导　　师： 贾德民

学科专业： 080502

授予学位： 博士

作　　者： ;

机构地区： 华南理工大学

摘　　要： 随着工业带来的环境污染的加剧，水污染已成为全球化问题，水处理成为世界各国环境保护工作的重点。壳聚糖具有环境相容性好、可再生、资源丰富以及高度可降解性等优点，在水处理领域已引起越来越多的关注。海藻酸钠具有低毒性，良好的生物相容性、增稠性、成膜性、凝胶性能以及高度可降解性，并且价廉易得，这些独特性能使其在众多领域中获得了广泛应用，而其内部的多孔结构使其成为良好的吸附材料。 壳聚糖分子链上含有大量的伯氨基，海藻酸钠分子链上含有大量的羧基，若将这两种天然高分子材料经过共混、交联等改性后制备出壳聚糖//海藻酸钠改性聚合物，作为高分子絮凝剂，有可能发挥二者各自的优点，产生性能上的协同作用，具有分子量分布广，活性基团点多，结构多样化、絮凝吸附性能好、安全无毒、可完全生物降解、原料来源丰富，价格低廉等特点，将是一种有发展前景的“绿色絮凝剂”。但迄今尚未见利用壳聚糖//海藻酸钠改性聚合物作絮凝剂的报道。 本文首先以壳聚糖、海藻酸钠作为主要原料，利用壳聚糖和海藻酸钠分子间的静电作用，采用直接法制备了壳聚糖//海藻酸钠改性聚合物/(M-CS//SA/)，用FTIR、SEM、X-RD及TGA等手段表征了其结构和性能。结果表明：SA的引入破坏了CS分子链间的有序排列，M-CS//SA表现为非晶态，具有多孔结构，其热稳定性比CS增加。对M-CS//SA用于印染废水处理及Cu~/(2+/)和Cr/)2O/_72-的吸附进行了研究。分别考察了M-CS//SA用量、吸附时间和pH值等因素对吸附Cu~/(2+/)、Cr2O72-的影响。吸附动力学研究表明，M-CS//SA对Cu~/(2+/)的吸附过程较为符合拟一级动力学方程，对Cr2O72--的吸附过程较为符合拟二级动力学方程。M-CS//SA对浊度去除率好，而对COD去除率不够理想，对Cu~/(2+/)和Cr2O72-的吸附效果比壳聚糖好。 为了优化壳聚糖//海藻酸钠聚合物的絮凝性能，采用醚化方法合成了壳聚糖//海藻酸钠交联聚合物（E-CS//SA）。FTIR、SEM、X-RD、TGA等分析测试结果表明：壳聚糖与海藻酸钠之间产生了明显的化学反应，M-CS//SA为非晶态物质，呈多孔结构，且比M-CS//SA更细密。以脱色率、COD去除率、除浊度等作为评价指标，确定了反应的最佳条件，同时也考察了各反应条件对产率的影响，以及脱乙酰度、溶液的pH值、聚合物的投加量、沉降时间、不同的水溶性染料等对E-CS//SA絮凝性能的影响。对E-CS//SA用于印染废水的处理进行了研究，发现其对印染废水有很好的吸附效果，在最佳反应条件下，E-CS//SA产率可达到80％以上，对实际染料废水的脱色率达到86％，COD去除率达92％，除浊率达97％。 考察了E-CS//SA对重金属离子Cr2O72-、Pb~/(2+/)、Cd~/(2+/)、Cu~/(2+/)、Zn~/(2+/)的吸附率和吸附容量，并对其吸附动力学进行了探讨，发现E-CS//SA对重金属离子吸附具有较快的动力学速度，在最佳条件下，E-CS//SA对Cr2O72-、Pb~/(2+/)、Cd~/(2+/)、Cu~/(2+/)、Zn~/(2+/)的吸附率分别达到88/%、94％、95％、80.43/%和58.33％，对Pb~/(2+/)、Cd~/(2+/)吸附容量分别为56.6mg//g、47.0mg//g。动力学研究表明：E-CS//SA对Zn~/(2+/)、Cu~/(2+/)吸附机理为化学吸附为主的单分子层吸附机制，且吸附速度明显比CS更快，说明了E-CS//SA的活性基团增多，对金属离子的螯合能力增强。扫描电镜照片显示，E-CS//SA改性聚合物吸附Cu~/(2+/)以后表面不再光滑。 为了改善醚化法所得聚合物的稳定性及进一步提高絮凝性能，以环氧氯丙烷作交联剂，制备了环氧氯丙烷交联壳聚糖//海藻酸钠/(C-CS//SA/)。以交联度作为评价指标，利用正交试验设计对交联过程的各个影响因素（CS:SA质量比、环氧氯丙烷用量、反应温度、反应时间）进行了分析，得出了交联过程的最佳制备条件。通过FTIR、SEM、X-RD和TGA等手段对C-CS//SA的结构形态进行了表征，结果表明：反应是按照设定的路径进行；SA的引入破坏了CS的晶体结构；C-CS//SA形成更好的空间结构，表面具有大量空穴结构，有利于吸附性能的提高。 利用C-CS//SA对Cu~/(2+/)的吸附，讨论了吸附时间、溶液pH值、絮凝剂投加量、交联度对吸附性能的影响，同时探讨了吸附动力学和吸附等温线，并将其应用于实际印染废水处理。结果表明：在实际印染废水处理中，C-CS//SA比M-CS//SA和E-CS//SA效果好。同时，探讨了C-CS//SA的溶胀度与溶胀时间、溶液pH、温度等条件的关系，得出了最佳的溶胀条件；探讨了C-CS//SA的吸附性能（脱色率、除浊率、COD去除率）与交联度的关系。在最佳条件下，C-CS//SA对印染废水的脱色率可达96.5/%，COD去除率为95.2/%，浊度去除率为99.5/%。 最后，对三种制备CS//SA改性聚合物的方法和所得产物的吸附性能进行了比较。三种制备方法各有优缺点，并且所得产物性能不尽相同，可根据具体情况选择。在对印染废水处理的实际应用中，以C-CS//SA为优选。 With the pollution caused by industrialization, water pollution has become a globalproblem. Therefore, water treatment has become an important facet of protecting environmentfor every country. Chitosan has good environmental compatibility, reproducibility, richresources and high biodegradation. It has aroused more and more attention in water treatmentfield. Sodium alginate has low toxicity, good biocompatibility, thickening property, the filmforming ability, gel performance, high biodegradation and cheap. These unique propertiesmake sodium alginate have wide applications in many fields, and its internal porous structuremakes it a good adsorption material. There are a large number of amino group on chitosan molecular chains, and there areplenty of carboxyl group on sodium alginate molecular chains. After blending andcrosslinking modification of the two natural polymers, the obtaining modified polymer basedchitosan and sodium alginate as a flocculant will have broad molecular weight distribution,many of active group points and structural diversity. It can be completely biodegradable andhas good 'environmental acceptability'. It will be a kind of 'green flocculant '. Howeverthere is no report of chitosan//sodium alginate modified polymer as flocculant till now. Using chitosan and sodium alginate as main raw materials, chitosan//sodium alginatepolymer /(M-CS//SA/) was prepared via electrostatic interaction between chitosan and sodiumalginate. The product was characterized with FTIR, SEM, X-RD and TGA. It was showed thatthe introduction of SA destroyed the regularity of CS molecular chains; M-CS//SA became apolymer with amorphous porous structure. Its thermal stability is better than CS. TheM-CS//SA was used for dyeing wastewater treatment and Cu~/(2+/)and Cr2O72-adsorption. Theeffects of adsorption time, pH value and M-CS//SA dosage on the adsorption Cu~/(2+/)and Cr2O72-were investigated. The adsorption of Cu~/(2+/)on M-CS//SA was followed the pseudo-first-orderdynamics, And the adsorption of Cr2O72-on M-CS//SA was followed the pseudo-second-orderdynamics. M-CS//SA is good for turbidity removal rate, but it is not ideal on the COD removalrate. M-CS//SA is better than CS to Cu~/(2+/)and Cr2O72-adsorption. In order to optimize the performance of chitosan//sodium alginate polymer flocculant,chitosan//sodium alginate polymer /(E-CS//SA/) was synthesized using the etherification method.Its structure and properties were investigated by using FTIR, SEM, X-RD, TGA, The resultsshow that: chitosan has obvious chemical reaction with sodium alginate. The structure ofM-CS//SA is amorphous and porous, and is more fine than CS. Taking decoloring rate, CODremoval rate and turbidity as evaluation indexes, the optimal conditions were found. At thesame time, the effects of the reaction conditions on the yield were investigated. The effects of deacetylation degree, solution pH value, polymer dosage, sedimentation time, different watersoluble dyes on the flocculation performance were also investigated. The product wasexplored to use for printing and dyeing wastewater treatment. It was found that the producthas a good adsorption effect on printing and dyeing wastewater. Under the optimum reactionconditions, E-CS//SA yield can reach more than80/%. To the actual dye wastewater,decolorizing rate of E-CS//SA reached86/%, COD removal rate reached92/%, and turbidityremoval rate reached97/%. The effect of E-CS//SA on Cr/_2O/_7~/(2-/),Pb~/(2+/),Cd~/(2+/),Cu~/(2+/),Zn~/(2+/)adsorption rate and the adsorptioncapacity was investigated. The adsorption dynamics was studied. The adsorption of E-CS//SAto heavy metal ions has quicker dynamic speed. In the best conditions, the adsorption rate ofE-CS//SA to Cr2O7~/(2-/),Pb~/(2+/),Cd~/(2+/),Cu~/(2+/),Zn~/(2+/)were88/%,94/%,95/%,80.43/%and58.33/%respectively. The adsorption capacity to Pb~/(2+/),Cd~/(2+/)were56.6mg//g and47.0mg//g. Dynamicsresearch showed that: the adsorption mechanism of E-CS//SA to Cu~/(2+/)and Zn~/(2+/)ismonomolecular layer adsorption mechanism in which chemical adsorption is primarily. Andadsorption speed is obviously faster than CS, which proved once again that E-CS//SA withmore active groups can increased chelating ability to metal ion. Scanning electron microscopyimages showed that the surface of E-CS//SA after adsorption Cu~/(2+/)was no longer smooth. In order to improve the polymer stability and flocculation performance, a new kind ofcrosslinked chitosan//sodium alginate flocculant/(C-CS//SA/) was prepared usingepichlorohydrin as the crosslinking agent. With degree of crosslinking as evaluation index,using the orthogonal experimental design to analyze the influence factors of crosslinkingprocess /(CS: SA ratio, epichlorohydrin dosage, reaction temperature, reaction time/), the bestpreparation conditions of the crosslinking process were obtained. The structure of the product was characterized by means of FTIR, SEM, X-RD and TGA.The results showed that the reaction was according to the path of the set, the introduction ofSA destroyed CS crystal structure, C-CS//SA formed better spatial structure, the surface has alarge number of holes, which is beneficial to the improvement of the performance of theadsorption. Using the polymer /(C-CS//SA/) to adsorption Cu2+, influence of adsorption time, thesolution pH value, flocculant dosage and degree of cross-linking on the adsorptionperformance were discussed. At the same time adsorption dynamics and adsorption isothermwere discussed, and the polymer was applied to the actual printing and dyeing wastewatertreatment. The results showed that C-CS//SA was the best in C-CS//SA, M-CS//SA andE-CS//SA on the actual printing and dyeing wastewater treatment.To obtain the best swelling conditions, the relationships of the polymer swelling degree with swelling time, solution pHand temperature were investigated, and the relationships of adsorption performance of thepolymer with degree of cross-linking were discussed. In the best conditions of crosslinkingand swelling, the decolorizing rate of C-CS//SA to printing and dyeing wastewater can reach96.5/%, COD removal rate was95.2/%, the turbidity removal rate is99.5/%. Finally, three methods of the preparation of CS//SA polymer and the adsorptionperformance of the products were compared. Three preparation methods have theiradvantages and disadvantages, and the products performance is not the same, which can bechosen in practical applications. In the printing and dyeing wastewater treatment, C-CS//SAwas the best.

关 键 词： 壳聚糖 海藻酸钠 改性聚合物 絮凝剂 吸附性能 染料废水

分 类 号： [X703.5]

领　　域： [环境科学与工程]