In the process of using alkaline zinc plating additives, we sometimes use CK-778 purifier to treat the plating solution, which can effectively remove heavy metal impurities and adsorb the decomposition products of additives, and has a good adsorption effect on oil stains and suspended solids.However, the end point of the plating solution treated with CK-778 purifying agent is not obvious during the titration analysis of zinc ions, which will lead to inaccurate analysis of zinc ions. What is the reason?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product alkaline galvanizing additive BZ-515.The titration end point is not obvious when analyzing the zinc ion concentration after the impurity removal treatment of the plating solution, and the end point cannot even be observed. This is because the indicator chrome black T is blocked.
Chrome black T is a common indicator for titration of Mg2+, Zn2+, Pb2+ plasma in weak alkaline solution.When there are Al3+, Fe3+, Cu2+, Co2+, Ni2+ plasma in the plating solution, the chrome black T will be blocked, resulting in the inability to determine the end point of the titration.It is often due to the poor quality of the reagent or distilled water that the above-mentioned ions are contained, which makes the indicator ineffective.
The solution is to add a masking agent to the solution to interfere with the ions to generate a stable complex, so that it does not interact with the indicator.The blocking of chromium black T by Al3+ and Fe3+ ions can be removed by adding triethanolamine;Cu2+, Co2+, Ni2+ plasma can be masked by KCN, and Fe3+ ions can also be reduced to Fe2+ by ascorbic acid, and then KCN is added to generate Fe(CN)2+4.
In addition, the calcium ion content in the water with higher hardness is higher, and the calcium ion will affect the chrome black T indicator, which will lead to no obvious color change when the titration is approaching the end point.In this case, a small amount of MgEDTA solution can be added to the buffer solution to ensure a clear endpoint.
Therefore, the end point of the plating solution using alkaline galvanizing additive is not obvious when analyzing zinc ions after treatment with CK-778 purifier, which can be solved by the above method, which can accurately analyze the content of zinc ions and improve production efficiency.If you are interested in alkaline galvanizing additives, please contact Bigolly customer service to get free samples and detailed technical information!
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