Huang Dandan, Xin Qingping, Ni Yazhou, Shuai Yingqian, Wang Shaofei, Li Yifan, Ye Hui, Lin Ligang, Ding Xiaoli, Zhang Yuzhong
State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University Tianjin 300387 P. R. China
School of Chemical Engineering and Energy, Zhengzhou University Zhengzhou 450001 P. R. China.
RSC Adv. 2018 Feb 7;8(11):6099-6109. doi: 10.1039/c7ra09794h. eCollection 2018 Feb 2.
In this study, composite nanosheets (ZIF-8@GO) were prepared an growth method and then incorporated into a polyimide (PI) matrix to fabricate mixed matrix membranes (MMMs) for CO separation. The as-prepared MMMs were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and water uptake measurements. Water uptake measurements establish the relationship between the gas permeability and water uptake of membranes and an increase in the water uptake contributes to the CO permeability owing to an increase in the CO transport channels. The MMMs exhibit excellent CO permeability in when compared with an unfilled PI membrane in a humidified state. The ZIF-8@GO filled membranes can separate CO efficiently due to the ZIF-8@GO nanocomposite materials combining the favorable attributes of GO and ZIF-8. First, the high-aspect ratio of the GO nanosheets enhances the diffusivity selectivity. Second, ZIF-8 with a high surface area and microporous structure is beneficial to the improvement of the CO permeability. Third, ZIF-8@GO possesses synergistic effects for efficient CO separation. The MMM with 20 wt% ZIF-8@GO exhibits the optimum gas separation performance with a CO permeability of 238 barrer, CO/N selectivity of 65, thus surpassing the 2008 Robeson upper bound line.
在本研究中，采用生长法制备了复合纳米片（ZIF-8@GO），然后将其掺入聚酰亚胺（PI）基质中，以制备用于CO分离的混合基质膜（MMM）。通过傅里叶变换红外（FT-IR）光谱、扫描电子显微镜（SEM）、X射线衍射（XRD）、差示扫描量热法（DSC）、热重分析（TGA）和吸水率测量对所制备的MMM进行了表征。吸水率测量确定了膜的气体渗透率与吸水率之间的关系，吸水率的增加由于CO传输通道的增加而有助于提高CO渗透率。与未填充的PI膜在加湿状态下相比，MMM表现出优异的CO渗透率。由于ZIF-8@GO纳米复合材料结合了GO和ZIF-8的有利特性，ZIF-8@GO填充的膜能够有效地分离CO。首先，GO纳米片的高纵横比提高了扩散选择性。其次，具有高表面积和微孔结构的ZIF-8有利于提高CO渗透率。第三，ZIF-8@GO具有协同效应，可实现高效的CO分离。含有20 wt%ZIF-8@GO的MMM表现出最佳的气体分离性能，CO渗透率为238巴耳，CO/N选择性为65，从而超过了2008年的罗布森上限线。
