The appeal of DIY air purification
Commercially available air purifiers with activated carbon filters cost anywhere from a few hundred to several thousand rupees. It’s natural to wonder whether a bag of activated charcoal from a hardware store, placed in a room, could achieve similar results. The short answer is: partially, but not really.
What activated charcoal does in air purification
Activated charcoal adsorbs gases and vapours — including VOCs (volatile organic compounds), formaldehyde, benzene, odours from cooking and pets, and some airborne chemicals. It does this purely through the physical adsorption mechanism: the gas molecule enters the pore network and sticks to the carbon surface via van der Waals forces.
A container of charcoal in a room will adsorb some VOCs from the air that diffuses past it. It does not actively draw air through — it passively adsorbs what comes into contact with it. This is far less effective than a fan-driven system that forces all the room air through a carbon bed at controlled face velocity.
For meaningful air purification, the carbon needs forced airflow. A bag of charcoal sitting on a shelf will adsorb what diffuses to it — which is a small fraction of the room air in any practical timeframe.
What it cannot do
Activated charcoal does not remove particulates — dust, pollen, smoke particles — from the air. It does not kill bacteria or viruses. For particulate removal, a HEPA filter is needed. For complete home air quality, the combination of HEPA filtration plus activated carbon is the standard approach.
The type of carbon matters
Not all activated charcoal sold for home use is the same. Coconut shell carbon with high CTC value is most effective for gas-phase VOC adsorption. Impregnated grades (with potassium permanganate, or specific reagents) are more effective for specific gases like formaldehyde. Generic “activated charcoal” from non-carbon suppliers may be low quality with limited adsorption capacity.