The Preparation And Performance Of Graphene Oxide Composite Membrane

The Graphene oxide（GO） is a very popular material that exhibits wonderful chemical, thermal stability and electrical conductivity. Especially in recent years, Graphene oxide have emerging nano-building blocks for separarion membrane. Due to the extremely thin feature, GO membrane have to be supported by a substrate in real separation processes. So the substrate has a significant impact on membrane separation. The hollow fiber was selected as substrate for GO membrane in this paper, as they are strong and rigid, giving a good support to the GO membrane. Also they are chemically and thermally stable, making them possible to work under harsh operating condition.To improve the pore size and surface roughness of porous ceramic tube, a nano-silica layer was prepared on the tube by a hot coating method. And then, Graphene oxide membrane was fabricated on the modified tube via a vacuum filtration method. The structure and morphology of as-prepared graphene oxide, silica layer and Graphene oxide membrane were characterized by infared spectrum（IR）, scanning electron microscope（SEM） and X-ray diffraction（XRD） respectively. Results show that the coated silica layer is beneficial to fabricate a compact graphene oxide membrane. The as-prepared membrane was further applied in dye and salts solution separation. Results show that the membrane displays a high rejection（>99%） for dye and moderate rejection for salt（>50%）. Water flux of the membrane is 0.5 kg·m^-2·h^-1·bar^-1.GO membrane will broke and peeled off completely after soaking in water for a few days, Tt was a great disadvantages in use of grapheme oxide membrane. A stable membrane was fabricated using polydopamine as covalent linker between GO layer and the alumina support. Polydopamine acts as molecular linker for anchoring the GO membrane onto the support surface to promote the stability of GO membrane in water. The GO membrane prepared on polydopamine modified Al₂O₃ display higher stability in water than those prepared on unmodified Al₂O₃ supports, most importantly rejection for the dye remain unchanged after staying in water for 30 days.Polymeric membrane are mostly widely used in gas separation. However many of them exihibit a higher selectiliy but a lower gas permeability,therefore it is not fitted to the advanced separation field. Composite membrane constituted of two different matrices have been recently developed in order to improve the permeation characteristics. In this research, a novel PSF-GO material was prepared by dip coating. Our approach to grapheme oxide embedded in PSF matrix is mainly focused on gas separation. The composite membrane present a highest gas permeability with highest（2% and 3%） the amount of GO were incorporated within PSF matrix. The H₂ permeability of 3% polysulfone（PSF）-GO membrane increased 5 times than pure PSF membrane.However, the selectivity of PSF-GO membrane remain unchanged...