Mannan rich palm handicraft waste, such as tagua nuts and bodhi roots, can be turned into valuable green chemicals instead of being burned or discarded, according to a new study.
"In many parts of the world, polished palm seeds are carved into jewelry and religious beads, but the cutting and drilling leave behind piles of fine powder that usually end up as waste," said first author Bin Hu of North China Electric Power University. "Our work shows that this overlooked by product can become a promising feedstock for clean chemical production."
The researchers examined two popular palm based handicraft materials: tagua nuts from Ecuador, sometimes called "vegetable ivory," and bodhi roots from Myanmar, a common material for prayer beads. Both are seed based biomasses that turned out to be unusually rich in carbohydrates and poor in ash and lignin, a combination that makes them easier to convert thermochemically.
Chemical analysis showed that holocellulose, the carbohydrate fraction, makes up about 93 percent of tagua nut and 87 percent of bodhi root, with lignin content as low as 2.5 percent and 4 percent, respectively. The dominant building block in both materials is mannan, a type of hemicellulose sugar; mannose accounted for around 88 percent of all detected monosaccharides in the seed carbohydrates.
To understand how these seeds break down when heated without oxygen, the team combined several advanced techniques. Thermogravimetry coupled with infrared spectroscopy tracked weight loss and gas evolution between 20 and 800 degrees Celsius, while in situ infrared measurements watched how solid functional groups disappeared as the materials decomposed.
They also used pyrolysis gas chromatography mass spectrometry to identify dozens of small molecules released at different temperatures, then validated these findings in a lab scale horizontal fixed bed reactor operating at set temperatures up to 700 degrees Celsius. Each experiment was repeated three times to confirm that the results were reliable.
Both tagua nut and bodhi root showed a rapid decomposition stage between about 180 and 380 degrees Celsius, with maximum weight loss at roughly 301 to 302 degrees Celsius, higher than typical xylan based hemicellulose but lower than cellulose. At 800 degrees Celsius, the remaining solid char was around 24 percent for tagua nut and 21 percent for bodhi root, reflecting their different fixed carbon contents.
The most striking result was the dominance of a single anhydrosugar, levomannosan, in the liquid products. In fast pyrolysis experiments, levomannosan made up more than 90 percent of the anhydrosugar fraction, reaching yields of 11.2 weight percent from tagua nut at 600 degrees Celsius and 10.9 weight percent from bodhi root at 500 degrees Celsius. In the fixed bed reactor, the maximum levomannosan yield in the condensed liquid was 5.8 weight percent for both feedstocks, while the important platform chemical 5 hydroxymethylfurfural peaked at 2.0 weight percent.
Bodhi root revealed a unique behavior: at temperatures above 400 degrees Celsius it began producing a noticeable amount of dodecanoic acid, a medium chain fatty acid, which was not observed for tagua nut. The authors attribute this to the higher fat content of bodhi root, which undergoes dehydration and condensation at high temperature.
By linking structural data with thermal behavior, the team proposed a detailed pathway for how mannan transforms during heating. As temperature rises, mannan chains first depolymerize into smaller sugars, then rearrange through transglycosylation to form ring structures that readily convert to levomannosan.
Further dehydration and bond cleavage reactions at higher temperatures generate 5 hydroxymethylfurfural, furfural and eventually small gases such as carbon dioxide, carbon monoxide and methane. In the fixed bed experiments, gas yields at 700 degrees Celsius exceeded those of water, oil and char combined, highlighting the tradeoff between maximizing levomannosan and avoiding its over cracking.
Senior author Qiang Lu explained that these results give practical guidance for using handicraft waste as a controlled chemical feedstock. "If the goal is to produce levomannosan as a high value intermediate, you want materials with high mannan and low ash and you want to keep the pyrolysis temperature in a moderate window," he said.
The study concludes that mannan rich palm handicraft residues, especially tagua nut and bodhi root powders, can serve as selective sources of levomannosan and related furan compounds when processed at carefully chosen temperatures around 500 to 600 degrees Celsius. By turning decorative waste into a platform for green chemistry, the work offers a new path to reduce biomass disposal problems while supplying building blocks for future bio based products.
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Journal reference: Hu B, Zhou GZ, Fu WY, Fu H, Liu JT, et al. 2026. Pyrolysis of the palm-based handicraft wastes: structure, reactions, and products. Energy & Environment Nexus 2: e003 doi: 10.48130/een-0025-0020
https://www.maxapress.com/article/doi/10.48130/een-0025-0020
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About Energy & Environment Nexus :
Energy & Environment Nexus (e-ISSN 3070-0582) is an open-access journal publishing high-quality research on the interplay between energy systems and environmental sustainability, including renewable energy, carbon mitigation, and green technologies.
