Sorption of 2,4,6-trichlorophenol in model humic acid-clay systems.
Sorption of 2,4,6-trichlorophenol in model humic acid-clay systems.
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DOI：
10.1021/jf048106r
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发表时间：
2005-04
影响因子：
6.1
通讯作者：
Xiao-ping Wang;X. Shan;L. Luo;Shuzhen Zhang;B. Wen
中科院分区：
文献类型：
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作者：
Xiao-ping Wang;X. Shan;L. Luo;Shuzhen Zhang;B. Wen
腐植酸和粘土是影响有机污染物吸附和解吸的重要土壤组分；然而，腐植酸如何影响有机污染物在粘土上的吸附和随后的解吸还不清楚。采用批量平衡法比较了腐植酸改性的K(+)、Ca(2+)蒙脱石和伊利石对2，4，6-三氯苯酚(2，4，6-TCP)的吸附和解吸性能。本试验采用商品腐植酸和从森林土壤中提取的腐植酸。商品腐植酸对2，4，6-磷酸三钙的吸附量几乎是提取土壤腐植酸的两倍。2，4，6-磷酸三钙在K(+)-和Ca(2+)-伊利石上的吸附大于在K(+)-和Ca(2+)-蒙脱石上的吸附。K(+)粘土对2，4，6-磷酸三钙的吸附效果优于Ca(2+)粘土。与未改性粘土相比，腐植酸改性的Ca(2+)、K(+)蒙脱石和伊利石对2，4，6-磷酸三钙的吸附增加。与未改性粘土相比，2，4，6-磷酸三钙在腐植酸改性的Ca(2+)和K(+)-伊利石上的吸附非线性显著增加。与未改性蒙脱土相比，2，4，6-磷酸三钙在腐植酸改性的Ca(2+)和K(+)蒙脱石上的吸附非线性略有增加。通过比较吸附和解吸的结果，我们观察到包括腐植酸、粘土和腐植酸改性粘土在内的所有吸附剂的滞后现象。吸附的非线性和滞后与腐植酸的结构有关。腐植酸的芳香度越高，吸附非线性和解吸滞后越大。此外，吸附容量(K(F)‘)与吸附剂中腐植酸的含量呈正相关。这些结果表明，腐植酸对粘土的改性不仅可以提高粘土的吸附能力，还可以影响2，4，6-磷酸三钙的吸附非线性，解吸滞后可能与腐植酸的结构特性有关。
Humic acids and clays are important soil components that influence the sorption and desorption of organic contaminants; however, it is unclear how humic acids influence the sorption of organic contaminants onto clays and their subsequent desorption. Sorption and desorption of 2,4,6-trichlorophenol (2,4,6-TCP) by and from humic acid-modified K(+)- and Ca(2+)-montmorillonite and -illite were compared with unmodified clays using batch equilibration methods. Commercial humic acid and the humic acid extracted from forest soil were employed in this experiment. The adsorbed amount of 2,4,6-TCP by commercial humic acid was almost twice as large as that adsorbed by the extracted soil humic acid. More 2,4,6-TCP was sorbed onto K(+)- and Ca(2+)-illite than onto K(+)- and Ca(2+)-montmorillonite. K(+) clays were more effective in adsorbing 2,4,6-TCP than Ca(2+) clays. Sorption of 2,4,6-TCP on humic acid-modified Ca(2+)- and K(+)-montmorillonite and -illite increased as compared with unmodified clays. The sorption nonlinearity of 2,4,6-TCP on humic acid-modified Ca(2+)- and K(+)-illite increased remarkably as compared with the unmodified clays. The sorption nonlinearity of 2,4,6-TCP on humic acid-modified Ca(2+)- and K(+)-montmorillonite increased slightly in contrast to unmodified montmorillonites. By comparing sorption and desorption results, we observed hysteresis for all sorbents including humic acids, clays, and humic acid-modified clays. Sorption nonlinearity and hysteresis were dependent on the structure of humic acids. Higher aromaticity of humic acids resulted in greater sorption nonlinearity and desorption hysteresis. In addition, sorption capacity (K(f)') was positively correlated with the humic acid content of the sorbents. These results show that modification of humic acids on clays can not only increase the adsorption ability of clays but also affect the sorption nonlinearity of 2,4,6-TCP, and the desorption hysteresis was probably due to the structural characteristics of humic acids.