Cd(II)与As(V)在一株土壤细菌Delftia sp.上的共吸附研究

在土壤中，重金属（如Cd、Pb）和类金属（As、Sb）的复合污染非常复杂，而目前，还未有研究关注Cd、As在土壤微生物界面的共吸附行为。本研究利用宏观批吸附实验、电位滴定及光谱学手段探讨Cd(II)-As(V)在一株土壤细菌（Delftia sp.）表面的共吸附特点和机制。结果表明：Delftia sp.细菌表面富含羧基、磷酰基、氨基和羟基等官能团，解离常数（pKa）分别为4.57、7.04、8.22和10.45；当pH<5时，Cd(II)在复合体系的吸附量大于单一体系，pH>5时，Cd(II)在复合和单一体系吸附量差异不大；在pH 2–9范围内，As(V)在复合体系的吸附量都小于单一体系；细菌表面的羧基和少量氨基参与了Cd、As在细菌表面的络合反应，且Cd、As会在这些位点发生竞争作用。本研究证实，土壤pH是影响Cd、As在微生物表面共吸附的重要因素.

Co-adsorption of Cd(II) and As(V) to Soil Bacterium Delftia Sp.

In this study, batch adsorption experiment coupled with potentiometric titration and spectroscopy techniques were applied to investigate the co-adsorption mechanisms of Cd(II) and As(V) to a soil bacterium Delftia sp. The results showed that carboxyl, phosphoryl, amino and hydroxyl groups abound in bacterial surfaces, with dissociation constant (pK_a) of 4.57, 7.04, 8.22 and 10.45, respectively; Batch results showed that the adsorption of Cd in binary system was larger than that in single system at pH<5, whereas no significant difference was found at pH>5; For As(V), the presence of Cd inhibited as adsorption over the whole pH ranges (2-9). XPS results demonstrated that carboxyl and amine groups participated in the complexation of heavy metals on bacterial surfaces, and Cd and As may compete with each other on the adsorption sites. This study confirmed that soil pH is an important factor affecting the co-adsorption of Cd and As on microbial surface.