Alkalinity alkali systems

Some important features regarding the structures of liquid silicates are revealed by recent volumetric studies of both alkali (9) and alkaline earth systems 55). First, the partial molar volume of silica in the alkali silicates is nearly equal to that of pure fused silica and is independent of the cation over wide compositional ranges. Second, at about 10 15 mole-% metal oxides, the thermal expansions show a sudden increase. The results for the alkali silicates are shown in Fig. 5. A similar behavior is found in the system... 

In the triphenyhnethanides, the metal is coordinatively and electronically saturated by the encompassing crown ether that occupies an equatorial plane around the metal, as well as by the axially located HMPA donors. This favorable cation coordination enviromnent is well established in alkaline earth metal chemistry. The hgands are free to adopt the most conformationally stable orientation, and steric demands force the rings away from planarity and in both the strontimn and barium systems the rings display the familiar propeller geometry, comparable to that seen for related alkali systems. 

In the laboratory and in industry there is a need for buffer solutions to maintain the alkalinity of systems. An alkaline buffer solution is a mixture of a weak alkali and its salt, such as a solution of aqueous ammonia with ammonium chloride. Ammonia in water is partially protonated (3) and its salt is fully dissociated (4). Alkaline buffer solutions work in a similar way to acidic ones to keep the pH of a system above 1. 

The TUE(VI) hydroxides have amphoteric properties. They are significantly soluble in concentrated alkaline solutions [80,83,85,86]. The highest Np(VI) and Pu(VI) concentrations are obtained in Li OH solutions [87]. The solubilities of Pu(VI) hydroxo compounds increase with an increase in the alkali concentration (from 3.2 10 M in IM NaOH to 110 " M in 10 M NaOH) [86]. The An(Vl)-alkaline solution systems are metastable and are characterized by the slow formation of a solid phase. In addition, these systems may contain high Np(VI) and Am(VI) concentrations (up to 10 M), and still higher Pu(VI) concentrations. 

Alkali metal and alkaline earth polyphosphates crystallize as short chains, two to six phosphate groups per chain or very long chains with hundreds to thousands of PO3 per chain. All polyphosphates in the alkali metal and alkaline earth systems are amorphous in the intermediate chain lengths. Control of the short chain length polyphosphates, both crystalline or amorphous, is a function of R, the M2O-P2O5 ratio. The control of the chain lengths of very long crystalline polyphosphates as Maddrell s salt, Kurrol s salt, and calcium phosphate fibers is not well understood. 

The interaction between alkali and polymer, to be discussed in this section, includes alkaline effect on polymer viscosity, polymer effect on alkafine/oil IFT, and alkaline consumption in alkaline-polymer systems. 

Laboratory test results show that alkaline consumption in an alkaline-polymer system is lower than in the alkaline solution itself. The reason is probably that polymer covers some rock surfaces to reduce alkali-rock contact. In an alkaline-polymer system, alkali competes with polymer for positive-charged sites. Thus, polymer adsorption is reduced because the rock surfaces become more negative-charged sites (Kmmrine and Falcone, 1987). Mihcakan and van Kirk (1986) observed that alkaline consumption in a radial core is smaller than that in a linear core. 

At the concentrations of alkali above that required for minimum interfacial tension, the systems become overoptimum. The excess alkali plays the same role as excess salt. When synthetic surfactants are added, the salinity requirement of alkaline flooding system is increased. NEODOL 25-3S is such a synthetic surfactant used by Nelson et al. (1984). Figure 12.4, shown earlier, is a composite of three activity maps for 0, 0.1, and 0.2% of NEODOL 25-3S as a synthetic surfactant for 1.55% sodium metasilicate with Oil G at 30.2°C. We can see in the figure that without the synthetic surfactant, the active region of this system is below the sodium ion concentration supplied by the alkali. However, with 0.1 and 0.2% of NEODOL 25-3S (60% active) present, the active region is above the sodium ion concentration supplied by the alkali, so additional sodium ions must be added to reach optimum salinity. 

Adding surfactant ORS-41 in the alkaline/oil system reduced the IFT to an ultralow level. Figure 13.8 shows the ASP/oil IFT at different distillate fractions here, the IFT increased with the heavy fractions among XI, X2, and X3. Because the oil fraction had lighter components, the reaction with the hydro-phobic composition became stronger, and the IFT was lower. However, for the heavy distillate fraction obtained above 360°C, the IFT was lower than those for X2 and X3. This result indicates that the dynamic IFT between ASP/oil is determined by the surface active materials generated from the reaction between the heavy components of cmde oil and alkali. When the boiling temperature... 

Figure 8 shows the formation of a thin liquid film in a crude oil/alkali system. When the crude oil is contacted with an alkaline solution, the film capacitance increases and reaches a stable value after several minutes. This implies that the film has another thinning mechanism after the gravity drainage. 

There exist natural surface-active substances in crude oil, such as petroleum acids and asphaltenes. The ionized acids formed by the reaction between the petroleum acids and the alkali can decrease the interfacial tension [1,5-7] and accelerate the thinning and breakdown of the film. At the same time, the asphaltenes can adsorb on to the interface and improve the stability of the film. When the film thickness is small enough (< 100 nm), it can keep this value for a long time because of the stabilization of the asphaltenes in the oil. In our study, almost all crude oil/alkali systems have this drainage process, and the crude oil/brine systems do not show it. So we can conclude that the drainage is correlated with the components, which have the interactions with alkaline solutions. 

Batteries that require a liquid electrolyte are called wet batteries. Corrosive battery fluid refers to either acid electrolytes syn. battery acid, like the common lead-acid automobile battery which uses a solution of sulphuric acid, or alkali electrolytes syn. alkaline corrosive battery fluid, like potassium hydroxide (1310-58-3) solutions in nickel-cadmium and other alkaline battery systems. Dry batteries or dry cells, like all primary batteries, use electrolytes immobilized in pastes, gels, or absorbed into separator materials. Some batteries are loaded with a dry, solid chemical (e.g., potassium hydroxide) which is diluted with water to become a liquid electrolyte. The hazards associated with handling and transportation prior to use are thereby reduced. 

Within the periodic Hartree-Fock approach it is possible to incorporate many of the variants that we have discussed, such as LFHF or RHF. Density functional theory can also be used. I his makes it possible to compare the results obtained from these variants. Whilst density functional theory is more widely used for solid-state applications, there are certain types of problem that are currently more amenable to the Hartree-Fock method. Of particular ii. Icvance here are systems containing unpaired electrons, two recent examples being the clci tronic and magnetic properties of nickel oxide and alkaline earth oxides doped with alkali metal ions (Li in CaO) [Dovesi et al. 2000]. 

The solubilities of Li, Na, and Ca hypochlorites in H2O at 25°C ate 40, 45, and 21%, respectively. Solubility isotherms in water at 10°C have been determined for the following systems Ca(OCl)2—CaCl2, NaOCl—NaCl, and Ca(OCl)2—NaOCl (141). The densities of approximately equimolar solutions of NaOCl and NaCl ate given in several product bulletins (142). The uv absorption spectmm of C10 shows a maximum at 292 nm with a molar absorptivity of 350 cm ( 5)- Heats of formation of alkali and alkaline earth hypochlorites ate given (143). Thermodynamic properties of the hypochlorite ion ate ... 

As may be seen from the diagram, silver in highly alkaline solution corrodes only within a narrow region of potential, provided complexants are absent. It is widely employed to handle aqueous solutions of sodium or potassium hydroxides at all concentrations it is also unaffected by fused alkalis, but is rapidly attacked by fused peroxides, which are powerful oxidising agents and result in the formation of the AgO ion Table 6.6 gives the standard electrode potentials of silver systems. 

On the other hand, Bartsch et al. have studied cation transports using crown ether carboxylic acids, which are ascertained to be effective and selective extractants for alkali metal and alkaline earth metal cations 33-42>. In a proton-driven passive transport system (HC1) using a chloroform liquid membrane, ionophore 31 selectively transports Li+, whereas 32-36 and 37 are effective for selective transport of Na+ and K+, respectively, corresponding to the compatible sizes of the ring cavity and the cation. By increasing the lipophilicity from 33 to 36, the transport rate is gradually... 

The addition of alkali metal or ammonium fluorides reduce the acidity of the system and shift the equilibrium between the two ions toward the formation ofNbOFs2 ions [60,61]. The shift depends on the alkalinity of the cation. The more alkaline the cation is (higher atomic weight), the stronger the shift toward NbOF52 ion formation. Fig. 48 shows typical Raman spectra of niobium-containing solutions before and after such additions were made. 

The catalytic system used in the Pacol process is either platinum or platinum/ rhenium-doped aluminum oxide which is partially poisoned with tin or sulfur and alkalinized with an alkali base. The latter modification of the catalyst system hinders the formation of large quantities of diolefins and aromatics. The activities of the UOP in the area of catalyst development led to the documentation of 29 patents between 1970 and 1987 (Table 6). Contact DeH-5, used between 1970 and 1982, already produced good results. The reaction product consisted of about 90% /z-monoolefins. On account of the not inconsiderable content of byproducts (4% diolefins and 3% aromatics) and the relatively short lifetime, the economics of the contact had to be improved. Each diolefin molecule binds in the alkylation two benzene molecules to form di-phenylalkanes or rearranges with the benzene to indane and tetralin derivatives the aromatics, formed during the dehydrogenation, also rearrange to form undesirable byproducts. 

A remarkable variety of compounds in the Ca-(B,C,N) system has opened a window for research in related fields. With the elements boron, carbon and nitrogen, substance classes such as borocarbides, boronitrides, and carbonitrides can be considered to contain anionic derivatives of binary compounds B4C, BN, and C3N4. Until now, most compounds in these substance classes have been considered to contain alkali, alkaline-earth, or lanthanide elements. Lanthanide borocarbides are known from the work of Bauer [1]. Lanthanide boronitrides represent a younger family of compounds, also assigned as nitridoborates [2] following the nomenclature of oxoborates. 

An important condition for potentiometry is high selectivity the electrode s potential shonld respond only to the snbstance being examined, not to other components in the solntion. This condition greatly restricts the possibilities of the version of potentiometry described here when metal electrodes are nsed as the indicator electrodes. The solntion shonld be free of ions of more electropositive metals and of the components of other redox systems (in particnlar, dissolved air). Only corrosion-resistant materials can be nsed as electrodes. It is not possible at all with this method to determine alkali or alkaline-earth metal ions in aqneons solntions. 

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