Stability of Nano-Al2O3 Sol and Properties of PVDF/Al2O3 Hybrid Membrane
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Abstract:
The nano-Al2O3 sol was prepared in a sol-gel process, using AIP as raw material. The effects of peptization agent, n(H+)/n(Al3+) and aging time on the particle size and stability of the sol were studied. The optimal conditions of preparing stable and transparent nano-Al2O3 sol were obtained. HNO3 was chosen as the best peptization agent. The optimal n(H+)/n(Al3+) ratio and aging time were 0.18~0.25 and 20 h, respectively. Then, in order to improve the ultrafiltration performance of PVDF membrane, PVDF/Al2O3 hybrid membranes with different PVDF contents were prepared via the in-situ polymerization of AIP and PVDF in a sol-gel process. The structure and properties of the hybrid membranes were characterized by means of SEM, AFM, FI-IR, DSC and TGA. The results indicated that the pure water flux of hybrid membranes declined with the increase of PVDF concentration, while the rejection rate increased gradually. The introduction of AIP can enhance the chemical bond between PVDF and Al2O3 of the hybrid membrane and hence greatly improved the mechanical properties and hydrophilicity of these membranes. The thermal decomposition temperature of hybrid membrane decreased to a lower temperature with the introduction of AIP, which meant tht the thermostability of hybrid membrane declined, while AIP had no obvious effect on the melting point of hybrid membrane.
