【作者】 李伟伟；

【导师】 高宝玉；

【作者基本信息】 山东大学 ， 环境工程， 2008， 硕士

【摘要】 从深海沉积物中分离出来的深海适冷菌Pseudoalteromonas sp.SM9913能分泌大量具有较强絮凝能力的胞外多糖（EPS）。本论文对EPS SM9913的絮凝性能和吸附性能进行了系列研究。首先,采用烧杯试验研究了EPS SM9913对高岭土悬浊液的絮凝效果,考察了多糖投加量、水样pH、不同阳离子和阴离子、盐度和温度对EPS SM9913絮凝性能的影响,通过测定Zeta电位和絮凝过程中絮体粒度的变化,探讨了EPSSM9913的絮凝机理,并针对EPS SM9913高度乙酰化的结构特点,通过脱乙酰对比EPS SM9913脱乙酰前后的絮凝效果,考察了大量乙酰基团的存在对EPSSM9913絮凝效果的影响,此外本论文还考察了存储方式对EPS SM9913稳定性的影响。结果表明,在1g/L的高岭土悬浊液中,当EPS投加量达10mg/L时絮凝活性达到最大值49.3（4.55mM CaCl₂）。pH值在5～8范围内EPS SM9913絮凝效果较好。二价阳离子Ca²⁺和Fe²⁺的加入可明显提高EPS SM9913的絮凝活性,而相同浓度的一价和三价阳离子则降低EPS SM9913的絮凝活性。向溶液中加入不同阴离子的钠盐,在Na⁺浓度相同的条件下,在含有NO₃^-的溶液中,EPSSM9913的絮凝效果最好。在5～40℃范围内,EPS SM9913的絮凝活性随温度降低逐渐升高并在5～15℃时达到最高值。当溶液中的盐度为5～100‰时,EPSSM9913的絮凝活性高于Al₂（SO₄）₃的。此外,EPS SM9913还能够有效地絮凝其它分散体系。从P.sp.SM9913提取的胞外多糖和其他生物絮凝剂之间的比较表明,该EPS是一种相对高效的生物絮凝剂。Zeta电位和絮体粒径的测定、扫描电镜的观察显示,吸附架桥是EPS SM9913絮凝的主要机理。乙酰基含量的减少使得EPS SM9913的絮凝效果有了明显的下降,在含盐模拟水样及低温下都失去了以前的优势。可见,乙酰基的大量存在对EPS SM9913保持良好的絮凝性能有着重要的意义。多糖无须烘干或冻干,以湿糖形式在4℃下即可保存,在长达一年多的试验期间未观察到多糖絮凝效果的下降。采用EPS SM9913分别对Pb²⁺和Cu²⁺进行吸附试验,研究了胞外多糖用量、pH、吸附时间和共存离子对其吸附规律的影响及EPS SM9913对Pb²⁺和Cu²⁺的吸附热力学。结果表明,EPS SM9913对Pb²⁺和Cu²⁺的吸附量随多糖投加量的增加而减小。在pH分别为4.5～5.5和4.5～6时,EPS SM9913对Pb²⁺和Cu²⁺的吸附效果较好。EPS SM9913对Cu²⁺的吸附平衡时间较短,90min后即可达到吸附平衡,而对Pb²⁺的吸附平衡时间则长达180min。共存离子Ca²⁺、Mg²⁺、Na⁺、K⁺的加入降低了EPS SM9913对Pb²⁺的吸附量,Ca²⁺、Mg²⁺的加入也降低了EPSSM9913对Cu²⁺的吸附量,但低浓度的Na⁺和实验范围浓度的K⁺不仅没有降低反而增加了EPS SM9913对Cu²⁺的吸附量。Freundlich和Dubinin-Radushkevich方程均能较好地描述EPS SM9913吸附Pb²⁺和Cu²⁺的热力学过程,由Dubinin-Radushkevich方程得到EPS SM9913对Pb²⁺和Cu²⁺的最大吸附量分别为243.3 mg/g（10℃）和36.7 mg/g（40℃）。胞外多糖吸附金属离子前后的红外光谱分析表明,多聚糖中C—O—C、乙酰基和羟基是起主要吸附作用的官能团。更多还原

【Abstract】 Pseudoaltermonas sp.SM9913,a psychrophilic bacterium isolated from 1855 m deep-sea sediment can secrets a lot of sticky exopolysaccharide.The flocculation and adsorption ability and mechanism was investigated in this paper.The flocculation performance in kaolin suspension has been studied first.The effects of EPS dosage,pH,co-ions,salinity and temperature on the flocculation of EPS SM9913 were investigated.The flocculation Mechanism of EPS SM9913 had been studied by determining zeta potentials and flocs sizes during flocculation process. By deacetylating EPS SM9913 and measuring the flocculating activity of the deacetylated EPS,the function of the acetyl groups was studied.Additionally,the best storage method of this EPS was also determined.The results show that EPS SM9913 has a peak flocculating activity of 49.3 in 1 g/L kaolin suspension with 4.55 mmol/L CaCl₂ and the optimum pH range of 5～8.It appears that the flocculating activity of EPS SM9913 is stimulated by Ca²⁺and Fe²⁺and is highest in NO₃^- solution among various anions solution.This study also found that EPS SM9913 shows a better flocculation performance than Al₂（SO₄）₃ at salinity of 5～100‰or temperatures of 5～15℃.In addition,EPS SM9913 is effective to flocculate several other suspended solids.The measured Zeta potentials,the size of flocs formed during the flocculation process and the surface profile of flocs revealed by scan electron micrograph suggest that bridging is the main flocculation mechanism of the studied EPS SM9913. Deacetylation of EPS SM9913 results in a significant decrease in its flocculating activity indicating that the large number of acetyl groups in EPS SM9913 plays an important role in its flocculation performance.EPS SM9913 could be stored without desiccation in 4℃,as it has no decrease in flocculating activity during study period.Biosorption of Pb²⁺and Cu²⁺by EPS SM9913 was also investigated.The influences of EPS dosage,pH,equilibrium time and coexisted-ions on adsorption property and the adsorption isotherm of this EPS were studied.The results show that the equilibrium adsorption capacity（Q_e）decreases with the increase of EPS dosage. The optimum pH for the adsorption of Pb²⁺is during 4.5～5.5,and for the adsorption of Cu²⁺is during 4.5～6.The Cu²⁺adsorption equilibrium is attained within 90min, while the Pb²⁺adsorption equilibrium time is 180min.Q_e of Pb²⁺decreases with the addition of co-ions as Ca²⁺,Mg²⁺,Na⁺ and K⁺.Addition of Ca²⁺、Mg²⁺also decreases the Q_e of Cu²⁺,but low dosage of Na⁺ and the tested dosage of K⁺ in study increases the Q_e of Cu²⁺.Both Freundlich and Dubinin-Radushkevich isotherm equations could well describe the thermodynamics process of Pb²⁺and Cu²⁺by the EPS.The maximum adsorption capacity determined by Dubinin-Radushkevich isotherm equation for Pb²⁺and Cu²⁺are 243.3 mg/g（10℃）and 36.7 mg/g（40℃）.IR analysis demonstrates that the group of C—O—C,acetyl and hydroxyl of polysaccharide are the main functional groups for binding metal ions.更多还原