Fabrication Of Hydrophobic Porous Inorganic Membrane And Distillation Performance Research

In this paper, preparation, hydrophobic modification and membrane distillation desalination performance of inorganic membrane was investigated. from which the preparation technology of the two kinds of membrane are obtained; then silane grafting modification was applied on the unsymmetrical structure of diatomite membrane and metal nickel membrane to get hydrophobic diatomite membrane and hydrophobic nickel membrane. Finally, the prepared hydrophobic diatomite membrane and hydrophobic nickel membrane were used in vacuum membrane distillation desalination experiment to study the membrane distillation desalination performance of these two kinds of membrane. The main conclusions are as follows:(1) Large aperture diatomite membrane was used as matrix and SiO2 sol was spraied on its surface for one time before it was sintered at 400℃ for 2 hours to get the unsymmetrical diatomaceous earth membrane. The porosity and average pore size of the unsy mmetrical diatomite membrane were determined to be 46% and 0.78μm. Triethoxyoctylsilane was used in the hydrophobic modification on aunsymmetrical diatomite membrane to obtain hydrophobic diatomite membrane. Parameters of the modification process: volume ratio of alcohol to water is 5:1, the concentration of triethoxyoctylsilane was 0.15 mol / L, modification time was 12 hours, curing temperature was 110℃, the curing time was 2 hours, modification number of times was 2. The contact angle of modified diatomite membrane with water can reach 149°, while gas flux decreased slightly, and pure water flux decreased significantly. Vacuum membrane distillation experiments indicate that modified diatomite membrane has good desalination performance. When the outer side of the membrane was contacted with 80℃, 3.5 wt% NaCl solution, the inner side of the membrane was vacuumized to 5×103 Pa, membrane water permeation flux was 2.57 L/m2·h, salt rejection was greater than 99.90%.(2) The metal nickel powder with average particle size of 0.5 μm was used as raw material. The nickel films with surface average aperture of 0.65 μm and porosity of 34.8% was prepared under the condition in which sintering temperature was 700℃, sintering time was 1 hour. Diatomite hydrophobically membrane modified process was used in the preparation of hydrophobically modification of nickel membrane. After modification, the surface morphology of the nickel metal membrane had no obvious change, but the contact angle of nickel membrane and water can be reached on 124°, while gas flux decreased slightly, pure water flux decreased significantly. The modified nickel film have good desalting performance in vacuum membrane distillation experiments but the permeate flux was low. Under the condition in which the liquid temperature was 80℃, the concentration of NaCl was 3.5 wt%, the inner membrane was vacuumized to 5×103 Pa, the flux of hydrophobic nickel membrane flux was 2.57 L/m2·h, salt rejection can reach 99.8%.