Non-ionic ethoxylated surfactants

Silicone oils, non-ionic ethoxylated surfactants, metal stearates, etc. 

A linear dependence of the fast micelle dissolution rate constant kf on CMC for over 30 different surfactants (taken from Ref [19]) and for non-ionic ethoxylated surfactants (taken from Ref. [42]) is obtained when plotting the data on a logarithmic scale as presented in Figure 13.4. These results were obtained essentially from... 

Despite the fact that physico-chemical and chemical degradations were not possible, the isolation of persistent metabolites of the CnF2n+i-(CH2-CH2-0)m-H compound generated by (3 and w oxidations of the terminal PEG unit of the non-ionic blend was reported, but environmental data about this type of compound are still quite rare [49]. TSI(+) ionisation results of the industrial blend Fluowet OTN have been reported in the literature [7,51]. Actual data of non-ionic fluorinated surfactants were applied using ESI- and APCI-FIA-MS(+) and -MS-MS(+), which reported the biodegradation of the non-ionic partly fluorinated alkyl ethoxylate compounds C F2 fi-(CH2-CH2-0)x-H in a lab-scale wastewater treatment process. 

Synthetic surfactants are commonly used in shampoos, sometimes for reasons of cost and sometimes for performance. Non-ideal mixing in micelles can result when the repulsions between different surfactant head-groups are not uniform, such as when an anionic sulfonate is mixed with a non-ionic ethoxylate or when an anionic is mixed with a betaine. This causes the cmc of the mixture to be smaller than would be the case for ideal mixing, or for either surfactant alone. Such a reduction in cmc can be used to reduce the surfactant monomer concentration in a shampoo. This is an advantage since reducing the monomer concentration reduces the amount of eye and skin irritation experienced when the shampoo is used [904], Other synthetics offer other benefits. For example, some silicone surfactants can not only function as emulsifiers in hair and skin care products, but also act to improve feel, gloss, sheen, emolliency, conditioning and foam stabilization [905]. 

With FAB, TOP, MALDI, ESI-MS, field desorption (FD) MS and GC-MS technique the analytical capabilities for non-ionic gemini surfactants were compared [157]. Parees et al. reported on the analysis of a series of oligomeric ethoxylated surfactants of this type which showed an improved surface activity. Even an antibacterial lipopeptide biosurfactant, lichenysin A, cultured and isolated, was analysed by EAB-MS and EAB-MS/MS, ESI-MS and various other methods [158]. The compound was characterised and the lipid moiety contained a mixture of 14 linear and branched P-hydroxy fatty acids from C12 to C17. 

The surfactant solutions used need to be optimized, following the principles discussed in Section 3.4, to achieve the desired contact angles and emulsifying properties. Non-ionic ethoxylates, possibly mixtures of high and low HLB, in alkaline solution are often used [21]. Acid solutions are used where inorganics need to be removed, for example, a dodecyl benzene sulfonic acid [21]. 

Aveyard et al. [49] have also made a study of the spreading behavior of alkanes on solutions of non-ionic ethoxylated alcohol surfactants. A complication with such... 

Somewhat curiously, Binks and Dong [73] report a case of partial wetting with 48 mPa s PDMS on solutions of a non-ionic ethoxylated silicone surfactant of quoted [73] formula... 

Low degrees of ethoxylation tend to render the surfactant oil soluble, whilst higher levels confer water solubility. The use of non-ionic surfactants may sometimes lead to the formation of small aggregates or grainy emulsions. This tendency is due to the weaker surface activity and the relative difficulty with which non-ionic surfactants form micelles. As a result of these deficiencies non-ionic/anionic surfactant mixtures are normally employed in emulsion polymerisation. The ionic component allows easy solubilising of the monomer whilst the non-ionic component confers emulsion polymer stability. 

It is important that any method for surfactant analysis maintains the same oligomer distribution in the extracted samples. LLE and SPE are generally combined with chromatographic methods for separation and resolution of non-ionic surfactants into their ethoxamers. An alternative is the use of SPME-HPLC, recently reported by Chen and Pawliszyn [141]. Alkylphenol ethoxylate surfactants such as Triton X-100 and various Rexol grades in water were determined by means of SPME-NPLC-UV (at 220 nm) [142]. Detection limits for individual alkylphenol ethoxamers were at low ppb level. 

The application range of cSFC-DFI-MS (Table 7.41) appears to be restricted either to the analysis of low-MW substances or to problems related to high-MW samples where low detection limits are not needed [124,444,445], The analysis of surfactants [446] by SFC-MS is frequently performed to demonstrate the feasibility of newly developed interface technology for practical applications. A rugged cSFC-MS method has been developed for the analysis of ethoxylated alcohols (AEs), which are non-ionic surfactants incorporated into a wide variety of industrial and consumer products [447]. cSFC-DFT-DFS was used for the analysis of low-MW, thermally unstable peroxides, and the higher-MW surfactants Triton X-100 and... 

For analysis of surfactants, i.e. detection, identification and quantification, LC-TSP-MS and MS/MS are also qualified methods for substance-specific information [600-602]. A mixture of non-ionic surfactants, comprising nonylphenol ethoxylates [C9Hi9-(CeH4)-0-(CH2-CH2-0)m-H], anionic surfactants and PEG, was... 

Bodin, A., et al., Identification and allergenic activity of hydroxyaldehydes — anew type of oxidation product from an ethoxylated non-ionic surfactant, Contact Dermatitis, 44, 207, 2001. 

Surfactants, such as linear alkylbenzene sulfonates (LAS) and alkylphenol ethoxylates, are present in whitewaters because of their use as cleaning agents or as additives in antifoamers, deinkers, dispersants, etc. The non-ionic surfactants alkylphenol ethoxylates (APEO) degrade to nonylphenol (NP) or to a... 

Both urban and industrial wastewater often contains high concentrations of surfactants. Cationic (like alkylbenzene sulphonates) and non-ionic surfactants (like alcohol ethoxylates) are among the most-used surfactants and are discharged into sewers in widely varying concentrations. Two on-line methods have been designed for the monitoring of cationic surfactants with UV spectrophotometry [46] and non-ionic surfactants by on-line titration [47]. The detection limits are around 10 mg L. ... 

III. Non-ionic surfactants LC-MS and LC-MS-MS of alkylphenol ethoxylates and their degradation products. . . ... 

The most representative non-ionic surfactants are the alkyl (alcohol) ethoxylates. These are adducts of a long-chain alcohol (12—18) with a variable number of EO units (3-11). Other non-ionic surfactants are derived from carbohydrates (glucoside and glucamide derivatives), organosilicones, fatty alcohols, and amides. Products in this category are as follows (compare also Table 1.2) ... 

Commercial AESs are produced via sulfation of AEs, which are also directly used as non-ionic surfactants (see below). AES preparations typically also contain some level of alkyl sulfates. The majority of technical AES blends are obtained from AE feed stocks that have alkyl chains in the range of 12-15 and an average degree of ethoxylation of three. 

Ethoxylation of alcohols, alkylphenols, fatty acids, and many other organic raw materials is also a very important reaction for the surfactant industry, used to produce a broad variety of surfactants, most of which belong to the non-ionics group. The reaction with propoxylation (PO) is also practised, although to a lesser degree. The product used for ethoxylation is EO, or PO in the case of propoxylation, and is conducted using alkaline catalysts such as NaOH or NaOCH3. 

Gas chromatography (GC) has developed into the most powerful and versatile analytical separation method for organic compounds nowadays. A large number of applications for the analysis of surfactants have emerged since the early 1960s when the first GC papers on separation of non-ionics were published. The only major drawback for application of GC to surfactants is their lack of volatility. This can be easily overcome by chemical modification (derivatisation), examples of which will be discussed extensively in the following paragraphs. This chapter focuses on surfactant types, and in addition discusses some structural aspects of alkylphenol ethoxylates (APEOs) that are important for, as well as illustrative of, aspects of separation and identification that are linked to the complexity of the mixtures of surfactants that are involved. 

The GC analysis of silylated derivatives of ethoxylated amines and fatty acid diethanolamides, among other non-ionic surfactants, has been described for many years and reviewed recently [43]. However, most of the determinations deal with the use of old packed columns for the characterisation of commercial blends and there are no applications of GC to their study in the environment. 

Aliphatic AEOs, considered as environmentally safe surfactants, are the most extensively used non-ionic surfactants. The commercial mixtures consist of homologues with an even number of carbon atoms ranging typically from 12 to 18 or of a mixture of even-odd linear and a-substituted alkyl chains with 11—15 carbons. Furthermore, each homologue shows an ethoxymer distribution accounting typically for 1—30 ethoxy units with an average ethoxylation number in the range 5—15. The separation of the AEO complex mixtures was achieved by reversed-phase and normal-phase chromatographic systems [74—76]. 

Equidistant or clustered signals, characteristic of some anionic, nonionic or cationic surfactants (cf. Fig. 2.5.1(a) and (b). So the presence of non-ionic surfactants of alkylpolyglycolether (alcohol ethoxylate) type (AE) (structural formula C H2 i i-0-(CH2-CH2-0)x-H) could be confirmed in the formulation (Fig. 2.5.1(a)) applying APCI-FIA-MS in positive mode. AE compounds with high probability could also be assumed in the heavily loaded environmental sample because of the patterns of A m/z 44 equally spaced ammonium adduct ions ([M + NH4]+) shown in its FIA-MS spectrum in Fig. 2.5.1(b). 

SPECTROMETRY—III. NON-IONIC SURFACTANTS LC-MS AND LC-MS-MS OF ALKYLPHENOL ETHOXYLATES AND THEIR DEGRADATION PRODUCTS... 

Here, the mixture analytical FIA-MS-MS approach reached its limitation to identify compounds. Hence, LC separations prior to MS analysis are essential to separate compounds with the same m/z ratio but with different structures. The behaviour in the LC separation will be influenced by characteristic parameters of the surfactant such as linear or strongly branched alkyl chain, the type, the number and the mixture of glycolether groups—PEG and/or PPG—and the ethoxylate chains. The retardation on SPE materials applied for extraction and/or concentration also depends on these properties and can therefore be used for an appropriate pre-separation of non-ionic surfactants in complex environmental samples as well as in industrial blends and household detergent formulations. A sequential selective elution from SPE cartridges using solvents or their mixtures can improve this preseparation and saves time in the later LC separation [22],... 

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