摘要 自然界土壤通常無法對有機污染物及無機重金屬兼具高親和力，一般土壤帶負電且對金屬離子具有高親和力，對於有機污染物則礙於低有機質含量導致吸持性較不顯著。傳統土壤之改質劑雖可增加土壤有機質含量且提高對有機污染物之吸持能力，但是對金屬離子並不具親和力。因此本研究選用四種具特定官能基之改質劑，以陽離子交換法製備改質土壤，利用該改質劑之特殊構造，使得改質土壤達到最大層隙間隙並可同時吸持非離子有機污染物及無機重金屬，而影響改質劑與吸持之因子也一併納入探討。 由基本特性分析發現，改質後土壤有機碳含量為2.06〜53.10 %，遠高於未改質的鈉蒙特石（0.02 %）。從小角度X 光繞射分析之測量結果得知，經改質過後之土壤層隙間距最大為49.57 Å，明顯大於原土樣之12.78 Å。土壤改質後其比表面積減少、孔洞大小增加，由FTIR的光譜圖可證實土壤表面含有特定官能基，最後以元素分析儀再次驗證官能基存在於改質土壤，綜合各分析結果，證實改質劑已成功置換至土壤表面。 土壤以有機相分佈之方式吸持BTEX，而改質後土壤提供良好的分佈介質，由吸持結果可觀察出改質劑的結構與疏水性分佈環境會影響BTEX的吸持，且分佈常數（Kd）與有機碳含量有明顯的相關性存在，經校正後得log Kom值皆大於文獻值。本研究之改質土壤對於Cu+2及Pb+2的吸附量皆高於文獻值，可證明土壤經含有特定官能基之改質劑進行改質後，確實可以增加改質土壤對無機重金屬之吸附能力。 ;Abstract Soil possesses negatively charged in nature and has a high affinity for cations. Soil is limit capacity of partitioning for nonionic organic pollutants, since the nonionic organic pollutants are carried out with sorption by the way of partition into soil organic contents. If the soil does not contain a high content of organic matters, the partition capacity of soil would be low. However, the inorganic and organic pollutants usually exist at the same time in the environment. The traditional methods of soil modification usually only improve the content of soil organic matter resuit in increasing partition capacity and decreasing capacity of adsorption for ionic pollutants.
In this study, we synthesized modified-montmorillonites using surfactants with different alkyl chain length and functional groups. Such modification makes Na-montmorillonites possible for simultaneous sorption of inorganic and organic pollutants. The X-ray diffraction (XRD) technique was applied to reveal intercalated materials in the layer, which provides informations on layered structure and the basal spacing. Experimental results showed that for the modified clay basal spacing was increased from 12.78 to ~ 49.57Å, and the inter-layer space was mainly dependent on the carbon chain length and dosage of the modifiers. Nitrogen adsorption-desorption isotherms confirmed that the amount of modifier resulted in increasing pore size than that of unmodified sample. Fourier transform infrared spectroscopy also indicated that the modified clay surface contains the respective functional groups and the intensity of corresponding peaks was relatively altered by the carbon chain length of the modifiers.
The experimental results show that the partitioning of BTEX in modified clay was disproportional to water solubility. In addition , the distribution and fates of BTEX in modified soils are affected by the environment and structure of the modifiers. The organic modifiers used in this study, indeed better enhanced the distribution of nonionic organic compounds. The adsorption experiments of Pb+2, and Cu+2 show that the adsorption capacity of Pb+2 is higher than that of Cu+2. This study suggests that soil organic modifiers is a viable technique in adsoption of cations.
