GO-TSC/聚酰亚胺混合基质膜的制备及气体分离性能研究

Study on preparation of GO-TSC/polyimide mixed matrix membrane and its gas separation performance

使用氨基硫脲(TSC)对氧化石墨烯(GO)进行改性,制备GO-TSC层状复合材料。随后,将该复合材料加入到Matrimid■5218(PI)基质中,制备用于二氧化碳分离的混合基质膜(MMMs)。通过TGA、SEM及气体分离性能测试考察了GO-TSC对膜热稳定性、结构和气体分离性能等的影响。SEM结果显示GO-TSC可均匀分散在聚合物基质上并与基质紧密结合;TGA结果显示混合基质膜在250℃以上仍保持稳定。与纯PI膜相比,MMMs显著增强了二氧化碳的渗透性。GO-TSC中所含的氨基与二氧化碳具有良好的亲和力,增加的碱性位点可以有效地转运二氧化碳。GO-TSC的层状结构增加了气体的传输路径,不利于大动态直径气体(甲烷、氮气)的通过,从而提高了分离性能。GO-TSC负载量为0.75%(质量分数)时混合基质膜的分离性能最佳。相比较纯PI膜,混合基质膜的二氧化碳渗透系数和二氧化碳/甲烷、二氧化碳/氮气分离系数分别提高了42.16%、95.79%和83.72%。

Graphene oxide(GO)was modified using thiosemicarbazide(TSC)for the fabrication of flat sheet GO-TSC cmposite.Subsequently,this composite was incorporated into the Matrimid■5218(PI)matrix to fabricate mixed matrix membranes(MMMs)for CO_(2)separation.Through TGA,SEM and gas separation performance tests,influence of GO-TSC on thermal stability,structure and gas separation performance of the mixed matrix membrane was investigated.SEM showed that GO-TSC could be uniformly dispersed in the polymer matrix and tightly combined with the matrix;TGA result showed that decomposition temperature of mixed matrix membranes was above 250℃.MMMs showed significantly enhanced CO_(2)permeability compared with pure PI membrane.The amino group contained in GO-TSC had a good affinity with CO_(2),and the increased amidogen sites could effectively transport CO_(2).The GO-TSC lamellar structure increased the gas transmission path,which was not conducive to the passage of large dynamic diameter gases(CH4,N2),thereby improving the separation performance.The MMMs doped with GO-TSC-0.75%showed optimal gas separation performance.Compared with pure PI membrane,the CO_(2)permeability,CO_(2)/CH4 selectivity and CO_(2)/N2 selectivity of the MMMs were increased by 42.16%,95.79%and 83.72%,respectively.