海藻酸钠—明胶-PVA包埋法固定化酵母菌吸附重金属研究

发布时间：2018-07-14 16:48

【摘要】：随着我国工业的快速发展,重金属污染的速度已日趋加快。如重金属铅、镉等具有较强的生物毒性,而这些重金属在正常环境下较为稳定,短时间内难以被降解。且这些重金属能通过食物链长期蓄积在生物体内,不易排出,对生物体造成较大的危害。传统方法处理重金属废水过程繁琐,易造成二次污染,而固定化微生物技术因具有吸附效率高、成本低廉等优点己成为研究重点。本文对海藻酸钠-明胶-聚乙烯醇固定化包埋酵母菌吸附重金属的能力进行研究。根据固定化材料包埋条件标准(直径、密度、机械强度、传质性能)优化包埋条件,以固定化空白小球吸附铅、镉的能力为考核指标,通过正交试验研究海藻酸钠、明胶和聚乙烯醇最佳配比为海藻酸钠2%、明胶0.5%、聚乙烯醇2%,此条件下制备的固定化空白小球对铅、镉的吸附率分别为68.72%和66.35%。采用最佳配比制得固定化酵母菌小球,扫描电镜分析,固定化酵母小球表面的褶皱以及内部的网状空隙都有利于微生物的生长,为固定化小球吸附重金属离子提供必要的基础。以pH、重金属离子起始浓度、酵母菌用量、环境温度、吸附时间为控制因子,开展不同环境条件下固定化酵母菌吸附重金属试验研究。结果表明固定化酵母菌最佳吸附条件为pH=5、重金属起始浓度为120mg/L、酵母菌用量10g/L、温度25℃、时间120min。在最佳吸附条件下,分别使用固定化酵母菌小球、酵母菌、固定化空白小球吸附重金属铅、镉,结果表明固定化酵母菌小球吸附效果均优于酵母菌和固定化空白小球。通过固定化酵母小球吸附Pb2+、Cd2+进行简单的机理探究,得出准二级反应动力学模型比准一级反应动力学模型更能很好的描述固定化酵母菌对Pb2+、Cd2+的吸附行为。准二级反应动力学模型拟合后的R2分别为0.9934、0.9977。Langmuir等温模型比Freundlich等温模型能更准确的描述固定化酵母菌对重金属铅、镉的吸附性能。Langmuir等温模型拟合后的R2分别为0.9914、0.9942。
[Abstract]:With the rapid development of industry in China, heavy metal pollution has been accelerated day by day. Heavy metals such as lead, cadmium and so on have strong biological toxicity, but these heavy metals are stable in the normal environment and difficult to be degraded in a short time. And these heavy metals can accumulate through the food chain in the organism for a long time, it is not easy to excrete, causing great harm to the organism. The traditional treatment process of heavy metal wastewater is cumbersome and easy to cause secondary pollution, but immobilized microorganism technology has become the focus of research because of its advantages of high adsorption efficiency and low cost. The adsorption of heavy metals by immobilized alginate-gelatin-polyvinyl alcohol immobilized yeast was studied in this paper. According to the standard of immobilized material embedding conditions (diameter, density, mechanical strength, mass transfer performance), the embedding conditions were optimized. The ability of immobilized blank pellets to adsorb lead and cadmium was taken as the evaluation index, and the sodium alginate was studied by orthogonal test. The optimum ratio of gelatin and polyvinyl alcohol was sodium alginate 2, gelatin 0.5 and polyvinyl alcohol 2. The adsorption rates of cadmium and lead were 68.72% and 66.35%, respectively. The immobilized yeast pellets were prepared with the best proportion. The results of SEM analysis showed that the surface folds of immobilized yeast pellets and the internal reticular voids were all beneficial to the growth of microbes, which provided the necessary basis for the immobilized microspheres to adsorb heavy metal ions. With pH, initial concentration of heavy metal ions, amount of yeast, environmental temperature and adsorption time as control factors, the adsorption of heavy metals by immobilized yeast under different environmental conditions was studied. The results showed that the optimum adsorption conditions for immobilized yeast were pH 5, initial concentration of heavy metals 120 mg / L, yeast dosage 10 g / L, temperature 25 鈩，

本文编号：2122285