Surfactants cationic-active

Sodium dodecyl sulfate is the universal analytical standard for the determination of anionic and cationic active matter. It is used to determine the analytical concentration factor of the cationic surfactant in the titration of anionic active matter and as titrant to determine the cationic active matter. 

The photoelectrochemical reduction of the N = N double bond of the diaryl azo dye methyl orange can be similarly sensitized by colloidal titanium dioxide les, isoj The reaction was sensitive to pH and the identity of the organic redox reaction could be shifted by conducting the photoreaction in the presence of surfactants. Cationic surfactants increased the efficiency of oxidative cleavage by inhibiting charge recombination. Polyvinyl alcohol instead favored reduction. The ambident photoactivity of methyl orange thus makes it an attractive probe for activity of irradiated semiconductor suspensions. 

Three different ways have been developed to produce nanoparticle of PE-surfs. The most simple one is the mixing of polyelectrolytes and surfactants in non-stoichiometric quantities. An example for this is the complexation of poly(ethylene imine) with dodecanoic acid (PEI-C12). It forms a solid-state complex that is water-insoluble when the number of complexable amino functions is equal to the number of carboxylic acid groups [128]. Its structure is smectic A-like. The same complex forms nanoparticles when the polymer is used in an excess of 50% [129]. The particles exhibit hydrodynamic diameters in the range of 80-150 nm, which depend on the preparation conditions, i.e., the particle formation is kinetically controlled. Each particle consists of a relatively compact core surrounded by a diffuse corona. PEI-C12 forms the core, while non-complexed PEI acts as a cationic-active dispersing agent. It was found that the nanoparticles show high zeta potentials (approximate to +40 mV) and are stable in NaCl solutions at concentrations of up to 0.3 mol l-1. The stabilization of the nanoparticles results from a combination of ionic and steric contributions. A variation of the pH value was used to activate the dissolution of the particles. 

Surfactants are used primarily as inert ingredients of pesticides, especially in agricultural applications. These surfactants usually have TSCA as well as inert pesticidal regulatory status in the US. Some surfactants are active components in pesticides. For example, the cationic surfactants benzalkonium chloride and didecyl ammonium chloride and their various derivatives are registered as active ingredients in disinfectant products with many household and industrial applications. 

Franklin et al. studied the in-situ anodic oxidation of barium peroxide (Ba02) in aqueous sodium chloride solutions containing cationic surfactants. An active intermediate, barium superoxide (BaO ), was formed which in turn converted carbon tetrachloride to soluble barium chloride and barium carbonate precipitate [45]. This work was extended to the destruction of 1,2-dibromomethane in aqueous solutions... 

Cationic Surfactants. Like the anionic surfactants, cationic surfactants also dissociate in an aqueous medium. However, the head (hydrophilic portion) is a cation, which is the carrier of the surface-active properties. Examples are the quaternary ammonium compounds. 

Chlorhexidine salts are cationic in solution and are therefore incompatible with soaps and other anionic materials. Chlorhexidine salts are compatible with most cationic and nonionic surfactants, but in high concentrations of surfactant chlorhexidine activity can be substantially reduced owing to micellar binding. 

The primary reaction of alkali with reservoir water is to reduce the activity of multivalent cations such as calcium and magnesium in oilfield brines. Upon contact of the alkali with these ions, precipitates of calcium and magnesium hydroxide, carbonate, or silicate may form, depending on pH, ion concentrations, temperature, and so on. If properly located, these precipitates can cause diversion of flow within the reservoir, leading to better contact of the injected fluid with the less-permeable and/or less-flooded flow channels. This then may contribute to improved recovery. Also, this reduction of reservoir brine cation activity will lead to more surfactant activity, resulting in lower IFT values (Mayer et al., 1983). 

Cationic surfactants appeared on the market in 1933. They were originally used as dye leveling agents in the textile industry, to improve the water fastness of direct and acid dyes on cellulose [1-3]. Some of the first cationic actives were synthesized by Ciba (Switzerland) and commercialized as Sapamines [1], Very quickly, the soft feel delivered by long-chain derivatives was noticed and exploited to restore the fabric finish. 

The 1980s were rich in innovation. As cationic actives precipitate in the presence of anionic surfactants, thereby losing most of their efficacy, the anionic surfactant concentration in the liquor must be kept as low as possible. Therefore, the fabric softener had to be introduced in the last rinse of the wash cycle, when the detergent carryover is at a minimum. That represented a true constraint if the washer did not contain a dispenser for softener. The user had to stay near the washer to introduce the product at the beginning of the last rinse or had to run an extra rinse at the end of the laundering. 

Ottewil et al. (1963) detected the maximum of floatability at the isoelectric point by varying the electrokinetic potential of silver iodide particles by adsorption of a cation-active surfactant. Furthermore, it has been established that the flotation rate is high within a narrow pH range and very low outside this range. In the former case the pH values correspond to very small potentials of the particle, i.e. in the vicinity of their isoelectric point, (Jaycock Ottewil 1963, Rubin Lackay 1968, Devivo Karger 1970). Addition of aluminium hydroxide extends the range of pH values which promotes flotation. 

Realisation of microflotation is ensured by opposite signs of the charges of the particle and the bubble and at low electrolyte concentration the effect of electrostatic attraction forces is extended over large distances and the depth of the potential well increases. Since particles and bubbles usually carry negative charges, it is expedient to use cation-active surfactants, which are predominantly adsorbed at bubbles in order to ensure contactless flotation. 

Cationic surfactant Cationic surfactant 35% active amphoteric Ether amine oxide Mi 1d surfactant Proprietary amine oxide Dialkyl quaternary... 

In the anionic flotation of quartz, activators such as multivalent metal ions are required to provide adsorption sites for surfactant. Cationic polymer can also adsorb on silica and offer adsorption site for surfactant. It is found that quartz can be activated by cationic PAMD for flotation by the anionic dodecylsulfonate [7]. 

Surfactant Surface active agent is a compound that alters the surface tension of a hquid in which it is dissolved. AH surfectants have large polar molecules. One end of the molecule is soluble in water (due to carboxyl, sulphate, hydroxyl, or srJphonate groups) and the other end is readily soluble in oils (organic groups). Synthetic sur ctants are of three types anionic, cationic and nonionic. 

Chen, Y.-C., Tsai, M.-F. (2000) Sensitivity Enhancement for Nitrophenols Using Cationic Surfactant-modified Activated Carbon for Solid Phase Extraction (SPE)/Surface-assisted Laser Desorption Ionization (SALDI) Mass Spectrometry. Rapid Commun. Mass Spectrom. 14 2300-2304. 

Neither anionic nor non-ionic surfactants impair Bronopol s antimicrobial efficacy. For that reason the product is a most suitable preservative for detergent solutions, bath foams, shampoos and hair rinses. Bronopol is also compatible with quaternary ammonium compounds (Section 16.1) and cationic active ingredients such as benzalkonium chloride. 

Non-ionic surfactants have an adverse effect on the activity of all phenolic microbicides (III.5) including p-hydroxybenzoates (III.6) (Fig. 35, p. 376) anionic surfactants have considerably less effect. Cationic active ingredients (III. 16.1) are inactivated by anionic components. 

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. 

The next sections deal with four types of surfactants anionic-active, cationic-active, amphoteric and non-ionic. More information on surfactants is to be found in Sect. 18.3, in Martindale and other literature [3,4,32]. Table 23.13 gives an overview of the main surfactants that are used in small-scale preparation. 

Molecules composed of hydrophilic as well as of hydrophobic parts are called amphiphilic, soaps are simple examples. In strongly polar (e.g., water) or apolar solvents (e.g., alkanes) their solubility as monodisperse molecules is small. The contact of the respective lyophobic moieties to the solvent can be avoided by accumulation at the interfaces of the solution, see Figure 14.1. The interfacial properties of solutions are determined distinctly by dissolved amphiphilic matter which for that reason is termed surfactant (surface active agent). Typical examples of ionic (cationic or anionic), zwitter-ionic, and nonionic surfactants of low molecular weight are sketched in Figure 14.2. 

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