Guia Covid-19
Imprimir Republish

Chemistry

No toxic residues

Patents generate products for the treatment of industrial effluents

eduardo cesar Synthetic clay eliminates liquid wastes from the dyeing process that uses blue textile dyeeduardo cesar

Two technologies for environment decontamination – one for the treatment of industrial effluents and the other one for the elimination of toxic compounds from soil – were developed by researchers from the State University of Campinas/Unicamp. Licensed to Contech Produtos Biodegradáveis, a company located in the town of Valinhos, São Paulo State, the technologies are ready to go to the market. “We began with a 50-militer balloon at the lab and nowadays we produce 500-kilogram batches,” says chemist Odair Ferreira, who started working on the development of a substance to treat textile effluents in 1999 as part of his master’s thesis. At present, Ferreira has continued doing research work as an employee of the company referred to.

The product to clean up effluents, developed at the university’s Chemical Institute lab, is based on synthetic clay nanoparticles which, when in contact with the liquid outflow from the dyeing process of textiles or paper, act like a sponge that absorbs the dyes. At the end of the process, the water is cleaned up and can be discarded without the risk of contaminating water tables and rivers; in addition, this water can be re-used in industrial processes. “Synthetic clay, nanostructured with specific properties, is made from mineral clay,” explains Ferreira. The particles’ small size – approximately 100 nanometers – comparatively, the thickness of a DNA molecule that stores a cell’s genetic material is two nanometers – increases the product’s contact area with the effluent, and consequently, its remedial efficiency.

The synthetic clay, in powder form, is placed in contact with the dyed effluent inside a stirring system. The dosage varies according to the nature and concentration of the chemical substances in each effluent. “Manufacturers often use higher quantities of dyes than the fiber can adsorb in dyeing processes, so that the textiles have brighter colors,” says Ferreira. Adsorption and absorption are different processes. A sponge absorbs water, but the water flows out easily when the sponge is squeezed, whereas in adsorption, the molecules or ions are retained on the surface of solids through chemical or physical interactions. Dye manufacturers are creating increasingly resistant substances. “The reactive 19 blue dye, extensively used by the textile industry, remains in the water for 50 years when it is discarded into a river,” he exemplifies.

The product can also be used in the treatment of residues from the manufacturing of colored paper and pulp, and in effluents from the petrochemical and metal-mechanic industries. “Activated charcoal, used under the same conditions, eliminates only 50% of the effluents’ color, in comparison with the 95% removed by the synthetic clay,” says professor Oswaldo Luiz Alves, coordinator of the Solid State Chemical Lab of Unicamp’s Chemistry Institute and adviser to Ferreira and to the research project. In 2002, professor Alves was granted the Unesco-Orcyt Award for Master’s Thesis from Mercosur Academic Institutions in the Chemistry category. Another advantage of the material developed at the university is that at the end of the process it can be recycled and re-used to discolor the effluents. This reprocessing can be done at least five times, which means less raw material consumption. At the end of the clay’s life cycle as an absorbent, it can still be used as raw material for other industrial processes to substitute pigments and mineral loads.

Industrial Residues
Since March 2005, when the National Environmental Council/Conama promulgated resolution 357, which established outflow standards for effluents, among which are the limits on the discharge of dyes into rivers, companies have begun searching for solutions to comply with the new environmental guidelines. At that time, Contech was contacted by a client searching for efficient treatment for its industrial effluents. Ricardo Lima Barreto, coordinator of research at the company’s Center for Development and Technology, who has a master’s degree from Unicamp, had heard of a patent from the University’s Innovation Agency/Inova’s portfolio and knew that this patent might solve the client’s problem and expand Contech’s business activities. Contech was established in Brazil in the 1990’s; its core business, which extends to Europe and South America, is to provide chemical systems and products for the pulp and paper industry.

The technology license negotiation was concluded in September 2007, two years after negotiations had begun with Unicamp. The pilot project is funded by the Financiadora de Estudos e Projetos/Finep agency, under the 2007 Program for the Subvention of Innovation in the field of nanotechnology. Once the pilot project is concluded, the company will begin to produce the system on a pre-industrial scale for some clients; at present, the company is launching the technology in the market under the trademark name of Dept. Three months after the license had been granted, Contech and Unicamp signed another technology transfer agreement; the technology had been developed at the Chemistry Institute’s Environmental Chemistry Lab by professor Wilson Jardim with the participation of researcher Juliano de Almeida Andrade. This time, the trademarks Fentox and Fentox TPH were also licensed, along with a chemical reagent for remedying contaminated areas.

The difference between the two products is that Fentox is used to decontaminate liquid substances, while Fentox TPH is used to decontaminate the soil. “The product increases the destructive power of hydrogen peroxide, a substance used to destroy toxic compounds,” says Barreto. A technique called advanced oxidation process is a chemical treatment procedure that places the product of the reaction, formed by the chemical agent and hydrogen peroxide, with water and soil contaminants, which are then destroyed and transformed into water and carbon gas. These contaminants include persistent organic pollutants, a category that includes pesticides such as DDT, aromatic compounds such as benzene, and some classes of dyes.

“The latest survey conducted by the Tecnologia de Saneamento Ambiental/Cetesb environmental authorities identified nearly 2,500 contaminated areas in the State of São Paulo,” says Barreto. These consist mostly of leaks from gasoline service stations and closed plants, which infiltrate into the water table, flow down to rivers and streams and harm the populations that live in the surrounding areas. In the case of contamination from oil by-products, the main problem lies in the leaks from underground storage tanks in service stations. When these tanks are very old, they undergo corrosion and end up contaminating the aquifers.

The idea of naming the product “Fentox” came during the lab research work. The name honors chemist Henry John Horstman Fenton, who was one of the first scientists to work with oxidation techniques in 1894, by using hydrogen peroxide and iron catalysts. In the 1980’s, nearly 90 years later, his formulas were used to eliminate toxic compounds in Europe, the United States and Canada.

Republish