Alkali component solubility

Ulmic acid (brown) and Humic acid (black), the components soluble in alkali... 

Hydroxyalkyl lignin derivatives were crosslinked with diisocyanates or with melamine in both solvent and aqueous emulsion-based adhesive formulations for wood products (51) (Figure 7). Adhesive performance was found to be related to component solubility and compatibility (51), The use of kraft lignin in aqueous alkali and that of lignin sulfonates in water has been explored in combination with emulsifiable diisocyanates (52) in wood adhesives. Satisfactory strength properties were reported. 

Earth materials with abundant soluble alkali components (such as cement or concrete) or acidic... 

For aqueous inks, the resins are water- or alkali-soluble or dispersible and the solvent is mosdy water containing sufficient alcohol (as much as 25%) to help solubilize the resin. To keep the alkah-soluble resin in solution, pH must be maintained at the correct level. Advances include the development of uv inks. These are high viscosity inks that require no drying but are photocurable by uv radiation. In these formulations, the solvent is replaced by monomers and photoinitiators that can be cross-linked by exposure to uv radiation. The advantage of this system is the complete elimination of volatile organic compounds (VOC) as components of the system and better halftone print quaUty. Aqueous and uv inks are becoming more popular as environmental pressure to reduce VOC increases. 

Alkali sihcates are used as components, rather than reactants, in many appHcations. In many cases they only contribute partially to overall performance. Utility factors are generally not as easy to identify. Their benefit usually depends on the surface and solution chemical properties of the wide range of highly hydrophilic polymeric siUcate ions deUverable from soluble sihcate products or their proprietary modifications. In most cases, however, one or two of the many possible induences of these complex anions cleady express themselves in final product performance at a level sufficient to justify their use (102). Estimates of the 1995 U.S. consumption of sodium sihcates are shown in Table 6. 

The auxiliary electrolyte is generally an alkali metal or an alkaline earth metal halide or a mixture of these. Such halides have high decomposition potentials, relatively low vapor pressures at the operating bath temperatures, good electrolytic conductivities, and high solubilities for metal salts, or in other words, for the functional component of the electrolyte that acts as the source of the metal in the electrolytic process. Between the alkali metal halides and the alkaline earth metal halides, the former are preferred because the latter are difficult to obtain in a pure anhydrous state. In situations where a metal oxide is used as the functional electrolyte, fluorides are preferable as auxiliary electrolytes because they have high solubilities for oxide compounds. The physical properties of some of the salts used as electrolytes are given in Table 6.17. 

The purpose of the alkali is to convert the insoluble free naphthol into its colloidally soluble sodium salt. An excess of sodium hydroxide is generally needed but too much will tend to promote hydrolysis of the amide groups present in most azoic coupling components. The actual amount required varies with the naphthol and processing conditions the manufacturer s detailed literature must be consulted. 

In 1904 Bally obtained a bluish violet solid by alkali fusion of benzanthrone at approximately 220 °C. Two isomeric compounds were isolated by vatting the reaction mixture and filtering off a sparingly soluble sodium salt. Oxidation of the filtrate gave a blue vat dye, violanthrone (6.75 Cl Vat Blue 20), as the main component. The less soluble residue similarly afforded a violet product, isoviolanthrone (6.76 Cl Vat Violet 10). The formation of isoviolanthrone can be suppressed by carrying out the fusion in a solvent such as naphthalene or a polyethylene glycol in the presence of sodium acetate and sodium nitrite. Dyes of this type are often referred to as dibenzanthrones. 

The most widely used positive resists are those that operate on the basis of a dissolution inhibition mechanism. Such resists are generally two-component materials consisting of an alkali soluble matrix resin that is rendered insoluble in aqueous alkaline solutions through addition of a hydrophobic, radiation-sensitive material. Upon irradiation, the hydrophobic moiety may be either removed or converted to an alkali soluble species, allowing selective removal of the irradiated portions of the resist by an alkaline developer. 

The hemicelluloses are soluble in alkali, and can therefore be readily separated from the cellulose component by alkali extraction. However, this can only be done when the wood has first been delignified. This is because they are probably linked to lignin via covalent ester linkages (see Chapter 3) which need to be cleaved... 

Wood contains a small proportion (usually less than 5%) of components which are extractable by organic solvents such as ethanol or dichloromethane. The proportion of these extractives varies in hardwoods and softwoods and also between species. Although many of these substances are removed during the chemical pulping process, some may still be retained in the final sheet of paper. Their chemical composition is very varied, and they include alkanes, fatty alcohols and acids (both saturated and unsaturated), glycerol esters, waxes, resin acids, terpene and phenolic components. The proportion which remains in pulp and paper depends upon the pulping process used. In general, acidic components such as the resin and fatty acids are relatively easily removed by alkali by conversion to their soluble... 

A modification of the pyrolysis process, developed by Hoppe-Seyler in 1871, involved the addition of water and alkali to biomass which was converted into oil, gas, water-soluble components, and carbonaceous material. " The addition of carbon monoxide and hydrogen in the liquefaction process allowed the production of liquid fuels from biomass. Asphalt substitutes have also been prepared from biomass under liquefaction conditions. ... 

One disadvantage of borosilicate glass is the low solubility of sulphates, molybdates, chromates, and halogenides, which may cause separation of metastable phases (Fig. 1) at relatively low contents of these components (1-3 wt%, dependent on glass composition Camara et al. 1980 Kawamoto et al. 1981 Stefanovsky 1989 Stefanovsky Lifanov 1989). At higher concentrations, yellow phase formation may occur (Morris Chidley 1976 Stefanovsky Lifanov 1988 Lutze 1988). The yellow phase, consisting of alkali and alkaline earth molybdates, sulphates, chromates, and halogenides, concentrates Cs and Sr radionuclides, and its presence increases leach rates of these radionuclides. 

Virginiamycin is a mixture of two components designated Mi and Si, which are both cyclic polypeptides. It is soluble in methanol, ethanol, acetic acid, ethyl acetate, acetone, chloroform, and benzene but is practically insoluble in water and dilute acid. It also dissolves in alkalis but is rapidly deactivated. 

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