Surfactant environmental effects

There is no official or universally accepted definition of what constitutes a "microemulsion." In fact, for several years, some leading scientists in microemulsion research considered the term to be an unnecessary and even an unfortunate one. Nevertheless (Table 1), during the years from about 1975 to 1980 the word ascended from obscurity to ubiquity. By the end of 1996 there were 13 widely available Knglish-language books (1 9) with the word "Microemulsion" in their tides (10). About 70 more books on surfactants are in print, of which those on industrial appHcations (9,11—18), and environmental effects (19—21) are of particular interest here. 

L.H.M. Vollebregt and J. Westra, Environmental effects of surfactants, Onderzoeks- en Adviescentrum Chemie Arbeid Milieu, University of Amsterdam, 1998. 

Chemical procedures that produce less waste or less hazardous waste are said to be green because they reduce harmful environmental effects. In chemical analyses with dithizone, you can substitute aqueous micelles (Box 26-1) for the organic phase (which has traditionally been chloroform, CHC13) to eliminate chlorinated solvent and the tedious extraction.2 For example, a solution containing 5.0 wt% of the micelle-forming surfactant Triton X-100 dissolves 8.3 X 10 5M dithizone at 25°C and pH < 7. The concentration of dithizone inside the micelles, which constitute a small fraction of the volume of solution, is much greater than 8.3 X 10 5M. Aqueous micellar solutions of dithizone can be used for the spectrophotometric analysis of metals such as Zn(II), Cd(Il), Hg(Il), Cu(ll), and Pb(II) with results comparable to those obtained with an organic solvent. 

With such a variety of available structures, how does one choose the proper surfactant for a particular purpose Alternatively, why are only certain surfactants used for a particular purpose and not other surfactants Economic factors are often of major importance—unless the cost of using the surfactant is trivial compared to other costs, one usually chooses the most inexpensive surfactant that will do the job. In addition, such considerations as environmental effects (biodegradability, toxicity to and bioconcentration in aquatic organisms) and, for personal care products, skin irritation are important considerations. The selection of the best surfactants or... 

Relationships have been found between the adsorption properties described above of surfactants and their environmental effects (toxicity, bioconcentration) on aquatic organisms (algae, fish, rotifers). The log of the EC 50 (the surfactant molar concentration in the water at which the organism population is reduced by 50% relative to a no-dose control) and the log of the BCF (the ratio of surfactant concentration in the fish relative to that in the water) have both been shown (Rosen, 1999, 2001c) to be linearly related to the parameter AG°d/u for a series of anionic, cationic, and nonionic surfactants. The values of asm and AG°d were obtained by the methods described above in Sections IIIB and IIIF, respectively. 

As a consequence of stronger chain-chain interactions between long chain alkanes and surfactants, the hydrophobic chains are straightened, while in the case of long chain alcohols the hydrophobic effect plays a major role compared to the chain-chain interaction, which are minor when the alcohol is diluted in a nonpolar liquid. Even if literature reports data in contrast to the weak environmental effects on compact, self-assembled monolayers, the influence of the liquid environment on the structure of self-assembled monolayers is relevant in the wetting properties of these monolayers. Wetting depends on how the liquid is in contact with it, because the surrounding liquid molecules influence the chain conformation. ... 

Contributions on the physico-chemical behavior of colloids and surfaces in the environment and their use in environmental technology demonstrate the high standard and usefulness of colloid science in this field. Latest results on the interaction of heavy metals and organics with soil minerals, transport properties of pollutants, and the relevance of surfactants as effective modifiers for natural interfaces were presented. Also, the use of colloids and surfactants in environmental technologies for soil remediation and waste water treatment was emphasized. This volume comprises a choice of papers dealing with these subjects. 

In the first part of this report, we discuss a fundamental aspect of shear-induced conformational transition of the PAA resulting from the interchain association that was monitored using the AuO fluorescence probe. Further, we discuss the influence of molecular environment on PAA conformation in relation to the DR behavior of the PAA. In the second part, we discuss a particular molecular environmental effect of cationic surfactants on the interchain association of the PAA, in that the chain conformation is dictated by the extent of the surfactant binding and the surfactant structure. 

Fluorochemical repeUents are commercially avaUable as emulsions or solvent solutions. The most widely used emulsions for fabrics and carpet are cationic, but nonionic emulsions are becoming more prevalent. The emulsifier in the formulation can affect the repeUency and durabUity of the product (28). Surfactants used in the fluorochemical emulsions or added to finish baths should be nonrewetting and have a minimum adverse effect on oU repeUency. Solvent solutions of fluorochemicals are becoming less common as a result of toxicity and environmental concerns. 

The overall set of partial differential equations that can be considered as a mathematical characterization of the processing system of gas-liquid dispersions should include such environmental parameters as composition, temperature, and velocity, in addition to the equations of bubble-size and residence-time distributions that describe the dependence of bubble nucleation and growth on the bubble environmental factors. A simultaneous solution of this set of differential equations with the appropriate initial and boundary conditions is needed to evaluate the behavior of the system. Subject to the Curie principle, this set of equations should include the possibilities of coupling effects among the various fluxes involved. In dispersions, the possibilities of couplings between fluxes that differ from each other by an odd tensorial rank exist. (An example is the coupling effect between diffusion of surfactants and the hydrodynamics of bubble velocity as treated in Section III.) As yet no analytical solution of the complete set of equations has been found because of the mathematical difficulties involved. To simplify matters, the pertinent transfer equation is usually solved independently, with some simplifying assumptions. 

The acute toxicity of ester sulfonates is mainly related to the length of the carbon chain of the fatty acid. The acute fish toxicity of tallow-based ester sulfonates is relatively high (LC0 = 0.4-0.9 mg/L) compared with coconut-based ester sulfonates (LC0 — 46 mg/L) [113]. In spite of this relatively high fish toxicity of the long-chain ester sulfonates both acute and long-term toxic effects can be excluded for normal environmental conditions. For example, the sum of all anionic surfactants in German rivers is stable on a level far below... 

In general, the cleanup of oiled shorelines has been by mechanical, labor-intensive means. The use of surfactants to deterge and lift the oil from the surface results in more complete and rapid cleaning. Not only is the cleaning process more efficient, but it can also be less environmentally damaging because potentially less human intrusion and stress on the biologic community occurs and because the chemicals can make the washing more effective at a lower temperature. 

Polyethylene and polystyrene are examples of plastics subject to environmental stress cracking. Crack resistance tests have shown that surfactants, alcohols, organic acids, vegetable and mineral oils, and ethers provide an active environment for stress cracking of polyethylene. Table 6 lists typical sterile devices and plastic materials used to fabricate them, while Tables 7-9 list the potential effects of sterilization processes on polymeric materials. The effect of gamma irradiation on elastomeric closures has been studied by the Parenteral Drug Association [15]. 

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