Surface waters linear alkylbenzene sulfonate

OCCURRENCE OF SURFACTANTS IN SURFACE WATERS AND FRESHWATER SEDIMENTS—II. LINEAR ALKYLBENZENE SULFONATES AND THEIR CARBOXYLATED DEGRADATION PRODUCTS... 

Surfactants and their biotransformation products enter surface waters primarily through discharges from wastewater treatment plants (WWTPs). Depending on their physicochemical properties, surface-active substances may partition between the dissolved phase and the solid phase through adsorption onto suspended particles and sediments [1,2]. Several environmental studies have been dedicated to the assessment of the contribution of surfactant residues in effluents to the total load of surfactants in receiving waters. This contribution reviews the relevant literature describing the presence of linear alkylbenzene sulfonates (LASs) and in particular of their degradation products in surface waters and sediments (Table 6.3.1). 

Sulfonated surfactants are also powerful protease deactivators [67]. The presence of the sulfonate group on benzene makes sodium dodecyl benzene sulfonate, also called LAS (linear alkylbenzene sulfonate), more surface active than SDS. As a result, LAS is an even more efficient denaturant than SDS [27] and alcohol ethoxy sulfates [32]. For instance, in a 0.02% LAS solution, the activity of the protease from Bacillus stearothermophilus is reduced to 20% of its value in water [68]. Likewise, the subtilisin saturation by surfactants at pH 7.4 has been reported to occur at surfactant to enzyme ratios (w/w) of 6.3 (SDS) and 3.2 (LAS) [69]. 

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