Nonionic surfactants isolation

Corti A, Frassinetti S, Vallini G, D Antone S, Fichi C, Solaro R (1995) Biodegradation of nonionic surfactants. I. Biotransformation of 4-(l-nonyl)phenol by a Candida maltosa isolate. Environ Pollut 90 83-87... 

The solvent sublation procedure of Wickbold [18] is another method that has been used for the analysis of LAS present in seawater [19,20], The solvent sublation technique (gaseous stripping into organic solvent, often ethyl acetate) has also been used to isolate and concentrate nonionic surfactants, e.g. AEs and APEO in aqueous samples [21,22], The co-extracted interferences can be eliminated by cation/anion ion-exchange and alumina chromatography [23,24]. 

In the second approach to self-assembly of polymer-silica nanocomposites, polymerizable surfactants are employed both to direct self-assembly into ordered mesophases and to serve as organic monomers which can be subsequently polymerized. For instance, Brinker et al. developed nonionic surfactants incorporating diacy-telene groups which could be polymerized upon irradiation by UV light.68 69 Similarly, poly(thiophene)70 and poly(pyrrole)71 have been successfully integrated into silica nanostructures in this manner. Importantly, this in situ polymerization produces isolated molecular wires, rather than clustered bundles of conductive polymer.70... 

Comparison of the competitive displacement of spread films of whey protein isolate (WPI) and (3-lactoglobulin from an air-water interface with the nonionic surfactant (polyoxyethylene sorbitan monolaurate) Tween 20. Note that the WPI network remains intact at surface pressures (tt) above those at which the (3-lactoglobulm network has failed. The image sizes are indicated in brackets below the images. 

Nonionic surfactants like alkylphenol ethoxylates (APEO) and their biodegradation products alkylphenol diethoxylate (AP2EO), alkylphenol monoethoxylate (APIEO), and AP are isolated from aqueous solutions with a number of different stationary phases. Kubeck et al. ° used C18 cartridges to adsorb NPEO, but first the water samples were passed through a mixed-bed ion exchange resin to remove all ionic species. Eor SPE of alcohol ethoxylates (AEO) C8 cartridges have been successfully applied from which the surfactants were eluted with methanol followed by... 

Kupfer" ° applied the same sublation procedure for isolation of cationic surfactants. Eor separation of anionic and nonionic surfactants, the sublation extract is passed through a cation exchanger. Afterwards, the adsorbed cationic surfactants are eluted with methanolic HCl. 

A broad variety of hydrophilic surfactants may also be used as alternatives to amphiphilic sulfobetaines. Isolable nanometal colloids soluble in water with at least 100 mg of metal 1 have been obtained with a wide range of cationic, anionic, and nonionic surfactants. Even, environmentally benign sugar soaps have been successfully applied [see Table 2 in Ref. [11]]. 

In another study, radiolabeled and fluorescent lipid nanocapsules were synthesized by using a phase inversion process that followed the formation of an o/w microemulsion containing triglycerides, lecithins, and a nonionic surfactant. Results of the experiment revealed that lipid nanocapsules were rapidly accumulated within cells through active and saturating mechanisms. Nanocapsules could bypass the endo-lysosomal compartment with only 10% of the cell-internalized fraction found in isolated lysosomes. When nanocapsules were loaded with paclitaxel, smallest lipid nano capsules (LNCs) also were found to trigger the best cell death activity. ... 

The extensive work on this subject by Macheboeuf and Tayeau (1941a, b) has been reviewed by Gurd (19W). It will be sufScient here to say that compounds containing hydrocarbon chains are able to displace lipids from lipoproteins and that their action is dependent on the nature of the surfactant (ionic, nonionic), length of the hydrocarbon chain, and their critical micellar concentration. A more detailed analysis of the interaction between nonionic surfactants and isolated serum lipoproteins will be given in the section concerning the mechanism of Triton WR-1339 hyperlipemia. 

In this section we consider some experimental results for the viscosity obtained for typical microemulsions. Here we mean microemulsions of the classical Winsor I (oil-in-water, O/W), II (water-in-oil, W/0), or III (bicontinuous, middle-phase microemulsion) types [44,45], where the O/W and W/0 systems contain isolated aggregates. Rheological measurements can yield information on the structure of the microemulsion and in particular, if they are present, the shape and interactions of individual aggregates. In addition, it will be of interest to see how the microstructural transitions (from one Winsor type to another) influence the macroscopic viscosity. Such transitions can be observed either by changing the temperature (for nonionic surfactants) or the salinity (for ionic surfactants). 

The synthesis of sodium decanesulfonate from the alkyl halide and Na2S03 can be carried out very conveniently in microemulsions based on nonionic surfactants [108]. The rate data fit a pseudophase model, and the nonionic surfactants make this method preparatively very useful because phase separation with a change of temperature allows recovery of the surfactants. This approach is very useful because surfactants have high molecular weights and large amounts are needed in preparative reactions and the solubilizing ability of surfactants complicates product isolation. Therefore, more research is needed... 

This chapter deals with the analysis of individual nonionic surfactants. Analysis of raw materials includes not only the determination of the active content, but also of impurities and by-products, and determination of oxyalkylene chain length. Any nonionic can be determined in formulated products by deionisation, which was described in section 4.6.2 and is not further discussed here. Nonionic fractions isolated in this way may have more than one principal active, and some of the methods given here are applicable to the analysis of such mixtures. There are also a few procedures for the determination of nonionics in formulated products. 

EAN IL was used in various reactions such as Biginelli reaction, condensation reaction, nitration of phenol, synthesis of P-amino ketone, ete. Nitration of phenol using ferric nitrate and clayfen in the IL, EAN, has been reported imder irltrasound irradiation [102]. Jaeger and Tucker in 1989 reported the Diels-Alder reaction involving EAN IL [ 103], IL EAN was prepared as per the literature method. EAN was found to be a more suitable solvent and catalyst for these reactions. In the presence of EAN, the reactions proceed in a shorter time, under milder conditions, and with excellent yield of products. EAN is liqttid at room temperature and is miscible with water thus, the separation and isolation of the product becomes easier. Its autoprotolysis constant is high, and the large electroactivity area and conductivity allow it to be used as a potential solvent. Araos et al. [104] reported the stability of a variety of lyotropic liquid crystals formed by a nttmber of polyoxyethylene nonionic surfactants in the room-temperature IL EAN. 

Islam a al. ° dispersed SWNTs (20mgmr ) in water with the assistance of surfactant SDBS using low-power, high-frequency (12W, 55 kHz) ultrasonication for 16-24 h. Atomic force microscopy observations exhibited that 63 5% of SWNT bundles were exfoliated into single tubes and most of SWNT objects were isolated SWNTs, which was less than a quarter of the SWNTs by mass. The nonionic surfactants such as polyoxyethylene-8-lauryl (CH3-(CH2)n (0CH2CH2)70CH2CH3) have also been reported to improve the dispersion and strong interaction between MWNTs and... 

Centrifugal partition chromatography, a type of countercurrent chromatography, has been demonstrated for automated extraction of a nonionic surfactant into ethyl acetate (18) and for isolation of phosphatidylcholine from natural phospholipids (19). This is an excit-... 

Ethoxylated nonionic surfactants are less soluble in water at higher temperatures. Thus, at high concentrations, some may be isolated simply by heating an aqueous solution above the cloud point of the surfactant, which forms a separate layer and can be removed. The process must be repeated several times for reasonable recovery. The separated phase will be enriched in the more hydrophobic homologs compared to the original surfactant. This phase may also act as an extraction medium to concentrate other components of the solution. 

I, Cationic surfactants from nonionic surfactants Dowex 50-X4, acid form 4—5 g of mixture dispersed in 100 mL water is stirred 4—5 hr with 20 g resin, keeping the mixture acid to Congo red by addition of HCl. The resin is wa.shed with 95% EtOH, the filtrate and washings neutralized and evaporated to dryness, then washed with acetone to isolate the nonionic. 42... 

In another version of this procedure the nonionic surfactant was first extracted batch-wise with sodium tetraphenylborate into 1,2-dichloroethane. The tetraphenylborate in the isolated organic phase was then titrated with a cationic surfactant, using Victoria Blue B as indicator (70). This titration can also be performed to an electrochemically detected end point. In this version, an excess of anionic surfactant is added to the cationic complex formed by the ethoxylated nonionic surfactant and potassium ion. The ion pair is extracted into dichloroethane, separated from the initial aqueous phase, then titrated with cationic surfactant in the presence of additional water. The ion pair of the anionic surfactant and Fe(II)(l,10-phenanthroline)3 is added as indicator. The end point of the titration is indicated when the last of the anionic surfactant is complexed by the cationic titrant, causing the iron-phenanthroline cation to migrate to the aqueous phase, where it is detected as a change in potential at a platinum electrode (71). 

Nonionic surfactants are usually isolated from natural waters on XAD resin at neutral pH. This is to prevent the co-adsorption of fulvic acids which occurs under acidic conditions (98). Very hydrophilic metabolites, such as low molecular weight PEG and PEG carboxylates, may not be adequately retained on XAD resin unless the procedures are specifically optimized for these compounds (99). 

Once the soil has been separated from the substrate, it is necessary to prevent its redeposition until it is removed in the rinsing process. There are two general mechanisms for the isolation of oily soils from the substrate micellar solubilization and emulsification. The solubilization of oily materials in surfactant micelles is probably the most important mechanism for the removal of oily soil from substrates and follows the general tendencies outlined in Chapter 6. It has generally been observed that oily soil removal from textile surfaces becomes significant only above the cmc for nonionic surfactants, and even for some anionic materials with low erne s. Removal efficiency reaches a maximum at several times that concentration. Since the adsorption of surfactants at interfaces involves the monomeric, rather than the micellar form, while solubilization involves only the micellar form, those results would appear to indicate that in these cases, solubilization is... 

A synthetic alternative to this is the chemical reduction of metal salts in the presence of extremely hydrophilic surfactants have yielded isolable nanometal colloids having at least 100 mg of metal per litre of water [105], The wide range of surfactants conveniently used to prepare hydrosols with very good redispersibility properties include amphiphilic betaines A1-A4, cationic, anionic, nonionic and even environmentally benign sugar soaps. Table 3.1 presents the list of hydrophilic stabilizers used for the preparation of nanostructured colloidal metal particles, and Table 3.2 shows the wide variety of transition metal mono- and bi-metallic hydrosols formed by this method [105,120],... 

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