摘要
探究了以活性和高温灭活酵母为生物吸附剂对低浓度放射性核素铀的吸附能力、相关的动力学特性及机理.结果显示,活性酵母菌和灭活酵母菌对铀的最佳吸附p H分别为5.5和4.5,达到吸附动态平衡所需时间分别为240 min和30 min,活性酵母菌对铀的最佳吸附温度为26℃,而灭活酵母菌对铀的吸附能力受温度影响不明显.不同温度下,活性与灭活酵母对铀的吸附动力学均能较好地符合准二级动力学模型,可决系数均在0.99以上,表明活性与灭活酵母菌对铀的吸附过程中,都存在着电子共用或电子转移过程.扫描电镜结果显示,吸附铀后的活性酵母菌菌体表面出现凹陷,少量块状铀沉淀附着在表面,而经过高温高压处理的灭活酵母菌菌体表面积明显增大,大量的纳米颗粒状铀沉淀附着在表面.红外光谱分析表明,在活性酵母菌对铀离子吸附的过程中,羟基、醛羰基、N—H、C—N等为主要的吸附位点,而羟基、酮羰基、P=O、—HPO_4^(2-)等为灭活酵母菌对铀离子吸附的主要位点.
The kinetic characteristics and mechanism for low concentration of uranium by live and heat-killed Saccharomyces cerevisiae were investigated.The results indicate that the maximum uranium adsorption capacity was observed at p H 5.5 and 4.5,and the reaction reached an equilibrium within 240 min and 60 min,for live and heat-killed cells,respectively. The optimal adsorption temperature for live cells was 26 ℃,while it had little effect on heatkilled cells. The kinetic investigations show that the sorption fitted the Pseudo-second order model well（ with R2〉0.99） at different temperatures for both live and heat-killed cells,indicating that there was a shared electronic or electron transfer adsorption process. The scanning electron microscopy（ SEM）results show that the surface morphology of live yeast cell was sunken and covered with little uranium precipitation after adsorption,while the body surface area of dead cell increased greatly,and a large number of nano-particle of uranium precipitation deposited on the cell surface. The Fourier transform infrared（ FTIR） illustrated that function groups such as hydroxyl,aldehyde carbonyl,N—H,C—N played important roles in complexation with uranium for live yeast cells,while hydroxyl,ketone carbonyl,P4O,—HPO42- were important in case of dead yeast cells.
出处
《环境科学学报》
CAS
CSCD
北大核心
2017年第1期169-177,共9页
Acta Scientiae Circumstantiae
关键词
吸附
酵母菌
低浓度铀
动力学模型
机理
adsorption
Saccharomyces cerevisiae
low-concentration uranium
kinetics
mechanism
