Alkyl biodegradable nonionic

An example of a successful esterification reaction on industrial scale is shown in Scheme 3.1. 6-0-Acyl derivatives of alkyl glucopyranosides, which are used as fully biodegradable nonionic surfactants in cosmetics [142], were synthesized from fatty acids and the corresponding l-O-aUcyl glucopyranosides under catalysis of thermostable Candida antarctica lipase B in the absence of solvents [137]. In order to drive the reaction towards completion, the water produced during the reaction was evaporated at elevated temperature and reduced pressure (70°C, 0.01 bar). 

Furthermore, aggregates of nonionic surfactants like polyoxyethylene alkyl/aryl ethers of the Tergitol, Triton, and Brij series were used as templates for the formation of mesoporous silica materials in neutral or acidic media. The pore diameters of the materials that can be obtained with these surfactants are restricted to around 5.5 nm. The advantages of these surfactants over triblock copolymers are that they are cheap, nontoxic, and biodegradable. An overview of the most commonly used SDAs is compiled in Table 3.1. 

A series of related experiments investigated nonionic surfactant sorption onto soil, mechanisms of nonionic surfactant solubilization of polycyclic aromatic hydrocarbon (PAH) compounds from soil, and microbial mineralization of phenanthrene in soil-aqueous systems with nonionic surfactants. Surfactant solubilization of PAH from soil at equilibrium can be characterized with a physicochemical model by using parameters obtained from independent tests in aqueous and soil-aqueous systems. The microbial degradation of phenanthrene in soil-aqueous systems is inhibited by addition of alkyl ethoxylate, alkylphenyl ethoxylate, or sorbitan- (Tween-) type nonionic surfactants at doses that result in micellar solubilization of phenanthrene from soil. Available data suggest that the inhibitory effect on phenanthrene biodegradation is reversible and not a specific, toxic effect. 

Alkyl polyglucosides (CAS No. 110615-47-9) are a relatively new class of nonionic surfactants, fully based on renewable vegetable resources and easily biodegradable, and hence they are finding increasing applications in many industrial fields, including the personal care industry. There is a book published by VCH publishers discussing their history, production, physicochemical properties, toxicity, and applications in various industries. There is also a Surfactant Science Series... 

Esterquats with improved stability and biodegradability are prepared by quaternization of a fatty acid (partially hydrogenated tallow) alkanolamine ester with an alkylating agent (dimethyl sulfate) in the presence of nonionic emulsifiers [126] or cosmetic oils [159]. This procedure avoids problems associated with the use of lower alcohols as solvents in the reaction, such as low ignition point, poor emulsifying capacity for perfume oils, poor skin compatibility, and a defatting action on the skin. Formulations of a triethanolamine-based Coco esterquat, oil, and a Ci-Cg alcohol are useful in cosmetic and sunscreen formulations [160]. 

The excellent ability of nonionics to solubilize and disperse hydrophobic soils such as fats, mineral oils, etc, in water leads to extensive use of this e of emulsifier. Their often superior detergency with respect to solids surfaces is due to a combination of relatively low critical micellar concentration (CMC), allowing emulsification to take place at low emulsifier concentrations, and an ability to adsorb hydrophobically to interfaces and thus, by steric repulsion forces, to disperse hydrophobic liquid or colloid matter. An important group of nonionic emulsifiers is based on ethoxylated alkyl alcohols. Increasing demands for biodegradability and low aquatic toxicity of degradation products of industrial chemicals is expected to make fatty alcohols ethoxylates and nonionic emulsifiers based on natural raw materials an even more important group of chemicals in the future. 

It is estimated that more than half of all fatty alcohols produced are ethoxylated prior to any further use. The dominance of f. as nonionic surfactants is increasing due to the fact that petrochemical alkyl phenol ethers are less biodegradable and have higher toxicity to fish. 

A great deal of work has also been carried out on the biodegradation of nonionic surfactants, in this case the ethoxylates used in detergents and cleaning agents. However, the metabolic mechanism has not been investigated to the same extent as with linear alkylbenzenesulfonate. The microbial attack takes place on the ethylene oxide chain and also on the alkyl group of the molecules. 

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