Guia Covid-19
Imprimir Republish

Environmental engineering

Environmental engineering

New products can remove oil spills from the sea

Mark Ralston / AFPGulf of Mexico oil spillMark Ralston / AFP

Oilspills in the sea are a problem for countries such as Brazil, most of whose oil exploration is conducted in a marine environment and where there is oil tanker traffic between the areas where the oil is pumped and the ports. Therefore, it was not the greatest accident of this kind (which occurred in the Gulf of Mexico, starting in April of this year as a result of the explosion and sinking of a British Petroleum (BP) platform, and leading to an oil spill of more than four million barrels, contained only in September) that drove Brazilian researchers to study, in greater depth, these environmental disasters. At least three groups recently presented the results of research that might soon become ocean decontamination products. They have two advantages: they are bio-remedial (because they are less toxic for the environment) and they are cheaper than the chemicals currently used. The first technology is the creation of a group of researchers from the Federal University of Minas Gerais (UFMG), comprised of professors Rochel Lago, Flávia Moura and Maria Helena Araújo. They developed a type of material that can absorb oil in accidents on land or in the water. Called a hydrophobic nanosponge, it repels water and has a great affinity for organic compounds, especially for oils.

The group was contacted recently by an American company that was interested in using the material in the Gulf of Mexico. However, some lab tests are still necessary before the product can be tested in the ocean. The research study initiated in 2005 by Flávia and Lago led to the development of a granular macroscopic material made from the mineral vermiculite, with granules measuring three to five millimeters in diameter, surfaced with a nanostructured layer that makes the material black. This mineral has been used for many years and is supplied by several companies around the world and from Brazil to absorb oil. The UFMG group’s experiment adds carbon to it and transforms the mineral into one with improved absorption capacity. “The carbon causes the vermiculite to have more affinity for oil than for water,” says Maria Helena. On its own, the mineral, which is a pale color, acquires a light, accordion-like structure when it is heated, and looks like a sponge floating in water. The problem is that without the carbon nanostructures, it absorbs more water than oil. What the researchers have done is to reverse this characteristic with nanotechnology.

Flávia explains that to produce the hydrophobic nanosponges, vermiculite must first be exfoliated and then submitted to a controlled heating process in an oven, with the introduction of a source of carbon such as ethanol, natural gas or even glycerin, which today is a byproduct of biodiesel production. “These sources decompose on the vermiculite surface, forming carbon with different shapes, such as nanotubes, filaments, graphite or amorphous carbon,” she explains. The process changes the characteristics of the vermiculite. “After the carbon is deposited, the mineral starts to absorb oil preferentially,” explains the PhD candidate Aluir Purceno, a member of the group. “Its capacity to absorb as much as six grams of oil per gram of material is greater than that of the other products found on the market,”

The product has further advantages. “Brazil is one of the world’s greatest vermiculite producers and, as compared to other materials, it’s very inexpensive,” says Purceno. The carbon used to make the hydrophobic nanosponges can be extracted from cheap and abundant sources such as glycerin. “Besides being used to remedy oil spills, it consumes part of the production of glycerin, which might become an environmental problem over the next few years,” says Miguel de Araújo Medeiros, a professor at the Federal University of Tocantins (UFT) who did his doctorate as a member of the group.

The vermiculite nanosponges are part of a technological platform of the UFMG group that won, in September of this year, first place in the Latin American section of the Idea to Product, an international competition held by the University of Texas in Austin, United States. In Brazil, this was organized by the Getulio Vargas Foundation’s Center for Entrepreneurship and New Business. The winners are to compete in the world stage in November, in the United States. Their partner in this undertaking was the company Verti Ecotecnologias from Minas Gerais state. One of the partners in the firm is professor Lago and it conducted the project’s technical and financial viability study. “We presented a technological platform that, in addition to the nanosponge, is comprised of a product called nanoamphil with contains vermiculite nanoparticles, an iron core and carbon nanostructures. It works as an emulsion breaker, a substance that separates oil from seawater in the oil platforms. The nanoparticles mixed into the oil adhere to the water drops. When we put a magnet close, the magnetic nanoamphil particles are drawn by the magnet’s field, which brings the drops together. After a few minutes the water has been totally separated from the oil,” says Purceno.

UFMGLeft, natural vermiculite. Next to it, vermiculite with carbonUFMG

The third technology that the platform comprises is a product that removes sulfur from oil in refineries. This research study yielded four scientific articles and two patents. The researchers were financed by Fapemig (the Minas Gerais State Foundation for Research Aid) and CNPq (the National Council for Scientific and Technological Development). By means of the Pappe program (Program of Research Aid for Small Companies) of the Ministry of Science and Technology, the company Vermiculita Isolantes Termoacústicos [Vermiculite Thermo-Accoustic Insulators] took part in the preparation of the vermiculite nanosponges. The company produces this clay and was interested in a partnering arrangement, supplying the mineral and taking part in the scaling process of the technology, i.e., expanding from a laboratory production scale to larger scale production.

Battery detergent
In the second group, instead of sponges, researchers from the Federal University of Rio de Janeiro (UFRJ), partnered by Cenpes [the Petrobras R&D Center ] developed a biodegradable detergent made by a bacterium to use in oil spills. Called a biosurfactant, this substance reduces the superficial tension of the border area between the water and the oil, making it easier for the two to mix and facilitating the subsequent degrading of the oil. The study started in 1999, when the researchers from the company and from the university isolated the PA1 strain of the bacterium Pseudomonas aeruginosa in the wastewater from oil exploration in the Northeast of Brazil. This microorganism was already known to produce biosurfactants of the rhamnolipid type, a natural detergent found in oil wells and that has even been tested in environmental accidents in the United States. In 1989, when the oil spill involving the Exxon Valdez tanker occurred near Alaska, a P. aeruginosa biosurfactant was used, with good results. This had been developed by the Engineering and Development Center of the Aberdeen Field Testing area of the American army in conjunction with the University of Illinois. However, the product developed with another strain failed to become commercial because nobody was able to produce it on a large scale, in big bioreactors. This type of pseudomonas naturally transforms carbon sources, such as oil, on which they feed, into a biodegradable detergent. The challenge that the researchers faced was making these microorganisms produce the biosurfactant on an industrial scale. The studies started thanks to the initiative of the researchers Denise Freire, from the Chemistry Institute da UFRJ, and Lídia Santa Anna, from Petrobras.

Denise and professor Cristiano Borges, from Chemical Engineering Program of Coppe (the Engineering Graduate Studies and Research Institute) of UFRJ were the advisors for the PhD these of Frederico Kronemberger, undertaken from 2002 to 2007. Its theme was to make the bioreactor production of these biosurfanctants feasible. “We developed an innovative oxygenation system using polymer membranes,” Kronemberger tells us. Until then, the supply of oxygen, essential for bacterial growth and biosurfactant product in these reactors was accomplished by injecting air, which rendered production unfeasible.

Despite the progress, production in lab scale bioreactors still failed to make conducting biosurfactant application trials in the field feasible. “Thanks to the partnering and financing of Petrobras, we started the project to develop a pilot unit for the production of biosurfactants, with a 200-liter bioreactor,” says Kronemberger. “In July of 2009, this was inaugurated. Ever since, production trials have been conducted.” The researchers are stocking the material to transfer it to Cenpes, which will take charge of conducting the ocean trials. The work has led to three scientific articles and one patent.

Chitosan microspheres
The bacteria are also the main suppliers of biosurfactants in a project of Padetec (the Technological Development Complex) from the Federal University of Ceará (UFC). The research, in which researchers from the federal universities of Pernambuco and of Bahia also took part, developed, under the coordination of professor Vânia Melo, from UFC, microspheres of chitosan with the cells of the Bacillus subtilis bacterium. These spheres were also capable of absorbing oil and feeding on it. Chitosan, a natural polymer, is extracted primarily from the exoskeleton (shell) and the head of shrimp rejected by the industry that raised them. It is a material used to absorb oil, even in the United States. The group’s innovation consisted of combining chitosan with the bacterium, also used to produce biosurfactants. The novelty led the group to be one of the winners of the Petrobras Inventor 2009 prize. “Now we’re developing equipment to produce these three-millimeter wide microspheres,” says professor Afrânio Craveiro, the director president of Padetec and one of the microsphere’s inventors. The group now wants to generate some 300 kilograms of the product and, in the form of a spray, conduct trials in the ocean and in lagoons. “This is not a product for large areas such as the Gulf of Mexico, but rather for far smaller contaminations.” The enterprise that is the main candidate for making this product is Polymar, incubated at Padetec. It now makes chitosan for use as a food supplement. “Polymar has priority, but there are other interested firms,” says Craveiro.

Scientific articles
MEDEIROS, M.A. et al. Modification of vermiculite by polymerization and carbonization of glycerol to produce highly efficient materials for oil removal. Applied Clay Science. v. 45, n. 4, p. 213-19. ago. 2009.
KRONEMBERGER, F.A et al. Oxygen-controlled biosurfactant production in a bench scale bioreactor. Applied Biochemistry and Biotechnology. v. 147, p. 33-45. mar. 2008.
BARRETO, R.V.G. et al. New approach for petroleum hydrocarbon degradation using bacterial spores entrapped in chitosan beads. Bioresource Technology. v. 101, n. 7, p. 2.121-25. abr. 2009.