Choi Jaeyoung
Korea Institute of Science and Technology, 290 Daejeon-dong, Gangneung, Gangwon-do, Republic of Korea.
Chemosphere. 2006 Jun;63(11):1824-34. doi: 10.1016/j.chemosphere.2005.10.035. Epub 2005 Dec 5.
Cadmium sorption experiments were conducted to infer Cd sorption mechanisms to a reference smectite and three fractions of a Vertisol soil. Untreated Vertisol has a higher adsorption capacity for Cd than that of reference smectite. Surface complex modeling was used to calculate the potential contributions of Cd complexation reactions with permanent charge sites and pH-dependent charge sites over ranges in pH, for soils with given surface areas, and sorption site densities. The Langmuir model produced relatively good predictions of Cd sorption on reference smectite and Vertisol. However, the results of the triple-layer model (TLM) were inadequate to describe Cd adsorption on fixed-charge sites because the model could not account for the ion-exchange reaction on the basal plane. Based upon the two geochemical models of Cd adsorption to the reference smectite and Vertisol, it appears that the basal plane siloxane cavities are the most important sites for Cd complexation at pH<6.5. For the pH-dependent sites, the edge-site aluminol appears to be the dominant surface functional group responsible for Cd adsorption at pH>6.5.
进行了镉吸附实验，以推断镉在一种参考蒙脱石和变性土土壤的三个组分上的吸附机制。未处理的变性土对镉的吸附能力高于参考蒙脱石。利用表面络合模型，针对给定表面积和吸附位点密度的土壤，计算了在不同pH范围内镉与永久电荷位点和pH依赖电荷位点络合反应的潜在贡献。朗缪尔模型对镉在参考蒙脱石和变性土上的吸附给出了相对较好的预测。然而，三层模型（TLM）的结果不足以描述镉在固定电荷位点上的吸附，因为该模型无法解释基面的离子交换反应。基于镉在参考蒙脱石和变性土上吸附的两个地球化学模型，似乎在pH<6.5时，基面硅氧烷空穴是镉络合的最重要位点。对于pH依赖位点，边缘位点铝醇似乎是在pH>6.5时负责镉吸附的主要表面官能团。
