Linear alkylbenzenesulfonate (LAS) surfactants in a simple test to detect refractory organic carbon (ROC): Attribution of recalcitrants to impurities in LAS
- Swiss Federal Inst. for Materials Testing and Research, St. Gallen (Switzerland)
- ETH-Zentrum, Zuerich (Switzerland). Inst. of Microbiology
The standard procedure to examine the biodegradability of a (group of) compound(s) in a trickling filter is a continuous-flow system. In this test, nondegraded metabolites from a commercial linear alkylbenzenesulfonate (LAS) surfactant are detected. This procedure has now been augmented by two phases in closed cycle to give a test for refractory organic carbon (ROC test). First, the concentration of nondegraded metabolites was increased by readdition of LAS to the solution being cycled through the filter. Second, the concentrated residues were further recycled till the net dissolved organic carbon (DOC) stabilized at a finite value and the net released CO{sub 2} stabilized at about zero. The organic compounds remaining at this phase of the experiment were considered recalcitrant and could be examined by global (e.g., DOC) and specific (e.g., HPLC) assays. Four different commercial preparations of LAS were examined, as were the (4-sulfophenyl)undecane homologue (C{sub 11}-LAS), the (4-sulfophenyl)dodecane homologue (C{sub 12}-LAS), and some related compounds. The four commercial LAS preparations contained different levels if impurities which were largely dialkyltetralinesulfonates (DATS) and branched-chain alkylbenzenesulfonates (bABS). The refractory organic carbon (ROC) remaining after biodegradation varied from 3 to 14%. The results were a characteristic of the LAS under study and were independent of the source of the biomass used in the experiment. Residues were examined by HPLC, and 50 to 100 peaks were observed, which were usually characteristic of the LAS studied. No peak has been conclusively identified. The authors consider the recalcitrants to represent carboxylated DATS and carboxylated bABS.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 42919
- Journal Information:
- Environmental Toxicology and Chemistry, Journal Name: Environmental Toxicology and Chemistry Journal Issue: 4 Vol. 14; ISSN ETOCDK; ISSN 0730-7268
- Country of Publication:
- United States
- Language:
- English
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