Preparation And Application Performance Of Ceramic Membrane With High Porosity

At the last century,the rise of a new separation technology-membrane separation technology and its application progress quickly,the inorganic ceramic membrane has a distinct advantage comparing with organic membrane,Such as good acid and alkali resistance,high temperature performance,high strength,easy to clean,low energy consumption and so on,and it has been applied in the environmental industry,food industry,metallurgy industry,pharmaceutical industry and other industries,it is still a kind of High-tech industry recent years.But the inorganic ceramic membrane device units have shortcoming of smaller loading area,the lower yield,less kinds of materials,these problem is obvious now.The secondary issues are long production cycle,high energy consumption and high cost,so it is necessary to alleviate these problems and promote the application of ceramic membrane technology.In this paper,a new method based on molding technology and gradation principle of size fraction pore-forming agent and the raw material powder has been proposed to reduce production costs,then made research on the preparation of ceramic membrane,the preparation of dynamic membrane and the application process of dynamic membrane based on ceramics and the membrane fouling model have been studied too,the main work having completed is as following items:Study on the preparation of the raw material powder: it is a kind of pre-process of ceramic membrane preparation technology,the main contents is optimization of the preparation conditions of Al2O3 powder used for sintering ceramic membrane.The experimental results show that ball-to-powder ratios of 9:1 to 11:1 and grinding times of 9h to 10 h are the optimal conditions.Ultrasonic wave may affect the agglomeration state of the powder but not the crystal type,particle size,and size distribution of the Al2O3.The powder-milled sample produced at the optimal wet ball grinding conditions can be directly sintered into ceramic membrane with high bending strength and high porosity.Optimized milling time is less than the optimal time of 30% related reports;the energy conservation effect is obvious.Study on the preparation of ceramic membrane: we made ceramic membrane green body with α-Al2O3 particles made by wet milling proceeds with an average diameter of about 10μm and pore-forming agent using carbon black by extrusion molding method.The plasticity index is about 0.42-0.55 when pressure is 4.0-6.0MPa.Pug characteristic analysis shows that the appropriate proportion of lubricants,binders and other additives adding,the mud shows good Bingham body mud characteristics.Sintering Experiment shows that: According to an initial sintering system,under sintering temperature 1400 ℃,holding time 9h conditions,we can prepared good performance alumina ceramic membranes effective porosity of 44%,the bending strength about 5.0 kN.Study on ceramic membrane apply: filtrated black liquor using self made ceramic membrane with pore diameter of 0.1 micron by the "pH adjustment + flocculation + ceramic membrane filtration " combined process,when the flocculants concentration is of 4.5mg/L,filter pressure is 0.12 MPa,obtain the black liquor solids concentration increased 4-6 times,the black liquor solids concentration reaching more than 55%,the initial membrane permeation is about 8000 L/(m2·h·MPa),we achieve a high porosity and high permeability membrane and this is about 8% higher than the common goods of ceramic membranes.Ceramic membrane corrosion experiments shows that the mass loss rate of the ceramic membrane is smaller,the average value is only 0.33%,it consider that the self made ceramic membrane have no corrosion and good chemical resistance.Study on the application of dynamic membrane based on the ceramic membrane: When the membrane particulate dosage 1.5g/L,filtration pressure 0.1MPa,the membrane surface flow rate of 1.0m/s,the membrane surface fluid under this condition can not only effectively reduce membrane fouling,high flux membranes,and this when a more dynamic membrane stability and integrity,to ensure a high retention rate,high-throughput operation.Dynamic membrane protein,milk fat,lactose retention rates were 69.25%,14.40% and 8.18%,it has achieved the goal of ultra filtration level filtration using ceramic microfiltration membrane by the experiment.Formation mechanism analysis showed that the dynamic membrane coating process about blocking the front part of the standard theory of 6min film,10 min after the coating process and the cake filtration stage.Ceramic membrane wear experiments shows that the ceramic membrane substrate in the conditions of wear is not obvious,the overall mass loss rate is very low,less than 1%,reflecting the advantage of ceramic membrane molding technology.Study on the laminate porosity modeling of ceramic membranes: we obtain the mathematical model with small error of 10% through the ceramic membrane stratified analysis,combined with the specific circumstances of the experiment preparation of ceramic membranes,improvements in the basic model,based on the introduction of a size parameter k.Study on the mathematical model of ceramic membrane filtration process: according to the theoretical study of fluid mechanics and the basic theory of filtering types,a mathematical model of ceramic membrane filtration process obtained.The effects of different operating modes,operating conditions,the ion concentration of the model parameters was found clogging coefficient,contamination of the membrane can be described by the model parameters.Conditions which can cause membrane fouling aggravated weakened(such as shortening filtration cycle,reduceing recovery,etc.),blockage factor reduce accordingly,it shows good agreement of the measured values with the predictions,this proved that the model is practical and scientific.