耐辐射奇球菌对放射性核素铀的吸附行为研究

Biosorption of Radionuclide Uranium by Deinococcus Radiodurans

采用耐辐射奇球菌活体为生物吸附剂,进行了对水溶液中放射性核素铀的批量吸附实验。主要研究了溶液pH、初始铀浓度对吸附放射性核素铀效果的影响,并通过红外光谱(FTIR)和扫描电镜/能谱仪(SEM/EDS)等手段分析了其吸附机理。结果表明:在pH 5,c0=100mg·L-1时其吸附效果最佳,而最大饱和吸附量qmax为240mgU·g-1。结合扫描电镜与能谱分析结果认为,耐辐射奇球菌表面附着了大量的含铀片状结晶物,并且其吸附过程主要以离子交换或表面络合的方式吸附铀。比较吸附铀前后菌体红外光谱图和红外分峰图发现,耐辐射奇球菌吸附铀后的整体谱形有了一定的变化,特别是蛋白质中酰胺基团、羟基、羧基以及磷酸基团等活性基团可能参与了吸附过程,并且在906cm-1处出现了一个新的峰,此峰为UO2+2的伸缩振动峰。可见,利用具有抗辐射特性的耐辐射奇球菌为生物吸附剂,以期在放射性环境中对放射性核素铀的吸附具有一定的潜在途径。

As a biological adsorbent ,Living deinococcus radiodurans was used for removing radionuclide uranium in the aqueous solution .The effect factors on biosorption of radionuclide uranium were researched in the present paper ,including solution pH values and initial uranium concentration .Meanwhile ,the biosorption mechanism was researched by the method of FTIR and SEM/EDS .The results show that the optimum conditions for biosorption are as follows ：pH= 5 ,c0 = 100 mg · L^-1 and the maximum biosorption capacity is up to 240 mgU · g^-1 .According to the SEM results and EDXS analysis ,it is indicated that the cell surface is attached by lots of sheet uranium crystals ,and the main biosorpiton way of uranium is the ion exchange or surface complexation .Comparing FTIR spectra and FTIR fitting spectra before and after biosorption ,we can find that the whole spectra has a certain change ,particularly active groups （such as amide groups of the protein ,hydroxy ,carboxyl and phosphate group ） are involved in the biosorption process .Then ,there is a new peak at 906 cm^-1 and it is a stretching vibration peak of Uo2^2＋ .Ob‐viously ,it is possible that as an anti radiation microorganism ,deinococcus radiodurans could be used for removing radionuclide uranium in radiation environment .