【作者】 史小利；

【导师】 吴坤；

【作者基本信息】 河南农业大学 ， 微生物学， 2008， 硕士

【摘要】 从土壤中分离筛选到一株对稀土离子La³⁺有较强吸附能力的菌株A01,经初步鉴定为黑曲霉（Aspergillus niger）。通过稀土离子对A01菌株生长影响的实验,结果表明当分别加入100mg /L的La³⁺、Ce³⁺会缩短菌株的稳定期,提前进入衰亡期。A01菌对La³⁺、Ce³⁺、Nd³⁺的耐受浓度分别为800mg/L、600mg/L、800mg/L,当培养基中稀土离子达到上述上限时,A01不能生长。稀土离子在相对低浓度时可以提高A01生长速率,当稀土离子提高到一定程度的时候,就表现出对菌体生长的抑制作用。由A01菌对稀土离子的单因素吸附条件试验,以及对温度、吸附时间、菌体添加量、稀土溶液初始浓度的正交试验,得出A01菌对La³⁺最佳吸附条件为:La³⁺初始浓40mg/L,温度32℃,转速200rpm,pH7.0,4mg/mL菌体（以干重计）,吸附时间1.5h。优化条件下A01菌对La³⁺的吸附量可达125.62 mg/g。A01菌对Yb、Lu、Ho的吸附量都达到了290mg/g以上,且A01菌对重稀土元素的吸附量总体上要高于对轻稀土元素的吸附量。A01菌选择性吸附稀土离子的实验结果表明,A01对稀土离子的选择性吸附能力不高。解吸实验发现,强酸解吸效果较好,解吸率最高的HNO3解吸率达到75.46%。扫描电镜结果显示A01菌吸附的稀土离子La³⁺在菌丝表面以晶体状的形式沉积。菌株对稀土离子La³⁺的吸附是一个快速的吸附过程,在吸附的15min内,吸附量有很大的提高,而从15min到45min内,吸附量的增加速度很慢,在45min时就已基本达到平衡,其吸附动力学过程可以用拟二级速度方程来描述。对经典的吸附模型进行了拟合,发现A01菌对Langmuri模型拟合程度比较好。更多还原

【Abstract】 One adsorption or accumulation La³⁺ fungi strain A01 was screened from soil ,and identified as Aspergillus Niger by investigating the characteristic of the strain.The tests on the effect of rare earth ions on A01 growth were carried out. The results show that it can shorten the stable phase of the strain ,move up the Decline phase .The concentrations of La³⁺、Ce³⁺ and Nd³⁺ which A01 strains couldn′t grow arrived at 800mg/L、600mg/L and 800mg/L.It’s also found the rare earth ions may promote the growth of A01 in some relative low concentration,and restrain it in high concentration.The studies on the conditions of adsorping La³⁺ by A01 indicate that the optimum conditions of adsorping La³⁺ is at initial concentration of La³⁺ 40mg/L ,temperature 32℃,rotation speed 200rpm, pH 7.0, biomass 4mg/50mL, biosorption of time 1.5 hour . On the optimum conditions of adsorpting La³⁺, the max adsorption capacity can reach 125.62 mg/g.From the test adsorping rare earth by A01,we can know that the adsorption capacity to Yb³⁺、Lu³⁺ and Ho³⁺ are high and are all more than 290mg/g.And the adsorption capacity to heavy rare earth elements are higher than to light rare earth elements.Results of A01 selective adsorption of rare earth ions tests show that the selective adsorption capacity of A01 is not obvious. The desorption rate are all not ideal, the highest rate can reach 75.46% by joining 0.1M HNO3.Electron microscopy revealed that La³⁺ crystal deposits at the cell surface, indicating that a precipitate formed at the cell surface.Biosorption kinectic results of A01 showed that the biosorption was very quick in the initial fifteen minutes, adsorption capacity is greatly improved. Then there was a very slow process and the adsorption uptake capacity increased very slowly. After forty five minutes, the adsorption equilibrium reached. This biosorption systems were better described by the pseudo-second kinetic model. Both of the Langmuir and Freundlich adsoption isotherms were studied ,which indicated that the Langmuir model well fitted this experimental data.更多还原