氧化石墨烯增强芳纶纳米纤维耐温耐腐蚀机理与空气过滤性能研究

As the increasing severity of air pollution in recent years, a higher standard is urgently required in terms of high temperature emission of dusty gas, which is produced by various boilers and furnaces in industry. The utilization of filtration materials is the key in high temperature filtration. However, the filtration efficiency of traditional materials is low, and the wind resistance is high. By contrast, filtrations that are made from nanofibers, have advantages by possessing massive uniformly distributed and inter-connected pores with small diameter. The nanofibers show lower resistance to wind, and are more effective in filtration. Their applications in air purification at high temperature area, however, have not been reported. Although aramid materials have been widely used in this area, their resistance to high temperature and corrosion needs to be improved. In this project, for the first time, graphene oxide (GO) is introduced into aramid nanofibers, by means of electrostatic spinning, in order to prepare air filtration materials for the high temperature applications. Owing to the exceptional barrier and insulation properties of GO, effects of GO features including size, content, and surface hydrophilicity/hydrophobicity, on the high-temperature and corrosion resistance of the hybrid aramid nanofiber membranes are investigated qualitatively and quantitatively. In the mean time, the relationships between the GO features and the filtration properties of the membranes are analyzed, according to the high aspect ratio and the increased specific surface area that is induced by GO, as well as its reduction effect on surface free energy of the membranes. From this study, a theoretical basis and the corresponding technical parameters are established for the development of high performance air-filtration materials for high temperature uses.

我国大气污染近年来持续加重，对各种工业锅炉、炉窑所排放出来的高温含尘废气排放标准要求更高，过滤材料是高温过滤的核心，传统过滤材料存在过滤效率较低或风阻大的问题。静电纺纳米纤维滤料相对于传统过滤材料，具有孔道贯通性好、孔隙率高、孔径小、孔径分布均匀的特点，具有高效低阻优势，但在高温空气净化应用的研究较少。芳纶高分子材料广泛应用于高温空气净化领域，但其耐温耐腐蚀性能仍需改进。本课题采用静电纺丝技术，首次制备氧化石墨烯掺杂芳纶纳米纤维高温空气净化滤料。基于氧化石墨烯的片阻隔效应，研究氧化石墨烯的尺寸结构、掺杂量、表面亲疏水性对掺杂芳纶纳米纤维滤膜的耐温耐腐蚀性能的影响与机理。基于氧化石墨烯比表面、孔道增加效应和降低滤料表面自由能效应，研究氧化石墨烯的尺寸结构、掺杂量、表面亲疏水性对掺杂芳纶纳米纤维滤膜的空气过滤性能的影响和机理。为制备高性能的高温空气过滤材料提供理论依据和相关技术支持。

我国大气污染近年来持续加重，对各种工业锅炉、炉窑所排放出来的高温含尘废气排放标准要求更高，过滤材料是高温过滤的核心，传统过滤材料存在过滤效率较低或风阻大的问题。静电纺纳米纤维滤料相对于传统过滤材料，具有孔道贯通性好、孔隙率高、孔径小、孔径分布均匀的特点，具有高效低阻优势，但在高温空气净化应用的研究较少。芳纶（PMIA）高分子材料广泛应用于高温空气净化领域，但其耐温耐腐蚀性能仍需改进。此外，聚酰亚胺(PI)是一种具有高热稳定性、良好化学稳定性等优异性能的聚合物材料，在高温气体过滤、组织支架、燃料电池、先进半导体和微电子等领域具有极大的应用潜力。 主要研究采用静电纺丝技术，首次制备氧化石墨烯掺杂芳纶和掺杂聚酰亚胺纳米纤维高温空气净化滤料。基于氧化石墨烯的片阻隔效应，研究氧化石墨烯的尺寸结构、掺杂量、表面亲疏水性对掺杂芳纶和掺杂聚酰亚胺纳米纤维滤膜的耐温耐腐蚀性能的影响与机理。 重要结果：（1）通过发现，当GO的添加量为1.0wt%时，纳米纤维膜的直径呈现更小尺寸分布，其疏水性和空气过滤性能均提高。进一步探讨了添加1.0wt%GO的复合纳米纤维膜的耐温性，经过210℃加热处理后，PMIA纳米纤维膜和PMIA/GO复合纳米纤维膜的空气过滤效率降低，但能维持在90%以上，阻力分别降至46.72Pa、62.28Pa。经过260℃加热处理后，PMIA纳米纤维膜的断裂强度、空气过滤效率和阻力大幅降低，纤维甚至出现断裂现象，而复合纳米纤维膜的空气过滤效率仍保持在89.49%，而阻力仅为58.94Pa。发现经过酸碱浸泡后，其的断裂强度和断裂伸长率均明显降低，过滤效率和阻力均提高，且阻力变化幅度较大。经酸碱溶液浸泡后，虽然过滤效率提高至99%以上，但阻力高达200Pa以上。经初步探究发现GO掺杂对纳米纤维膜的耐腐蚀性改善不明显。（2）确定PI的电纺适宜浓度范围是6.0–12.0 wt%，最佳PI浓度为10.0 wt%，其纤维平均直径最小为264 ± 54 nm，最佳过滤效率为90.4 %。电纺GO/PI复合纳米纤维膜的热稳定性较纯PI纳米纤维膜提高了15 °C，GO含量为0.75 wt%时电纺GO/PI复合纳米纤维膜的整体过滤性能最佳。电纺f-Gr/PI复合纳米纤维膜对0.3 μm DOP的过滤效率最高达到99.99 %。电纺PI及GO/PI、NG/PI复合纳米表现出良好的耐酸。