What is in this article?:
- Study finds more effective way to dry ethanol, reduce costs
- 100 percent starch
• After fermentation, ethanol contains between 6 percent and 12 percent water, which must be removed to make it fuel-grade.
•Many ethanol plants use corn grits, which absorb water, or molecular sieves, silica-based particles with tiny pores that only retain water molecules.
• Researchers have found that tapioca pearls work better than the conventional corn grit adsorbents.
100 percent starch
While tapioca pearls are 100 percent starch, corn grits also contain fiber, protein and other substances that are not efficient for absorbing water.
Starch-based adsorbents like tapioca pearls also take up the heat created during drying, allowing that heat to be reused to evaporate water during regeneration of the drying bed.
"This combines fundamental biochemistry, biology and engineering with thermodynamics to obtain an efficient separation system," Ladisch said.
After trying several options to maximize water absorption, including corncobs and wood chips, inspiration struck Ladisch while watching his mother-in-law fix Thanksgiving dinner. As she started mixing up homemade tapioca pudding, Ladisch noticed that the tapioca pearls looked similar to the beads used in molecular sieves.
"I started thinking, 'It's a starch. Might this work?'" Ladisch said.
Ladisch said tapioca pearls may be used effectively in U.S. ethanol facilities, but he believes they could be more significant in facilities in South America and Africa where the plant used to create tapioca — cassava — is grown.
Ladisch and Kim said they would continue to test uses for tapioca pearls, including drying other alcohols. They also plan to create synthetic, starch-based adsorbents from other cheaper materials to lower the cost.
Ladisch is chief technology officer at Mascoma, a renewable fuels company based in New Hampshire. He received no funding from the company for this research. Archer Daniels Midland funded the work.