新型还原氧化石墨烯/氮化碳复合纳滤膜制备及其性能

高性能石墨烯基复合膜的制备是目前国际研究热点，但是石墨烯基纳滤膜在脱盐中水通量较低，限制其在脱盐中的应用。采用聚多巴胺(PDA)改性聚砜(PSF)膜为基膜，将还原氧化石墨烯(rGO)和超薄氮化碳(uCN)纳米片通过真空抽滤法在基膜表面自组装制备新型还原氧化石墨烯/氮化碳复合纳滤膜。通过场发射扫描电子显微镜、透射电子显微镜、X 射线衍射仪、傅里叶变换红外光谱仪和X射线光电子能谱仪等研究uCN添加对膜结构和形貌的影响，并考察不同uCN添加比例、rGO用量及压力复合纳滤膜性能变化规律。结果显示当在100 mg·L^-1的rGO中添加uCN为20 mg·L^-1时所制备的rGO/uCN复合纳滤膜不仅保持良好盐离子截留率(对Na₂SO₄截留率85.86%，对NaCl截留率30.17%)，且水渗透系数是rGO膜的2.15倍(88.50 L·m^-2·h^-1·MPa^-1)。

Preparation and performance of novel rGO/uCN composite nanofiltration membrane

High performance graphene-based composite membranes have attracted great attentions, however, graphene-based nanofiltration membranes usually exhibit low water flux in removing salt ions, which limits its application in water desalination. Novel reduced graphene oxide (rGO)/ultrathin carbon nitride (uCN) composite nanofiltration membrane was prepared by self-assembling rGO and nanoporous uCN nanosheets on polydopamine (PDA) modified polysulfone (PSF) support via vacuum filtration. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy analysis (XPS) were applied to evaluate the changes in structure and morphology of membranes by introducing uCN. The effects of addition ratios of uCN, rGO content and operating pressure on the performance of composite membranes were also investigated. With 20 mg·L^-1 uCN content in 100 mg·L^-1 of rGO, the prepared rGO/uCN composite membrane not only maintained satisfied salt rejection rates (85.86% for Na₂SO₄, 30.17% for NaCl), but also possessed 2.15 times water permeance (88.50 L·m^-2·h^-1·MPa^-1) that of pure rGO membrane.