eduardo cesarBecause of expected growth in the demand for biodiesel in the Brazilian market over the next few years, the production system is evolving, in order to become more efficient and environmentally friendly. One of the current industrial barriers to this is the use of methanol, a poisonous product derived from natural gas, which still has no commercial counterpart derived from biomass. Another problem is the deficiency in the transesterification process for transforming vegetable oil into biodiesel, which results in non-useable and low quality waste in the end product, regardless of the oleaginous grain used. One path for the evolution of this system lies in the studies currently conducted by researchers from the Lorena School of Engineering (EEL) at the University of São Paulo (USP). They are making a new contribution to the transformation of vegetable oil into fuel. Instead of methanol, they are using ethanol from sugar cane, a renewable ingredient, plus lipasis, an enzyme that acts on the function of the catalyst in the reaction, breaking down and transforming the oil molecules into biodiesel and glycerin.
In order to function well in engines, vegetable oil needs to go through an alcoholic chemical reaction, transesterification, which yields glycerin as a sub-product, a substance used in the chemical industry. What researchers did was to change the ingredients of this process without altering the essence of the end products, biodiesel and glycerin, while also improving their quality. The enzyme used by the researchers from USP occurs naturally in the pancreas and human intestine, where it is involved in the process of digesting fatty foods. But it is also produced by fungi, yeasts and bacteria, which allows lipasis to be used on an industrial scale, by growing these microorganisms in the appropriate substrates. It is used in various industries, such as pharmaceuticals, fine chemicals, cosmetics, oil chemistry, leather, paper and pulp, and in the treatment of waste. In the food industry, for example, it can be used in the production of margarines and vegetable creams that are free of transfats, a substance that causes a series of health problems, including an increase in levels of bad, LDL cholesterol and a reduction in levels of good, HDL cholesterol.
“In the case of biodiesel, using ethanol and lipasis is an environmentally attractive relationship because besides using a renewable reagent and catalyst, it reduces waste from the whole process”, says Professor Heizir Ferreira de Castro, study coordinator. She has been working for nearly fifteen years with the so-called green chemistry in processes that minimize the environmental impact of industrial chemical processes. “Our group works mainly with biocatalysis in non-conventional means, in studies related to the application of enzymes for the development of new processes for obtaining innovative products, or products that already exist, but at a more competitive cost”, says Heizir. The work with biodiesel began in 2003, when this USP unit in Lorena was autonomous, public, and called the Lorena School of Chemical Engineering (Faenquil). The results indicate an alternative path to current techniques, in that they produce biodiesel using procedures that are less damaging to the environment, with clean technology.
In the work that resulted in the production of biodiesel with lipasis, grant holders Ana Moreira and Victor Perez from USP and a researcher from the State University of Maringá, Professor Gisella Zanin, under the coordination of Heizir, published a study in the scientific journal Energy & Fuels in which they describe the use of lipasis in the transesterification of palm oil with ethanol to produce biodiesel. This oil, also known as dende, comes from the plant with the best yield of raw material for this purpose (some 4,000 l/ha), whereas soybeans, which is currently the most widely used, yields about 400 l/ha. The researchers used lipases produced from different microorganism sources: two species of fungus, Thermomyces lanuginosus and Penicillium camembertii, a yeast, Candida Antarctica and two bacteria, Pseudomonas fluorescens and Burkholderia cepacia, in addition to lipasis from the pancreas of pigs. The most efficient enzyme for producing fuel came from P. fluorescens, which converted 98% of the oil into biodiesel. Moreover, the fuel is high quality relative to the traditional process, principally in terms of its viscosity and humidity and because it meets the specifications of the American Society for Testing and Materials (ASTM).
The reaction time with lipasis in the production of biodiesel was 24 hours. This is still a disadvantage in relation to the strictly chemical process that uses catalysts such as sodium hydroxide (NaOH), common caustic soda, and potassium hydroxide (KOH), carbonates and alkoxides that last from four to five hours. But the time can be offset by the greater ease of the recovery of glycerin and the catalyst at the end of the reuse period. In the case of lipasis, the researchers developed a method that allows them to recycle it for reuse by immobilizing this enzyme in a solid matrix, called a hybrid polysiloxane-polyvinyl alcohol support, made from silica and PVA (polyvinylic alcohol). Lipasis is a powder and when it is bound to a substrate it does not dissolve in the liquid.
The same type of matrix was used in another sequence of experiments to immobilize a preparation of low cost lipasis, extracted from the pancreas of pigs, to produce biodiesel from the oil of the fruit of the babaçu tree, a typical palm from the Amazon region and from Brazil’s Northeast. Three types of alcohol were used: ethanol from sugar cane and butanol and propanol, from the refining of petroleum. The biodiesel yield reached 75% with ethanol, 80% with propanol and 95% with butanol. “Each type of enzyme is sensitive to a particular environment and produces a result. In this particular case, the production of biodiesel with lipasis of pig origin proved to be feasible, regardless of the type of alcohol, although butanol has been a little more productive”, explains Heizir. Studies also showed that the lipasis used serves to produce surfactants, chemical compounds used in the production of detergents and other materials. The work was published in the Journal of Chemical Technology and Biotechnology, in its January 2007 edition, signed by postgraduate students Ariela Paula and Daniele Urioste and by Professor Julio Santos, from EEL, who is also a member of the group.
Despite the good laboratory results, Professor Heizir believes it is still too early to transpose the experimental data to a wider scale. First, it will be necessary to carry out a technical and financial study to calculate the overall cost of the enzymatic process. One of the bottlenecks concerns the high cost of lipases, as they are not yet produced on an industrial scale in Brazil. The main producers are companies in Denmark, the USA and Japan.
However, there are still many alternatives to be tested. One of them is to use microwaves to speed up the catalytic reaction in the biodiesel production process, leading to a consistent productivity increase. In line with this, research under way in Professor Heizir’s group, particularly the work of master’s degree candidate Patrícia Caroline, is focusing on the application of high frequency electro-magnetic fields in enzymatic processes, particularly in the synthesis of biodiesel from low cost vegetable oils, such as babaçu and palm oil, using lipasis as a catalyst. Reactions influenced by microwaves are also in the initial investigation phase in many countries.
Integrated production of biodiesel and emulsifiers from babaçu oil using stabilized derivatives from pancreatic and microbial lipasis
Regular line of help for research
Heizir Ferreira de Castro – Unicamp
R$ 58,843.75 (FAPESP)