Is the pH of the brine adjusted before or after using the Kay membrane?
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In one instance, the brine was unstable due to magnesium content in the raw salt; generally, 0.2–0.3 excess of alkali was used. As a result, the pH is above 12 after the brine passes through the membrane. I would like to ask my colleagues whether you make any adjustments; if so, do you add acid before the fluid enters the membrane or at the outlet of the membrane? Also, for the pH after adding acid, should it be measured using test strips or a pH meter, as there is a significant difference between the values obtained from these two methods.
Our company specializes in exporting acid, pH meters, and automatic detection devices behind membranes.
We’re doing the same thing now, but recently I’ve been thinking that if we made adjustments before the material enters the membrane, wouldn’t the filtration precision be higher? After all, a high alkali content can lead to the precipitation of magnesium, aluminum, and other elements.
It must be adjusted behind the membrane; if it were adjusted in front of the membrane, then what’s the point of having such a high pH value? Moreover, if it becomes too acidic, it will be useless. It is recommended to use online automatic pH adjustment for stability; temporary sampling, no matter how precise the test strips or pH meters may be, cannot ensure long-term stability.
Pre-membrane adjustment: if acid addition causes problems and leads to the presence of free chlorine, the membrane’s lifespan will be shortened.
Saltwater membranes are not affected by free chlorine; in most current processes, sodium hypochlorite is added to ensure the presence of free chlorine and thus prevent microorganisms from clogging the membrane, with sodium bisulfite being used afterward to neutralize it. By adding calcium and magnesium before the membrane, it becomes ions, allowing smooth passage through the membrane.
The membrane is used to remove calcium carbonate; the addition of acid creates local acidity, and the calcium and magnesium precipitates are converted into ions that pass through the membrane, which affects the efficiency of removing calcium and magnesium. Therefore, it is necessary to add acid after the membrane.
The membrane is used to filter suspended particles (mostly calcium carbonate); adding acid before the membrane can cause some calcium and magnesium to turn into ionic forms, thereby affecting the quality of the brine.
PH can be monitored online and compared with laboratory analysis results; the online PH value needs to be calibrated regularly
Acid must be added after the filtration membrane; with so much calcium carbonate and magnesium hydroxide present before the membrane, adding acid will inevitably cause the calcium and magnesium ions to become ionized, thereby reducing the quality of the brine. What do you think?
Acid is added after the Kai membrane for adjustment, with online pH monitoring