| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 102 === The synthesized poly(vinylidene fluoride) (PVDF) flat-sheet membrane was used in the Direct Contact Membrane Distillation (DCMD) and Vacuum Membrane Distillation (VMD) for desalination, and the performances of the membrane distillation system were studied. The simulated seawater of 3.5 wt% NaCl solution was adepted as the feed. The dope solution of PVDF, Triethyl phosphate(TEP) and Tween-20, and the flat membranes were prepared by varying the concentration of TEP in the coagulation bath. The membrane structures were observed by the SEM analysis.
The performances of DCMD and VMD were measured under various operating parameters included feed temperature (50~70oC), feed flow rate (0.3~0.7 L/min) and feed concentration (0~15wt% NaCl).
In DCMD and VMD the experimental results showed the higher flux performance than original membranes which prepared by higher weigh percent of TEP solution, and membrane have large pore size in the top surface is increasing the weight percent of TEP in coagulant bath. And increasing the temperature of the feed can significantly increase the flux, but the polarization phenomena become more serious, increasing feed flow rate the effect is not obvious on the flux, but the temperature polarization phenomenon can be reduced by the feed flow rate as the high feed temperature.
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