Structure-activity relationships for biodegradation of linear alkylbenzenesulfonates

The anionic surfactant linear alkylbenzenesulfonate (LAS) is widely used in detergents and cleaning products and has been considered a readily biodegradable alternative to branched chain alkylbenzenesulfonates. The mineralization and kinetics of LAS in river water and sediments were studied for a series of phenyl isomers and pure-chain homologues. Biodegradation appears to be independent for different homologues and individual mineralization rates were not adversely affected by competing homologues or high concentrations of suspended sediments. Little variation in degradation was found among different isomers and homologues. Mineralization half-lives, which ranged from 15 to 33 hrs, did not significantly differ in either sediments or river water. About 80% of LAS isomers and homologues were mineralized and followed first-order kinetics. Neither length of alkyl chain or phenyl position significantly affected rate or extent of mineralization. The isomers and homologues used bracket those present in commercial LAS formulations.