光谱法研究酵母菌对铜离子的吸附机理

采用AAS,FTIR,SEM/EDS等方法研究了啤酒酵母对铜离子的吸附作用.酵母菌经丙酮和NaOH处理后对Cu2 的吸附量明显增加,而将羧基酯化和将氨基甲基化使得酵母菌对Cu2 的吸附能力显著降低.化学修饰与酵母菌对Cu2 吸附的吸附结果表明,细胞壁上的羧基、氨基在酵母菌吸附铜时起着重要的作用.红外光谱表明,酵母菌表面有结合金属的官能团,如羟基、羧基、氨基等,吸附Cu2 后,3 392cm-1处的吸收峰紫移至3 404,1 405 cm-1处的峰红移到1 383 cm-1,细胞的主要成分和结构保持完整.SEM/EDS分析表明,吸附后酵母菌表面变化不大,酵母菌仅结合少量Cu2 .

Study on Mechanism of Beer Yeast Adsorbing Copper Ion by Spectroscopy

Copper ions adsorption by beer yeast was studied by AAS, FTIR, SEM/EDS etc. The quantity of copper biosorption by NaOH-treated yeast and acetone-treated yeast increased significantly, while the esterification of carboxylate functionalities and the methylation of amino group presented in the cell walls of yeast resulted in a marked decrease in copper adsorption. These results show that amino and carboxylate groups in yeast cell wall play a great role in binding copper. According to IR spectra, the dominating bands near 1 652, 1 539 and 1 237 cm(-1) are assigned to amide I , amide II and amide IlI, the characteristic IR absorption of protein which could be one of the significant components of cell walls. The peak near 1 456 cm(-1) is attributable to the bending stretching of CH2- and CH3-. The changes in the spectra of the copper-exposed yeast biomass were in the stretch of hydroxyl groups or amino groups, which shifted from 3 392 to 3 404 cm' , and in the symmetrical stretch of carboxylate groups, which shifted from 1 405 to 1 383 cm(-1). The components and structure of the exposed-copper biomass remain intact. SEM/EDS analysis shows that the main elements of beer yeast are carbon, oxygen, and magnesium, while the surface of yeast is rough, and the copper-loaded yeast only binds little copper.