1.Characteristics of reverse osmosis element membrane.
A. The salt removal rate is high, the water recovery rate is high, and the solute of various nano materials can be intercepted.
B. Under the standard of constant temperature, the solute and water can be separated, and the thermistor compound can be separated. Concentration energy consumption is lower compared with the change of peeling method.
C. Choose low pressure as the driving force of the membrane separation equipment. The separation equipment is simple and the operation process is simple. Maintenance and mechanical automation are simple, and the site is safe and healthy.
D. The reverse osmosis element membrane has a wide coverage of sediment.
2. Features of reverse osmosis ro membrane.
The water permeability and solute repellency of the reverse osmosis ro membrane are related to the ratio of the membrane pore size and the thickness of the pure water adsorption layer.
The wall thickness of the adsorption layer is t, the diameter of the membrane pores is d, and the ratio is m=d/t. The larger the m, the greater the water permeability, and the smaller the rejection of the solute; on the contrary, the smaller the m, the smaller the water permeability, and the greater the rejection of the solute. Moreover, the membrane generally thinks that d=2t is the critical damping. At this time, the repellency and water permeability are very large, and it is most suitable for the separation of water and solute. It is also called the critical point diameter.
When the critical point diameter is used, great water permeability and solute repellency can be obtained together. As shown below, the thickness of the pure water adsorption layer on the surface of the reverse osmosis ro membrane is t, which means that the effective rejection range of the reverse osmosis ro membrane to solute is t. When the membrane pores are less than 2t, the area of all membrane pores is within the range, so the solute permeability is equal to zero; but because the membrane pores are too small, the water permeability is not large. When D=2t, the repelling range of the membrane around the pores is exactly at the intersection of the pore centers, and the solute permeability is still equal to zero, but because the membrane pores are larger than before, the water permeability will also expand.
When D>2t, the repulsive force of the membrane around the pores cannot reach the pore center, and there is no repelling zone around the pore center. The larger the ratio m, the larger the area occupied by the non-rejection area. According to the diameter of the membrane in ro plant, the non-rejection area is a safe exit for the solute; the larger the safety exit, the greater the solute permeability. Therefore, when d>2t, although the water permeability is good, the solute rejection rate will be greatly reduced.