Separation of phosphorous acid from sodium chloride
Thread Content
There are many substances that are difficult to separate, and this is one of them. For example, phosphorous acid and sodium chloride. We currently plan to use membranes, but we’re not sure if there are any better options.
That day, I heard from a senior colleague about using concentration followed by a membrane process; I’m not sure if it will work
For membrane filtration, I’m not sure if it will work; also, I’m not sure what method to use for separating molecules with similar molecular weights. For example, separating formaldehyde from water.
At a certain temperature, phosphorous acid is almost completely miscible with water, while the solubility of sodium chloride is around 35; therefore, what is obtained through concentration and crystallization is mostly sodium chloride. It is important to control the temperature. This post was last edited by nwno2 on 2008-3-6 14:10]
Concentrated crystallization is possible, but separation cannot still be achieved completely. Because at high temperatures, some sodium chloride still enters the liquid phase along with the filtrate. Complete separation of sodium chloride from phosphorous acid has not been achieved.
Phosphorous acid has a very low melting point, around 80 degrees I think; it’s necessary to evaporate the water and heat the substance to its melting point, followed by solid-liquid separation. However, phosphorous acid decomposes into toxic gases at high temperatures, around 200 degrees or so
By the way, the solubility of sodium chloride changes very little with temperature.
Dissolving it is possible, but I think it’s a bit difficult in actual production. Could you provide a device flowchart?