Sodium hydroxide for etching |lifetime |disposal |

[elementHTTP]

Hi there :)
I have 10g of NaOH whit 1 liter of water for photo etching
Solution is one year old, and do i need to make new one (is there a lifespan of solution) ?
If yes how to dispose it safely ? (can it be disposed in regular drain ?)

thanks for your time :)

 

[Borek]

Quite likely it absorbed enough atmospheric CO₂ it doesn't qualify as "NaOH" solution, but NaOH/Na₂CO₃ solution.

At this concentration you can safely pour it down the drain.