Construction Of MoS₂ Composite Nanofiltration Membrane And Its Separation Performance

The layered transition metal dichalcogenides,molybdenum disulfide（MoS₂）have received increasing attention and hold great potential application in membrane separation field due to its unique properties.In this paper,2D MoS₂ nanosheets were employed as building blocks to fabricate composite membrane in Polyacrylonitrile（PAN）and ceramic substrate by using LbL method and hydrothermal method.These composite membranes with 2D transfer channel were used to retention of dyes from aqueous solution.Firstly,polyelectrolyte modified MoS₂ nanosheets（PDDA@MoS₂）were prepared and then incorporated into polyelectrolyte multilayers through LbL method to get a MoS₂/polyelectrolyte hybrid membrane on PAN substrate and ceramic substrate.The morphology and structure of the resulting PDDA@MoS₂ nanosheets were characterized by X-ray diffraction（XRD）,scanning electron microscope（SEM）,transmission electron microscopy（TEM）,which founding that the dispersive stability in aqueous solution of the PDDA@MoS₂ nanosheets was improved and the interlayer spacing also enlarged,which was beneficial to the mixing of inorganic particles and polyelectrolyte to improve the membrane separation performance.Under the optimal conditions,the PDDA@MoS₂-PDDA/PSS hybrid membrane showed 98.4%retention of methyl blue with flux of 194.5L·m^-2·h^-1·MPa^-1 and the tubular PSS/PDDA-MoS₂@PDDA hybrid membrane showed 97.8%retention of methyl blue with flux of163.2L·m^-2·h^-1·MPa^-1,which was at least 2.3 times than that of pure polyelectrolytes membrane.Under the long-term stability test both two MoS₂/polyelectrolyte hybrid membranes showed good stability.Secondly,tubular ceramic substrate was used as the support,and MoS₂ nanosheets were grown on the ceramic substrate by in-situ method.The formation of MoS₂nanosheets on the ceramic was characterized with an XRD,SEM,EDS and so on.The results show that the MoS₂ nanosheets are successfully grown on the ceramic substrate.Furthermore,through adjusting the membrane-forming conditions（reaction time and the precursor concentration）the best performance was obtained.On the optimal conditions the MoS₂/tubular ceramic composite membrane showed 98.4%retention of methy blue with flux of 375.0L·m^-2·h^-1·MPa^-1,99.7%retention of congo red with flux of 390.6L·m^-2·h^-1·MPa^-1,98.1%retention of eriochome black T with flux of 406.2L·m^-2·h^-1·MPa^-1,42.4%retention of methy orange with flux of 414.1L·m^-2·h^-1·MPa^-1.Under the long-term stability test MoS₂/ceramic composite membranes showed good stability.