嗜铅益生菌JT_1菌株可逆性表面吸附铅的研究

Reversible Surface Binding of Lead by Lead-resistant Bacteria JT_1

以嗜铅益生菌JT_1为生物吸附剂,研究pH对该菌吸附铅及其可逆性,其它金属阳离子对吸附过程的影响。应用透射电子显微镜对该菌吸附铅前、后的形态进行分析,揭示该菌体外吸附铅的作用过程。结果表明:溶液pH对该菌吸附铅的影响较大,当pH较低时,JT_1对Pb2+的吸附能力较弱。随着试验溶液pH的升高,JT_1对Pb2+吸附能力显著增加,当pH为6.0时,吸附率最高,达71.72 mg/g;该菌对铅离子的选择性吸附作用非常强,基本不受其它金属阳离子的干扰;菌体吸附铅具有可逆性,可被解离剂解离。透射电子显微镜照片显示:吸附铅离子后的菌体表面有大量金属沉积物。JT_1对铅离子的吸附主要发生在菌体表面,吸附率与pH值具有相关性。推测静电作用、离子交换和络合作用可能在吸附过程中起重要作用。

The lead-resistant bacteria JT_1 was used as biosorbent. The effect of pH on adsorption of lead, reversibility of lead binding and the effect of other cations on lead adsorption were studied. The in vitro lead adsorption process was revealed by observing the morphology of the biomass before and after Pb adsorption with transmission electron microscope（TEM）. The results showed that, the pH of the solution greatly influenced lead adsorption. The adsorption capability was poor at low pH values, but increased along with medium pH elevation and maximized at pH 6.0,reaching up to 71.72 mg/g. The adsorption displayed high selectivity to lead and was nearly not interfered by other cations. The lead adsorption process was reversible and the absorbed lead could be detached by desorbents. TEM showed large metal deposits on the surface of the biomass after lead binding. Therefore, lead bound mainly to the surface of the biomass and the adsorption rate depended largely on the medium pH. It was proposed that electrostatic interactions, ion exchange and complexation played major roles in lead absorption.