微生物絮凝剂MBFA9去除水中Pb^(2+)的机理

Removal Mechanism of Lead(Ⅱ) Ions by Bioflocculant MBFA9 from Aqueous Solution

从土壤中筛选得到一株类芽孢杆菌A9,所产微生物絮凝剂MBFA9对水中Pb2+具有较高的去除作用,并进一步考察了MBFA9对Pb^(2+)的吸附动力学和热力学过程.结果表明:当水中初始Pb2+质量浓度为56.20 mg/L,MBFA9吸附25 min后的去除率最高可达92.73%;MBFA9捕集Pb2+的理论最大值为196.08 mg/g,吸附速率常数k2为0.019 g/(mg·min),动力学特征符合准二级动力学模型,其等温吸附模型与Langmuir方程拟合较好,相关系数R2=0.96;结合红外光谱检测、场发射扫描电镜和能谱分析,探讨了M BFA9去除Pb2+的机理为其表面的官能团如羟基、酰胺基、羧基等在捕集Pb2+过程中与之发生配合作用,对Pb2+的去除贡献了重要作用.

The bioflocculant produced by a stain of Paenibacillus sp. A9 which separated and purified from soilhada high removal rate of Pb2+in the water, and the adsorption kinetics and thermodynamic process of MBFA9 were further investigated. The results showed that the removal rate of Pb2+reaches 92.73% at initial concentration of 56.2 mg/L. The theoretical maximum capacity was 196.08 mg/g, and the adsorption rate constant k2was 0.019 g/(mg·min-1). The dynamic characteristics of MBFA9 capturing Pb2+in the water are in accordance with pseudo-second kinetic model, and the adsorption isotherm model of MBFA9 capturing Pb2+agrees well with the Langmuir equation of thermodynamics with the correlation coefficient R2=0.96. Comparison among the IR spectra, SEM and EDS of MBFA9 capturing Pb2+showed that the main component of MBFA9 is polysaccharides and the reaction mechanism is that functional groups on the surface of flocculant and Pb2+formed chelate by chelation. There is chemical reaction between hydroxyl, amido, carboxyl and Pb2+in the trapping process, and there is also a floc of sweep function, so MBFA9 has better removal effect on Pb2+. © 2016, Editorial Department of Journal of Northeastern University. All right reserved.