# Why can potassium hydroxide not be used to remove atmospheric carbon dioxide?

As we know that $\ce{KOH}$ absorbs $\ce{CO2}$, then why can't it be used to remove the excessive $\ce{CO_2}$ present in the atmosphere?

## 3 Answers

$\ce{KOH}$ is produced by electrolysis of aqueous $\ce{KCl}$ solutions. Taking into account that the electrical energy still mostly comes from power plants that burn fossile fuels, it doesn't look like the most clever idea to release $\ce{CO2}$, just in order to capture it from the atmosphere again.

While it doesn't make sense to tackle the global $\ce{CO2}$ problem with $\ce{KOH}$ or other hydroxides, they do nevertheless bind $\ce{CO2}$ just as you said. Consequently, these hydroxides were and are still used for the individual protection against $\ce{CO2}$ (self)poisoning in emergency cases and/or in confined spaces. Rebreathers used by fire brigades, divers or miners are typical examples. Initially, $\ce{KOH}$ was indeed used, but nowadays, these $\ce{CO2}$ filters mostly contain mixtures of sodium hydroxide and calcium hydroxide.

KOH can affect us when inhaled and by passing throught the skin.It is a highly corrosive chemical and contact can severely irritate and burn the skin and eyes leading to eye damage.Inhaling it can irritate the lungs. Highly exposures may cause a build-up of fluid in the lungs (pulmonary oedema) a medical emergency.In addition to these adverse effects, it can also cause headache, dizziness, nausea and vomiting and also may cause a skin allergy.

So by observing these we can surely say that KOH can never be an option to absorb carbondioxide of the atmosphere.If we use it then we will just be gambling our life to death.

• You are absolutely right on the health risks of these hydroxides! Nevertheless, when properly embedded in filtering devices, they can safe lifes because they can prevent self-poisoning by carbon dioxide. – Klaus-Dieter Warzecha Feb 27 '14 at 14:52

"Potassium hydroxide is usually sold as translucent pellets, which will become tacky in air because KOH is hygroscopic." from Wikipedia. This clears that if KOH is used to absorb the excess carbon dioxide from atmosphere ,there is greater chance of absorption of water molecules from the atmosphere which in turn can change the atmospheric contents resulting in some imbalance atmospheric conditions if KOH is used in excess.

• Wet $\ce{KOH}$ doesn't stop to react with $\ce{CO2}$. – Klaus-Dieter Warzecha Feb 27 '14 at 7:23
• Its not about reaction with carbondioxide because there is large amount of carbondioxide in our atmosphere nowadays that to control that, large amount of KOH should be used which will surely absorb large amount of moisture as well changing the atmospheric condition which might cause a lot of problems. – CCR Feb 27 '14 at 7:30
• Taking into account that 70% of the surface of the earth is covered by water, which is in equilibrium with the vapour in the atmosphere, I'd like to see a rough estimation on how much $\ce{KOH}$ is needed to cause an ecological problem due to "drying the atmosphere". – Klaus-Dieter Warzecha Feb 27 '14 at 7:38
• Oh i'm so sorry that i didn't take account on the fact but i have come up with one of the best answer for the question please have a glance of it. – CCR Feb 27 '14 at 14:23