| Summary: | 碩士 === 中原大學 === 化學工程研究所 === 105 === In order to increase the porosity of PSf membrane, the asymmetric porous PSf was prepared by wet phase inversion method using the casting solution with PEG 200 as pore forming agent. To fabricate a positively charged nanofiltration membrane, graphene oxide was functionalized by amine monomer. The amino-functionalized graphene (NGO) was incorporated into chitosan (CS) polymer solution crosslinked by glutaraldehyde (GA). Then this solution was cast onto PSf support membrane to fabricate amino-functionalized graphene oxide/chitosan (NGO/CS-GA) hybrid membrane. This membrane was applied to nanofiltration for aqueous salt solution.
The effects of membrane fabrication condition (degree of deacetylation of chitosan, concentration of glutaraldehyde, NGO loading, and spin rate), membrane fabrication method (solution casting and spin coating), and amino-modified process of graphene oxide (types of coupling agent and monomer), and nanofiltration operating condition (feed concentration, feed pH value, type of inorganic salt, and anti-fouling) on the characteristics and separation performance of membrane was investigated systematically.
Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and field emission scanning electron microscope (FESEM) were used to characterize the chemical structure and morphology of membrane, respectively. The effect of GA concentration on crosslinking degree of membrane was characterized by X-ray photoelectron spectroscopy (XPS). The roughness was analyzed by atomic force microscopy (AFM).
NGO/CS-GA composite membrane prepared by spin-coating method with spin rate of 4000 rpm using the casting solution composed of 1.5 wt% CS(DD=80%), 0.6 wt% GA, and 5 wt% PEHA-GO(based on CS by weight) showed the best nanofiltration performance. The pure water flux was 8 L/m2h and rejection to MgCl2 was 91%. The order of rejection to inorganic salts was MgCl2 > MgSO4 > NaCl > Na2SO4. This trend was similar with most positively charged nanofiltration membrane in the literature. In the antifouling experiment, both positively charged foulant (CTAB) and negatively charged foulant (BSA) were dissolved in MgCl2 solution as feed solution. The flux recovery ratio of PGO/CS-GA composite membrane were about 90%.
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