Bacillus coagulans BP-2非活性菌株对Cd2+的吸附特性及机理研究

摘要

为寻找 Cd2+经济、高效、环保的微生物吸附剂,探讨微生物对重金属的吸附特性和机理,从采自韶关大宝山矿区的土壤样品中分离、筛选耐镉功能菌株,以BP-2菌株为研究对象,采用16S rDNA方法对菌株进行了分子鉴定;通过批式试验系统研究了不同环境变量对菌株吸附Cd2+的影响;利用等温吸附模型、动力学模型模拟了吸附过程;采用红外光谱(FTIR)、X射线衍射(XRD)和X射线光电子能谱(XPS)分析手段,探讨了菌株吸附镉的作用机理.结果表明,16S rDNA序列相似性表明该菌株隶属芽孢杆菌属,将其命名为Bacillus coagulans BP-2.当Cd2+初始质量浓度为100 mg·L-1,吸附时间为80 min,菌株生物量为2.5 g·L-1时,菌株对Cd2+的吸附效果最好,吸附量可达73.26 mg·g-1;菌株对Cd2+的吸附过程符合Langmuir等温模型(r2=0.9911),最大吸附量为86.19 mg·g-1,二级动力学方程(r2=0.9814)能够更准确地描绘菌株对Cd2+的吸附过程.XRD分析显示,吸附后在13.3°、39.1°处出现Cd2+的特征峰,说明Cd2+成功被吸附到菌株的表面.FTIR和 XPS结果表明Bacillus coagulans BP-2细胞壁上的-OH、-NH和-C=O基团参与了Cd2+的吸附.利用Bacillus coagulans BP-2非活性菌株作为经济、高效、环境友好生物材料能够有效吸附溶液中 Cd2+.该研究可为含镉重金属废水的去除提供理论基础和实践依据.%The aim of this paper is to isolate and screen Cd2+-resistant functional strains, investigating the adsorption characteristics of Cd2+, adsorption kinetics and mechanism. So that it can provide theoretical foundation and practical platform for the bioremediation of other heavy metals. The functional strain BP-2 was studied as research object, molecular identification was carried out based on 16S rDNA. The influence of different environmental variables on the adsorption of Cd2+was studied by batch test system, and the adsorption process was analyzed by isothermal adsorption model and kinetic model. The mechanism for the adsorption of Cd2+was discussed by Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis methods. The results indicated that the 16S rDNA sequence similarity of the strain belonged to be Bacillus, and named as Bacillus coagulans BP-2.The optimum adsorption capacity was achieved at initial Cd2+mass concentration of 100 mg·L-1, biomass 2.5 g·L-1with the contact time of 80 min, and under this condition, the maximum adsorption capacity could reach 73.26 mg…g-1. The adsorption isotherm and kinetic models showed that the adsorption processes followed the pseudo-second-order kinetic model (r2=0.991 9), and were well described by Langmuir isotherm (r2=0.981 4). XRD characterization results exhibited that the area of 13.3 ° and 19.1 ° appeared a strong characteristic peak after adsorption, which implied the successfully adsorption of Cd2+to the surface of the inactive strain. The results of FTIR and XPS demonstrated that the functional groups such as -OH, -NH and -C=O on the surface of strain were the involvement of the adsorption for Cd2+. Thus, the inactive strain Bacillus coagulans BP-2 can be employed as a potential economic, efficient and environmental-friendly biological material for the effective removal of Cd2+from the aqueous solutions, and it is of great practical significance to the sustainable development of ecological environment.