Effect of the operation variables on the wettability of membrane and the performance in membrane distillation process = 막 증류 공정에서 조업 변수가 막의 젖음도와 성능에 미치는 영향

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In this study, membrane distillation was investigated to develop an effective separation process of dilute volatile organic compound from aqueous stream, and purification process for water/nonvolatile mixture. This study consisted of three branches, First, the wettability of hydrophobic membranes was investigated to determine the upper limit concentration of isopropanol using direct contact membrane distillation. The effect of operation variables on the wettability factor of membrane was also investigated. Second, the effect of operation variables on the flux and selectivity in air gap membrane distillation was investigated. A predictive model was also proposed based on the first principles of heat and mass transfer. Third, the effect of operation variables on the removal rate of isopropanol from aqueous solution was investigated using vacuum membrane distillation. The analysis of experimental results was performed by the evaluation of overall mass transfer coefficients. Details of each branch were summarized as follows. A simple method is described for the determination of the wettability of polyvinylidenefluoride (PVDF) and polytetrafluoroethylene (PTFE) membranes used in membrane distillation modules. This very simple in-situ method in termed the “pH method”. A wettability factor which varies from 0 to 1 is defined, and this factor is determined by the measurements of pH in feed and permeate reservoir. With water/isopropanol mixtures, effects such as the feed temperature, the pore size and the surface energy of membrane were shown to seriously affect wettability of flat membranes. Using this technique, the isopropanol concentration start to be wetted $C_{p,pc}$, were determined with different operating conditions. On PTFE 0.2㎛ membrane, a value of $C_{p,pc}$ was about 410 g/L at 37℃,and the value of $C_{p,pc}$ is reduced with increasing feed temperature. Membrane distillation was investigated as a possible technique for separation of nonvolatile/volatile co...
Advisors
Hong, Won-Hiresearcher홍원희researcher
Description
한국과학기술원 : 화학공학과,
Publisher
한국과학기술원
Issue Date
2001
Identifier
169558/325007 / 000965321
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학공학과, 2001.8, [ x, 107 p. ]

Keywords

flux; wettability; operation variable; membrane distillation; selectivity; 선택도; 플럭스; 젖음도; 조업변수; 막 증류

URI
http://hdl.handle.net/10203/28868
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=169558&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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