功能性纤维素气凝胶的制备及其在水净化中的应用研究

发布时间：2018-06-05 14:39

本文选题：纤维素 + 功能化改性　；参考：《浙江理工大学》2017年硕士论文

【摘要】：在世界各国均面临着石化资源日益匮乏和环境问题日益恶化的背景下,利用丰富的农林生物质资源,开发环境友好、可循环利用的生物质基功能材料,最大限度地替代或部分替代石油基材料并应用于各个领域,具有重要的理论意义和实际应用价值。纤维素作为地球上含量最丰富的天然高分子材料,具有可再生、生物可降解、生物相容、机械性能好、易化学改性等诸多优异性能,因此,采用绿色化学技术,研究和开发纤维素基功能材料一直是化工、材料、能源环境、生物医药等诸多领域的重要研究课题。本论文以废弃棉纤维为纤维素原料,通过绿色、温和、简单的工艺技术制备了一种低密度、高孔隙率的纤维素气凝胶,考察了不同纤维素浓度对其形态结构、物化性质等的影响。在此基础上,利用甲基三氯硅烷(MTCS)对纤维素气凝胶进行化学改性,制备了疏水性纤维素气凝胶,研究了疏水性纤维素气凝胶的油水分离性能;另一方面,采用化学原位沉积法制备了纤维素/氧化石墨烯/氧化亚铜(CE/GO/Cu_2O)三元杂化气凝胶,进一步研究了三元杂化纤维素气凝胶对有机染料甲基橙的可见光催化降解性能。论文研究结果如下:(1)纤维素气凝胶的制备及其物化性能:以废弃棉纤维作为纤维素原料,N,N-亚甲基双丙烯酰胺为交联剂,采用冷冻干燥技术制备出具有三维连通多孔结构的纤维素气凝胶。研究发现,纤维素溶液浓度对其凝胶化时间、气凝胶的微观结构及力学性能等均具有显著影响。室温条件下,当纤维素浓度从2 wt%提高到4 wt%时,凝胶化时间从265 min缩短到165 min;所得纤维素气凝胶的孔径由0.05-4μm增大至200μm,其密度相应的由0.027增加至0.056 g cm~(-3),孔隙率均高达96%以上,呈现出良好的三维多孔结构;同时,所制备的纤维素气凝胶具有优异的力学性能,当其压缩形变为80%时,纤维素气凝胶(2-4wt%)的压缩强度达到1.10-3.85 MPa。(2)疏水性纤维素气凝胶的制备及其油水分离性能:采用化学气相沉积法(CVD)对浓度为2 wt%的纤维素气凝胶进行硅烷化改性,得到疏水性纤维素气凝胶。FTIR、XPS等分析结果表明,MTCS与纤维素分子表面的羟基形成了C-O-Si共价结合,从而赋予了纤维素气凝胶优异、持久的疏水性能。接触角测试发现,经硅烷化改性的纤维素气凝胶表面水接触角达到141°,内部的接触角也达到了128.4°,5天后,其表面接触角仍保持在131°。这主要得益于纤维素气凝胶相互贯通的多孔网络结构;对不同油类和非极性有机溶剂的吸附性能研究发现,疏水性纤维素气凝胶呈现出优良的油水分离能力,其对泵油、植物油、氯仿和甲苯的吸附量分别高达59.32、55.85、46.23和40.16 g g~(-1);此外,通过简单的吸收挤压方式即可以实现循环油水分离,经十次循环后,疏水性纤维素气凝胶对泵油和氯仿的吸附量仍分别达到37.5 g g~(-1)和38 g g~(-1),具有良好的循环使用性能。(3)CE/GO/Cu_2O三元杂化气凝胶的制备及其光催化性能:将纤维素气凝胶的大比表面积和高吸附能力与氧化亚铜(Cu2O)的可见光催化活性相结合,采用化学原位沉积法制备了CE/GO/Cu_2O三元杂化气凝胶。SEM观察发现,正八面体的Cu_2O纳米颗粒均匀地镶嵌在三元杂化气凝胶的孔壁上,有效地抑制了纳米颗粒的团聚;UV-vis漫反射光谱和PL光谱分析表明,与纯Cu_2O相比,纤维素气凝胶和氧化石墨烯的引入,不仅扩展了CE/GO/Cu_2O三元杂化气凝胶的光吸收能力,同时还提高了光生电子和空穴的分离效率;经350 W氙灯模拟光照120分钟,MO的光催化降解率可达92%,经5次循环后,对MO的光催化降解率仍保持在80%,展现出良好的光催化稳定性。本论文以废弃棉纤维为原料,采用绿色、温和、简单的工艺方法制备得到了具有相互贯通三维多孔结构的纤维素气凝胶。经功能化改性,分别获得了具有疏水性的纤维素气凝胶及具有光催化活性的纤维素复合气凝胶,并研究了其在油水分离、有机染料的可见光催化降解中的应用潜能。论文研究结果对实现纤维素资源在水环境控制与治理中的应用提供了理论依据和技术支持。
[Abstract]:In the context of the increasing shortage of petrochemical resources and the worsening environmental problems all over the world, the utilization of abundant agricultural and forestry biomass resources, the development of environmentally friendly, recyclable biomass based functional materials, and the maximum replacement or partial substitution of petroleum based materials, should be used in various fields, which have important theoretical significance and reality. Cellulose is the most abundant natural polymer material on the earth. It has many excellent properties, such as renewable, biodegradable, biocompatible, mechanical properties, chemical modification and so on. Therefore, the use of green chemical technology, the research and development of cellulose based functional materials has been the chemical, material, energy environment, biological medicine. In this paper, a low density, high porosity cellulose aerogel was prepared by green, mild and simple technology, and the effects of different cellulose concentration on its morphological structure and physicochemical properties were investigated by using the waste cotton fiber as the cellulose material, and on this basis, the methyl three chlorosilane (M) was used. TCS) cellulose aerogels were chemically modified, hydrophobic cellulose aerogels were prepared, and the oil and water separation properties of hydrophobic cellulose aerogels were studied. On the other hand, cellulose / graphene oxide / copper oxide (CE/GO/Cu_2O) three element hybrid aerogels were prepared by chemical in situ deposition, and the three element hybrid fibers were further studied. Photocatalytic degradation of organic dye methyl orange by plain aerogels. The results are as follows: (1) the preparation and physicochemical properties of cellulose aerogels: cellulose as raw material, N, N- methylene double acrylamide as crosslinking agent, and the preparation of cellulose with three-dimensional connected porous structure by freeze drying technology It is found that the concentration of cellulose solution has significant influence on the gelation time, the microstructure and mechanical properties of the aerogels. When the concentration of cellulose is increased from 2 wt% to 4 wt%, the gelation time is shortened from 265 min to 165 min, and the pore size of the fibrin aerogel is increased from 0.05-4 to 200 mu m, and the density of the fibrin aerogel is more than 200 mu m. The corresponding degree increases from 0.027 to 0.056 g cm~ (-3), the porosity is above 96%, showing a good three-dimensional porous structure. At the same time, the prepared cellulose aerogels have excellent mechanical properties. When the compression deformation is 80%, the compressive strength of the cellulose aerogel (2-4wt%) reaches to 1.10-3.85 MPa. (2) hydrophobic cellulose aerogel. Preparation and oil and water separation performance: chemical vapor deposition (CVD) was used to silane the cellulose aerogel with a concentration of 2 wt%, and the hydrophobic cellulose aerogel.FTIR and XPS were obtained. The results showed that the MTCS was combined with the hydroxyl group on the surface of the cellulose molecule, which gave the cellulose aerogel excellent and lasting. The contact angle test found that the surface water contact angle of the silicone modified cellulose aerogels reached 141 degrees, and the internal contact angle reached 128.4 degrees, and the contact angle of the surface remained at 131 degrees after 5 days. This was mainly due to the porous network structure of the cellulose aerogels, and the different oil and non polar organic solvents. The adsorption properties of the hydrophobic cellulose aerogels show a good oil water separation ability. The adsorption capacity of the oil, vegetable oil, chloroform and toluene is up to 59.32,55.85,46.23 and 40.16 g g~ (-1), respectively. In addition, the cyclic oil and water can be separated by a simple absorption and extrusion method. After ten cycles, the hydrophobic fiber can be obtained. The adsorption capacity of the prime aerogels to pump oil and chloroform still reached 37.5 g g~ (-1) and 38 g g~ (-1), and has good recycling performance. (3) the preparation and photocatalytic performance of CE/GO/Cu_2O three hybrid aerogels: the combination of the large surface area and high adsorption energy of the cellulose aerogel with the visible photocatalytic activity of copper oxide (Cu2O). The CE/GO/Cu_2O three element hybrid aerogel.SEM was prepared by chemical in situ deposition. It was found that the Cu_2O nanoparticles of the positive eight sides were inlaid evenly on the pore wall of the three element hybrid aerogels, which effectively inhibited the agglomeration of the nanoparticles. The UV-vis diffuse reflectance spectrum and the PL spectrum analysis showed that the cellulose aerogels and oxidation were compared with the pure Cu_2O. The introduction of graphene not only expands the light absorption capacity of the CE/GO/Cu_2O three element hybrid aerogels, but also improves the separation efficiency of photogenerated electrons and holes. The photocatalytic degradation rate of MO can reach 92% after 120 minutes of simulated illumination by 350 W xenon lamp. After 5 cycles, the photocatalytic degradation rate of MO remains at 80%, showing a good photocatalytic stability. In this paper, the cellulose aerogels with three-dimensional porous structure were prepared by green, mild and simple process using waste cotton fiber as raw materials. The hydrophobic cellulose aerogels and cellulose composite aerogels with photocatalytic activity were obtained by functional modification. The application potential of oil and water separation and visible photocatalytic degradation of organic dyes. The results of the paper provide theoretical basis and technical support for the application of cellulose resources in the control and treatment of water environment.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;TQ427.26

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