Non-ionic and amphoteric surfactants

Adsorption can be measured by direct or indirect methods. Direct methods include surface microtome method [46], foam generation method [47] and radio-labelled surfactant adsorption method [48]. These direct methods have several disadvantages. Hence, the amount of surfactant adsorbed per unit area of interface (T) at surface saturation is mostly determined by indirect methods namely surface and interfacial tension measurements along with the application of Gibbs adsorption equations (see Section 2.2.3 and Figure 2.1). Surfactant structure, presence of electrolyte, nature of non-polar liquid and temperature significantly affect the T value. The T values and the area occupied per surfactant molecule at water-air and water-hydrocarbon interfaces for several anionic, cationic, non-ionic and amphoteric surfactants can be found in Chapter 2 of [2]. 

Hidaka H, Nohara K, Zhao J, Pelizzetti E, Serpone N. Photodegradation of surfactants. XIV. Formation of NH and NO, ions for the photocatalyzed mineralization of nitrogen-containing cationic, non-ionic and amphoteric surfactants. J Photochem Photobiol A Chem 1995 91 145-52. 

Features Substantive, iow foaming compat. with non-ionic and amphoteric surfactants not compat. with anionic surfactants Properties Ci. yei. iiq. 75% act. ... 

Lines 1 and 2 in Fig. 3.60 extend over the region characteristic for non-ionic or amphoteric surfactants (except for the oxyethylated ones), and correspond to AG h =-(2.9-t-3.3) kJ/moI. Lines 3 and 4 confine the region of ionic surfactants, yielding the values AG°h, = -(2.7-1-3.8) kJ/mol. These values of the increments are approximately 10% larger than those calculated for these surfactants in the previous sections. This inconsistency is possibly due to the fact that the AG value is not exactly equal to zero (as also the difference AG, ... 

The best agreement with the entire scope of the experimental data was obtained for AGp= -4.25 kJ/mol the theoretical lines calculated from Eq. (3.26) with this AGp value are shown in Fig. 3.61. For the non-ionie and amphoteric surfactants the lines 1 and 2 correspond to AG h =-(2.6 3.0) kJ/mol, and for ionic surfactants the lines 3 and 4 correspond to... 

Leon-Gonzalez et al.[31] proposed an FI spectrophotometric method for the determination of Triton-type non-ionic surfactants based on their reaction with alizarin fluorine blue. An on-line ion-exchange column was incorporated in the system to eliminate interferences from ionic and amphoteric surfactants. In case of interferences from non-ionic surfactants, an on-line Amberlite XAD-4 adsorption column was used to retain selectively the Triton-type surfactant, which was subsequently eluted by ethanol. However, no information was given regarding interferences from refractive index effects at the ethanol/aqueous interface and their elimination. 

Numerous laboratory sorption studies have been conducted for the most common surfactants non-ionics, such as AE and alkylphenol ethox-ylates (APEOs) anionics such as LAS, secondary alkane sulfonates (SASs) and sodium dodecylsulfates (SDS) and on different natural sorbents [3,8,15-17], Until now, cationic and amphoteric surfactants have received less study than the other types, probably because they represent only 5 and 2%, respectively, of the total surfactant consumption in Western Europe (1998) [18]. 

A broad range of information pertaining to the toxicity of several classes of surfactants including anionic (linear alkylbenzene sulfonates (LAS), alkylether sulfates (AES), alkyl sulfates (AS), non-ionic (alkylphenol ethoxylates (APEO)), cationic (ditallow dimethyl ammonium chloride (DTDMAC)—a group of quaternary ammonium salts of distearyl ammonium chloride (DSDMAC)) and amphoteric surfactants (alkyl-betaines) is available. Several reviews of the scientific literature have been published [3-5,20]. 

The HLB concept, introduced in Section 3.6.1 is probably the most useful approach to predicting the type of emulsion that will be stabilized by a given surfactant or surfactant formulation. The HLB concept was introduced [207,209] as an empirical scale that could be used to describe the balance of the size and strength of the hydrophilic and lipophilic groups on an emusifier molecule. Originally used to classify Imperial Chemical Industries non-ionic surfactant series of Spans and Tweens the HLB system has now been applied to many other surfactants, including ionics and amphoterics. 

Petrochemical surfactants are mainly derived from ethylene, propylene, butylenes, benzene, and also naphthalene as building blocks [46]. The most important emulsifiers for emulsion polymerization are anionic and non-ionic surfactants. Cationic and amphoteric surfactants are only used in special cases and are of minor importance as emulsifiers for polymerization. 

Wetting, dispersing, stabilising Numerous anionic, non-ionic, cationic and amphoteric surfactants/dispersants... 

G. Marti-Mestrcs. F. Nielloud, R. Marti, H. MailloLs. Optimization with e.xperimental design of non-ionic, anionic, and amphoteric surfactants in mixed system. Drug Dev. Ind, Phann, 23(10) 993-998. 1997,... 

The molecular structure of surfactants controls not only the concentration of the surfactants at the interface and the resulting reduction in surface/interfacial tensions, but also affects the orientation of the molecules at the interface. The hydrophilic group is either ionic in nature or highly polar. Based on the nature of the polar group, surfactants can be classified as anionic, cationic, non-ionic or amphoteric. Among these types, anionic and non-ionic surfactants are preferably employed in enhanced oil recovery processes (EOR) due to their low adsorption on reservoir rocks. Therefore, these surfactants are briefly described. 

Figure 2.1. Chemical structures of different surfactants CTAB (cationic) sodium Aerosol OT (anionic) Brij 30 (non-ionic) and lauryl betaine (amphoteric). Note the pair of chains in case of sodium Aerosol OT.

Following on reports (referred to above) of macromolecule absorption facilitated by surfactants, there have been successful attempts to achieve insulin absorption per rectum [127-129, 126]. Non-ionic ethers, anionic, cationic and amphoteric surfactants, as well as bile acids, increased absorption. The optimal effect has been obtained with 1 % polyoxyethylene (9) lauryl ether [128], the effect of both polyoxyethylene chain length and alkyl chain having been... 

Features Compat, with non-ionic, anionic and amphoteric surfactants med. foam Properties Gardner 11 max, liq. m.w. 910 flash pt. (PM) 258 F 95% quat. min. Varisoft 137 [Evonik Goldschmidt GmbH]... 

The two distinctive affinities in the surfactant molecule mentioned above serve as the basis for the commonly accepted definition of surfactant groups. According to the charge of their hydrophilic moiety, surfactants can be classified into four categories anionic, non-ionic, cationic and amphoteric. 

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. 

Therefore, a C13-AE, a cationic (quaternary ammonium) surfactant (quat), an amphoteric Ci2-alkylamido betaine, and the non-ionic fatty acid diethanol amide (FADA) as presented with their FIA-MS spectra in Fig. 2.5.12(a)-(d) were analysed as pure blends and as mixtures always obtained from two blends in FIA-MS multiple ion detection mode (MID). Mixtures as well as pure blends contained identical concentrations of surfactant homologues. For AE quantitation the mass traces of all A m/z 44 equally spaced homologues (m/z 306-966) of the C13-AE were recorded. The cationic (quaternary ammonium) surfactant, the amphoteric Ci2-alkylamido betaine, and the non-ionic FADA were quantified recording the mass traces at m/z 214 and 228, or 184, 212, 240, 268, 285, 296, 313, 324 and 341, or 232,260, 288, 316 and 344, respectively. 

Fig. 2.5.12. APCI-FIA-MS(+) overview spectra of industrial surfactant blends used as pure blends or mixtures in the examination of ionisation interferences, (a) C13-AE, (b) cationic (alkyl benzyl dimethyl ammonium quat) surfactant, (c) amphoteric C12-alkylamido betaine, and (d) non-ionic FADA all recorded from methanolic solutions. 

A broad range of silicone surfactants are commercially available, representing all of the structural classes—anionic, non-ionic, cationic, and amphoteric. The silicone moiety is lyophobic, i.e. lacking an affinity for a medium, and surfactant properties are achieved by substitution of lyophilic groups to this backbone. The most common functionalities used are polyethylene glycols however, a broad range exist, as shown in Table 2.8.1 [2,3]. 

To reduce the potential risk of environmentally harmful surfactants, requirements of a minimum primary degradation amounting to 80% for anionic and non-ionic surfactants was stipulated as far back as 1977 [4]. However, within this early regulation no restraints were included regarding cationic or amphoteric surfactants as these did not hold a significant market share when the laws came into force. 

In a field study performed with nine surfactants from all groups except amphoteric [125], the laboratory effect concentrations were either lower than or similar to the mean in situ EC50 values for cationic and non-ionic surfactants. In contrast, for C12 and C13 LAS, the laboratory EC50 values were higher than the in situ effect concentrations. The short-term photosynthetic response to the same... 

The hydrophilic portion of a surfactant may carry a negative or positive charge, both positive and negative charges or no charge at all. These are classified respectively as anionic, cationic, amphoteric (or zwitterionic ) or non-ionic surfactant. 

Surfactants are generally classified by ionic types which relate to their chemical structure and are described as anionic, non-ionic, cationic and amphoteric. Following descriptions of the theory behind surfactants, each category is considered with a brief summary of methods of manufacture but with the main emphasis on properties and applications. 

After cyclodextrins and co-solvents, other approaches can be applied including the use of surfactants and micelle forming agents. Surfactants can be classified as amphoteric (lecithin), non-ionic (Tween 80 or Cremophor EF) or ionic (sodium lauryl sulfate or sodium palmitate). Cremophor is a polyoxyethylenated castor oil derivative which is a common solubilizing excipient in a number of formulations including those for paclitaxel, propofol, teniposide and clanfenur... 

Chapter 1 gives a systematic view of different classes of surface active substances non-ionic, anionic, cationic, amphoteric and zwitter-ionic surfactants. For each class, the synthesis of a surfactant from different initial substances (including the reaction mechanisms, main production routes, conditions for the best performance etc.), and the chemical analysis of the product properties are summarised. Reference information about manufacturers, nomenclature... 

Some reviews were published dealing with this type of interface and its application in environmental analysis [24, 42, 123). Qualitative and quantitative analysis of polar pollutants by FAB or CF-FAB was performed with extracts of aqueous matrices, such as wastewater, surface water, seawater, raw and drinking water [124-129], for all types of surfactants (non-ionics, anionics, cationics and amphoterics) in urban wastewaters, receiving waters (rivers and costal receiving areas), and groundwater [124-148], for metabolites of surfactants [130, 149-153], and bromi-nated surfactants [137, 154). 

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