Advantages Of Pervaporation

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Compared with the process of distillation, pervaporation has advantages, such as can be separated into each other with a similar molecular weight, can separate azeotropic solution, effective for small-scale separation, not require additives, pollution-free, takes little space (compact module), low investment costs, and requires less cooling water.
The pervaporation process is complicated and involves the transfer of mass and energy. In the process, the feed is in the liquid phase and the permeate obtained in the gas phase.
The mechanism of separation takes place based on the solubility and diffusion that occurs in three phases :
1. Selective absorption by the membrane on the feed side
2. Selective diffusion through the membrane
3. Desorption
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Swelling of the membrane volume will affect the amount of permeate flux. Swelling relatively low and the result is decreased in permeates flux; a relatively large swelling on the contrary will result in separation selectivity decreased.
Downstream made as low as possible with a vacuum pump. Both sides of the pressure difference are the driving force that directed to the mass transfer in the membrane. Good pervaporation is higher selectivity than distillation. The disadvantage is the permeate flux is very small.

2.5. Magnitude in Pervaporation Pervaporation performance in the separation of ethanol-water mixture can be expressed by the mass flux (L/m2.hr) and separation factors are expressed with selectivity (α). Good membrane has a mass flux and high selectivity. Large mass flux in the membrane can be expressed as a large rate of mass transfer through the membrane per unit of membrane surface area per unit time, as the following equation : J =V/(A x t) (2.1)
Where : V = Volume of permeate (L) A = Membrane surface area (m2) t = Sampling time (hours)
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Influential Factors on Pervaporation There are several factors that influence the pervaporation. Factors that influence the pervaporation include pressure, time, operating temperature and feed concentration.
2.6.1. Operating Pressure
Driving force in pervaporation is different of pressure. Permeate pressure has always attempted as small as possible (near vacuum) in order to generate a maximum permeation rate. Vacuum pressure is obtained by adjusting the vacuum pump such that the obtained pressure is much smaller than the vapor pressure of each component. Increased pressure on the bottom side of the membrane in pervaporation can reduce the separation factor.

2.6.2. Operating Temperature
The higher temperature, the flux will also increase. In addition, the higher temperature, vapor pressure penetrant will also increase, so that activity in upstream side is greater and it will cause a flux increases.
2.6.3 Concentration Feed
Various in feed composition directly affect the sorption phenomena in liquid-membrane interface. Penetrant mass transfer characteristics of the membrane are very dependent on the concentration of the feed for the diffusion in the membrane. The higher concentration of penetrant which interacts with the

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