Hydrogen production, and turning NaAlO2 back into Aluminium
Posted On: Feb 1, 2021 13:00:15 GMT
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Post by John Skieswanne on Feb 1, 2021 13:00:15 GMT
I am very interested in the production of hydrogen as it can be used for so many applications, including as an experimental lifting gas but also as a green fuel source.
Everyone knows that one can produce hydrogen by splitting water using electricity. But in a self-sufficient community, usage of electricity needs to be wise, and I feel the more we have things that do not depend on electricity, the more stable our community will be. Besides, splitting water electrically doesn't create just hydrogen, it also gives off oxygen, and care must be taken if we want to harvest pure hydrogen.
That's why one of the members here has begun investigating electricity-less hydrogen generation.
Aluminium inside water would theoretically cause the water to emit hydrogen. However the oxygen part of water binds with the aluminium, creating aluminium oxide, and the process stops working very rapidly.
By adding lye (NaOH) to the process, the process runs perfectly, and hydrogen is produced. I have read reports that 5 grams of aluminium could, in this fashion, yield several liters of hydrogen. One of the members here confirmed this on multiple occasions.
The waste product was however a topic of concern. After reacting with aluminium, the lye solution turns a dark color.
Production of hydrogen with this methods at first seems like a wasteful method, however if we are smart about this, we can realize that the aluminium is still present in this dark liquid, which is a solution of NaAlO2, also called Sodium Aluminate:
Al + NaOH + H2O = NaAlO2 + H2
Now, it seems boiling Sodium Aluminate in Water breaks sodium off, giving Aluminium Hydroxide (which should look like a white, hard powder?), and Sodium Hydroxide (lye):
2 H2O + NaAlO2 → Al(OH)3 + NaOH
Then, according to the Chemical Equation Balancer (https://en.intl.chemicalaid.com/tools/equationbalancer.php?equation=Al%28OH%293+%2B+H3O+%3D+Al+%2B+H2O), the addition of H3O would force the Al(OH)3 to give up its OH:
Al(OH)3 + 3H3O → Al + 6H2O
(Note: H3O is present in acidic water, or water that has bee exposed to air:
"Pure water is neutral, but most water samples contain impurities. If an impurity is an acid or base, this will affect the concentrations of hydronium ion and hydroxide ion. Water samples that are exposed to air will absorb some carbon dioxide to form carbonic acid (H2CO3) and the concentration of H3O+ will increase due to the reaction H2CO3 + H2O = HCO3− + H3O+. The concentration of OH− will decrease in such a way that the product [H3O+][OH−] remains constant for fixed temperature and pressure. Thus these water samples will be slightly acidic. If a pH of exactly 7.0 is required, it must be maintained with an appropriate buffer solution." - wiki)
Thus giving us water... and pure aluminium.
If this sequence of chemical operations is correct, then it would be possible to recycle our waste back into refined aluminium, and into lye, with no need to buy any more aluminium or lye, and produce even more hydrogen from these recycled matter. This loop would enable us to produce hydrogen forever in a waste-free fashion, as long we have water available.
Everyone knows that one can produce hydrogen by splitting water using electricity. But in a self-sufficient community, usage of electricity needs to be wise, and I feel the more we have things that do not depend on electricity, the more stable our community will be. Besides, splitting water electrically doesn't create just hydrogen, it also gives off oxygen, and care must be taken if we want to harvest pure hydrogen.
That's why one of the members here has begun investigating electricity-less hydrogen generation.
Aluminium inside water would theoretically cause the water to emit hydrogen. However the oxygen part of water binds with the aluminium, creating aluminium oxide, and the process stops working very rapidly.
By adding lye (NaOH) to the process, the process runs perfectly, and hydrogen is produced. I have read reports that 5 grams of aluminium could, in this fashion, yield several liters of hydrogen. One of the members here confirmed this on multiple occasions.
The waste product was however a topic of concern. After reacting with aluminium, the lye solution turns a dark color.
Production of hydrogen with this methods at first seems like a wasteful method, however if we are smart about this, we can realize that the aluminium is still present in this dark liquid, which is a solution of NaAlO2, also called Sodium Aluminate:
Al + NaOH + H2O = NaAlO2 + H2
Now, it seems boiling Sodium Aluminate in Water breaks sodium off, giving Aluminium Hydroxide (which should look like a white, hard powder?), and Sodium Hydroxide (lye):
2 H2O + NaAlO2 → Al(OH)3 + NaOH
Then, according to the Chemical Equation Balancer (https://en.intl.chemicalaid.com/tools/equationbalancer.php?equation=Al%28OH%293+%2B+H3O+%3D+Al+%2B+H2O), the addition of H3O would force the Al(OH)3 to give up its OH:
Al(OH)3 + 3H3O → Al + 6H2O
(Note: H3O is present in acidic water, or water that has bee exposed to air:
"Pure water is neutral, but most water samples contain impurities. If an impurity is an acid or base, this will affect the concentrations of hydronium ion and hydroxide ion. Water samples that are exposed to air will absorb some carbon dioxide to form carbonic acid (H2CO3) and the concentration of H3O+ will increase due to the reaction H2CO3 + H2O = HCO3− + H3O+. The concentration of OH− will decrease in such a way that the product [H3O+][OH−] remains constant for fixed temperature and pressure. Thus these water samples will be slightly acidic. If a pH of exactly 7.0 is required, it must be maintained with an appropriate buffer solution." - wiki)
Thus giving us water... and pure aluminium.
If this sequence of chemical operations is correct, then it would be possible to recycle our waste back into refined aluminium, and into lye, with no need to buy any more aluminium or lye, and produce even more hydrogen from these recycled matter. This loop would enable us to produce hydrogen forever in a waste-free fashion, as long we have water available.