• 关键词：面包酵母菌  KMnO₄  化学修饰  Cd²⁺  生物吸附

• 基金项目：四川农业大学"双支计划"基金

• 姜友军
• 四川农业大学生命科学与理学院, 雅安 625014

• 张云松
• 四川农业大学生命科学与理学院, 雅安 625014

• 王仁国
• 四川农业大学生命科学与理学院, 雅安 625014

• 尹元江
• 四川农业大学生命科学与理学院, 雅安 625014

• 曾武
• 四川农业大学生命科学与理学院, 雅安 625014

• 肖朝萍
• 中国科学院成都有机化学研究所, 成都 610041

• 摘要：研究了用KMnO₄修饰面包酵母菌对溶液中Cd²⁺的吸附作用,探讨了不同KMnO₄浓度、pH、吸附时间、Cd²⁺初始浓度、修饰酵母菌用量等5个因素对KMnO₄修饰面包酵母菌吸附Cd²⁺的影响.结果表明,随着修饰剂KMnO₄浓度的增大,修饰面包酵母菌的吸附能力增强,KMnO₄浓度达到20 mmol · L^-1时,吸附能力是相同条件下原菌的2倍.在pH为5.0~7.0范围内,吸附效果最好;反应30 min后,吸附可达到平衡;Cd²⁺初始浓度为100 mg · L^-1时,吸附基本达到饱和;KMnO₄修饰面包酵母菌的最佳用量为6 g · L^-1左右.KMnO₄修饰面包酵母菌吸附Cd²⁺的过程适宜用准二级速率方程来描述,而Langmuir方程对其吸附等温线的描述效果最好.SEM、FTIR、XPS等分析结果表明,面包酵母菌主要通过表面的羟基、羧基、氨基、磷酰基等基团进行吸附.KMnO₄修饰可使面包酵母菌表面变得较为粗糙,表面结构发生变化,提高菌表面吸附镉活性位点的数量.同时,KMnO₄氧化面包酵母菌时在表面被还原成纳米MnO₂和Mn²⁺,其对Cd²⁺吸附也起到了协同作用.

• Abstract：The adsorption of aqueous Cd²⁺ by baker's yeast modified by KMnO₄ was explored. Several factors, including the concentration of KMnO₄ used to modify the baker's yeast, pH, adsorption time, the initial concentration of Cd²⁺, and the dosage of KMnO₄ modified yeast, were investigated to evaluate the adsorption effect. The results showed that the adsorption capacity of modified baker's yeast was improved with the increasing KMnO₄ concentration and the optimal amount of KMnO₄ modified baker's yeast was about 6 g · L^-1. When the concentration of KMnO₄ was 20 mmol · L^-1, the adsorption capacity was double that of untreated yeast under the same conditions. In the range of pH 5.0~7.0, the adsorption was the best; adsorption equilibrium was reached at 30 min. When the initial concentration of Cd²⁺ was 100 mg · L^-1, KMnO₄ modified baker's yeast attained saturated adsorption. Kinetics studies indicated that the adsorption behavior can be described with a pseudo-second-order rate equation. The Langmuir adsorption isotherm exhibited the best fit to the experimental data. The biosorbent was characterized with SEM, FTIR and XPS, the results show that Cd²⁺ was adsorbed by functional groups on the surface of the biosorbent, such as —OH, —COOH, —NH₂ and —PO₄^3-. KMnO₄ modification not only makes the surface of baker's yeast become rougher, but also changes the surface structure, and increases the number of active sites. Simultaneously, on the surface of baker's yeast, KMnO₄ was reduced to nano-MnO₂ and Mn²⁺, which also played a role in the adsorption of Cd²⁺.

• Key words：baker's yeast  KMnO₄  chemical modification  Cd²⁺  biosorption

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