The best substance for drying ammonia is typically concentrated sulfuric acid (H2SO4). This process involves passing the ammonia gas through a drying tower or column packed with the concentrated sulfuric acid.
Here's why concentrated sulfuric acid is commonly used for this purpose:
Strong drying agent: Concentrated sulfuric acid is an extremely hygroscopic substance, meaning it has a strong affinity for water molecules. It can effectively remove water vapor from the ammonia gas stream, thereby "drying" it.
Chemical reaction: When ammonia gas reacts with concentrated sulfuric acid, the following reaction takes place:
2NH3 + H2SO4 → (NH4)2SO4
The reaction forms ammonium sulfate, a solid salt, and water, which further helps in removing water vapor from the ammonia.
Non-volatile and non-reactive: Concentrated sulfuric acid is non-volatile, which means it won't evaporate or react with the ammonia gas itself, ensuring that it doesn't introduce any impurities to the gas stream.
Availability and cost-effectiveness: Sulfuric acid is readily available and relatively affordable compared to other drying agents, making it a practical choice for industrial applications.
It's essential to handle concentrated sulfuric acid with extreme care as it is a highly corrosive and hazardous substance. Proper safety protocols and equipment should always be used when working with such chemicals. If you are not experienced with handling dangerous chemicals, it's best to seek assistance from qualified professionals.