Study On Coating Technology Of Inorganic Ceramic Membrane Tube

Separation technology of inorganic membrane turns to high efficient and green separation technology because of its high temperature resistance,corrosion resistance and high separation efficiency,it has been widely used for liquid-solid and liquid-liquid separation in fields such as food,medicine and chemical industry etc,and has broad application prospects especially in the aspect of gas-solid separation at high temperature.In order to improve the separation accuracy of inorganic membrane and ensure the conditions of treatment flux and stability at the same time,usually coat surface layer on the support surface to form an asymmetric membrane separation structure.In this study,ceramic membrane tube hanging external filter of SiC material was set as a support,and suitable coating materials were screened to develop new surface coating technology.Factors affecting coating film was studied and optimized,and separation properties such as treatment amount and separation efficiency before and after coating were observed;for coating materials,fly ash rich in Al₂O₃ and SiO₂was mainly investigated to achieve that PM_2.5 fine particulate matters can be efficiently trapped by asymmetric separation membrane element after coating,and achieve diversification and technical&economic competitiveness of membrane materials and coating technology.The main contents are as follows:1.Coating technology.A simple and practicable coating technology and device was developed,which can realize coating fast and efficient on surface,and control thickness of film and quality of finished membrane by adjusting parameters such as flow rate,time and coating frequency etc.According to its characteristics,the new technology was named blowing-spin coating deposition coating technology.2.Screening of membrane materials.The purpose was to set fly ash rich in Al₂O₃and SiO₂as coating material.Firstly,set Al₂O₃and SiO₂as coating material,added Ti O₂ as flux agent,prepared ingredients according to constitution of Al₂O₃ and SiO₂in fly ash and flux agent,and had experiments with the new coating technology,which provided theoretical direction for fly ash as coating material;secondly,set fly ash as coating material,and do Coating experiments.3.Film characterization and performance testing.Designed and built by relative performance detecting equipment to text the preparation of the film characterization and performance.At the same time,under optimum condition of experimental parameters,analyze crystal phase of the film composition and micro-structure morphology by means of XRD,SEM.Using fly ash as raw materials,the coated ceramic tube was obtained with average pore size of 2.32μm in film;flux of 152.72m³·m^-2·h^-1under 400Pa;porosity of 35.54%;and 99.29%rejection rate for PM_2.5 dust particles,and the film can be seen by a scanning electron microscope a certain pore.Compared with the separation of original film without coating,the coating film can effectively improve the separation accuracy,retention and achieve the performance improvement of separation membrane element.The new coating technology was successfully developed in this study.The technology enables rapid surface coating with advantages of easy film-forming,well-distributed and simple operation etc.,which achieves the diversification of coating technology.For screening of raw materials,based on setting fly ash as coating material,the membrane was successfully prepared on the support with rejection rate of above 99.29%for PM_2.5 fine particulate matters,which broadens the choice of coating materials and reduces the production cost of ceramic membranes.