Solid solution water interlayer

Hydrotalcite-like compounds (HTlcs) have attracted much attention in recent years as catalyst precursors and catalyst support. This is due to (i) their ability to accommodate a large variety of bivalent and trivalent cations (ii) the homogeneous mixture of the cations on an atomic scale and (iii) the formation of thermostable mixed oxides, often denoted as ex-HTlcs, with high surface area upon decomposition. The first two properties are a result of the precursor while the last property appears to be related to the decomposition mechanism. The transitions in the structural properties of Co-based hydrotalcites upon high temperature treatments have been extensively studied in our group.15,16 In the first decomposition step, water is removed from the structure. This transition is followed by dehy-droxylation and decarbonation, as well as carbonate reorganization in the interlayer. Thermal treatment in air finally leads to a solid solution of cobalt spinels (Co(Co, A1)2C>4). Mixtures of CoO and C0AI2O4 are formed upon treatment in inert. 

It may also be argued that the simulation of water-rock interactions should allow for solubility equilibria involving feldspars, micas, etc. For such studies the choice of solublity product constants and free energies must and should be made by the investigators. We cannot propose such values here when an enormous range of values and properties (solid-solutions, interlayering, defects, surface areas, etc.) is known to exist for these minerals and reversible solubility behavior has not been demonstrated. 

C-S-H gel is participating in chemisorption and adsorption of chloride ions too. According to Beaudoin [206] and Ramachandran [207], the three types of chloride ions can be distinguish the free ions easily extracted in an alcohol, the chemisorbed ones on the gel surface, and in the interlayers area—they cannot be extracted by alcohol and, finally—the strongly bound chlorides, presumably occurring as a solid solution in C-S-H. The latter cannot be leached by water. The C-S-H ability of chloride ions binding depends on the H/S and C/S ratio and increases with them [207]. 

HUP and many other natural or synthetic compounds belong to the torbernite mineral group of general formula M, y(U02X04)(H30)y. 3H2O where X is P or As and M" " is a cation such as K, NH4", Na, Li, Ca, Pb, Ag or AP. The role of interlayer cations and water molecules in torbernite is similar to that in zeolites, clay minerals, some feldspars and micas, jarosites, autunites and clathrate compounds. In all these materials solid solutions between protonic and ionic derivatives are readily observed ion exchange and protonic conductivity can thus be expected. 

Polyvinyl butyral resins n. A member of the polyvinyl acetal family. Resins formed by reacting polyvinyl alcohol with butyraldehyde. It is a rough, sticky, colorless, flexible solid, used primarily as the interlayer in automotive safety glass. Other applications include adhesive formulations, base resin for coatings, solutions for rendering fabrics resistant to water, staining, and abrasion. 

The adsorption of neutral molecules on smectites is driven by various chemical interactions hydrogen bonds, ion-dipole interactions, coordination bonds, acid-base reactions, charge transfer, and van der Waals forces. Several polar molecules, such as alcohols, amines, and acids, form intercalation complexes with montmorillonites. The intercalation can be performed from the vapor, liquid, or even solid state. In intercalation from solution, solvent molecules are generally coadsorbed in the interlayer space. Guest molecules may be intercalated in dried clay minerals or may displace the water molecules of hydrated montmorillonite. 

The exchange of the interlayer phosphate ions with the phosphate ester ions were carried out by a similar procedure described elsewhere the respective mixture of mono- and di-esters (about 20 g) was disolved in a 100 ml mixture of equal volumes of acetone and water, into which 2 g of y-zirconium phosphate was dispersed and heated for 24 h under reflux at a pot temperature of 70 C. The solution was renewed and the refluxing was repeated to assure the completion of the exchange reaction. The dispersed solid was separated by filtration, washed with acetone and air dried. The derivatives obtained by the above exchange reactions with the phosphoric acid esters CH3-(OCH2CH2) n OP03H2 (n=l-3) are referred to as ZrP-EtOj, (n=l-3), respectively. 

Given the size of clay particles (10-1,000 nm), they are found in solution as colloidal dispersions or gels. At low water content, they can be obtained as dry powders, and can form solid porous materials upon compaction. In all these regimes, their properties crucially depend on the charge density and on the nature of the counterions. Most counterions are mono- or divalent, usually alkaline (most commonly sodium Na" or potassium or alkaline earth cations (most commonly calcium Ca " ). They are not incorporated in the clay layers. Rather, they are located near the surface, either between different layers, in the so-called interlayer porosity, or on the external surfaces of clay stacks (typically 10 layers). Such stacks are called particles, and their assembly to form a porous material then leaves voids called interparticle porosity, with sizes between a few nanometers to tens of nanometers, which are usually saturated by an electrolyte solution. 

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