| 摘要 |
The permeability gradient is in the direction of flow of the fluid to be treated, with the mean porosity of a band increasin the direction of fluid flow. Independent claims are also included for the following: (i) a membrane incorporating the above support; (ii) the production of the support by immersing a macroporous support vertically into a barbotine or organic solution; and (iii) a macroporous support saturated with liquid to produce a gradient of free volume. Preferred Features: The gradient of mean porosity matches a gradient of impregnation starting from the external surface of support. The pore diameter in the impregnated zone is 0.1-0.8 times that of the non-impregnated zone, preferably 0.3-0.5 times. mean outlet porosity/inlet porosity ratio 1.1-4, with the initial porosity being 15-45%. The macroporous support is immersed in solution for 0-15 seconds for the least and most immersed parts respectively, preferably 0.5-8 seconds. Alternatively, the suppo is impregnated by the barbotine or organic solution being sprayed onto the support, with the spraying zone being moved along. Th speed of displacement of the spray nozzle is 0.1-3 cm/s, preferably 0.7-1.7 cm/s. The material flow through the nozzle is variab along the support while the speed of displacement is constant, or vice versa. Alternatively, the support is saturated with water then gas is injected into it while the outlet is open, partially open or completely closed and the support is then immersed horizontally into a barbotine or organic solution. |
