As we kown, some kinds of corrosion products are easy to be oxidized, so could somebody tell me how to avoid the oxidation of corrosio products during processo di salvataggio and pre-processing of analysis. Or could someone tell me how to put away the FexOy in the corrosion products?
In my understanding oxides, like your mentioned FexOy, are corrosion products. Generally, Fe oxidizes in the presence of e. g. oxygen if the dissociation pressure of the respective Fe-Oxide is exceeded. Consequently, to prevent oxidation or to dissolve oxides one way could be to lower the oxygen partial pressure in the resepctive gas atmosphere below the dissociation pressure of the respective oxide. Unfortunately, the dissociation pressures of the common oxide are in general very low but increase with increasing temperature.
Hope this suits in parts your question. Best regards.
That depends on what you are planing to do next.
If you want to maintain the oxidation state of Iron products you can purge your sample with Pure Nitrogen for a couple of hours and then blanket it with Nitrogen, you can also add oxygen scavenger in a closed sample bottle filled to the top with the water sample .If you don't care about the oxidation state of the iron product but like to prevent the corrosion product from precipitating you can decrease the pH of the sample to below 3 using HCl or sulfamic acid
I hope this answers your question
If the intent of your question is to ask how do you maintain the specific iron oxy(hydroxide) species that form as corrosion products during a test so that you can analyze them without fear that the form(s) of the oxy(hydroxides) have changed during post test processing of the sample, then you are going to need to remove the samples from test in a controlled environment without any oxygen present. This can best be done in a glove box that is filled with argon. The sample can be removed for the test apparatus, rinsed with alcohol (that has been purged with Ar to remove any dissolved O2), and then placed in a desiccator for storage and/or transfer to analysis.
I would warn against the use of nitrogen for this because the nitrogen bottles often come with low levels of oxygen. The amount of oxygen in nitrogen depends upon the grade, but a few ppm might be enough to cause a change. It is easier to simply avoid this through the use of Ar.
Hi,
It is difficult to avoid the oxidation of products corrosion. But, in general, the suitable scale of potential range its important to use to prevent the oxidation later.
To Avoiding Corrosive Situations
Choose couple metals close on the galvanic series
Use large anode, and small cathode areas
Electrically insulate dissimilar metals
Connect a more anodic metal to the system
Avoid turbulent flow and impingement in pipe systems
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