用FTIR、XPS、TEM等表征方法对溶液中大肠杆菌吸附钯(Ⅱ)的机理行了研究.结果表明,该吸附过程与大肠杆菌和钯(Ⅱ)间静电作用有关,在pH为2.0时吸附量最大,可达120.08 mg/g;对大肠杆菌进行化学修饰,FTIR结果表明细胞表面的氨基、羧基可能为吸附钯(Ⅱ)的主要基团,涉及到表面络合机制;TEM及XPS结果显示吸附6 h后菌体内有尺寸为5~15 nm的钯纳米颗粒生成,说明该吸附过程还存在还原反应.大肠杆菌对钯(Ⅱ)的吸附过程是静电作用、表面络合、氧化还原等机制共同作用的结果.
The adsorption mechanism of Pd(Ⅱ) onEscherichia coliwas investigated by using FTIR, XPS, TEM and other characterization methods.The results revealed that the adsorption process was related to the electrostatic interaction betweenE. coli and Pd(Ⅱ) with a maximum adsorption capacity of 120.08 mg/g at pH 2.0. After thechemical modification ofE. coli, FTIR results showed that the amino and carboxyl groups on the cell surface may be the major groups for binding Pd(Ⅱ), suggesting a surface complexation mechanism involved.TEM and XPS results showed that palladium nanoparticles with a size of 5~15 nm were deposited on E. coli, indicating the existence of reduction process.Therefore,it can be concludedthat several mechanisms such as electrostatic adsorption, surface complexation and bioreduction, are involved in the biosorption process of Pd(Ⅱ) onE. coli. However, the confirmation of the electron donor and the site of the biological reduction needs further research.
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