Nanofiltration membrane and reverse osmosis membrane which is better to use

Release Time:

2022-02-17 09:24

Both nanofiltration membranes and reverse osmosis membranes are used for fine filtration in industrial water treatment. The filtration accuracy of these two industrial filtration membranes is very high. Compared with nanofiltration membranes and reverse osmosis membranes, which one is better?

What is the difference between nanofiltration membrane and reverse osmosis membrane

Nanofiltration membrane is a kind of filtration membrane between ultrafiltration and reverse osmosis. chemical balance between. The electrostatic interaction is formed between the nanofiltration membrane and the electrolyte ions. The charge strength of the electrolyte salt ions is different, resulting in the difference in the ion retention rate of the membrane. Because there are negatively charged groups on the nanofiltration membrane or the membrane, they interact through electrostatic interaction. In a multi-component system containing ions of different valences, due to the Daunan effect, the selectivity of the membrane to different ions is different, and the proportion of different ions passing through the membrane is also different. The charge density of the nanofiltration membrane is 0.5~2 meq/g.

The reverse osmosis membrane is to use a high-pressure pump to apply a higher pressure than the natural osmotic pressure in salty water, so that the influent water permeates in the opposite direction, and the water molecules in the raw water are forced to the other side of the membrane, the concentrated water of the membrane. The side is polluted water with impurities, and the fresh water side of the membrane is pure water without pollutants, which finally achieves the purpose of removing impurities and salts in the water and achieves the effect of dehydration.

The operating pressure of the nanofiltration membrane is within 0.3-0.7MPa, and cannot be lower than 0.3MPa, otherwise the reverse osmosis equipment cannot operate normally.

The operating pressure of the reverse osmosis membrane is much larger than that of the nanofiltration membrane, and the operating pressure of the reverse osmosis membrane is generally 10.5MPa.

The reverse osmosis membrane has a higher over-precision, up to 0.0001 μm, which is 1 nanometer, and can filter out bacteria, impurity colloids and other substances in the water.

The choice of nanofiltration membrane and reverse osmosis membrane mainly depends on the filtration requirements of the factory, and different filtration membranes are selected for different filtration precision requirements. In general, there is no better way to say that, different use environments have different requirements for membranes.

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