Sorangium cellulosum NUST06纤维堆囊菌胞外多糖对重金属离子的吸附特性

【作者】 刘秋兰；

【导师】 蒋鹏举； 张建法； 杨树林；

【作者基本信息】 南京理工大学 ， 生物化工， 2004， 硕士

【摘要】 粘细菌Sorangium cellulosum NUST06能产大量的胞外多糖，经研究确定了粗多糖对Pb²⁺和Cu²⁺的吸附性能最佳。多糖对Pb²⁺的吸附量大于Cu²⁺，分别为123.3mg／g和54.73mg／g。Langmuir等温模型比Freundlich模型能更好地描述Pb²⁺和Cu²⁺的等温吸附，虽然均有高的相关系数。吸附反应在10min内完成，是一个快速、稳定的过程，动力学数据可以用拟二阶方程描述。随着体系初始pH的增大，Pb²⁺和Cu²⁺的吸附容量增大，最佳pH分别在3.96和4.51。在同一吸附体系中，Pb²⁺的体系pH逐渐增大，而Cu²⁺的体系pH逐渐减小的。低温或高温都不利于Pb²⁺的吸附，但多糖对Cu²⁺的吸附则是一个吸热的过程。低浓度的轻金属离子促进Pb²⁺的吸附，而在高浓度的轻金属吸附体系中，可以观察到竞争多糖上有限的吸附位点。Pb²⁺的吸附不受低浓度Cu²⁺和Ni²⁺的影响，高浓度的Cu²⁺和Ni²⁺促进Pb²⁺的吸附。而Na⁺、K⁺、Mg²⁺、Ca²⁺、Pb²⁺和Ni²⁺与Cu²⁺的发生严重的竞争吸附。Pb²⁺、Cu²⁺的动态穿透曲线的穿透点都是在490mL左右，过柱液的体积分别超过640mL和610mL时，固定化多糖吸附己达到饱和。0.5M的HCl溶液能把吸附的Pb²⁺完全洗脱下来，动态穿透曲线不符合Thomas模型。红外光谱初步证实，Pb²⁺、Cu²⁺是与多糖上的-COOH和-OH发生反应。该多糖对Pb²⁺表现的特殊吸附机理初步推测为疏水缔合机理。更多还原

【Abstract】 A novel exopolysaccharide was produced by Myxobacterium Sorangium cellulosum NUST06. Coarse EPS exhibited the optimal performance on lead and copper ions by study. The adsorptive capacity of EPS on lead ions was excel to that on copper ions, 123.3mg/g and 54.73mg/g dry weight individually. The Langmuir isotherm was more suitable for describing the biosorption of Pb2+ and Cu2+ by EPS than the Freundlich adsorption model, although they both had high coefficients. The adsorptive reaction was completed in ten minutes and was a fast and steady course. The kinetic data could be modeled by the pseduo-second order equation. For both metal ions, uptake increased with medium pH, being maximal at 3.96 and 4.51 respectively. In the same system, the pH increased gradually in lead ions solution while declined in copper ions solution. High or low temperature was not beneficial to the biosorption of lead ions but high temperature was good for copper ions. The light metal ions at low initial concentrations promoted the removal of lead ions, nevertheless, competition for binding sites on EPS was observed at high initial light metal ion concentrations. The removal of lead ions was independent of Cu2+ and Ni2+ at low initial concentration, but Cu2+ and Ni2+ at high initial concentration enhanced the removal. Opposition to lead ions, the metal ions such as Na+, If, Mg2+, Ca2+, Cu2+ and Ni2+ were competitive with copper ions severely. The breakthrough point of lead and copper ions both occurred at the volume of 490mL, and fix-bed was saturated completely at 640 and 610mL respectively. The biosorbed lead ions were effectively eluted by 0. 5M HCL solution. Breakthrough curve was not in good agreement with Thomas model. Lead and copper ions reacted with -COOH and -OH on EPS primarily by IR testify. The peculiar mechanism of lead biosorbed by EPS was regarded as hydrophobically elementarily.更多还原