Biodegradability anionic surfactants

Linear alkylbenzenes are made from linear terminal olefins and benzene and are important precursors of biodegradable anionic surfactants (LAS, linear alkylbenzenesulfonates). The conventional catalyst is HF, first to be replaced by a fluorinated silica-alumina in the DETAL process. The DETAL process is safer than the HF process and also more cost-effective because no special metallurgy is required and no calcium fluoride waste stream exists.52 Zeolites such as Beta may come to the fore here because they display a higher selectivity to the desired 2-phenyl isomers.55... 

EEC Directive on methods of testing the biodegradability of anionic surfactants... 

Alkyl benzene sulfonates (ABS). Branched-chain anionic surfactants. Slow to biodegrade. Seldom used. 

Linear alkyl benzene sulfonates (LAS). Straight-chain anionic surfactants. Somewhat slow to biodegrade. Most common surfactants in use. 

Linear primary alcohol sulfates often need only one day for 95 % primary biodegradation and degrade faster than other anionic surfactants, which usually need several days. This difference has been confirmed by Ruschenberg [412, 413]. 

White GF, NJ Russell (1994) Biodegradation of anionic surfactants and related molecules. In Biochemistry of Microbial Degradation (Ed C Ratledge), pp. 143-177. Kluwer Academic Publishers, Dordrecht, The Netherlands. 

The main disadvantage in using poly(acrylamide) systems is that they are not biodegradable and the monomers are toxic. Extensive purification is also required to remove the organic solvents, anionic surfactants, and residual monomers. Edman et al. [74] produced biodegradable poly(acryldextran) particles by incorporating dextran into the poly(acrylamide) chain. These particulate systems were metabolized and eliminated faster, both in vivo and in vitro, than poly(acrylamide) particles. 

NPEO-SO4 is one of the rare anionic surfactant compounds on which aerobic biodegradation monitoring has been performed, where metabolites could be observed by API-MS. Using FIA-MS, however, differentiation of precursor compounds and metabolites was impossible. Both compounds showed the same molar masses but could be recognised because of their quite different RTs in RP-LC [15]. MS CID performed by trap confirmed a fragmentation behaviour of the metabolite quite different from precursor NPEO-SO4 compounds, whose structure is not yet clear. 

EEC, Council Directive of 31 March 1982 amending Directive 73/405/EEC on the approximation of the laws of the Member States relating to methods of testing the biodegradability of anionic surfactants (82/243/EEC), Official Journal of the European Communities, No. L 109/18. 

The lack of detection of LAS metabolites in sediments was also discussed by Sarrazin et al. [13] determining the biodegradability of the anionic surfactant in artificially contaminated sediments from a shallow pond. During the experiments, no LAS metabolites were observed. This was explained by the high solubility of these compounds, which may be quickly eliminated from the sedimentary layer by dissolution and diffusion into the pond water. 

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