Non-ionic surface active compounds

Low concentrations of sodium chloride, in fact, reduce detergent power but any increase above 2 g/1 produces a rapid improvement. This effect is apparent with the non-ionic surface-active compounds as well as with the sodium alkyl sulphates. 

P. Becher, Non Ionic Surface Active Compounds. V. Effect of Electrolytes, J. Colloid Science, 17 325 (1962). 

Anionic and non-ionic surface active compounds are not important as microbicides for the protection of materials. On the contrary, aqueous anionic or nonionic detergent solutions need the addition of in-tank/in-can preservatives for protection against contamination and proliferation of micro-organisms. 

Thiomersal is highly effective against Gram-positive and Gram-negative bacteria and is mainly used as a preservative in pharmaceutical preparations addition rates 100-200 mg/litre. It is not compatible with non-ionic surface active compounds and proteins. In the EC list of preservatives allowed for cosmetics Thiomersal is mentioned with a maximum authorized concentration of 0-007% (of Hg) for eye make-up and eye make-up remover only on the label there must be printed the warning Contains Thiomersal. 

Chlorophen works best in an acidic, neutral or weakly alkaline environment, where it is in the undissociated effective form. Optimum pH range 4 to 8. Chlorophen is compatible with anionic surfactants and soaps and to a certain extent with non-ionic surface active compounds, too, however, not with cationic surfactants. Starting from a concentrate, containing 10% Chlorophen +25% sec. alkane sulphonate +20% isopropanol +45% demineralized water, Chlorophen exhibits microbicidal effects in water at concentrations listed in Table 68. 

As we have seen, the presence of ethoxylated non-ionic surface-active compounds can enhance the susceptibility of the foam of solutions of anionic surfactants to antifoam. This appears to be a general phenomenon that is also manifest with PDMS-hydrophobed silica antifoams in wash cycles with drum-type, front-loading, textile washing machines. This well-known effect is exemplified in Figure 8.13 where the addition of ethoxylated alcohols is seen to diminish the foam profile of solntions of sodinm alkylbenzene snlfonate (LAS) in the presence of PDMS-hydrophobed silica antifoam. Sawicki [7] has shown that the effect of these ethoxylated componnds does not concern either the precipitation of cloud phase drops (see Section 4.6.3.2) or marked changes in dynamic or equilibrium air-water solution snrface tensions. One possible explanation could concern a putative inhibiting effect of ethoxylated compounds upon the rate of PDMS-hydrophobed silica antifoam deactivation. However, this would afford no explanation for the effect of those componnds on the antifoam action of hydrophobic precipitates where no oil is present (see Section 8.2.2). 

Quaternary ammonium compounds (QACs Chapter 10) such as cetrimide, and also the bisbiguanide, chlorhexidine, are notoriously prone to promote clumping. A non-ionic surface-active agent of the type formed by condensing ethylene oxide with a long-chain fatty acid such as Cirrasol ALN-WF (ICI Ltd), formerly known as Lubrol W, together with lecithin, added to the diluting fluid has been used to overcome this effect. 

CNSL is obtained as a by-product of the cashew nut industry, mainly containing anacardic acid 80.9%, cardol 10-15%, cardanol, and 2-methyl cardol (Fig. 10). CNSL occurs as a brown viscous fluid in the shell of cashewnut, a plantation product obtained from the cashew tree, Anacardium oxidentale (Bhunia, et al., 2000). CNSL is used in the manufacture of industrially important materials such as cement, primers, specialty coatings, p)aints, varnishes, adhesives, foundry core oils, automotive brake lining industry, laminating and rubber compounding resins, epoxy resins, and in the manufacture of anionic and non-ionic surface active agents. CNSL modified phenolic resins are suitable for many applications and perform improved corrosion and insulation resistance. 

The long-chain, fatty acid esters of sucrose are non-ionic, nontoxic, and biodegradable, and compare well in overall performance with other surface-active compounds in detergency, emulsification, and... 

Surfactants are surface-active compounds, which are used in industrial processes as well as in trade and household products. They have one of the highest production rates of all organic chemicals. Commercial mixtures of surfactants consist of several tens to hundreds of homologues, oligomers and isomers of anionic, non-ionic, cationic and amphoteric compounds. Therefore, their identification and quantification in the environment is complicated and cumbersome. Detection, identification and quantification of these compounds in aqueous solutions, even in the form of matrix-free standards, still poses the analyst considerable problems. 

The rate of fixation of the monochlorotriazinyl dyes is very much slower. The result is that there is abundant opportunity for the normal acid dyeing mechanism to give uniform distribution of the dye molecules before they become permanently anchored by covalent bond formation. It has been found that, for some unknown reason, cationic surface active compounds tend to reduce skitteriness, if a non-ionic compound is also present to prevent the precipitation of the cation-dye complex. In order to prevent foaming which can become troublesome the addition of a silicone antifoaming product has been recommended. 

Surfactants are surface-active compounds that consist of a hydrophihc head group attached to a hydrophobic tail (usually a long alkyl chain). They have a high affinity for water or oil depending on the dominant moiety (Walz, 1998 McClements, 2004). When present in sufficiently high concentrations, surfactants form a monolayer at the interface between the oil and water, with the hydrophobic tails of the surfactant orientated towards the oil phase and the hydrophilic head groups towards the aqueous phase. There are four categories of surfactants available in the food industry ionic, non-ionic, zwitterionic and cationic. 

Partly fluorinated or perfluorinated sulfonic and carboxylic acids are compounds with excellent surface activity combined with an extreme stability against chemical or physico-chemical attacks as also described for non-ionic fluorine containing surfactant compounds. The anionic surfactants are shown with their structural formulae in Fig. 2.11.24(1)—(III). A selected ESI-FIA-MS(-) spectrum of a partly fluorinated surfactant (CF3-(CF2)4-(CH2)8-S03H, m/z 461) is presented in Fig. 2.11.25. The FIA spectrum also contains ions of the by-products CF3-(CF2)2-(CH2)8-S03H (m/z 361) and CF3-(CF2)3-(CH2)8-S03H (m/z 411). 

The common gangue material quartz (silica) is naturally hydrophilic and can be easily separated in this way from hydrophobic materials such as talc, molybdenite, metal sulphides and some types of coal. Minerals which are hydrophilic can usually be made hydrophobic by adding surfactant (referred to as an activator ) to the solution which selectively adsorbs on the required grains. For example, cationic surfactants (e.g. CTAB) will adsorb onto most negatively charged surfaces whereas anionic surfactants (e.g. SDS) will not. Optimum flotation conditions are usually obtained by experiment using a model test cell called a Hallimond tube . In addition to activator compounds, frothers which are also surfactants are added to stabilize the foam produced at the top of the flotation chamber. Mixtures of non-ionic and ionic surfactant molecules make the best frothers. As examples of the remarkable efficiency of the process, only 45 g of collector and 35 g of frother are required to float 1 ton of quartz and only 30 g of collector will separate 3 tons of sulphide ore. 

Applications of FAB have been succesfully performed in the characterization of a wide range of compounds (dyes, surfactants, polymers...) but little attention has been devoted to the capabilities of this technique to solve environmental concerns, such as organic pollutants identification in water. The widespread use of surfactants in the environment has required the emplo yment of both sensitive and specific methods for their determination at trace levels. GC/MS and HPLC procedures has been used for the determination of anionic (LAB s) and non ionic surfactants (NPEO) in water (1-4). Levsen et al (5) identified cationic and anionic sirrfactants in surface water by combined field desorption/ collisionally activated decomposition mass spectrometry (FD/CAD), whereas FAB mass spectrometry has been used for the characterization of pine industrial surfactants (6-8). 

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