Issues with endpoint detection in the preparation of sodium hypochlorite solutions
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Our company uses chlorine and dilute alkali to produce sodium hypochlorite. For endpoint detection, samples are taken using a sampling cup and then tested by adding phenolphthalein; this approach poses certain safety risks, as the manhole cover is left open, and once the endpoint is reached, chlorine can easily escape. Does anyone have a better, more reliable method for detection?
Haven’t you tried online detection methods? Such as ion detection, or alternative detection approaches like density or refractometry. First, identify the physical and chemical properties that change significantly at the beginning and end of the reaction; start with these properties to find suitable online detection methods
During the production of sodium hypochlorite, chlorine is dissolved in a strong alkaline solution, and it is necessary to maintain a certain level of alkalinity throughout the process. By carrying out online monitoring of alkalinity or pH, it is entirely possible to prevent the leakage of chlorine. Near the end of the reaction, the flow rate to chlorine needs to be adjusted to a lower level. Furthermore, this preparation process can be carried out perfectly according to the specified ratio; so how could it possibly go past the optimal point?
Answering the question upstairs is no easy task. 1. The stoichiometric ratio is not easy to control; chlorine is in gaseous form, and mass transfer at the gas-liquid interface is poor, making it difficult to calculate the amount of unreacted chlorine that escapes ； 2. Online detection is not feasible for many materials due to the strong alkalinity and strong oxidizing properties of the medium; even those that can tolerate it have a short service life.
I think your factory produces 84 disinfectant on a temporary basis, mixing it manually in large tanks. If that’s the case, then there’s no need to consider any other testing methods; just spend a little more money and have the laboratory technicians conduct the tests several times. I’ve never seen in chlor-alkali plants that chlorine production from sodium hypochlorite cannot be measured.
:(It can monitor temperature/PH/chlorine concentration in the air; over time, one should be able to figure out how to use it. In my previous company, we generally monitored the PH and temperature curves.)
I’m wondering if there’s anything good that I can use as a reference; it’s too time-consuming to figure things out on my own
The main consideration is to find a mature solution; it always seems that this medium is highly corrosive and difficult to work with