嗜铅菌对水中重金属Pb~(2+)的吸附研究

研究了实验室提供的嗜铅菌对水中铅离子吸附的条件和机理.讨论了吸附时间、pH、铅离子的质量浓度和菌的质量浓度对吸附的影响.结果表明,在pH=7.0、铅离子初始质量浓度为25mg/L、离心湿菌的质量浓度为1.06g/L、吸附时间为60min时,铅离子的吸附率达96.88%;实验条件下超标25倍的含Pb~(2+)废水,可迭排放标准;Pb~(2+)的最大吸附量为150mg/g.数学模型Langmuir和Freundlich方程均能很好地描述嗜铅菌对Pb~(2+)的吸附过程.对Pb~(2+)吸附前后的红外光谱表征表明,嗜铅菌表面多糖、蛋白质的羟基峰和羰基峰均有不同程度的紫移,羟基峰、糖苷峰等峰宽略增,说明菌体吸附,主要是表面基团的作用所致.用原子力显微镜对吸附前后的嗜铅菌检测可见,吸附后菌体的弹性变小、粘性变大、部分茵体有一定的收缩,说明以表面吸附为主的吸附过程,对菌细胞的聚合度有影响,菌体内部对铅也有一定的生物积累.

ADSORPTION INVESTIGATION OF Pb~(2+) BY DOMINANT BACTERIA IN AQUEOUS MEDIA

The adsorptive conditions and mechanism of lead ion by lead-resistant strain provided by laboratories in aqueous media were conducted. The adsorptive effects of adsorption time, pH,mass concentration of lead ion, mass concentration of strain to adsorption are discussed. The results indicate that lead ion removal rate can reach up to 96.88% in the following conditions: pH=7.0, initial mass concentration of lead ion was 25mg/L, the mass concentration of bacteria was 1.06g/L, adsorption time is 60min. Under experimental conditions, the wasting water whose lead ion concentration exceeds 25 folds can reach the discharge standard. The highest adsorptive capacity of Pb~(2+) may reach up to 150mg/g under the experimental conditions. Mathematic model Langmuir and Freundlich equations both can simulate the adsorption of lead ion by lead-resistant strain very well. Before and after the adsorption to lead ions by lead-resistant strain, the IR spectra show that the hydroxyl and carbonyl groups of polysaccharide and protein exhibit blue shifts in various degrees, the peak width of hydroxyl groups and C-O-C widened a little bit, which shows that the adsorption is mainly resulted from the function of the surface groups. The AFM detections indicate that the elasticity of bacteria decreases, the adhesiveness increases and part of the mycelium shrinks a little after adsorption, which shows that the adsorption mainly to the surface adsorption process has effect on the aggregation degree of strain cells, lead was also biologically accumulated in the mycelium meanwhile.