My hand slipped.
(please don't imitate at home)
said in the push two days ago that if you corrode the metal part of the can with acid or alkali, you will eventually see a transparent polymer film on the inside of the can. this polymer coating is responsible for separating the beverage from the metal. After posting the article, I also tried to do this experiment. I will show you the results below.
first of all, the first step is to use a polishing strip to remove the printing layer and protective layer on the surface of aluminum cans, so that the printed handwriting can hardly be seen. It will take some time (I forgot to take a picture here. ).
next I chose sodium hydroxide to react with aluminum, a process that produces sodium metaaluminate and hydrogen. Reaction formula: 2 Al + 2 NaOH + 2H2O → 2 NaAlO2+ 3H2
the solution I used was probably less than 2mol/L (because a little more water was added later) and was only submerged to less than half of the can. It takes a long time to react, at least for more than an hour.
(the open empty can is filled with some water to prevent it from drifting, and hang it with a plastic rod. Originally, I wanted to shoot a complete delay, but the unscraped printing layer fell off and made the solution very muddy and black. there was nothing to see at all. )
here is the moment to witness the little secret of cans:
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this polymer film is really thin, inelastic, and certainly not very strong (epoxy coating: nonsense. I'm not the one in charge of anti-stress. When washing, the film was accidentally poked a hole with the mouth of the bottle.
so I'm going to take back my foreword, which is not suitable for playing with _ (: scratch "∠) _