DMDAAC改性纤维素滤纸的制备及其性能研究

发布时间：2018-08-31 20:26

【摘要】：染料广泛应用于材料的染色。由于生产过程着色材料的洗涤和染料的不完全着色等原因,约有10%到15%的染料被排放至自然水体中,而且大多数有机染料具有毒性、不可生物降解性、致畸致癌性和致突变性,对人类健康和水体生物产生了严重威胁,极大地影响了生态平衡。因此,开发高效的染料吸附材料成为研究热点。纤维素是自然界中储藏量最丰富的一种具有生物可降解性、高强度和高热稳定性的低成本天然高分子化合物。对纤维素进行改性,研发具备优良吸附染料性能的新型纤维素材料具有重要的应用价值。论文采用原子转移自由基(ATRP)法,以二甲基二烯丙基氯化铵(DMDAAC)为单体改性纤维素滤纸,通过控制单体与引发剂的比例,制备了不同接枝率的改性纤维素滤纸(Paper-PDMDAAC)。随着单体DMDAAC投量的增加,Paper-PDMDAAC的接枝率线性增大。通过ATR-FTIR和XPS对滤纸改性前后的表面组成和结构进行了分析,单体DMDAAC以共价键形式与滤纸表面纤维素成功接枝。采用扫描电镜分析表面形貌,改性前后滤纸形貌几无变化,保持了滤纸的原有结构形貌。静态水接触角测试表明,Paper-PDMDAAC有着优良的亲水性。论文研究了 Paper-PDMDAAC对阴离子型染料甲基橙的吸附。随着接枝率的增大,甲基橙的平衡吸附量逐级增加。随着甲基橙溶液pH值的减小,吸附能力增强。在低浓度的甲基橙溶液中,Paper-PDMDAAC对甲基橙的吸附快速达到吸附平衡,且脱色率很高。随着甲基橙溶液中NaCl浓度的升高,Paper-PDMDAAC对甲基橙的平衡吸附量明显下降,吸附平衡量对溶液中离子浓度十分敏感。当甲基橙溶液初始浓度为100 mg/L,体积为50 mL,pH为4.6,吸附温度为25 o℃时,质量为75 mg、接枝率12.5%的Paper-PDMDAAC对甲基橙的脱色率达90%以上。Paper-PDMDAAC对甲基橙的吸附符合Langmuir等温吸附模型及伪二级动力学模型,而且为单分子层吸附,接枝率12.5%的Paper-PDMDAAC对甲基橙的理论最大吸附量为243.9 mg/g。经过6次再生测试后,Paper-PDMDAAC对甲基橙仍有良好的吸附效果,表明其具有良好的重复使用性和稳定性。论文研究了 Paper-PDMDAAC对阴离子型染料甲基橙和阳离子型染料罗丹明B的选择性吸附能力。Paper-PDMDAAC可以快速高效吸附去除甲基橙;而Paper-PDMDAAC吸附罗丹明B的效果差。甲基橙和罗丹明B的混合溶液吸附分离研究表明,随着接枝率的增加,选择性吸附分离效果愈加明显;当Paper-PDMDAAC的接枝达到12.5%时,吸附分离达到了一种平衡的状态;对甲基橙的脱色率高达99.07%,而对罗丹明B脱色率低至3.33%;Paper-PDMDAAC对甲基橙和罗丹明B混合溶液表现出了优良的选择性吸附分离。经过6次再生使用后,Paper-PDMDAAC对甲基橙的脱色率仍高于95%,而对罗丹明B的脱色率仍低于6%,同时抗张强度仍高于28 kN/m2,Paper-PDMDAAC有着良好的重复使用性和稳定性。进一步对Paper-PDMDAAC选择吸附分离混合染料的机理进行研究,滤纸平均孔径远大于染料分子直径,几乎不依靠物理拦截。Paper-PDMDAAC与染料分子之间主要靠静电作用吸附结合,对甲基橙表现出静电引力,对罗丹明B表现出静电斥力,从而致使其具有选择吸附效能。
[Abstract]:Dyes are widely used in dyeing materials. Due to the washing of coloring materials and incomplete coloring of dyes, about 10% to 15% of the dyes are discharged into natural waters. Most organic dyes are toxic, non-biodegradable, teratogenic, carcinogenic and mutagenic, which have produced effects on human health and aquatic organisms. Therefore, the development of efficient dye-adsorbing materials has become a research hotspot. Cellulose is one of the most abundant natural macromolecule compounds with biodegradability, high strength and high thermal stability. Cellulose is modified to develop excellent adsorbing dyes. The modified cellulose filter paper (Paper-PDMDAAC) with different grafting ratio was prepared by atom transfer radical (ATRP) method and DMDAAC as monomer to modify cellulose filter paper by controlling the ratio of monomer to initiator. The surface composition and structure of filter paper before and after modification were analyzed by ATR-FTIR and XPS. The monomer DMDAAC was successfully grafted with cellulose on the surface of filter paper in the form of covalent bond. The adsorption of methyl orange by Paper-PDMDAAC was studied in this paper. With the increase of grafting ratio, the equilibrium adsorption capacity of methyl orange increased step by step. With the decrease of pH value of methyl orange solution, the adsorption capacity increased. With the increase of NaCl concentration in methyl orange solution, the equilibrium adsorption capacity of Paper-PDMDAAC on methyl orange decreased significantly, and the adsorption equilibrium was very sensitive to the ionic concentration. When the initial concentration of methyl orange solution was 100 mg/L, the volume of methyl orange solution was 50 mL, and the pH was 0. Paper-PDMDAAC with a grafting rate of 12.5% and a mass of 75 mg had a decolorization rate of over 90% for methyl orange. The adsorption of methyl orange by Paper-PDMDAAC conformed to Langmuir isothermal adsorption model and pseudo-second-order kinetic model. The amount of Paper-PDMDAAC was 243.9 mg/g. After six regeneration tests, Paper-PDMDAAC still had good adsorption effect on methyl orange, indicating that it had good reusability and stability. The selective adsorption ability of Paper-PDMDAAC on anionic dye methyl orange and cationic dye rhodamine B was studied. Methyl orange was adsorbed by Paper-PDMDAAC, but Rhodamine B was not adsorbed by Paper-PDMDAAC. The results of adsorption separation showed that the effect of selective adsorption was more obvious with the increase of grafting ratio. When the grafting ratio of Paper-PDMDAAC reached 12.5%, the adsorption separation reached a balanced state. The decolorization rate of Paper-PDMDAAC for methyl orange and Rhodamine B was still higher than 95% after 6 times of regeneration, while that for rhodamine B was still lower than 6%, and the tensile strength was still higher than 28 kN/m2, Pape-PDMDAAC showed excellent selective adsorption and separation. R-PDMDAAC has good reusability and stability. The mechanism of selective adsorption and separation of mixed dyes by Paper-PDMDAAC was further studied. The average pore size of filter paper was much larger than that of dye molecules, almost independent of physical interception. Gravitation exhibits electrostatic repulsion on Rhodamine B, resulting in its selective adsorption efficiency.
【学位授予单位】：福建农林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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