Filtration of titanium silicalite zeolite suspensions by airlift ceramic membrane equipment

To overcome the membrane fouling problems and increase the flux of membrane, the aeration process was introduced into the ceramic membrane filtration process. Liquid circulation velocity, gas holdup and membrane surface shearforce were calculated under different aeration conditions. The filtration of titanium silicalite (TS-1) zeolite suspension by airlift ceramic membrane equipment was performed. The effect of solid content (mass concentration), aeration rate and transmembrane pressure on the membrane filtration performance was investigated systematically by using ZrO₂ ceramic membrane with a pore size of 200 nm. The results show that the liquid circulation flow rate and gas holdup increase when the aeration rate increases; in addition, the pattern of gas-liquid two phases is slug flow when the aeration rate increases from 416 to 2 333 mL/min, and the membrane surface shearforce in the gas slug area is 3-10 times of that in liquid slug area. The rejection of TS-1 by ceramic membrane can reach 100%. When solid content is 1%, and the aeration rate increases from 100 to 850 mL/min, the steady flux is increased by 33%, and then decreases when the aeration rate further increases. Steady flux decreases with the increase of solid content. When solid content is 1%, aeration rate is 850 mL/min, the trans-membrane pressure increases from 0.1 MPa to 0.2 MPa, and the steady flux is reduced by 41%, and then increases when the trans-membrane pressure is further increased to 0.3 MPa. By calculation and analyses of membrane filtration resistance, the aeration process is effective in the control of concentration polarization, however, it has little effect on the removing of cake and pore blocking fouling.