RMIT University turns eucalyptus bark into porous carbon for filtration and carbon capture

Eucalyptus tree bark - the part typically peeled from logs and thrown away - has been shown to work remarkably well for cleaning contaminated water, locking up airborne pollution, and taking in carbon dioxide.

A research group in Australia has demonstrated a way to make this waste bark into a high-performing filtration material using a method that is less complex than many processes used commercially.

The work comes from RMIT University, where a team led by PhD researcher Pallavi Saini developed a technique to turn eucalyptus bark into a highly porous carbon.

Filtering carbon with eucalyptus bark

Porous carbon isn’t a new concept. Activated carbons are already widely used in water filters, air purifiers and industrial gas treatment equipment.

Their effectiveness comes from a tightly interconnected network of tiny pores that catch unwanted molecules as water or air flows through.

In practice, the key factor is not the starting feedstock, but how reliably the pore structure is created and preserved.

The RMIT team reported that eucalyptus bark can be processed into a porous carbon using a relatively straightforward method, while achieving performance comparable to materials produced through much more involved routes.

Many porous carbons currently depend on multi-stage manufacturing that requires substantial energy input and specialised infrastructure. By contrast, the method used in this study is based on a single-step process.

“It is usually treated as low-value waste, but with a simple process we were able to convert it into a highly porous material with strong adsorption performance,” Saini said. “It highlights how overlooked biomass can be transformed into something useful.”

Wasted tree bark has big potential

Across the globe, scientists are investigating a wide range of plant-based waste streams as precursors for this kind of carbon, from agricultural residues to forestry offcuts and industrial by-products.

The same practical issues keep coming up: how plentiful the feedstock is, how sustainable it is, how challenging it is to process, and what its real-world performance looks like.

On these points, eucalyptus bark performs strongly, especially in Australia, which has more than 900 species of eucalypts and closely related trees.

Because standard forestry practices already strip bark away, using it does not demand additional land, extra water, or competition with food production. It is simply an existing waste stream available at scale.

“The strength of this approach lies in its simplicity,” said study co-author Dr Deshetti Jampaiah, a research fellow from RMIT University.

“We are converting a widely available waste material into a functional carbon with promising performance, without relying on complex processing steps. That makes it highly relevant for real-world environmental applications.”

Carbon capture and filtration

The range of possible uses is quite wide. Around the world, similar materials are being assessed for drinking-water purification, wastewater treatment, and filtration of air and industrial gases.

At the same time, interest is increasing in applying porous carbons to carbon dioxide capture, although success depends heavily on the pore architecture, how effectively the material can be regenerated, and the cost of producing it at scale.

For nearer-term, practical use, the researchers point to point-of-use filtration in regional and remote communities.

Such systems could be particularly valuable where dependable access to clean water is limited and large industrial infrastructure is not an option.

However, this is not technology that can be rolled out widely overnight. The team still needs to test durability and examine how well the material can be regenerated after it has been used.

They also need to confirm performance in real operating systems, rather than primarily under laboratory conditions. Even so, the early results suggest more promise than the low-value feedstock might imply.

“This work shows how eucalyptus bark can be transformed into materials that support cleaner water, cleaner air, and carbon capture,” said study co-author Suresh Bhargava, a distinguished professor from RMIT University.

“At CAMIC, we combine circular-economy innovation with real societal impact, while mentoring the next generation of researchers to ensure the work remains purposeful.”

Indigenous insights shape research

A notable part of the team’s next steps is the intention to take the work beyond the lab.

With more than 900 eucalypt species in Australia, and with meaningful differences in chemistry and structure between species, performance as filtration media may vary depending on which trees the bark comes from.

Working out which species are most suitable is not only a question for bench testing.

The researchers intend to partner with Indigenous people and organisations who hold deep, long-established knowledge of eucalyptus species across the continent. This understanding has been built over generations, and it is not something that scientific measurements alone can reproduce.

The team also emphasised that any such partnership would be undertaken with genuine respect, rather than being treated as a token addition.

It stands out as an uncommon point in an otherwise materials-science-focused study. Yet it underlines a broader truth: deciding which trees to use, and the reasons behind that choice, is exactly the kind of problem that can benefit from more than one way of knowing.