Monitoring the concentration of ammonium and zinc ions in pre-flux solutions used to prepare steel in the plating industry by titration
The surface of steel which is subject to galvanising has to be prepared for the plating process.
Part of this surface preparation involves treating with a pre-flux solution containing ammonium and zinc chlorides.
It is important to monitor the concentration of both ammonium and zinc ions, as well as measuring the ferrous ion content of the solution, an indicator of corrosion of the steel surface.
Multitrator determines both the ammonium and zinc concentrations in a single acid/base titration sequence.
The ammonium content is reacted with formaldehyde, forming hexamethylene tetramine (hexamine) and protons (acid).
After reaction, the solution is titrated with standard sodium hydroxide to give two endpoints, The first endpoint represents the acid produced by the reaction of the ammonium with formaldehyde.
The second endpoint represents the hydrolysis of the Zn(II) aquo ion to form zinc hydroxide.
The determination of both the ammonium and zinc contents is highly precise.
The ferrous ion content is easily determined by a thermometric redox titration using potassium dichromate as the titrant.
Multitrator is able to offer a compact two burette system to handle this analytical task.
With appropriate training, it is suitable for use by relatively unskilled operators in a field laboratory environment.
