title: Degradation of surface-active compounds in a constructed wetland determined using high performance liquid chromatography and extraction spectrophotometry.
abstract: Degradation of anionic and nonionic surfactants in a constructed wetland with horizontal subsurface flow was studied using high performance liquid chromatography and extraction spectrophotometry. The ratio of individual homologues of linear alkylbenzene sulfonates (LAS) and the efficiency of their removal were studied. Tridecyl-, dodecyl-, undecyl-, and decylbenzene sulfonates were removed with efficiencies of 92.9%, 84.3%, 64.7%, and 41.1%, respectively. These differences are due to sequential shortening of the alkyl chain in homologues during degradation (the higher homologue can provide the lower one). The formation of sulfophenyl carboxylic acids during ω-oxidation of the alkyl chain followed by successive α- and/or β-oxidation is also a possible mechanism for removal of LAS. Solid phase extraction using Chromabond® HR-P columns was used for preconcentration of the analytes prior to their determination by HPLC. Methylene blue active compounds were determined using extraction spectrophotometry. The average efficiency of their removal was 84.9% in this case. The efficiency of nonionic surfactant removal (98.2%) was significantly higher in comparison to that for anionic surfactants. The concentration of the endocrine disruptor nonylphenol (a product of nonylphenol polyethoxylate surfactant degradation) determined in the profile of the wetland was beneath the limit of detection (0.4 μg/L). The average outflow concentrations of anionic and nonionic surfactants determined by spectrophotometry were 0.54 and 0.021 mg/L, respectively. The average outflow concentrations of decyl- and tridecylbenzene sulfonates determined by HPLC were 0.195 and 0.015 mg/L. Efficiencies of 86.4% and 92.2% were obtained for removal of organic compounds as indicated by chemical and biochemical oxygen demand (COD(Cr) and BOD(5)). These results demonstrate the suitability of the constructed wetland for degrading surface-active compounds.
authors: Department of Applied Chemistry, University of South Bohemia, Faculty of Agriculture, České Budějovice, Czech Republic. simajan@seznam.cz
authors: Jan
authors: J
authors: Šíma
authors: Marek
authors: M
authors: Pazderník
authors: Jan
authors: J
authors: Tříska
authors: Lubomír
authors: L
authors: Svoboda
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D013501:Surface-Active Agents / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D053833:Wetlands
chemical_list: D017738:Alkanesulfonic Acids; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; C030641:alkylbenzyl sulfonic acid