Lertpaitoonpan Warisara, Ong Say Kee, Moorman Thomas B
Department of Civil, Construction, and Environmental Engineering, Iowa State University, 490 Town Engineering, Ames, IA 50011-3232, United States.
Chemosphere. 2009 Jul;76(4):558-64. doi: 10.1016/j.chemosphere.2009.02.066. Epub 2009 Apr 5.
Batch sorption of sulfamethazine was conducted using five soils with organic carbon (OC) contents ranging from 0.1% to 3.8% and solution pHs ranging from 5.5 to 9. Sorption of sulfamethazine was found to be impacted by OC, soil surface area and soil solution pH, with higher K(d) values for soils with higher OC and lower K(d) values as the pH increased. However, OC was found to be the more dominant parameter. Linear partition coefficients at pH 5.5 were found to be 0.58+/-0.17 Lkg(-1) for soil with 0.1% OC and 3.91+/-0.36 Lkg(-1) for soil with 3.8% OC. At pH 9, the K(d) values were found to decrease by more than 50% to 0.23+/-0.06 Lkg(-1) (soil with 0.1% OC) and 1.16+/-0.05 Lkg(-1) (soil with 3.8% OC). Hydrophobic sorption was probably involved for pH<7.4 (pK(a,2)=7.4 for sulfamethazine) due to the non-ionized form of sulfamethazine while surface sorption was probably involved for pH>7.4 due to the ionized form of sulfamethazine. This was confirmed by regressing the estimated sorption coefficients of cationic, uncharged, and anionic species against the soil properties. A stepwise linear regression model incorporating the anionic fraction of sulfamethazine ionization and soil properties were developed and were found to estimate the K(d) values of other studies using soils of different pH and soil properties.
使用五种有机碳（OC）含量在0.1%至3.8%之间且溶液pH值在5.5至9之间的土壤进行了磺胺二甲嘧啶的批量吸附实验。研究发现，磺胺二甲嘧啶的吸附受有机碳、土壤表面积和土壤溶液pH值的影响，有机碳含量较高的土壤具有较高的K(d)值，且随着pH值升高K(d)值降低。然而，有机碳是更主要的参数。发现在pH 5.5时，有机碳含量为0.1%的土壤的线性分配系数为0.58±0.17 Lkg(-1)，有机碳含量为3.8%的土壤的线性分配系数为3.91±0.36 Lkg(-1)。在pH 9时，发现K(d)值下降超过50%，分别降至0.23±0.06 Lkg(-1)（有机碳含量为0.1%的土壤）和1.16±0.05 Lkg(-1)（有机碳含量为3.8%的土壤）。对于pH<7.4（磺胺二甲嘧啶的pK(a,2)=7.4），由于磺胺二甲嘧啶的非离子化形式，可能涉及疏水吸附；而对于pH>7.4，由于磺胺二甲嘧啶的离子化形式，可能涉及表面吸附。通过将阳离子、不带电荷和阴离子物种的估计吸附系数与土壤性质进行回归分析，证实了这一点。开发了一个包含磺胺二甲嘧啶电离的阴离子分数和土壤性质的逐步线性回归模型，发现该模型能够使用不同pH值和土壤性质的土壤来估计其他研究中的K(d)值。
