球衣菌吸附重金属Hg^(2+)的理化条件及其机理研究

Study on biosorption mechanism and physiochemical conditions of Hg ^(2+) by Sphaerotilus natans

采用球衣菌(Sphaerotilusnatans)FQ32为生物吸附剂,研究了初始离子浓度、吸附剂用量、菌龄、pH值、温度和吸附时间等理化因素对其吸附重金属Hg2+的影响,并进一步研究了吸附机理.结果表明,球衣菌在Hg2+浓度为16mg·L-1、吸附剂用量0.4g·L-1、菌龄16h、pH7、温度30℃、吸附时间90min时的优化条件下,对Hg2+的吸附量为72.86mg·g-1;该吸附过程是一个快速的过程,在吸附5min时,吸附量达总吸附量的74.10%,90min达到吸附平衡;此过程符合Langmuir等温方程.等温模型、透射电镜观察和红外光谱分析显示,菌体细胞表面的活性基团与Hg2+的络合反应是球衣菌吸附Hg2+的主要机理.

The Sphaerotilus natans FQ32 was used as bio-sorbent, the effect of series factors such as the initial concentration of Hg^2＋ , biomass concentration, the culture time of the bacteria, pH value, temperature and the adsorption time on the adsorbing to Hg^2＋ were determined, and the adsorption mechanism was further discussed. The results showed that the maximum adsorption capacity for Hg^2＋ of S. natans was reached 72.86 mg·g·-1 dry biomass under the optimal conditions with the Hg^2＋ concentration of 16mg. L- l , the bacteria cultured after 16hm with the biomass of 0.4mg·g·-1 , and incubation at 30℃ , pH 7 for 90 mins. The kinetic study of the adsorption showed that Hg^2＋ uptake was reached to 74.10% of the total uptake in the initial 5 minutes, and finished in 90 minutes. The adsorption process was well accorded with the Langmuir model. The analysis of the isotherm model, TEM and IR spectrum indicated that the combination of the Hg^2＋ with the active groups in the cell wall of S. natans was the main biosorption mechanism.