Naturally occurring surfactant

Carboxylic Acid Esters. In the carboxyflc acid ester series of surfactants, the hydrophobe, a naturally occurring fatty acid, is solubilized with the hydroxyl groups of polyols or the ether and terminal hydroxyl groups of ethylene oxide chains. 

Sulphonic acids are water soluble, viscous liquids. Their acidity is akin to that of sulphuric acid feey form salts with bases but fail to undergo esterification with alcohols. Their properties vary according to the nature of R some are prone to thermal decomposition. They are used as surfactants and in the dye industry some have biological uses. 2-Amino-ethanesulphonic acid is the only naturally occurring sulphonic acid. 

Carboxylates (9.4, where R is the long-chain hydrophobe and X the cation) represent the oldest type of surfactants, since they could be obtained from naturally occurring fats and oils long before the advent of the petrochemical industry sodium heptadecanoate (9.5), for example, incorporates the cetyl group as hydrophobe. Sodium stearate, sodium palmitate and sodium oleate are the simplest carboxylates generally used as surfactants. Alkylaryl compounds (9.6) are also known. 

Gold nanostructures of various sizes and morphologies were synthesized at room temperature using naturally occurring biodegradable plant surfactants [ 76]. The sizes and shapes (spherical, prisms, and hexagonal) of the synthesized nanopartides were dependent on the concentration of the gold ions and the type of plant surfactant used for preparation. 

Phospholipids are perhaps the most ubiquitous of chiral surfactants in cell biology. It is well known that only the L-isomer is naturally occurring in the cell membrane of most living organisms, yet the question of whether or not this homochirality plays a role in the regulation of cell chemistry has barely... 

There are two different classes of surface-active materials in seawater, those that are naturally present and those that have been added to the oceans by man s activities. Most of the analytical methods proposed for use in seawater actually measure the anthropogenic input, and attempt as much as possible to eliminate interferences from naturally occurring compounds. Yet sea foam was known to exist long before detergents. It is to be expected that both kinds of surfactants would be concentrated at the air-sea interface. 

The available data summarised in this review support previous conclusions that trisiloxane silicone surfactants should be relatively benign in the natural environment. Primary degradation is rapid and ultimate degradation to naturally occurring compounds, i.e. C02, H20 and Si(OH)4, is indicated, though not yet demonstrated unequivocally. 

Biosurfactants are naturally occurring surfactants synthesized by certain strains of bacteria, yeasts, and fungi. See Biosurfactants—General (T0119) in the RIMS library/database for more information on this type of surfactant. 

Monolayers are best formed from water-insoluble molecules. This is expressed well by the title of Gaines s classic book Insoluble Monolayers at Liquid-Gas Interfaces [104]. Carboxylic acids (7-13 in Table 1, for example), sulfates, quaternary ammonium salts, alcohols, amides, and nitriles with carbon chains of 12 or longer meet this requirement well. Similarly, well-behaved monolayers have been formed from naturally occurring phospholipids (14-17 in Table 1, for example), as well as from their synthetic analogs (18,19 in Table 1, for example). More recently, polymerizable surfactants (1-4, 20, 21 in Table 1, for example) [55, 68, 72, 121], preformed polymers [68, 70, 72,122-127], liquid crystalline polymers [128], buckyballs [129, 130], gramicidin [131], and even silica beads [132] have been demonstrated to undergo monolayer formation on aqueous solutions. 

Clays-pillared clays or organoclays 2D, 3D varies Purification and ion exchange by surfactants of naturally occurring products or synthesis Weeks to months Interlayer distance could be varied and precisely determined X-ray diffraction measurements particles could be grown in situ or incorporated between layers complex supramolecular architecture was possible 478,480,482... 

AES are typically measured in environmental matrices by nonspecific colorimetric analyses (MBAS) that collectively measure LAS, AS, and naturally occurring anionic surfactants. Alternatively, a specific gas chromatographic method for AES, developed by Neubecker (55), was employed to measure AES concentrations in influent and effluent from STPs and river water. Total AES measured in influent wastewater to a STP was 1.88 mg/L. AES removal of 94-100% was measured during actual sewage treatment by activated sludge the resulting effluent concentration was 0.06 mg/L. Total AES levels in river water were less than 0.01 mg/L. AES accounted for 6-13% of MBAS measured in natural water. 

Additional naturally occurring lipids may be minor components of oral lipid-based formulations. Terpenes such as peppermint oil (>50% menthol) are fairly hydrophobic but can provide some solvent capacity. Steroids such as cholesterol, while important in topical and in parenteral liposomal products, are not important as oral pharmaceutical adjuvants. Phospholipids (e.g., egg or soybean phosphatidylcholine) an essential component of cell membranes, are considered polar lipids, and have surfactant properties. 

One last consideration during the selection process of a suitable surfactant or other facilitating agent must be an examination of toxicity and biodegradability issues so that no adverse impact on the environment or on human health occurs. For example, upon completion of SEAR, any residual HOCs or surfactants remaining in the aquifer should be easily biodegradable or, at minimum, have a relatively low toxicity. Because NOMs and cyclodextrins are naturally-occurring materials, they may have less of an environmental impact than conventional chemical surfactants and may be... 

The use of mixed micelles for chiral recognition was discussed in Section 5.3.3, using cyclodextrins. In addition to cyclodextrins, however, metal-amino acid complexes can also be used in a mixed mode arrangement. Bile salts are naturally occurring chiral surfactants that can be used as alternatives to, or in addition to, SDS for chiral recognition. In the presence of SDS, the migration times are faster. Table 5.5 shows initial operating conditions that can be used in chiral CE as a start to methods development.40... 

Another class of surfactants that are used in cosmetics and personal care products is the phosphoric acid esters. These molecules are similar to the phospholipids that are the building blocks of the stratum corneum (the top layer of the skin, which is the main barrier for water loss). Glycerine esters, in particular, triglycerides, are also frequently used. Macromolecular surfactants of the A-B-A block type [where A is PEO and B is polypropylene oxide (PPO)] are also frequently used in cosmetics. Another important naturally occurring class of polymeric surfactants is the proteins, which can be used effectively as emulsifiers. 

The use of surfactants in the food industry has been known for centuries. Naturally occurring surfactants such as lecithin from egg yolk or soybean and various proteins from milk are used for the preparation of many food products, such as mayonnaise, salad creams, dressing, and desserts. Polar lipids such as monoglycerides have been introduced as emulsifiers for food products. More recently, synthetic surfactants such as sorbitan esters (Spans) and their ethoxylates (Tweens), sucrose esters, have been used in food emulsions. It should be mentioned that the structures of many food emulsions is complex, and in... 

Artificial analogues of the chloride transporter prodigiosin are effective symport HC1 carriers as exemplified in the model systems developed by the groups of Gale [39] and Davis [40], Biological inspiration is also behind another Cl- carrier. Cholic acid is a naturally occurring bile acid that functions as a surfactant in the intestine. Derivatives with three binding sites known as cholapods are able to transport isolated anions across lipid bilayers [41],... 

By analogy with the polysorbate ester reaction, similar surfactant ester feedstocks that feature a free hydroxyl function can undergo oxyethylation to materials of higher HLB and these include glycerol, polyglycol and sucrose esters. In addition, many naturally occurring fats and oils can react with ethylene oxide to raise their water solubility. Castor oil is a common base for oxyethylation and the obvious site is the hydroxyl group in the ricinoleic... 

Betaine, or trimethyl glycine, is a naturally occurring zwitterionic nutrient that was first discovered in beets but occurs in a wide variety of plants and animals. Surfactant betaines are structurally analogous compounds but they are manufactured synthetically. 

---