Rescuing the Lake with the Pseudostem of the Plantain Plant
May 30, 2024
In the labs of the School of Chemistry of Universidad Central de Venezuela, researchers Ray Arteaga and Manuel Fermín used the pseudostem of the plantain plant to create a small sponge capable of absorbing large amounts of crude oil. They are working on it so that it can be used to clean up Lake Maracaibo, into whose waters between 200 thousand and 300 thousand barrels of crude oil are released each year, according to experts.
PHOTOS: FAMILY ALBUM / JOHANNA OSORIO HERRERA
Right in the heart of the groves of the College of Sciences of Universidad Central de Venezuela lies the School of Chemistry. There is a lab in one of the classrooms with windows through which the sunlight streams in and trees and palms can be seen. All over the place, there are containers labeled with names scientists know well. Though this lab looks nothing like the ones in the movies, it may be more fascinating than any other: Venezuelan chemists Ray Arteaga and Manuel Fermín have been working there for over a year on a solution to help clean up Lake Maracaibo by use of a white, porous material they affectionately call quesito [one that resembles cheese/cheese’ish], which is actually a biodegradable absorbent material made from the pseudostem of the plantain plant.
Into the waters of Lake Maracaibo, one of the oldest in the world and the largest in South America, the state-run oil company discharges from to 200,000 to 300,000 barrels of crude oil each year (this, of course, according to experts, for no official figures have been made available), endangering the biodiversity of the lake.
Ray and Manuel began working on their experiment before the COVID-19 pandemic brought the world to a halt, but with a different purpose in mind: someone interested in biodegradable paper or textiles for commercial use contacted Dr. Fermín. At the time, Arteaga, a graduate student, was working on his degree project on a related topic. They teamed up for the task. However, for reasons beyond their control, the project was cut short. But they were already in awe of what they had devised and decided to continue on their own.
Their efforts were stalled for months by the pandemic; even so, they went back to the lab at their first chance.
What was it that they found? They first came up with a compound from residues from agriculture; later on, they discovered the ability of waste from plantains and bananas to absorb crude oil.
When Ray was a child, he used to go to his grandmother’s during holidays and vacations. He chased chickens, climbed trees, and ate oranges, mangoes, tangerines, mandarins and bananas. He saw how, once the plantain fruit was harvested, the entire pseudostem of the plant was cut off and discarded. But he grew up, became a chemist and learned that the pseudostems could be put to better use.
As a graduate student, and with an interest in new trends in the utilization of cellulose, Ray researched literature on cellulose nanocrystals and their applications, including for the long-term release of drugs or for thermal insulation in other industries, and he decided he was going to create his own nanocrystals.
For another chemist, getting all the cellulose needed for the tests could have been an almost insurmountable hurdle. But, for Ray, the solution was clear: right there, in the backyard of his grandma’s house, he had all the raw material at his disposal.
Between 2017 and 2018, he joined paths with Dr. Manuel, who, by the way, had been his first chemistry professor at the university.
They got together and began to create.
This is how Manuel and Ray developed their chemical process: they took the brown, dry pseudostem from a plantain plant or a banana plant and converted it into white, soft cellulose through a series of steps, and then they transformed that cellulose into cellulose nanocrystals. One of the features of nanocrystals seems particularly self-contradictory: the smaller the nanocrystal, the larger its surface area (if a cube, with its six faces, is divided by four, the result is four cubes and their corresponding faces, that is, 24 small faces, which is more than six large faces). These nanocrystals become a hydrogel, which is a substance similar to a gel. The hydrogel is then frozen and the water removed through a process called lyophilization, with no thawing involved (it transitions from ice directly into a vapor without turning into water, so as not to alter the chemistry of the gel).
The product of this process is an aerogel: our quesito.
Each kilogram of dry pseudostem yields about 270 grams of cellulose, whose weight does not vary that much when it is made into an aerogel.
And that sort of firm, porous, very light sponge is capable of absorbing 80 percent its own weight in oil.
It is worth noting at this point that this was not always the goal. The truth is that this sponge came into being well before the purpose for it had been determined. But all roads lead to Rome or, in this case, to the place where the cellulose nanocrystal aerogel made by Manuel and Ray was most needed: Lake Maracaibo, in the state of Zulia.
Once the material had been completed, both chemists decided to present it at an international congress organized by the Network of Student Research of Universidad del Zulia.
It was November of 2022, Ray’s first time in Maracaibo, and Dr. Manuel’s second time, for he had been there before for the annual ceremony where Our Lady of the Rosary of Chiquinquirá, or La Chinita, is taken down from the altar in which she rests and carried during a procession.
For Manuel, a lover of the Venezuelan scenery, traveling the country has a special meaning. So, wherever he goes, he takes pictures and saves them in a folder of memories. And that’s why, during their visit to the congress, where they received the Best Research Paper award, he proposed to Ray to go for a walk around the lake’s promenade.
It was 6:00 in the afternoon; the breeze was warm; the sun had just engaged in its dance of dim lights before nightfall. Manuel and Ray took a picture with each other and then a picture of the landscape, or rather of the lakeshore, which did not smell good and was littered with garbage.
Zooming in on the photos, they noticed oil stains on the stones. They were disheartened by the sight of it. But then something happened that would give meaning to all their years of effort and research:
“It could be used to remove this stuff!”
And so, the quesito became a possible cure.
Back in Caracas, they decided to test it. They filled a small plate with some water and splashed it with oil. Then, they took a small amount of the aerogel and put it on the oil stain with tweezers.
And it worked.
The little sponge has seen some improvements over the past year: it is now hydrophobic. It repels water and absorbs oil better, and it floats and can be easily removed. Additionally, thanks to the work of other chemists*, studies are being conducted for its production at an industrial scale.
As they make progress, the situation in the lake has but worsened. Between the verdín —a microalgae that blocks oxygen in the water and has spread through the organic waste that is dumped in the lake and the sewage that is discharged into its waters— and the oil spills, it’s cleanup is a pressing and urgent matter.
On the impact of CeluZulia, the name they have given their project, they prefer to err on the side of caution, for it’s something that they will know for sure when the sponge is actually tested. But, according to their lab reports, each gram of aerogel is capable of absorbing between three and four grams of oil. In the lake, the results will vary with the actual environmental conditions and the type of crude oil at issue.
As for the raw material, according to their measurements, there are between 20,000 and 30,000 hectares of banana crops in the state of Zulia, out of the 60,000 hectares in the entire country. Five tons of pseudostems per hectare are collected every three to six months, which is three tons of waste, 40 percent of which can be converted into cellulose. In other words, from each tone of waste, 400 kilograms of cellulose may be obtained that can absorb four times its own weight in crude oil.
It is an unprecedented project in Venezuela.
In November of 2023, thanks to their aerogel*, Manuel and Ray received the Best Research award for the second time. Not only for its potential to absorb crude oil, but also for its social component, which for them is of paramount importance: the pseudostem that is discarded in the fields of plantain and banana—two staples of Zulian cuisine— could be collected and sold, thereby creating new jobs and additional income for the farmers. It could also make communities and chemists work together for a common cause: to clean up Lake Maracaibo.
* The research has been supported by the work of other Venezuelan chemists to whom the protagonists of this story would like to express their gratitude: María Rodríguez, Jairo Bermúdez, Jimmy Castillo, Felipe Spena, Gerardo Villamizar, Melani Guacarán, Oriana Balza, Cristina Halabi, José Daniel Tovar, Sofía Salazar, Elsy Bastidas and Ynés Rojas.
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