Cation active substances

Cation-active substances are also used to increase the wet-fastness of direct dyes. An example of such a product is Fixanol C, which is cetyl pyridinium bromide ... 

Practically all unshrinkable treatments tend to make wool rather harsh and after-treatment with softening agents is desirable. These are usually cation-active substances (see Chapter 9), the effective ion of which is deposited on the negatively-charged fibres. When these ions are of such a nature that they will tend to reduce friction, they will lubricate the surface of the fibre and produce a soft handle. A typical example, and probably the fore-runner of all the others, is Sapamine KW ... 

Removal of the dye is brought about most effectively by sodium hydrosulphite in the presence of a cation-active substance such as Lissolamine A (Cetyl trimethyl ammonium bromide). Fhe goods are treated at the boil for about IS minutes in a liquor made up with 2 per cent of Lissolamine A, 12 per cent of caustic soda 72 Tw (32-5 per cent) and the temperature is then dropped to just below the boil and 5 to 6 per cent of sodium hydrosulphite is added. After a further 30 to 45 minutes, the liquor is run off and stripping is completed by bleaching with sodium hypochlorite. 

Fig. 12.3. The distribution of charge signs in the primary and secondary double layers in the presence of cation-active substances of rather low surface activity...

The selection of the surfactant is mainly based on the compatibility with the active substance. Sodium lauryl sulfate is an anionic surfactant and therefore incompatible with cationic active substances. Cetomacrogol emulsifying wax BP is incompatible with high concentrations of phenolic substances due to an interaction of the phenolic group with the polyethylene glycol chains in the macrogol cetostearyl ether. It is compatible with acids, high concentrations of electrolytes and cations. 

Cationic-active substances Quatemairy ammonium salts BenzaUconium chloride Cetrimonium bromide... 

The electrical forces may also act on dust particles before these come into contact with the surface (see 12), i.e., in principle, there may be such a thing as a dust-repellant coating, chiefly in relation to the dust particles floating in the air. Alkyd-styrene construction paints with a low binder content are an example of this [255]. A similar result may be achieved by treating the object with a 1% aqueous solution of a cation-active substance, such as Arkvad 18 which, according to the American firm of Armour [256], prevents dust accumulating on objects for several months. 

Chromium coordination complexes with compounds containing — NH2, — NH—, epoxide, amide, and isocyanate groups [52-54] are also used. Cation active substances such as cationic styrene aminosilanes are recommended by Dow Coming (U.S.) as coupling agents. For example. 

The potentiometry sensor (ion-selective electrode) controls application for determination of polymeric surface-active substances now gets the increasing value. Potentiometry sensor controls are actively used due to simple instmment registration, a wide range of determined concentrations, and opportunity of continuous substances contents definition. That less, the ionometry application for the cation polymeric SAS analysis in a solution is limited by complexity of polycation charge determination and ion-exchanger synthesis. 

In presence of polyamines the maximum of light absorption of indicated triphenylmethane dyes displaces on 10-30 nm, for azo dyes the shift of the band reaches 50-80 nm. The greatest difference of light absorption of associates and reagents is watched for BKM at pH 5,05, for BPR at pH 4,20, for CPR in an interval pH 5,05-5,45. At these pH dyes are anions, it promotes interaction with a cationic surface-active substance. The ratios between polymer and BKM, BPR, CPR are established by spectroscopy method, its equal 1 20, 1 20 and 1 30 accordingly. 

Active matter (anionic surfactant) in AOS consists of alkene- and hydroxy-alkanemonosulfonates, as well as small amounts of disulfonates. Active matter (AM) content is usually expressed as milliequivalents per 100 grams, or as weight percent. Three methods are available for the determination of AM in AOS calculation by difference, the two-phase titration such as methylene blue-active substances (MBAS) and by potentiometric titration with cationic. The calculation method has a number of inherent error factors. The two-phase titration methods may not be completely quantitative and can yield values differing by several percent from those obtained from the total sulfur content. These methods employ trichloromethane, the effects from which the analyst must be protected. The best method for routine use is probably the potentiometric titration method but this requires the availability of more expensive equipment. 

Adsorption of surface-active substances is attended by changes in EDL structure and in the value of the / -potential. Hence, the effects described in Section 14.2 will arise in addition. When surface-active cations [NR] are added to an acidic solution, the / -potential of the mercury electrode will move in the positive direction and cathodic hydrogen evolution at the mercury, according to Eq. (14.16), will slow down (Fig. 14.6, curve 2). When I ions are added, the reaction rate, to the contrary, will increase (curve 3), owing to the negative shift of / -potential. These effects disappear at potentiafs where the ions above become desorbed (at vafues of pofarization of less than 0.6 V in the case of [NR]4 and at values of polarization of over 0.9 V in the case of I ). 

Kimerle [27] reviewed the ecotoxicology of LAS focusing on the results rather than on the method of analysis, for which the author referred to the review undertaken by Painter and Zabel [30], alluding only to two papers on biota sample preparation. Litz et al. [31] determined the concentration of LAS in rye grass by Azure A active substances (AzAAS). AzAAS is a non-specific colorimetric method, which has not been used as frequently as MBAS (see Chapter 3.1). Briefly, it consists of the formation of an ion association complex with a dyed solution of Azure A (cationic). The complex formed is solvent-extractable and is separated from unreacted dye prior to colour measurement. 

The purification of some enzymes inactivates them because substances essential for their activity but not classed as a prosthetic group are removed. These are frequently inorganic ions which are not explicit participants in the reaction. Anionic activation seems to be non-specific and different anions are often effective. Amylase (EC 3.2.1.1), for example, is activated by a variety of anions, notably chloride. Cationic activation is more specific, e.g. magnesium is particularly important in reactions involving ATP and ADP as substrates. In cationic activation it seems very likely that the cation binds initially to the substrate rather than to the enzyme. 

Among chromenes, only the spiropyrans and their heterocyclic derivatives have found a wide practical application as photochromic substances.5 6,7-Chromenediols have been proposed as analytical reagents for the spectrophotometric assay of rare earth cations.279 Chromenes with structure and activity similar to those of hashish constituents have been prepared.280 A number of chromenes, mostly with aryl substituents in positions 2,3, and 4 have been patented as biologically active substances.126,280 290... 

The cationic nature of Ziegler catalysts have been proposed by Sinn, Winter and Tirpitz (90) who found that the polymerization of styrene, of vinylethers, of butadiene and of isoprene by Ziegler catalysts required the presence of trace amounts of proton-active substances. These same cationic catalyst species isomerized heptene and isoheptene. No definite results could be obtained for propylene and it... 

Such anionic surfactants that form ion pairs with methylene blue and that are extractable with chloroform are known as Methylene Blue Active Substances (MBAS). Other cationic dyes, such as crystal violet dye, may be used instead of methylene blue. Extraction of such an ion-pair complex into benzene has been reported (Hach, 1989). Detection Limit = 10 pg/L. 

Strzelbicki, J. and Schlosser, . (1989) Influence of surface-active substances on pertraction of cobalt(II) cations through bulk and emulsion liquid membranes. Hydrometallurgy, 23, 67. 

It is now well established that a variety of organic molecules such as polynuclear aromatic hydrocarbons with low ionization energies act as electron donors with the formation of radical cations when adsorbed on oxide surfaces. Conversely, electron-acceptor molecules with high electron affinity interact with donor sites on oxide surfaces and are converted to anion radicals. These surface species can either be detected by their electronic spectra (90-93, 308-310) or by ESR. The ESR results have recently been reviewed by Flockhart (311). Radical cation-producing substances have only scarcely been applied as poisons in catalytic reactions. Conclusions on the nature of catalytically active sites have preferentially been drawn by qualitative comparison of the surface spin concentration and the catalytic activity as a function of, for example, the pretreatment temperature of the catalyst. Only phenothiazine has been used as a specific poison for the butene-1 isomerization on alumina [Ghorbel et al. (312)). Tetra-cyaonoethylene, on the contrary, has found wide application as a poison during catalytic reactions for the detection of active sites with basic or electron-donor character. This is probably due to the lack of other suitable acidic probe or poison molecules. 

Cationic softener, 100% active substance, in flake form, cold water soluble, excellent exhaustion to be used on all fibers and in the dyebath with cationic dyestuffs high fiber smoothness. 

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