| In order to improve the compatibility between Silicalite-1 zeolite and polyamide (PA), and reduce non-selective voids, zeolite nanoparticles are modified by the diglycidylether of bisphenol-A with commercial code BE188 (epoxy equivalentweight, EEW = 188). Hybrid membranes are fabricated by interfacial polymerization in the presence of zeolites.Further research of the separation performance, the chlorine resistance , the electrical charge, the chemical stability, and the anti-fouling of resulted membranes are investigated too.Firstly, the surface of the silicalite-1 zeolite nanoparticles is modified by a ring-opening reaction between the epoxy group of BE 188 and the silanol of zeolite under the catalysization of stannous chloride. Then, original and modified silicalite-1 zeolites are characterized by IR, 1H-NMR, EDX, XRD and TEM. The results confirm that the organic shortchain was grafted on the zeolite surface successfully. Moreover, the dispersibility in n-hexane and the hydrophobicity of modified zeolite are improved.The hybrid reverse osmosis membrane is prepared by an interfacial polymerization between MPD and TMC with zeolite. After adding the modified zeolite, the hybrid membranes not only maintain a high hydrophilic, but also an increased negative charge. From TEM images, it has been found that the dispersibility of zeolite in PA matrix increases and the compatibility between them is improved too. The prepared membranes are used for reverse osmosis desalination with 2000ppm NaCl aqueous solution. The separation performance of hybrid membranes filled with modified zeolite is better than the ones filled with original zeolite. When the loading of modified zeolite is 0.1%, the flux is 38.72 L·m-2·h-1, which is ca. 1.5 times as much as that of bare PA membrane, and the rejection improves as well.Finally, the investigation of the hybrid membranes with modified zeolite is carried out, containing the chlorine resistance , the chemical stability, anti-fouling of BSA. The organic shortchain on modified silicalite-1 zeolite surface can improve the acid resistance of the reverse osmosis membrane. The benzene ring of the modified zeolite surface reduces the replacement of chlorine to the polyamide matrix, making membranes structure are not seriously damaged. Therefore, the use of BE188 plays a certain role to prevent the chlorination of polyamide membrane. As the Zeta potential of the hybrid membrane loaded modified zeolite is lower than that of membrane loaded original zeolite, the electrostatic repulsion is strongger between the membrane surface and hydrated salt ions, which makes them maintaining high rejection in the test pH range , while the flux remained almost unchanged. The chemical stability of the polyamide membranes filled with modified zeolite is improved, and the performance of the resistance to protein contamination enhanced at the same time, extending the running time of the reverse osmosis membrane. |
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