The issue of free chlorine in removing organic matter

By adding sodium hypochlorite to saltwater to remove organic substances, the strong oxidizing properties of hypochlorite ions are utilized to break down these organic substances into CO2 and water. This process works well in alkaline conditions; in acidic conditions, hypochlorous acid is formed, which is unstable, and excessive amounts of it can result in the release of chlorine gas. Lol, if it doesn’t work, you can give it a try in the laboratory. The organic substances present in saltwater cannot be trapped by KAI membranes; however, some organic substances can be captured, such as those found in activated carbon. The pore size of KAI membranes is 0.2–0.5 microns, which is quite large, so it’s not possible to retain the corrosive substances present in saltwater. With so many tests conducted by your company, could it be that less mercury sulfate, which acts as a masking agent, was used, resulting in some chloride ions remaining free? You can try testing for TOC (Total Organic Carbon) to see if there is an issue with the testing. As a supplementary note, COD stands for Chemical Oxygen Demand; anything in water that can be oxidized is taken into account, whether it’s organic or inorganic. Generally, we use the chromium method for this purpose. Chromium in the +7 valence state has strong oxidizing properties; under the action of concentrated sulfuric acid and silver sulfate as catalysts, everything that can be oxidized in water is oxidized. What is detected does not necessarily refer to organic substances; it is only the substances remaining after removing inorganic substances that are organic.

Oh, the levels of organic matter and total ammonia in the raw salt used by our company are quite high. That’s why we want to keep adding chlorine dioxide. This substance wasn’t used in the original processing method. We’re mainly looking to find out the best place to add it, as well as whether it’s necessary to control its concentration; if too much is added, we need to know how to remove it. After all, brine used in production processes cannot contain free chlorine. Currently, it’s required that chlorine dioxide be added at the baffle tanks in the salt dissolving area, so as to maintain a free chlorine level of 3–5 milligrams in the crude brine. Excess free chlorine is then removed at the outlet. We’re not sure if this approach is appropriate. Most of the tanks in our company don’t have any anti-corrosion measures – could excessive free chlorine cause severe corrosion?

Salt contains ammonium; for the brine obtained from salt processing, it may be advisable to use an ammonium removal tower. Sodium hypochlorite is added to this tower, followed by sodium sulfite, and then further purification is carried out. If your equipment does not have corrosion resistance, corrosion will be severe, so handle sodium hypochlorite with caution. If you have any further questions, please contact me by phone at 15279334385

The COD error is too large; try using TOC to see

During the single-stage purification of saline water, when analyzing COD, whether using the chromium method or other methods, the interference and impact of chloride ions are very significant; therefore, it is not recommended to measure COD directly. Instead, TOC, which provides a better representation of organic matter, should be used for analysis. Moreover, some TOC analysis methods can handle low levels of organic matter in high-concentration salt solutions without any problems. Additionally, the detection of ammonia nitrogen in saline water is part of safety testing; again, due to the influence of high concentrations of sodium chloride, sample processing and testing are affected to varying degrees, so it is necessary to carefully select the analysis method.