灭活酿酒酵母菌对U(Ⅵ)的吸附行为及减量化研究

Study on adsorption of uranium by inactivated Saccharomyces cerevisiae and volume reduction

采用静态吸附法研究了灭活酿酒酵母菌对水溶液中U（Ⅵ）的吸附特性,考察了pH 值、吸附剂投加量、初始浓度、吸附时间对吸附的影响,用FT-IR 和SEM 表征了灭活酿酒酵母菌吸附U（Ⅵ）前后的形态及结构变化,探讨了灭活酿酒酵母菌对U（Ⅵ）的吸附机理、减量化和U（Ⅵ）富集效果.结果表明,灭活酿酒酵母菌能够有效去除水体中的U（Ⅵ）,最大去除率和吸附容量分别为96.8%和45.44mg/g.灭活酿酒酵母菌对U（Ⅵ）的吸附平衡时间为60min,吸附剂投加量增大,温度升高,溶液pH 值=3.0时有利于U（Ⅵ）的去除;吸附行为符合准二级动力学模型及Langmuir等温吸附模型.经5-6次循环吸附可将100 mg/L的U（Ⅵ）溶液浓度降至0.040mg/L以下,达到国家含铀废水排放标准.灭活酿酒酵母菌对U（Ⅵ）的吸附机理：U（Ⅵ）首先通过静电引力作用快速吸附到细胞表面,随后细胞表面的羟基、氨基、羧基和羰基等负电荷基团与铀酰离子发生络合或配位反应并伴随细胞上无机元素的离子交换作用.利用灭活酿酒酵母菌处理放射性废水可以使放射性废液的减重效果高达上千倍,有利于后续固化等后处理环节.

The adsorption characteristics of U( Ⅵ) on inactivated saccharomyces cerevisiae were investigated by conducting a series of batch adsorption experiments in this study. The influence of solution p H,adsorbent dosage,initial U( Ⅵ)concentration,contact time were investigated. Scanning electron microscope( SEM) and Fourier transform infrared spectrometer( FT-IR) were used to characterize the surface structure and properties of the inactivated Saccharomyces cerevisiae before and after U( Ⅵ) adsorption,and to analyze the adsorption mechanism and adsorption kinetics of U( Ⅵ) on inactivated Saccharomyces cerevisiae. The experimental results showed that U( Ⅵ) removal rate increased with the increase of adsorbent dosage,and the highest adsorption reached at p H = 3. 0. The adsorption process fits pseudo-secondorder kinetic model and Langmuir isotherm equation,and the maximum adsorption capacity for U( Ⅵ) was 45. 44 mg / g.The initial concentration of 100 mg / L of U( Ⅵ) can be dropped to below 0. 040 mg / L after 5-6 times cycle adsorption,and meet the national uranium wastewater discharge standards. Speculation for the behavior of U( Ⅵ) adsorption by inactivated Saccharomyces cerevisiae was both physical adsorption and chemical adsorption,exhibiting joint action of electrostatic attraction,redox reaction,chelating ligand and ion exchange. Hydroxyl,amidogen,carboxylic and carbonyl are the main functional groups in the reaction with U( Ⅵ). The result suggested that the inactivated saccharomyces cerevisiae may be potential application for wastewater treatment.