The PVDF Membrane Infiltration In Static SDBS Solution And Dea Solution

Hydrophobic micro porous membrane has been successfully applied in membrane contactor of gas absorption and membrane distillation. In the membrane contactor, the hydrophobic micro porous membrane provides support to gas-liquid interface, so that the two phases can contact with each other effectively and not blended. During normal operation, the membrane pores are filled with gas instead of liquid. However, when the solution contains component which has low surface tension, solute molecules will be adsorbed on membrane pore wall, reducing the hydrophobicity of the wall. Since diffusion rate of components in liquid is much smaller than that in gas, membrane infiltration will increase of membrane resistance and decline of the overall mass transfer coefficients and mass flux. Membrane infiltration phenomenon, which contains very important and valuable scientific problems, is caused by the interaction between solution and the membrane material.The infiltration process of polyvinylidene fluoride (PVDF) membrane, which includes flat membrane and hollow fiber membrane, in static diethanolamine (DEA) solution and sodium dodecyl benzene sulfonate (SDBS) solution has been investigated by directly measuring membrane weight. The increasing ratio of membrane weight was obtained under different temperature, concentration of solution as well as different contact mode between membrane and liquid, and the ratio increased along with time.The experimental results indicated that, SDBS solution drop and DEA solution drop on the flat membrane changes from non-wetting to wetting; They are both spontaneous process that SDBS solution and DEA solution infiltrate PVDF micro porous membrane, the difference between the two is that swelling does exist in the latter. The increasing ratio significantly slowed down after fast growth; and a short-term decline appeared before the fast growth when the wetting membrane pores contacted with air in the experiment; reducing the temperature and concentration of solution in a certain range could help to retard the membrane infiltration process. The different contact modes also influenced membrane infiltration rate due to the difference of air resistance.Infiltration of hydrophobic micro porous membrane is a spontaneous process. The solvent molecules in the three-phase line spread to the gas-solid interface, forming a precursor film which is coated on the gas-solid interface and increases the gas-solid surface tension, reducing the contact angle.This work describes microscopic behaviors that may occur, causes, drivers, etc. in infiltration process. It considers the molecular mass transfer, the contact angle changes into the infiltration mechanism and proposes optimization guess of Washburn equation for subsequent researchers to obtain a more accurate infiltration equation.