球衣菌(Sphaerotilusnatans)吸附Ag+的影响因素及其机理
MECHANISM OF Ag+ BIOSORPTION BY SPHAEROTILUS NATANS
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摘要: 采用球衣菌(Sphaerotilus natans)为生物吸附剂,研究了初始离子浓度、吸附剂用量、菌龄、pH值、温度和吸附时间等因素对其吸附硝酸银溶液模拟废水中Ag+的影响及其吸附机理.结果表明,球衣菌在初始Ag+14 mg·L-1、吸附剂用量0.2 g·L-1、菌龄32 h、pH 8、温度30 ℃、吸附时间60 min的优化条件下,对Ag+的吸附率为71.75%,吸附量为50.23 mg·g-1;该吸附过程是一个快速的过程,在吸附5 min时,吸附量已达总吸附量的91%,并且以被动吸附为主;吸附动力学符合准二级动力学方程.透射电镜观察和红外光谱分析显示,球衣菌细胞表面的活性基团与Ag+发生络合反应,同时还有少量Ag+通过主动吸收过程进入活细胞内.
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关键词:
- 生物吸附剂 /
- 球衣菌(Sphaerotilus natans) /
- Ag+ /
- 因素 /
- 吸附机理
Abstract: Using a strain of Sphaerotilus natans as biosorbent,the factors for Ag+ adsorption in simulated waste water containing AgNO3, such as the initial concentration of Ag+, biomass concentration, the culture time of the bacterium, pH value, temperature and the adsorption time were determined, and the adsorption mechanism was further discussed. The results showed that the maximum adsorption capacity for Ag+ on S. natans reached 50.23 mg·g-1 dry biomass, and the adsorption rate was 71.75% under the optimal conditions with the Ag+ concentration of 14 mg·L-1, 0.2 g·L-1 biomass precultured for 32 h, incubation temperature of 30 ℃, pH 8, and incubation time of 60 min. The process was fast and passive. In the initial 5 minutes, the adsorption of Ag+ reached 91% of the total capacity. The dynamic model of Ag+ adsorption was consistent with the pseudo-second order kinetic model. TEM and IR spectrum indicated that the main biosorption mechanism included the interaction of Ag+ with the active groups on the cell surface of S. natans, as well as the process of trace Ag+ entering live cells.-
Key words:
- biosorbent /
- Sphaerotilus natans /
- Ag+ /
- factor /
- adsorption mechanism
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