Active Biochar, an Eco-Friendly Solution for Capturing Toxic Gases from the Air

In today’s modern era, clean air is becoming increasingly scarce. One major culprit is volatile organic compounds (VOCs) released into the atmosphere from industrial activities, fuel combustion, and even everyday use of paints and solvents. VOCs such as toluene and acetone easily evaporate, polluting the air and posing serious threats to human health, including respiratory problems, cancer, and damage to the ozone layer.

To address this issue, researchers are turning to active biochar — an environmentally friendly material made from biomass waste that can efficiently and affordably absorb pollutants like VOCs.

What is Biochar?

Biochar is a natural charcoal produced by burning organic matter (such as agricultural residues, nutshells, or seeds) in a low-oxygen or oxygen-free environment. This process, known as carbonization or pyrolysis, produces a highly porous, carbon-rich material with exceptional adsorption capacity.

While biochar is widely known for improving soil health, it is now also being explored for capturing harmful gases from the air.

Activating Biochar: Boosting Its Adsorption Power

Biochar can be made far more effective through chemical activation — treating it with substances such as sulfuric acid (H₂SO₄) or potassium hydroxide (KOH). Activation increases its surface area, adds more pores, and creates new adsorption sites.

In a recent study, biochar was produced from rapeseed cake and walnut shells. After carbonization, it was activated using H₂SO₄ and KOH, then tested for its ability to capture two types of VOCs: acetone (polar) and toluene (nonpolar).

Surprising Results

• Non-activated biochar could adsorb only about 26.65 mg of VOCs per gram.

• Activated biochar could adsorb up to 166.72 mg per gram — an increase of more than six-fold.

• Biochar activated with sulfuric acid (H₂SO₄) performed better than that activated with KOH.

Why the difference? H₂SO₄ created more micropores and larger surface areas, allowing more VOC molecules to be “trapped” and retained.

Biochar: A Low-Cost, High-Impact Air Cleaner

Active biochar offers several compelling advantages:

✅ Low-cost – Made from abundant agricultural waste.

✅ Eco-friendly – Requires no heavy metals or toxic chemicals.

✅ Highly effective – Strong adsorption capacity even for difficult-to-capture VOCs.

✅ Versatile – Suitable for air filters in homes, factories, and vehicles.

With further development, active biochar could become a key component in future air purification systems, replacing expensive technologies that are often inaccessible to small industries or local communities.

Air pollution from volatile organic compounds is a serious problem that demands simple, affordable, and effective solutions. Active biochar may be the answer. By using agricultural waste and minimal chemical activation, we can create a natural air filter capable of removing toxic pollutants from the atmosphere.

In the face of climate change and global pollution, it’s time to turn back to nature. A big solution can come from something as simple as walnut shells and rapeseed cake — transformed into biochar, the air-saving champion.

Discover more about SAWA’s Innovative Biochar production and its impact on sustainable farming.

Explore SAWA Biochar