Pretreatment cationic agents

Wu, T.S., Chen, K.M., 1992. New cationic agents for improving the dyeability of cellulose fibers. Part 1— pretreating cotton with polyepichlorohydrin-amine polymers for improving dyeabihty with direct dyes. J. Soc. Dyers Color. 108 (9), 388-394. 

Adsorbent materials are used medicinally to absorb toxins in vivo. The enterotoxin of Pseudomonas aeruginosa is implicated in the aetiology of diarrhoea adsorbents such as kaolin are used to decrease the toxicity of such agents by removal of the toxin by adsorption. Armstrong and Clarke have investigated the adsorption sites on kaolin by measurement of electrophoretic mobility in the presence of surfactants and other materials as a function of pH [58]. In particular they studied the uptake of gentian violet on to koalin treated with anionic and cationic agents. Kaolin pretreated with cetrimide showed a marked decrease in adsorptive capacity. On the other hand, when pretreated with sodium hexadecyl sulphate the adsorptive capacity was increased (Fig. 9.22). 

The valence of both the anion of an acid and the cation of a base have a substantial influence on the character of the surface charge and on the value of PZC and IP59 . PZC and IP of a mineral are further affected by the mineral s genesis, by a preparative pretreatment of its surface with chemical agents, the presence of impurities (other minerals), isomorphism, temperature pretreatment, and age of the surface58 60 61 . 

M. Kataoka et al., Effect of cation-exchange pretreatment of aqueous soil extracts on the gas chromatographic-mass spectrometric determination of nerve agent hydrolysis products after tert.-butyldimethylsilylation. J. Chromatogr. A 824, 211-221 (1998)... 

Clearly some form of sample pretreatment is required for soils and sediments. Total levels may be obtained following sodium carbonate-boric acid fusion and the dissolution in hydrochloric acid employing lanthanum as a buffer and releasing agent. If the determination of silicon is not required, it may be volatilized as silicon tetrafluoride using hydrofluoric acid, although some calcium may also be lost as calcium fluoride. For many samples, however, it may be more appropriate to determine the exchangeable cation content of the sample. Here, the sample may be shaken with an extractant solution, for example, 1 mol 1 ammonium chloride, ammonium acetate, or disodium EDTA, prior to filtration and analysis. Where final solutions contain more than - 0.5% of dissolved material, the standards should also contain the major constituents, even where no chemical interference is expected, in order to match the viscosity and surface tension and avoid matrix effects. 

The analysis of solvent and perfumes in formulations is performed by GC. For solvent analysis in surfactants sample pretreatment with organic solvent is used for the separation of inorganic impurities. Regarding surfactants and complementary compounds, applications may be mentioned such as the separation of a hardness agent (sodium laurate) in liquid laundry detergent by GC and the Hofmann degradation and analyses of cationic surfactant of the alkyltrimethyl- and dialkyldimethylammonium type in fabric softener and hair rinse. 

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