| With the membrane technology developing in the new century, more and more bettermembrane properties are needed. Metal membrane and ceramic membrane show uniqueadvantages. Ceramic membrane is brittle material, and has seal difficulty problem. It isprobably to be suddenly destroyed. However, the metal membrane has high strength, hightemperature resistant, high pressure resistant and good sealing performance, but the apertureis difficult to control. Metal-ceramic composite membrane prepared by porous metal substrateand ceramic material has combination of properties of them. It maintains high intensity, goodsealing performance. At the same time, the surface ceramic layer improves the metalmembrane separation accuracy and can protect the substrate from corroding quickly. Thecomposite membrane is becoming a new type of membrane research hotpot, but there is lessstudy on the water purification treatment with metal-ceramic composite.Metal-SiO2/Al2O3composite membrane based on porous thin304stainless steelsubstrate was prepared by sol-gel method. The main technological parameters were got andwere used in preparation of metal-SiO2/Al2O3composite membrane. Ink dye wastewater,escherichia coli water, and natural lake water were purified by metal-SiO2/Al2O3compositemembrane. The treatment effect was studied. Fouling mechanism and model analysis weredescribed. Composite membranes wer recycled by flushing, ultrasonic vibration and hightemperature sintering. Main conclusions are as follows:Parameters of the preparation of metal-SiO2composite membrane:400mesh metalmembrane was used as substrate material, dip-coating for four times with coating liquid ofsol SiO2A,20second at a time, slowly rising to90℃by5℃/min, considering sinteringconditions of keeping2hours in400℃temperature. Three methods for sintering themembrane: sintering a time after dip-coating for four times, sintering a time after dip-coatingfor twice and then do repetitive operation, sintering a time after dip-coating for one time andthen do repetitive operation for three times.Parameters of the preparation of metal-Al2O3membrane:400mesh metal membraneused as substrate material, dip-coating for seven times with coating liquid of sol Al2O3D,20second at a time, slowly rising to90℃by5℃/min, considering sintering conditions of keeping2hours in400℃temperature. Methods for sintering the membrane of sintering atime after dip-coating for one time and then doing repetitive operation for six times wereexperimented and analyzed.As the increasing of dip coating and sintering times, membrane layer was formed and thecrack defect in composite membrane surface was repaired. The sol particles were stacked andthen filtering channel was formed, thus the filtration function. Composite membranes were inthe field of microfiltration or ultrafiltration through the analysis of the removal of the knowndistribution particle size.SiO2composite membrane by sintering a time and Al2O3composite membrane bysintering for seven times wer selected. Ink dye waste water with concentration of100ppm waspurified, with the flux of19.7L/(m2h),14.93L/(m2h)and the rejection rate of98.4%,99%.With the increase of operating pressure, the flux was in the slower rate of growth aftermembrane fouled. The operation pressure was0.15Mpa. As the dye concentration increasing,the flux of composite membrane decreased continuously and the removal effect remainedstable. And with the increasing of separation time, the flux decreased and the reject rateincreased. The two had the good antibacterial effect with the aseptic rate for escherichia coliwas more than99.9997%and99.996%. To natural lake water, turbidity removal was86%and92%. Filtered water from the metal-ceramic membrane was transparent and had no peculiarsmell, with the turbidity lower than1NTU. To the total bacteria in water, the eliminating ratewas more than97.64%and99.62%, with the water flux of18.5L/(m2h),16.42L/(m2h).The polluted water has good purification effect after treated by composite membrane.Fouling mechanism and model analysis were described. Combining strength under highpressure operation and acid-alkali corrosion resistance of SiO2, Al2O3composite membraneswere studied. The combining strength is high and the mass loss is lower than5%. The ceramicmembrane protected the substrate membrane. Composite membranes were recycled throughthe flushing, cleaning agents, ultrasonic vibration washing, and resintering at a hightemperature. The composite membrane had a good effect of flux recovery. |
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