Spruce Bark Waste Transformed into Dye Adsorbent: An Eco-Friendly Solution for Polluted Water

Water pollution caused by dye-laden industrial waste has become a global concern. Synthetic dyes discharged into rivers or lakes not only discolor the water but also block sunlight, hinder aquatic photosynthesis, and threaten entire ecosystems. Due to their resistance to natural degradation, these dyes are classified as high-priority pollutants.

But did you know that spruce bark, often discarded or burned as fuel, can be transformed into a highly effective dye-absorbing material?

From Wood Waste to Clean Water Solution

Researchers have found a way to convert spruce bark into biochar—a porous, carbon-rich material similar to activated charcoal, known for its ability to absorb chemicals from water. To further boost its performance, the biochar was modified with nitrogen, making it more reactive and efficient at capturing dye molecules from contaminated water.

This nitrogen modification was achieved through high-temperature pyrolysis (burning in the absence of oxygen) at around 900°C, using phosphoric acid (H₃PO₄) and melamine as nitrogen sources. The result? A nitrogen-enriched biochar with significantly greater dye absorption capacity than regular biochar.

How Effective Is It?

In laboratory tests, this nitrogen biochar was used to absorb Reactive Orange 16 (RO-16), a common dye in the textile industry. The findings were remarkable:

• Regular biochar absorbed up to 100.6 mg of dye per gram.

• Nitrogen biochar absorbed up to 173.9 mg per gram—almost double the capacity!

Interestingly, the adsorption worked best under slightly acidic conditions and wasn’t just about pore size—it involved strong molecular interactions such as:

• Electrostatic forces,

• Hydrogen bonding,

• Lewis acid–base interactions,

• And π–π interactions (between the aromatic structures of the biochar and the dye).

Reusable and Economical

One major advantage of this nitrogen biochar is its reusability. In regeneration tests, it maintained stable performance for up to five cycles of use, making it both cost-effective and sustainable.

Beyond just RO-16, the biochar was also tested in synthetic wastewater containing various dyes and chemicals, simulating real industrial effluent. Impressively, it removed up to 66% of pollutants from this complex wastewater.

Turning Wood Waste into Environmental Guardians

Spruce bark waste, once simply burned or discarded, now becomes a valuable water-cleaning agent, offering a solution to two major environmental issues:

1. Reducing biomass waste from the wood industry,

2. Purifying polluted water from hazardous dyes—without producing secondary waste or using toxic chemicals.

With its low-cost materials, accessible production methods, and strong performance, this biochar technology could be adopted in many developing countries struggling with water pollution.

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

Explore SAWA Biochar