Preparation And Properties Of Oxide Ceramic Flat Membrane

Compared with the organic membrane,the ceramic membrane has the advantages in high temperature,corrosion,microbial resistance,and with high strength and large throughput.In recent years,the ceramic membrane has been widely concerned and studied in the field of filtration and separation,environmental protection,chemical industry,medicine,food and other industries.The plate-type ceramic membrane has the advantages of high specific surface area,high packing density and small filtration resistance.The combination of bioreactor and membrane bioreactor?MBR?has been widely used in domestic sewage and industrial wastewater treatment,and gradually extended to other areas.However,the development of flat ceramic membrane,relative to the tubular ceramic membrane in terms of its low strength,become a bottleneck restricting its wider applications.In this thesis,ZrO₂ ultrafiltration membrane and SiO₂ nanofiltration membrane were prepared on the Al₂O₃ ceramic microfiltration membrane.The effects of particle size,slurry viscosity and coating process on the composition,microstructure and related properties of the prepared membrane were studied.In this thesis,the sub-micron Al₂O₃ powder with narrow particle size distribution was obtained by milling the received ?-Al₂O₃ powder,and the milled powder has high activity and can sintered at 1250? to get microfiltration membrane.Through the optimization of the process parameters such as thickening of membrane paste,film slurry concentration and sintering temperature,a continuous and complete membrane with a thickness of 15-20?m was obtained.This ceramic microfiltration membrane was used for industrial wastewater treatment,reached a alass A emission standards.Aiming at the shortcomings of the filtration precision of the microfiltration membrane,on the basis of alumina microfiltration membrane,zirconia ceramic ultrafiltration membrane was prepared by using ZrO₂ powder with an average particle size of 100nm,and an ultrafiltration membrane with uniform pore size distribution was obtained at 950 ?.The ZrO₂ ultrafiltration membrane with pore size of 50nm and thickness of 10?m was prepared by impregnating with 5wt%ZrO₂ slurry for 15s and sintered at 950 ? for 1h.Good results were obtained in the filtration of vinegar by using this ZrO₂ ultrafiltration membrane.Based on the above work,SiO₂ nanofiltration membranes were prepared by using S10 and S80 silica sol with average particle size of 10nm and 80nm as raw materials.The suitable coating process and sintering temperature of silica sol were investigated,and the relationship between silica sol concentration and membrane thickness was established.The suitable sintering temperature of S10 and S80 are 600? and 700?,respectively.A 1?m SiO₂ nanofiltration membrane with spherical compact,uniform structure was obtained at 600 ? with S10 silica sol coating at a concentration of 16.9wt%.