Analysis of the advantages and disadvantages of ferric trichloride and sodium polyacrylate as sedimentation aids in brine purification
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This post was last edited by sunjl1981 on 2013-1-6 at 20:04. Generally, chlor-alkali companies use ferric trichloride as a sedimentation aid in brine purification; which companies use sodium polyacrylate? Which one is more cost-effective to use? This post was last edited by yzhms on 2009-3-17 14:38 ] # ， ， &
I’ve never used sodium polyacrylate; it must be related to what kind of brine purification process is used
Sodium polyacrylate was very popular in the past, but now hardly any devices use it. Experts, please analyze the specific reasons; it would be great to learn from it*learn*! :lol
Sodium polyacrylate is generally used in the brine purification process of Dow clarifying tanks
Current ion-exchange membrane caustic soda production facilities should use ferric chloride; both of them have flocculating properties. The main difference seems to be that ferric chloride is an inorganic substance, while sodium polyacrylate is an organic one, and its addition has an impact on the ion-exchange membrane. I’m not too sure about the other aspects; please feel free to provide more information
Sodium polyacrylate is generally used in the brine purification process of Dower clarifying tanks; our company uses ferric chloride as a sedimentation aid in its floating clarifying tanks.
It seems that sodium polyacrylate accumulates on the anode, affecting the economic operation of the electrolyzer. Meanwhile, ferric trichloride has a much lesser impact on the electrolytic cell under alkaline conditions. When I started working, it was ferric chloride, and I didn’t study it in much detail. Hehe.
Also, ferric trichloride can be well regenerated and restored in the filters currently in use, whereas sodium polyacrylate does not achieve good regeneration efficiency once it becomes contaminated in the filters.
Sodium polyacrylate, also known as PAS, is a water-soluble linear polymer that forms insoluble salts when it comes into contact with metal ions having a valence of two or more (such as aluminum, lead, iron, calcium, magnesium, zinc), leading to molecular cross-linking and subsequent gelation and precipitation. It swells when in contact with water, changing from a transparent gel state to a viscous liquid. It is soluble in aqueous solutions of sodium hydroxide, and precipitates in aqueous solutions of calcium hydroxide, magnesium hydroxide, etc. It can adsorb the Mg(OH)2 and CaCO3 suspensions in saline water to its surface, causing them to precipitate rapidly. If not treated thoroughly, it will adhere to the membrane, affecting its permeability. This post was last edited by yzhms on 2009-3-21 21:37.]
Sodium polyacrylate and FeCl3 can both be used in the ion exchange membrane process. FeCl3 is used under alkaline conditions; since brine has a weakly alkaline nature, adding too much of it will make the brine acidic and increase its iron content. Sodium polyacrylate is alkaline in nature, and its solution contains electrons that enable the reaction particles to have an adsorptive effect, facilitating the binding of larger particles. It contains ammonium salts, and excessive amounts of these salts can cause a rapid increase in pressure in subsequent filters. If they reach the resin columns, it can render the resin ineffective, while if they enter the membranes, it can cause serious damage. The concentration of both substances should be controlled at 1 ppm. Last edited by yzhms on 2009-3-21 21:36
Sodium polyacrylate is widely used in the Daoer clarification tank process; it easily binds to large particles, but it has a certain impact on the resin tower. Iron trichloride is primarily used in the floating and clarification tank process, but an excessive amount of it can increase the iron content in the secondary brine; currently, this process makes use of iron trichloride quite frequently.
Our factory uses FeCl3; due to unstable addition amounts, too much of it is often added, which causes the resin to change color, the inlet and outlet pipes of the electrolytic cell to turn red, and the membrane to change color as well. [This post was last edited by yzhms on 2009-3-21 at 21:37]
Our company uses PAS for its diaphragm systems – which are Dow clarifying tanks – but for capacities of 200,000 tons, we use FeCl3 and floating tanks; it seems to be related to the equipment chosen :) This post was last edited by yzhms on 2009-3-21 at 21:39.]
The interaction between sodium polyacrylate and ferric chloride is the same. However, sodium polyacrylate has a much greater impact on ion exchange membranes than ferric trichloride. Sodium polyacrylate has a slightly better sinking effect.