Saltwater purification
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When recycling industrial brine as a raw material for ion-exchange membrane chlor-alkali production (a 17% sodium chloride solution), a high TOC level was observed; after using extractive distillation, the TOC level dropped to around 50 mg/l. Activated carbon adsorption was then applied, and this reduced the TOC level to approximately 30. The problem remains severe; it cannot be used. Why is it still so high after activated carbon adsorption? What other ways are there to deal with this?
Try oxidation treatment by adding ozone or chlorine dioxide; the reaction will eliminate it
To analyze the composition of TOC, it is generally necessary to look at the ratio of COD to BOD, which helps in selecting an appropriate treatment process.
By adding sodium hypochlorite and hydrochloric acid, the TOC dropped from 30 to 10, but then it stopped decreasing. In the laboratory, an excessive amount of sodium hypochlorite was added and the temperature was raised to 80 degrees, yet the value only dropped to 8. We hope to bring it below 5.
Since it is 17% saline solution, COD cannot be analyzed
The waste brine has already been extracted and distilled; I guess stripping won’t be of much use either
The oxidizing power of chlorine dioxide and ozone is much greater than that of sodium hypochlorite. Give it a try; you can also try Fenton oxidation – there’s nothing that can’t be dealt with. If that doesn’t work, use large-pore resin or activated carbon for adsorption
The mode of existence of the total organic carbon therein can be assumed. The first type are volatile organic compounds in molecular form; these can be emitted or vaporized when heated, or captured by activated carbon. The second type consists of volatile organic substances in molecular form that are either soluble in water or have an extremely high molecular weight (which is unlikely); activated carbon can handle these easily. The third type are organic substances in ionic form, which can be either anions or cations; however, neither evaporation nor activated carbon is effective in dealing with them. For this, ion exchange or oxidation is the only options. The fourth one, I can’t imagine it. In the case of large-scale production, it basically involves just heating it, passing it through activated carbon, and then through ion exchange resin – there should be no problems then.