界面活性劑同時具有親水基及疏水基的構造，使其與溶解性有機質（Dissolved Organic Matter, DOM）同樣對環境中的非離子性有機化合物（Nonionic Organic Compounds, NOCs）在水系統中具有相同的增溶（Solubility Enhancement）效果。故當界面活性劑存在水中時，對非離子性有機化合物（NOCs）的增溶能力，會影響污染物的移動性與生物分解性。本研究針對界面活性劑特性，對非離子性有機化合物（NOCs）存在於土壤－水系統中之分佈行為加以深入探討。選用陰離子性及陽離子性界面活性劑各一種、兩種土壤對四種非離子性有機化合物（NOCs）在界面活性劑存在之水溶液和土壤間分佈行為加以研究。 研究結果顯示，隨著界面活性劑添加濃度的增加，NOCs的Kd*值（系統中含界面活性劑之分佈常數）會有很明顯的先升後降情形；且此現象隨水溶解度增加，而漸不顯著。這種現象是由於界面活性劑會先被土壤所吸附，增強土壤分佈NOCs的環境；待土壤吸附達飽和後溶液中界面活性劑以微胞的方式形成，使溶液產生增溶效應，而減少NOCs分佈至土壤的量。因為低水溶解度的NOCs受疏水環境的影響較大，故造成其變化的幅度較為顯著。 兩種高低有機質含量的土壤，於兩種不同類型界面活性劑存在之水溶液中吸附四種NOCs之行為所呈現出來的結果恰好相反，主要是來自於土壤對兩種界面活性劑的吸附行為不同所致；增加對陰離子性界面活性劑分佈的土壤有機質含量，會降低陽離子性界面活性劑的吸附位置，因而造成其吸附結果相反。 Surfactants have a characteristic molecular structure consisting of a hydrophilic and hydrophobic groups which can enhanced nonionic organic compounds (NOCs) dissolved in aqueous solution. The chemical structures of surfactants are expected to influence the NOCs behaviors in soils such as degradation and migration, as well as the distribution of NOCs in soil/aqueous system. In this study, we selected anionic and cationic surfactants (DBS and DB), two soils with high and low organic matter content (fOC=11.6 % and 1.88 %) and four NOCs (BTEX) to investigate the fates of NOCs in the soil/aqueous system. The data presented in this research indicated that initials NOC Kd* values (partition coefficients in surfactant solutions and soil) increased with increasing surfactant concentrations. For anionic surfactants system, the Kd* value reaches a plateau at the concentration of Ce = X, and then began to decline. The changes of Kd* values would slow down while NOCs solubility increasing. Surfactants adsorbed by soil may produce partition medium for NOCs. However, as the adsorbed surfactants increase, the amount of form micelles in solution may increase, which could then reduce the impact of the surfactant on NOCs uptake. For low water solubility NOCs, the impacts of hydrophobic medium formed on soils were significant resulting in the changes in Kd* values. BTEX adsorbed on two soils in surfactant solutions showed the different Kd* resulting from the difference mechanism of soils in adsorbing the anionic and cationic surfactants. Soils with high organic matter could enhance the uptake of anionic surfactant and reduce the amounts of the adsorptive cationic surfactant to show above phenomena.
