烟曲霉胞外聚合物对Pb^(2+)的吸附特性

Biosorption of Pb^(2+) by extracellular polymeric substances produced by Aspergillus fumigatus

采用阳离子交换树脂(CER)法提取了烟曲霉胞外聚合物(EPS),并分析了其生物化学成分.同时,考察了烟曲霉EPS对重金属离子Pb2+的去除效果,探讨了其生物吸附机理和动力学特性.结果表明,CER法提取的烟曲霉EPS多糖含量较高,对细胞破坏程度较小.烟曲霉EPS吸附Pb2+的平衡时间约为3h,最佳吸附pH为6.5,吸附平衡时Pb2+去除率为73.48%.烟曲霉EPS对Pb2+的吸附平衡均能较好地用Langmuir模型和Freundlich模型来描述,而且更适用Langmuir模型,最大吸附量qm为32.22mg·g-1.烟曲霉EPS的FTIR分析结果表明,多聚糖中的羟基、羧基和C—O—C等是与Pb2+发生了作用的基团,而其中蛋白质的作用不明显.

CER extraction was used to extract extracellular polymeric substances from Aspergillus fumigatus.The biochemical composition of the EPS was determined.The adsorption of Pb2＋ by the EPS was investigated and the equilibrium and the mechanism of biosorption of Pb2＋ by EPS are discussed.The results showed that the CER process extracted high amounts of the EPS carbohydrate with hardly any cell lysis.The biosorption equilibrium time was about 3 hours.At pH 6.5,the lead removal efficiency could reach 73.48%.Both the Langmuir isotherm and Freundlich isotherm models could describe the biosorption equilibrium well,but the Langmuir isotherm fit better.The maximum uptake capacity of lead was estimated to be 32.22 mg·g-1 EPS.Analysis of FTIR spectra demonstrated that hydroxyl,carboxyl and C—O—C groups of the polysaccharide were the main functional groups in the reaction between Pb2＋,and the binding capacity of protein to Pb2＋ was weak.