Friday is here, and the 'A Taste of Science for the Weekend' corner is back — number 81.
This time: sugarcane, and its fascinating connections to bioplastics, jet fuel, and LEGO pieces.
-
Sugarcane is the highest-yielding crop in the world — over 2 billion tonnes per year.
From sugarcane we extract sucrose, which at the end of the refining process becomes the white sugar we find at the supermarket. Sucrose is made of glucose and fructose (also known as fruit sugar) bonded together by a chemical bond.
The fact that sucrose is composed of this pair of sugars is important: the bond they form with each other prevents them from forming other chemical bonds, allowing them to store more energy.
Sugarcane stalks arriving at the factory are pressed, and the juice extracted from them is heated under high pressure and temperature to evaporate the water and separate out the sucrose.
To make the sucrose crystallize into small sugar granules rather than large clumps, powdered sugar is introduced into the vessel — each tiny grain of powder serves as a crystallization nucleus around which a larger sugar crystal forms.
Sucrose can be fermented, distilled, and converted into ethanol, which is used as fuel for cars in countries such as Brazil.
The viscous syrup that remains after the sucrose is separated is called molasses, and although it is used as animal feed, it may well be sitting in your kitchen cupboard too.
-
Sugarcane has a secret that helps it thrive even in hot climates.
RuBisCO is an extremely common enzyme in nature, whose role is to capture carbon dioxide from the atmosphere and fix it into organic matter in plants.
At excessively high temperatures, RuBisCO binds oxygen in addition to carbon dioxide, greatly reducing the efficiency of the photosynthesis process that allows plants to grow.
Sugarcane uses a sophisticated mechanism called C4. In this mechanism, a different enzyme — one that does not bind oxygen — captures carbon from the air. This enzyme transfers the carbon inward to an environment that is isolated from the outside oxygen, where RuBisCO then processes it.
-
After sucrose is extracted from the stalks, a very large quantity of dry fibrous material called bagasse remains.
In the past it was considered waste and was burned in the open air. Today, however, it serves as fuel for a small power plant inside the sugar mill, supplying all the energy needed for the refining process without any connection to the electrical grid.
This makes sugar mills a rare phenomenon — they are completely energy self-sufficient, and sometimes even generate electricity for other consumers.
-
One of the most interesting products derived from sugarcane is bioplastic.
The ethanol undergoes a chemical conversion process to ethylene gas and then to polyethylene, which is similar to synthetic plastic. This material is used, among other things, to manufacture LEGO pieces such as leaves and trees.
In a similar way, a fuel analogous to kerosene — jet fuel for aircraft — is produced. This fuel is known as SAF (Sustainable Aviation Fuel) and is already approved for use as a standard fuel, even if its price remains high.
From bagasse (sugarcane waste) it is also possible to produce consumer goods such as particleboard and packaging, but the more interesting application stems from the fact that nearly half of bagasse is cellulose — a material common in plant cell walls.
Researchers have developed a method to extract nanocellulose from this cellulose: tiny cellulose needles whose specific strength exceeds that of steel. Incorporating them into other materials imparts exceptionally high strength and durability.
In the video: manufacturing packaging from sugarcane waste.
Shabbat Shalom 😊
--
If you enjoy this corner, you're welcome to follow along and catch it again next week.
Video credit: The Factoran
#ATasteOfScienceForTheWeekend