Abstract:

Two-dimensional materials have a unique layered structure and stable physical and chemical properties. Recently, two-dimensional membranes composed of layered two-dimensional materials have shown the extraordinary potential application of membrane separation. Here, La³⁺ ions were intercalated into the MoS₂ membrane during the membrane formation by mixing MoS₂ nanosheets and La³⁺ solution. The atomic force microscope and X-ray photoelectron spectroscopy were used to confirm the structure and composition of the MoS₂ lamella. The structure and interlamellar spacing of the La³⁺-MoS₂ membrane were studied by scanning electron microscopy and X-ray diffraction spectroscopy. The permeability of the membranes was investigated by pressured filtration device and forward osmosis device. The results showed that the La³⁺ ions were successfully intercalated into the MoS₂ membranes, resulting in the high-water flux of the La³⁺-MoS₂ membrane. The pure water flux of the La³⁺-MoS₂ membrane was 18.5 times higher than that of the blank MoS₂ membrane. The La³⁺-MoS₂ membrane indicated a remarkable sieving effect for dyes with molecular weight from 400 to 800g/mol based on the steric hindrance effect. Moreover, the Na⁺, K⁺, Mg²⁺ and Ca²⁺ ions were rejected by the La³⁺-MoS₂ membrane due to the Donnan effect. In the repeatability experiment, the Na⁺ rejection rate of La³⁺-MoS₂ membrane can still be maintained at more than 95%, showing good repeatability and stability. The results provided a new method for the modification strategy of MoS₂ membrane and the treatment of printing and dyeing wastewater.

Key words: two-dimensional membrane, membranes, separation, waste water, desalination

摘要：

二维材料具有独特的层状结构、稳定的物理化学性质等特点。近年来，由二维材料层层堆叠构成的二维膜在膜分离领域展示了非同凡响的应用潜力。本文采用成膜中共混方法将La³⁺插入到MoS₂膜层间，利用原子力显微镜（AFM）和X射线光电子能谱仪（XPS）技术表征了MoS₂片层结构和成分；利用扫描电镜（SEM）和X射线衍射仪（XRD）技术表征了膜结构与层间距；通过加压过滤装置和渗透装置考察了La³⁺-MoS₂膜的渗透截留性能。实验结果表明，La³⁺插层改性后的MoS₂膜由于层间距增加而显著地提高了纯水通量，La³⁺-MoS₂膜的纯水通量相较于MoS₂膜提高了约18.5倍。La³⁺-MoS₂膜对分子量300~800g/mol染料表现出了基于空间位阻理论的截留作用，对金属离子（Na⁺、K⁺、Mg²⁺、Ca²⁺）表现出了基于Donnan排斥理论的截留作用。重复性实验中，La³⁺-MoS₂膜对Na⁺的截留率仍能维持在95%以上，表现出了良好的性能稳定性。

关键词: 二维膜, 膜, 分离, 废水, 脱盐