氧化石墨烯尺寸调控及其复合膜分离性能研究

Study on size regulation of graphene oxide nanosheets and separation performance of composite membranes

通过改进Hummers法制备了氧化石墨烯(GO),通过控制氧化程度与超声破碎时间从化学与物理两方面调控制备不同尺寸GO纳米片.对得到的GO纳米片利用傅里叶转换红外光谱分析仪(FTIR)、X射线光电子能谱分析(XPS)、X射线衍射仪(XRD)和透射电子显微镜(TEM)进行了表征分析,结果表明,控制氧化程度对GO尺寸变化的影响远小于超声破碎时间的影响.同时用死端过滤的方法制备了GO/PAN复合纳滤膜,使用扫描电子显微镜(SEM)对复合膜表面及断面形貌进行了表征,并对该复合膜的纯水通量、盐(NaCl、MgSO4)的截留率和染料(活性黑KNB)的截留率以及亲水性能进行了测试.结果表明,在相同条件下GO纳米片尺寸越小,制备的复合膜亲水性越好,对NaCl、MgSO4的截留率分别从52.9%、74.8%降低至34.5%、47.6%,而对KNB染料的截留率一直保持在96%以上,纯水通量也从47 L/(m2·h·MPa)上升至162 L/(m2·h·MPa).

Graphene oxide(GO) nanosheets were fabricated via modified Hummers’ method and the effects of chemical structure and physical process on the size of GO nanosheets were investigated by the degree of oxidation and the ultrasonic treating time, respectively. Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), X-Ray powder diffraction(XRD) and transmission electron microscopy(TEM) were employed to characterize the obtained GO nanosheets, which indicated that ultrasonic time played an important role in determining the size of GO nanosheets. At the same time, a dead-end filtration device was used to coat GO nanosheets on the surface of PAN membrane(GO/PAN). The scanning electron microscopy(SEM) was used to characterize the surface and cross section of the composite membrane, then pure water flux and the rejection of salt(NaCl, MgSO4), rejection of dye(reactive black KNB) and the hydrophilicity were conducted for PAN membranes coated with GO nanosheets of different sizes with the same loading. The results show that, with the decrease of GO nanosheets sizes, the hydrophilicity of the composite membranes is increased, and the rejection of NaCl solution reduces from 52.9% to 34.5%, for MgSO4 reduces from 74.8% to 47.6% and KNB dye has remained above 96%. Meanwhile, the pure water flux increases from 47 L/(m2·h·MPa) to 16.2 L/(m2·h·MPa), which can be explained by the hydrophilicity of the GO/PAN composite membranes.