Ionic anionic

Experiments with various species simultaneously carried out in ponds, streams or mesocosms have been reported for non-ionic, anionic and cationic surfactants. NP bioconcentration has been studied in the shrimp Crangon crangon, the mussel M. edulis and the fish... 

FIGURE 3.6 Solubility (Krafft point KP) of ionic (anionic or cationic) surfactants in water (as a function of temperature). 

Depending on the nature of the active center, chain-growth reactions are subdivided into radicalic, ionic (anionic, cationic), or transition-metal mediated (coordinative, insertion) polymerizations. Accordingly, they can be induced by different initiators or catalysts. Whether a monomer polymerizes via any of these chain-growth reactions - radical, ionic, coordinative - depends on its con-... 

CftNBr-CTFNa (cationic-anionic) system. The common cat ionic-anionic mixture of HC surfactants is highly surface active (17), showing the strong interactions between the two oppositely charged surface active ions. Similar re.-sults have been observed in the case of CeNBr-CrFNa system. The "y-log C plot in Fig.5 illustrates such an interaction, lile can see that the 1i1 CeNBr-C-rFNa mixture is much more surface active than CsNBr or CjFNa, The cmc value of surfactants mixture is much more smaller than that of CaNBr or CyFNa, and the-yeme the mixed solution is very low (< 15 rnNrn- ) mixtures with various raolal... 

Compound Temperature (°C) Cationic Conductivity ionic Anionic Conductivity ionic total) Electronic Conductivity tytotal)... 

Emulsifiers may be divided according to their behavior into ionic (anionic and cationic) and nonionic... 

Ionization of the pyrimidines (deprotonation or protonation) may occur in different ways resulting in the possibility of a number of tautomeric ionic (anionic and cationic) species. In the case of nucleosides, the number both of tautomeric conversions of the pyrimidines and of their molecular-ionic transformations is, smaller than in the case of the bases themselves. 

In contrast to classic initiating systems, other less known processes have been used successfully in telomerisation of fluoroalkenes these systems involve hypofluorites, hypobromites, or concern ionic (anionic and cationic) or unusual telomerisations depicted below. 

One of the parameters characterising quantitatively the process of film rupture is the lifetime ta of a black film under a-particle irradiation. Fig. 3.65 shows the ra(Cei) dependences for films stabilised with various kinds of surfactants (non-ionic, anionic and cationic) subjected to a-particle irradiation (Am241) [97,324,325]. At fist the lifetime decreases, reaching a minimum value for all films studied. Then, with the increase in electrolyte concentration in the initial solution, the lifetime starts to increase (for non-ionic and anionic surfactants) or remains constant (for films from the cationic surfactant). There is either a flexion or a plateau in the curves which correspond to Ceicr for the CBF/NBF transition. The sharp downward slope of the curve for all studied films reflects the decrease in thickness of CBF with the increase in electrolyte concentration. However, the right-hand side... 

Odor Not objectionable on dilution pH On dilution, essentially neutral Ionic nature Non-ionic, anionic... 

Preparation Easily extended in water at 100-200 deg. F. Compatibility Excellent with non-ionic, anionic and cationic auxiliaries and dyes. 

Surfactants Ionic, anionic (e.g., sodium dodecyl sulphate, Cj2H250S03 Na ), cationic (e.g., cetyl trimethyl ammonium chloride, Ci,H33-N+(CH3)3C1-), zwitterionic [e.g., 3-dimethyldodecylamine propane sulphonate (betaine CJ2H25-N" (CH3)2-CH2-CH2-CH2-S03)], nonionic, alcohol ethoxylates C H2 +i-0-(CH2-CH2-0) -H, alkyl phenol ethoxylates C H2 +i-CgH4-0-(CH2-CH2-0) -H, amine oxides (e.g., decyl dimethyl amine oxide, C10H21-N ( 113)2 0), and amine ethoxylates. 

Duoteric. [Rhone-Poulenc Ltd.] Non-ionic/anionic blend emulsifiers for agrochemical fcxmulations. 

MerinoL [Tsdcemoto Oil Fat] Non-ionic/anionic surfactant blends for worsted processing. 

Enzyme activity loss because of non-productive adsorption on lignin surface was identified as one of the important factors to decrease enzyme effectiveness, and the effect of surfactants and non-catalytic protein on the enzymatic hydrolysis has been extensively studied to increase the enzymatic hydrolysis of cellulose into fermentable sugars [7, 9 19]. The reported study showed that the non-ionic surfactant poly(oxyethylene)2o-sorbitan-monooleate (Tween 80) enhanced the enzymatic hydrolysis rate and extent of newspaper cellulose by 33 and 14%, respectively [20]. It was also found that 30% more FPU cellulase activity remained in solution, and about three times more recoverable FPU activity could be recycled with the presence of Tween 80. Tween 80 enhanced enzymatic hydrolysis yields for steam-exploded poplar wood by 20% in the simultaneous saccharification and fermentation (SSF) process [21]. Helle et al. [22] reported that hydrolysis yield increased by as much as a factor of 7, whereas enzyme adsorption on cellulose decreased because of the addition of Tween 80. With the presence of poly(oxyethylene)2o-sorbitan-monolaurate (Tween 20) and Tween 80, the conversions of cellulose and xylan in lime-pretreated com stover were increased by 42 and 40%, respectively [23]. Wu and Ju [24] showed that the addition of Tween 20 or Tween 80 to waste newsprint could increase cellulose conversion by about 50% with the saving of cellulase loading of 80%. With the addition of non-ionic, anionic, and cationic surfactants to the hydrolysis of cellulose (Avicel, tissue paper, and reclaimed paper), Ooshima et al. [25] subsequently found that Tween 20 was the most effective for the enhancement of cellulose conversion, and anionic surfactants did not have any effect on cellulose hydrolysis. With the addition of Tween 20 in the SSF process for... 

The properties of a microemulsion will to a great extent depend on the nature of the surfactant. Surfactants may be non-ionic, anionic or cationic. Previous studies have shown that a suitable system for the preparation of metallic nanoparticles consists of a non-ionic surfactant such as pentaethyleneglycol-dodecylether, hexane and water (Figure 2). A water-soluble precursor can be added to the system and thus, a reasonable amount of nanosized metal particles may be obtained. In some particular cases, systems based on ionic surfactants such as AOT or cationic surfactants such as cetyltriammonium bromide (CTAB) will give a lower solubility of the metal precursor. ... 

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... 

ROP is carried out in solution, in the melt, in the bulk or in suspension. The involved mechanism can be ionic (anionic or cationic), coordination-insertion or free-radical polymerization [19].The cationic pol)rmerization is initiated by only two catalysts, trifluoromethane-sulphonic acid and its methyl ester [10, 15]. Initiators such as potassium methoxide, potassium benzoate, zinc stearate, n-, sec-, fer-butyl lithium or 18-crown-6-ether complexes are added for the anionic polymerization to induce a nucleophilic reaction on the carbonyl to lead to an acyl-oxygen link cleavage. According to Jedkinski et al. only the primary alkoxides, such as the first mentioned catalyst, can yield polymers with negligible racemization, transesterification and termination [10]. 

Surfactants in Aqueous Solution A very important component that is usually present in the lyophobic colloids is the surfactant. These molecules are amphiphilic, that is, a part of the molecule is much more polar than the other part. On the basis of the nature of the polar groups in the surfactant molecule, they are classified as ionic (anionic or cationic) and nonionic. When ionic-type surfactants are adsorbed onto polymer particles, they provide stabilization by electrostatic repulsion between them and when the nonionic type are adsorbed instead the mode of stabilization is by steric repulsion. Electrosteric stabilization is provided by polyelectrolyte chains that give place to both modes of repulsion electrostatic and steric. 

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). 

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,... 

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