【作者】 刘莉；

【导师】 潘思轶；

【作者基本信息】 华中农业大学 ， 食品科学， 2008， 硕士

【摘要】 魔芋葡甘聚糖（Konjac Glucomannan,简称KGM）是继淀粉和纤维素之后,一种较为丰富的可再生天然高分子资源,已成为具有应用前景的环境友好生物材料。本文以魔芋葡甘聚糖为主要研究对象,在了解魔芋葡甘聚糖在不同pH值的溶液行为的基础上,研究了魔芋葡甘聚糖进行交联羧甲基改性的最佳条件,探讨了交联羧甲基魔芋葡甘聚糖对金属离子的吸附及解吸性能,表征了魔芋葡甘聚糖、交联羧甲基魔芋葡甘聚糖（Crosslinked Carboxymethyl Konjac Glucomannan,简称CCMKGM）及其吸附金属离子后产物（Metal Crosslinked Carboxymethyl Konjac Glucomannan,简称MCCMKGM）的结构特点。本实验的主要结论如下:1.魔芋葡甘聚糖在不同pH值的溶液构象初探采用粘度法研究不同pH值下魔芋葡甘聚糖（KGM）溶液的特性粘度,采用刚果红染色法分析了不同pH值和尿素浓度对KGM溶液构象的影响。特性粘度实验表明:在pH值为4、6、7、8、10时,0.6g/L的KGM的特性粘度分别为1520.2 mL/g、1472 mL/g、1616.6 mL/g、1590.5 mL/g、1414.1 mL/g,代入已建立的Mark-Houwink方程[η]=5.96×10^-2 M_W^0.73,求得对应pH值下KGM的重均摩尔质量M_W分别为1.07×10⁶、1.04×10⁶、1.18×10⁶、1.16×10⁶、0.99×10⁶;刚果红（CR）实验表明:KGM可能具有某种螺旋结构,而高pH值条件可能致使这种螺旋结构发生解体。2.交联羧甲基魔芋葡甘聚糖改性条件的研究以异丙醇为分散剂,环氧氯丙烷为交联剂,在碱性介质中由一氯乙酸和魔芋葡甘聚糖（KGM）反应,制备交联羧甲基魔芋葡甘聚糖（CCMKGM）,通过二次回归正交旋转组合设计对其进行了优化,根据SAS分析得出最佳制备条件:NaOH为12mL、MCA为12mL、ECH为1mL,在最佳条件下测得取代度为0.6068。改性KGM对金属离子Cu²⁺、Cr³⁺、Cd²⁺、Pb²⁺的吸附率及其吸附容量:对Cu²⁺的吸附率为78.62%,Cr³⁺的吸附率为85.47%,Cd²⁺的吸附率为74.20%、Pb²⁺的吸附率为99.15%;对Cu²⁺的吸附容量为24.94mg/g,Cr³⁺的的吸附容量为24.27mg/g,Cd²⁺的吸附容量为23.92mg/g,Pb²⁺的吸附容量为26.04mg/g。3.交联羧甲基魔芋葡甘聚糖对金属离子的吸附及解吸性能研究考察了金属离子初始浓度、吸附时间、吸附剂用量、pH、温度对交联羧甲基魔芋葡甘聚糖吸附水中Cu²⁺、Cd²⁺、Cr³⁺以及Pb²⁺的影响,对吸附动力学进行了探讨。结果表明,金属离子初始浓度、吸附时间、吸附剂用量、pH是影响吸附效果的重要因素,在金属离子初始浓度为200mg/L、吸附剂用量0.75%、pH值为5、温度为25℃时对金属离子的吸附率最好。经过20min,四种金属离子在交联羧甲基魔芋葡甘聚糖上的吸附可达平衡,吸附率分别为Cu²⁺93.51%、Cd²⁺91.02%、Cr³⁺89.68%、Pb²⁺97.64%。对交联羧甲基魔芋葡甘聚糖吸附金属离子后的解吸试验可知:采用0.3mol/L的HCl、在20min的条件下对Cd（99.6%）、Cu（86.3%）的解吸效果较好,而对Cr（21.8%）、Pb（5.8%）的解吸效果较差。4.魔芋葡甘聚糖、交联羧甲基魔芋葡甘聚糖及其吸附金属离子后产物的结构表征通过傅立叶红外光谱、拉曼光谱、X-射线衍射光谱以及扫描电镜等现代仪器分析手段,对魔芋葡甘聚糖、交联羧甲基魔芋葡甘聚糖及其吸附金属离子后产物进行了结构表征。由红外光谱图谱和拉曼光谱图谱分析:KGM存在乙酰基,通过交联羧甲基改性后,在CCMKGM中乙酰基被脱除。另外,在指纹区,三者的结构也发生了很大的变化。X-衍射图谱分析:KGM的X-衍射图谱,KGM主要呈现无定型结构,仅有少数结晶。CCMKGM晶型结构也没有发生大的变化,但有新的衍射峰出现。而MCCMKGM峰的强度明显降低,面间距变小。电镜扫描分析:魔芋葡甘聚糖表层的细胞壁层排列相当紧密,表面光滑。羧甲基交联魔芋葡甘聚糖颗粒表面凸凹不平,呈褶皱状。交联魔芋葡甘聚糖吸附金属后,在表面形成一层层厚厚的吸附层。更多还原

【Abstract】 Konjac glucomannan（KGM）,an abundant natural polysaccharide coming out after starch and celluloses,gradually became promising environment friendly material.This article make KGM as main object of research,basing on the solution behavior of KGM in different pH values,intends to study the optimization synthesis conditions and the capacity of adsorption and desorption for metal ions of Crosslinked Carboxymethyl Konjac Glucomannan,analyse the structural characteristic of KGM,CCMKGM and MCCMKGM via Fourier Transform Infrared Spectrum,Laser Raman Spectrum,X-Ray Diffraction and Scanning Electron Microscopy etal.The main results of this paper are as follows:1.Primary study on solution conformation of Konjac Glucomannan in different pH valuesThe instrinsic viscosity in different pH values of Konjac Glucomannan（KGM） solution was studied finely by viscosimetry.The effects of pH value and urea concentration on KGM conformation are discussed by KGM-Congo red complex.The instrinsic viscosity experiment showed that the instrinsic viscosity of 0.6g/L KGM solution is 1520.2mL/g,1472mL/g,1616.6mL/g,1590.5mL/g,1414.1mL/g in pH value 4,6,7,8 and 10,so the correlative Molecular Weight（Mw）is 1.07×10⁶,1.04×10⁶, 1.18×10⁶,1.16×10⁶,0.99×10⁶.The KGM-Congo red complex experiment suggested that KGM might have certain helical conformation,which is destroyed at high pH value.2.Study on preparation of Crosslinked Carboxymethyl Konjac GlucomannanUnder alkaline conditions,isopropyl alcohol as dispersing agent,epichlorohydrin （ECH） as crosslinking,Crosslinked Carboxymethyl Konjac Glucomannan（CCMKGM） was prepared through reaction of monochloroacetic acid（MCA） and konjac glucomannan.Conditions of preparation of modified KGM were studied and optimized by quadratic regress revolving cross-experiment.The optimization synthesis conditions analyzed by SAS soft were NaOH 12mL,MCA 12mL,ECH 1mL.Under this condition, the degree of substitution of CCMKGM is 0.6068.3.Study on the capacity of adsorption and desorption for metal ions of Crosslinked Carboxymethyl Konjac GlucomannanThe effect of metal ions concentration,contact time,pH,adsorbent amount and temperature on the adsorption of Cu²⁺,Cd²⁺,Cr³⁺ and Pb²⁺ in water onto CCMKGM are investigated in this paper.The Adsorption Kinetics of CCMKGM for metal ions are discussed.The results show that metal ions concentration,contact time,pH,adsorbent amount are the affecting factors on adsorption capacity.The optimization adsorption conditions are metal ions concentration 200mg/L,adsorbent amount 0.75%,pH value 5, temperature 25℃.The adsorption equilibrium of the four metal ions onto CCMKGM can carried out after 20 mins,then,the adsorption rates are Cu²⁺ 93.51%,Cd²⁺ 91.02%,Cr³⁺ 89.68%and Pb²⁺ 97.64%.The desorption for metal ions results show that the desorption capacity is Cd²⁺99.6%,Cu²⁺86.3%,Cr³⁺21.8%and pb²⁺5.8%.4.Study on the structural characteristic of KGM,CCMKGM and MCCMKGMStudy on the structural characteristic of KGM,CCMKGM and MCCMKGM via Fourier Transform Infrared Spectrum,Laser Raman Spectrum,X-Ray Diffraction and Scanning Electron Microscopy etal.Fourier Transform Infrared Spectrum and Laser Raman Spectrum suggested that An acetyl group exists in KGM structure,deacetylation occurs on CCMKGM after the reaction of Crosslinked Carboxymethyl.In addition,many structures have changed in fingerprint district.The X-ray diffraction pattern analysis revealed that the X-ray diffraction patterns of KGM mainly show amorphous structure and only a few crystal.CCMKGM crystal structure has no big change,but find some new diffraction peaks,the peak intensity of MCCMKGM decreased significantly and surface spacing became smaller.Scanning electron microscope suggested that KGM surface of the cell wall are very close and smooth.The surface of CCMKGM granule is bumpiness and grievances.It formed a thick absorption layer on the surface of MCCMKGM.更多还原