Operations in Mineral Processing... [Pg.285]

Example In flotation, for a solid particle to float on a liquid surface, the upward pull of the meniscus around it (reflected in 6) must at least balance the weight of the particle. Any natural tendency of the particles to float or not float, depending on 6, can be modified by adding oils or surfactants to alter the interfacial properties. A mineral particle that does not float (Case 1) can be floated by adding surfactant (Case 2) as follows. [Pg.93]

In this chapter, the relationship of geological origins and interfacial properties of bentonite clay will be reviewed first. Then we will discuss the migration of water-soluble substances in rocks and soil, and the effect of sorption on the migration. A linear model will be derived by which the quantity of ion sorbed on rocks can be estimated when the mineral composition and sorption parameters of the mineral components are known. Surface acid-base properties of soils will be discussed, and the sorption of an anion (cyanide ion) will be shown on different soils and sediments. [Pg.169]

Bentonite rocks have many uses in the chemical and oil industries and also in agriculture and environmental protection. The usefulness of bentonite for each of these applications is based on its interfacial properties. These properties are determined by geological origin, chemical and mineral composition (especially montmorillonite content), and particle size distribution, and they include the specific surface area (internal and external), cation-exchange capacity (CEC), acid-base properties of the edge sites, viscosity, swelling, water permeability, adsorption of different substances, and migration rate of soluble substances in bentonite clay. [Pg.169]

The results show that the sorption of cyanide on soils and sediments is fast it reaches equilibrium within 10 minutes. The sorbed quantity, however, is low. From 10 4-10 3 mol/dm3 cyanide solutions, it is about 10 7 mol/g. This means an approximately 10-3 dm3/g distribution ratio for cyanide ion. This value is typical for the anion sorption of soils, and it is explained by the interfacial properties of soil components. The main mineral components of soils (primary silicates, clay minerals, oxides) have negative surface charges at pH applied (about 8.5), inhibiting the... [Pg.202]

The book consists of four chapters. The first one deals with the individual components of the studied systems the solid, the solution, and the interface. Solid means rocks and soils, namely, the main mineral and other solid components. In order that the solid/liquid interactions become possible, these must be located in the Earth s crust where groundwater is present. The liquid phase refers to soil solutions and groundwater, and also any solutions that are part of laboratory experiments studying interfacial properties with the objective of understanding the principles behind the reactions. In Chapter 1, the characteristics and thermodynamics of the... [Pg.247]

When mineral particles are contacted with water, they will undergo dissolution, the extent of which is dependent upon the type and concentration of chemicals in solution. The dissolved mineral species can undergo further reactions such as hydrolysis, complexation, adsorption and even surface or bulk precipitation. The complex equilibria involving all such reactions can be expected to determine the interfacial properties of the particles and their flotation behavior. The concentration of each dissolved mineral species can be calculated from various solution equilibria of the minerals. The calculated results are plotted as log C-pH diagram. The equilibria in selected salt-type mineral systems with special reference to calcite and apatite are examined below. [Pg.57]

For the above sparingly soluble minerals, the effect of dissolved species on interfacial properties can be marked. Results obtained for the zeta-potential of apatite and calcite in water and in 2 x 10 M KNO3 solutions are given in Fig. 3.7. It can be seen that the isoelectric points of calcite and apatite in both water and KNO3 solutions are about 10.5 and 7.4, respectively. The effect of the supernatant of calcite on the zeta-potential of apatite is also shown in Fig. 3.8. [Pg.62]

The intensity of intermolecular interactions at the interfaces between condensed phases is one of the critical factors determining the conditions for wetting and spreading. A large number of important technological processes, such as mineral processing (flotational enrichment and separation), are based on these phenomena. The ability to alter interfacial properties by surfactant addition allows one to gain fine control over these processes. [Pg.165]

Two observations can be derived from this brief review of previous studies. First, X-ray reflectivity techniques have been applied to a diverse range of phenomena, providing a powerful and robust probe of interfacial properties. Second, the use of these techniques in studying the mineral-fluid interface has been limited to a few research groups. This suggests that application of these techniques to mineral-fluid interface structures and processes is still in its infancy. This review uses examples of recent work carried out at Argonne National Laboratory that were chosen to represent the diverse range of mineral-fluid interface phenomena that can be studied with X-ray reflectivity techniques. [Pg.151]

Chander S, Fuerstenau DW (1984) Solubility and interfacial properties of hydroxylapatite A review. In Adsorption On and Surface Chemistry of Hydroxyapatite. Misra DN (ed) Plenum Press, New York Chen XB, Wright JV, Conca JL, Peurrang LM (1997) Evaluation of heavy metal remediation using mineral apatite. Water Air Soil Poll 98 57-78... [Pg.82]

Soluble salt flotation occurs in saturated solution in which the salt crystal surface is in dynamic balance between crystallization and dissolution, making it difficult to examine the interfacial properties using traditional experimental measures. In this regard, the water structure at selected alkali halide salt surfaces has been studied using MD simulation. Equilibrium surface charge signs for these salt minerals in saturated solution have been calculated by considering the ion hydration and water dipole distribution at salt-saturated brine interfaces, and the results are compared with... [Pg.118]

The utility of clay minerals is strongly linked to their interfacial properties, especially with water. Thus, the ability to fabricate a complexly shaped ceramic body depends on the ability of the fine-grained raw materials, clay minerals, quartz and feldspar principally, to be formed while wet into the desired shape and retain that shape while drying. Without the plasticity erf the wet day, the shaping would not be possible. In fact, a clay is a clay because it is plastic when wet with an appropriate quantity of water. The plastidty is a result of complex interactions between the water and the surfaces of the constituents of the clay, principdly the clay minerals. [Pg.45]

While the electrokinetic surface, or -potentials, originate from the surface or interfacial properties of solid materials, they are actually situated about 0.3 to 0.5 nm outside a material s surface and have to be extrapolated inward to the (i/>o) potential at the actual surface, using Eq. 5.54. The electrostatic free energy of interaction, AG, between two surfaces, 1, reaches a value of about -M.O mJ/m at V o 75 mV, in an aqueous medium with a 100 mM salt content of a mono-mono-salt see Table 5.1. Now various clay and other mineral particles can have V o-potentials that are between 50 and 90 mV, in which case AG, while not dominant, is no longer negligible. For instance for a contact between two platey clay particle surfaces over about 100 nm (= 10 ° cm ) an attraction of 1 mJ/m still corresponds to w 2,500 kT. Thus, it is always wise to measure -potentials, from which the actual surface, or V o-potential can be derived. [Pg.213]


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