Your question is a little confusing in that I'm not sure whether you are talking about pH stability of your silica nanoparticle coatings or the Al containers.
The one bit that does make sense is the statement about between pH 3 and 9. Al forms a passive (corrosion resistant) metal oxide between about pH 3.9 - 8.6. Below 3.9 it will form Al3+ which is soluble and therefore corrodes and above 8.6 it also corrodes. The stability also depends on the electrochemical potential of your system but I don't think that's too important here. Essentially if the material you want to store in the Al bottles has a pH < 4 and > 8.6 your bottle will corrode.
My gut feeling is that your SiO2 in ethanol/water mix is probably around pH7, but it's worth checking the coating with a piece of universal indicator. That should give you a ballpark value for the pH.
Thank you for your answer, and sorry for my confusing question.
My question was actually based a bit on both, whether one would react with the other and the other way around.
I have done a bit of testing with universal indicator paper, and found that my coatings approximately has the values of;
- pH 5
- pH between 2-3
- pH 7.
Which would mean that the coatings with pH between 2-3, would cause my bottles to corrode?
My products will have a shelf life on around 1 year. I have tried to do a bit of research, and it says it can cause a "slow chemical corrosion". Is it possible to give an indication on when the corrosion begins, how long time there goes before it has any effect, and whether or not it can ruin my nano coatings effect?
My supplier of the Al bottles also has a bottle that they call "Chemical pesticide insecticide agrochemical pharmaceutical Alluminum bottle", does this bottle do any difference regarding the possible reaction with Al? Perhaps it corrodes at a lower og higher pH value?
Also when my supplier of the coatings indicates the products has a chemical stability between 1-13, what does that mean?
Sorry for my poor knowledge, and thank you very much for the help, i'm very grateful.
The key will be the pH of your product. The nanoparticulate silicate (SiO2) should have no effect on aluminum. However, the pH of the complete formulation will have an effect. If the pH of your product is around 7.0 (+/- 2.0) You should not have nay problems with an aluminum bottle. The bottle manufacturer's spec range for pH (pH=1-13) is rather large for aluminum.
The simplest was to prove the stability of this container is to accurately weigh an empty bottle, put your product in it and warm it to the highest temp possible without boiling. If you have ethanol in your product, you may just want to store it at about 25-30C. After several weeks, empty the bottle, rinse it out, and reweigh it. If the weight of the bottle has either increased or decreased, you may have a problem. If the weight is unchanged and there no obvious appearance changes, you are probably OK with this bottle.
Hope this helps!
We have just had manufactured a series of shampoo, conditioners, and treatments based on the conditioners at a contract manufacturer. The manufacturing went well until two months later when we have a reaction in the bottle with the conditioners. In some cases, they make a fizz sound like when you open a soda bottle and continue oozing. The Ph range is between 3.07 and 3.54 for the conditioners and 4.97 to 5 for the shampoos. The bottles have an inner coating of epoxy resin. The caps are aluminium with a double silicon wad to prevent leakage. When the bottles were cut in 1/2, the inner coating in some cases was back to bare aluminium.
The supplier is a major supplier to the personal care industry for this type of product.
The micro passed at manufacture, and we had it tested as soon as we had the issue, and it is fine.
Any input you can provide to assist with understanding what is happening and how we can fix it.