Harnessing the Power of Tree Gum Waste

22 Mar 2021

Tree Gum

Could recycling discarded tree gums offer a simple, cost-effective and sustainable solution that can help meet global energy demands while reducing waste?

Naturally derived gums are used for a variety of purposes in the food industry, including as thickening agents, emulsifiers, gelling agents or stabilisers. For example, Arabic gum is collected from the sap of Acacia trees, Karaya gum from Sterculia trees, and Guar gum from guar beans. But only high-grade gums with better purity are suitable for human consumption – and the lower grade, contaminated gums are often discarded. It is challenging to find uses for these low–value biomaterials due to their sticky nature and impurities.

Researchers have previously shown that flowing water over nanostructured carbon can capture small amounts of energy and convert it into usable electricity. As low–grade gum waste often possesses high carbon content, this could potentially offer new opportunities for its exploitation. Finding ways to synthesize carbon-based nanomaterials from gum waste could pave the way to a new generation of low–cost energy harvesting devices. This could provide a self–sustaining, cost-effective way to power electronics – as well as reducing waste.

Extracting Value From Inedible Tree Gums

In a new study, published in Green Chemistry, researchers develop a method to recycle non–food–grade tree gum wastes into nanoporous carbon (nC) and demonstrate its potential for harvesting energy from tap water.¹ In the synthetic procedure, low–grade gums – including Arabic gum, Karaya gum and Guar gum – were pre–carbonized followed by potassium hydroxide activation in a furnace. The team used water generated by an ELGA PURELAB® laboratory water purification system to remove any impurities that may affect the end product.

The researchers characterised the synthesized nC, finding that it has a high surface area and abundant micropores – making it well–suited for water-driven effective electrical energy conversion by enabling the fast evaporation of tap water via capillary action. The team went onto demonstrate that the nC–based fabricated energy harvesters can generate sufficient power to turn on a commercial light-emitting diode (LED). Importantly, these devices can be scaled up to turn on objects requiring higher voltages and currents, such as a university logo.

Scalable, Renewable and Practical

In this study, researchers successfully develop a simple, cheap and efficient method to synthesize nC from low–grade gum wastes. The method is highly versatile and can be used on a wide variety of gums, which were all transformed into nC with high surface area and pore volume. The fabricated nC offers real-world practical applications for harvesting electrical energy from tap water, showing a high capability for electricity production and reliable output generation, easily turning on an LED using a stored power source.

This is the first step towards building a sustainable solution to help overcome the world’s energy challenges, converting biodegradable and non–toxic gum wastes into carbon nanomaterials for green energy harvesting that is scalable, renewable, and practical.

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Reference:

Ventkateshaiah, A. et al. Recycling non–food–grade tree gum wastes into nanoporous carbon for sustainable energy harvesting. Green Chem 2020;22:1198

Dr Alison Halliday

After completing an undergraduate degree in Biochemistry & Genetics at Sheffield University, Alison was awarded a PhD in Human Molecular Genetics at the University of Newcastle. She carried out five years as a Senior Postdoctoral Research Fellow at UCL, investigating the genes involved in childhood obesity syndrome. Moving into science communications, she spent ten years at Cancer Research UK engaging the public about the charity’s work. She now specialises in writing about research across the life sciences, medicine and health.