Scientists from Embrapa Instrumentação in São Carlos (SP) have succeeded in producing super-resistant nanocrystals from sugar cane bagasse and straw (biomass). These structures are similar in shape to grains of rice, but are about 200,000 times smaller.
Cellulose nanocrystals are still new to the industry. Since they are very hard and light, they can contribute to the construction of more resistant materials. The possible uses are diverse and range from packaging to car covers.
They are obtained from the cellulose contained in sugar cane, as the chemical engineer Cristiane Farinas, researcher at Embrapa and one of the study participants, describes in an article published in the journal Industrial Crops and Products late last year.
“A material with a proportion of 0.1 to 1% of nanocrystals already has improved mechanical strength,” says Farinas.
Brazilian research arises from a desire to make the biorefinery a more sustainable and economically profitable company. In these plants, biomass from various sources is converted into fuels such as ethanol.
Very few of these mills are currently able to produce so-called second-generation ethanol from sugar cane bagasse, which is less economically advantageous.
“Our original idea was to propose new technologies and ways to make full use of sugar cane, not just making ethanol and sugar as is already practical. Since nanocrystals have a high added value, there is the potential to make biorefineries economically viable, ”says Farina.
Sugarcane bagasse can be burned to generate electricity, and at least some of the plant’s straw remains in the soil to aid in nutrient cycling, making the soil richer.
According to the scientist, nanocrystals from eucalyptus pulp are already being produced on a commercial scale in the USA, Canada and Europe.
In order to get to nanocrystals, scientists have to deconstruct the structures of the sugar cane residue. “You have to think of the process as an onion losing its layers,” says Farinas. An organic solvent will help reduce the material and remove some of the biomass. Through chemical hydrolysis with acid, it then reaches the crystalline part of the material – the so-called nanocrystals.
During this deconstruction, other bagasse and straw molecules are removed. Some of them, like lignin, may also be reused by industry in the future to protect against sunlight.
Farinas says the team is now investigating alternative ways, which are less aggressive to the environment, to reach the nanocrystals, using enzymes and organic acids. The research is funded by FAPESP (São Paulo State Research Support Foundation).