Aşçi Y, Nurbaş M, Açikel Y Sağ
Department of Chemical Engineering, Eskişehir Osmangazi University, 26480 Bati Meşelik, Eskişehir, Turkey.
J Hazard Mater. 2008 Jun 15;154(1-3):663-73. doi: 10.1016/j.jhazmat.2007.10.078. Epub 2007 Oct 30.
Recent research has demonstrated that biosurfactants, especially rhamnolipids, can enhance recovery of soil-bound metals. To propose the success of remediation process of soils by rhamnolipids, both sorption and desorption characteristics of soils having different clay mineralogy should be known exactly. To assess sorption of Cd(II), batch equilibrium experiments were performed using three soils characterized with different proportions of clay minerals from Eskişehir region of Turkey. Soil pH, initial metal concentration and clay mineralogy affected the sorption process. For comparisons between soils, the sorption process was characterized using the Langmuir, Freundlich, Redlich-Peterson, Koble-Corrigan sorption models. The Freundlich model showed the best fit for the Cd(II) sorption data by the soils, while the Langmuir-type models generally failed to describe the sorption data. Soils with higher clay content characterized by having smectite as a dominant component had the greatest sorption capacity and intensity estimated by the KF and n parameters of the Freundlich model. The soil C has the highest sorption efficiency of 83.9%, followed by soils B and A with sorption efficiencies of 76.7% and 57.9%, respectively. After the soils were loaded by different doses of Cd(II), batch washing experiments were used to evaluate the feasibility of using rhamnolipid biosurfactant for the recovery of Cd(II) from the soils. The Cd(II) recovery of the soils were investigated as a function of pH, amount of Cd(II) loaded to the soils, and rhamnolipid concentration. Cd(II) recovery efficiencies from the soils using rhamnolipid biosurfactant decreased in the order of soil A>soil B>soil C. This order was the reverse of the Cd(II) sorption efficiency order on the soils. When 80 mM rhamnolipid was used, the recovery efficiencies of Cd(II) from the soils A, B, and C was found to be 52.9%, 47.7%, 45.5% of the sorbed Cd(II), respectively. Rhamnolipid sorption capacity of the soils in the presence of Cd(II) ions decreased in the order of soil A>soil B>soil C.
近期研究表明，生物表面活性剂，尤其是鼠李糖脂，能够提高土壤中金属的回收率。为了说明利用鼠李糖脂修复土壤过程的成功性，必须准确了解具有不同粘土矿物学特征的土壤的吸附和解吸特性。为了评估镉（II）的吸附情况，采用来自土耳其埃斯基谢希尔地区的三种具有不同粘土矿物比例特征的土壤进行了批次平衡实验。土壤pH值、初始金属浓度和粘土矿物学对吸附过程有影响。为了比较不同土壤之间的情况，使用朗缪尔、弗伦德利希、雷德利希 - 彼得森、科布尔 - 科里根吸附模型对吸附过程进行了表征。弗伦德利希模型对土壤吸附镉（II）的数据拟合效果最佳，而朗缪尔型模型通常无法描述吸附数据。以蒙脱石为主要成分、粘土含量较高的土壤，根据弗伦德利希模型的KF和n参数估算，具有最大的吸附容量和强度。土壤C的吸附效率最高，为83.9%，其次是土壤B和A，吸附效率分别为76.7%和57.9%。在土壤加载不同剂量的镉（II）后，采用批次洗涤实验来评估使用鼠李糖脂生物表面活性剂从土壤中回收镉（II）的可行性。研究了土壤中镉（II）的回收率与pH值、加载到土壤中的镉（II）量以及鼠李糖脂浓度之间的关系。使用鼠李糖脂生物表面活性剂从土壤中回收镉（II）的效率顺序为土壤A>土壤B>土壤C。这个顺序与土壤对镉（II）的吸附效率顺序相反。当使用80 mM鼠李糖脂时，从土壤A、B和C中回收镉（II）的效率分别为吸附镉（II）量的52.9%、47.7%、45.5%。在镉（II）离子存在的情况下，土壤对鼠李糖脂的吸附容量顺序为土壤A>土壤B>土壤C。
