功能性CA复合纳米纤维膜的制备及其性能研究

发布时间：2018-07-03 09:20

  本文选题：静电纺丝 + 醋酸纤维素　； 参考：《五邑大学》2014年硕士论文

【摘要】：静电纺丝作为一项制备纳米纤维材料的新技术,其所制备的纳米纤维膜具有纤维直径小、比表面积大、孔隙率高等特点,从而使静电纺纳米纤维膜在水体有害物质过滤及吸附方面有着极大的应用潜力。 本文通过以环保型材料醋酸纤维素(CA)为主要组分,聚丙烯腈(PAN)为添加组分,利用静电纺丝法制备了CA/PAN复合纳米纤维膜。在此基础上,通过对复合膜后期的改性处理制备了功能化CA复合纳米纤维膜,进一步研究了其对水溶液中六价铬离子(Cr6+)的吸附分离性能,本文主要进行了以下几个方面的工作：首先在探讨了CA. PAN混合溶液特性的基础上,利用多喷头静电纺丝制备了CA/PAN复合纤维膜,通过扫描电镜(SEM)对纤维形貌表征发现,在以强极性溶剂二甲基亚砜(DMSO)为溶剂时,PAN的混入提高了共混溶液的可纺性。红外图谱(FT-IR)分析表明,在以CA为主要组分的复合纤维中,CA、PAN存在一定程度的分子级相容,为部分相容体系。其次,通过对不同比例的纤维膜力学性能及热性能分析发现,PAN含量的增加有助于提高复合膜的断裂强力和热稳定性,且CA/PAN复合比例在7/3时断裂强力达到最大值294.6cN,断裂伸长率9.33%,但再继续增大PAN的比例复合膜的力学性能将下降,从而确定了最佳的CA/PAN复合比例为7/3。在此基础上,进一步探讨了各纺丝参数对纤维直径大小及纤维膜比表面积的影响,并通过对纺丝工艺条件的优化,获得纤维直径分布均匀且大小在200nm左右的复合纳米纤维膜。最后,利用盐酸羟胺溶液对CA复合膜进一步改性处理,FT-IR图谱分析表明,本文成功制备了含有偕胺肟基团的CA复合纳米纤维膜,并通过对复合膜中腈基转化率的探讨及改性后复合膜力学性能的表征,获得了最佳的改性条件。 对Cr6+吸附数据表明,CA复合膜的改性处理显著提高了其对重金属离子的吸附性能,且对Cr6+吸附过程符合朗格缪尔(Langmuir)单分子层等温吸附模型,吸附过程为定向吸附且存在饱和吸附值,各温度点的最大理论吸附量分别为74.29mg/g(30℃)、77.10mg/g (40℃),79.24mg/g (50℃),且复合膜对Cr6+吸附过程符合准二阶动力学吸附反应。吸附热力学研究发现,纤维膜对Cr6+的吸附为吸热过程,且吸附过程可自发进行,吸附过程除存在物理和化学吸附反应之外,纤维膜与Cr6+之间可能还发生了离子交换反应。
[Abstract]:Electrospinning is a new technology for preparing nanofiber materials. The nanofiber membrane has the characteristics of small fiber diameter, large specific surface area, high porosity and so on. Therefore, the electrospun nanofiber membrane has great application potential in the filtration and adsorption of harmful substances in water body. In this paper, CA / pan composite nanofiber membranes were prepared by electrospinning with cellulose acetate (CA) as the main component and polyacrylonitrile (pan) as the additive component. On this basis, the functionalized CA nanofiber membrane was prepared by the late modification of the composite membrane, and the adsorption and separation properties of Cr 6 in aqueous solution were further studied. The main work of this paper is as follows: firstly, CAA is discussed. On the basis of the properties of pan mixed solution, CA / pan composite fiber membrane was prepared by multi-nozzle electrostatic spinning. The morphology of the fiber was characterized by scanning electron microscopy (SEM). When dimethyl sulfoxide (DMSO) was used as solvent, the spinnability of the blend solution was improved. The infrared spectra (FT-IR) analysis showed that there was a certain degree of molecular compatibility of CAPAN in the composite fibers with CA as the main component, and it was a partial compatibility system. Secondly, through the analysis of the mechanical and thermal properties of fiber membrane with different proportion, it is found that the increase of pan content can improve the fracture strength and thermal stability of the composite membrane. When the ratio of CA- / pan composite is 7 / 3, the maximum breaking strength is 294.6 CN, the elongation at break is 9.33, but the mechanical properties of the composite membrane with increasing the ratio of pan will decrease, and the optimum ratio of CA-PAN is 7 / 3. On this basis, the effects of spinning parameters on fiber diameter and fiber membrane specific surface area were further discussed. By optimizing the spinning process conditions, the composite nanofiber membrane with uniform fiber diameter distribution and size about 200nm was obtained. Finally, the FT-IR spectra of CA composite membrane modified by hydroxylamine hydrochloride solution showed that the CA composite nanofiber membrane containing amidoxime group was successfully prepared. The optimum modification conditions were obtained by discussing the conversion of nitrile group in the composite membrane and characterizing the mechanical properties of the modified composite membrane. The adsorption data of Cr _ 6 show that the modification of the composite membrane can significantly improve the adsorption performance of heavy metal ions, and the adsorption process of Cr _ 6 is in accordance with Langmuir monolayer isotherm adsorption model. The adsorption process is orientated and saturated, and the maximum theoretical adsorption capacity at each temperature is 77.10 mg / g (40 鈩，

本文编号：2093165