Surfactants aquatic toxicity

In particular for the assessment of ecological risks with surfactants, aquatic toxicity is of outstanding importance since this is the most deleterious effect such a compound can exert on the environment (9-11). 

Both approaches are useful and they are also complementary because it is important to know where a chemical that may be best in its class falls out with respect to hazard. For example, a surfactant that is best in its class will be rapidly biodegradable, but most surfactants have some aquatic toxicity because they are surface active. However, surfactants as a class are typically close to the green end of the hazard spectrum because they tend to have low hazard ratings for most other endpoints. It is also possible to have chemicals that are best in their class but that are still problematic. For example, some dioxin congeners are less toxic than others but one would not presume that a dioxin congener that is best in its class is green . Concurrent use of the best in class approach with the absence of hazard approach is also important because it drives continual advancement within a class toward the ideal green chemistry. Once innovation occurs and a chemical or product is developed that meets the same or better performance criteria with lower hazard, what was once considered best in class shifts. 

Hager CD (1998) Alkylphenol ethoxylates - biodegradability, aquatic toxicity and environmental activity. In Karsa DR (ed) Annual surfactant review. Sheffield Academic Press,... 

The presence of surfactants and their biodegradation products in different environmental compartments can invoke a negative effect on the biota. The ecotoxicity of surfactants to aquatic life has been summarised in the scientific literature [1—5]. Nevertheless, some information is still lacking in relation to the aquatic toxicity of surfactants, especially knowledge regarding the toxicity of the degradation products, the effect of surfactants on marine species, the ecotoxicity of mixtures of chemical compounds with surfactants, the relationship between toxicity and chemical residue and the effect of surfactant presence in specific environmental compartments (water, particulate matter, pore-water, sediment). 

The three transitions mentioned above, replacement of branched alkylben-zene sulfonates by linear alkylbenzene sulfonates, replacement of alkylphenol ethoxylates by alcohol ethoxylates and substitution of ester quats for stable quats are all driven by environmental concerns. Rate of biodegradation and aquatic toxicity are the major parameters taken into account, and, in order to pass the regulations that the European Union has adopted, a surfactant must pass the criteria of showing ... 

Fig. 2 Environmental assessment of surfactants is based on values of biodegradation and aquatic toxicity. A surfactant must lie within the shaded areas in order to meet the OECD regulatory directives...

Table 5.3 DfE Criteria for Safer Surfactants surfactants with higher aquatic toxicity must degrade rapidly to be acceptable in DfE products.

QIM of Schiiurmann for Oxyethylated Surfactants Schiiurmann [63] studied Kow and its relation to aquatic toxicity for polyoxyethylene compounds of the type shown in Figure 13.5.4. The contribution of the -CH2-CH2-O- group is not a constant but depends on the length of the oxyethylene chain. For the insertion of a -CH2-CH2-O- group, Schiiurmann reports a variation from — 0.10 for long-chain molecules to —0.19 for short-chain molecules. 

Kimerle, R.A., R.D. Swisher, and R.M. Schroeder-Comotto. 1975. Surfactant structure and aquatic toxicity. In Proc. IJC Symposium on Structure Activity Correlations in Studies on Toxicity and Bioconcentration with Aquatic Organisms, pp. 22-25, March 11-13, 1975. 

Morall, S.W., M.J. Rosen, Y.P. Zhu, D.J. Versteeg, and S.D. Dyer. 1997. Physical chemical descriptors for the development of aquatic toxicity QSARs for surfactants, Proceedings of the 7th Internatl. Workshop on QSARs in Environmental Science, SETAC Press, USA, in press. 

Uppgard L, Sjostrom M, Wold S. Multivariate quantitative structure-activity relationships for the aquatic toxicity of alkyl polyglucosides. Tenside, Surfactants, Detergents 2000 37(2) 131-8. 

Another area of unmet need is in the identification of surfactants in textile wastewater. The effects of surfactants can be readily measured in terms of reduction of surface energy, foaming, aquatic toxicity, turbidity, and the like. However, it is often desirable to identify the exact concentration and identity of surfactants in wastewater. This is helpful, for example, in efforts to evaluate waste treatment system removal efficiency, or to reduce the detrimental effects of surfactants on the environment by pollution prevention (or cleaner production as it is called outside the USA). At present, there is no reasonable scheme for surfactant identification in textile wastewater. 

Table 4 Aquatic toxicity of some anionic surfactants ...

There are different types of emulsion breakers and inhibitors, some of which are best used when little water is present, which is referred to as a closed system, and others that are best used on the open water, referred to as an open system. For example, some contain surfactants that are very soluble in water and are best used in closed systems so that they are not lost to the water column. Others contain polymers that have a low water solubility and thus are best used on open water. The aquatic toxicity of the products also varies widely. 

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