Left: Solution containing cellulose extracted from sugarcane bagasse. Right: Fiber in contact with material contaminated by glyphosate and presented for the method to determine glyphosate levels at different pH. Credit: Maria Vitória Guimaraes Leal
Researchers at São Paulo State University (UNESP) in Brazil have developed a strategy to remove glyphosate, one of the world's most commonly used herbicides, from water. Inspired by the concept of circular economy, this technology is based on sugarcane bagasse, a waste material produced by sugar and ethanol plants.
“Separated and chemically functionalized sugarcane bagasse fibers can be used as an adsorbent material. Glyphosate sticks to its surface and is removed from the water by filtration, settling or centrifugation,” María Vitória Guimarães Leal told Agência FAPESP. Is removed as a contaminant.”
She is the first author of the article on the research published in the journal pure and applied chemistry , Adsorption is a process whereby molecules dispersed in a liquid or gaseous medium adhere to a solid insoluble surface, which is usually porous.
Because of its low cost and high ability to increase crop yields, glyphosate is widely used to control the growth of unwanted plants, such as weeds, invasive species, and agricultural pests, but scientific studies have shown That it could be a threat to human health. There may be a particular risk of cancer.
The use of products containing glyphosate is banned or restricted in other countries, including Austria, Bulgaria, Colombia, Costa Rica, Denmark, El Salvador, Germany, and Greece. However, annual use of such products in Brazil averages 173,150.75 metric tons. A part of them is washed away by rain into rivers, wells and other aquatic environments.
Scientists from UNESP's School of Sciences and Technology (FCT) at Presidente Prudente discovered a way to remove glyphosate products from water in research led by postdoctoral fellow Guilherme Dognani and FCT-UNESP Professor Aldo Aloisio Job.
how it works
Dognani explained the process. “The bagasse is crushed and the cellulose is separated from the hemicellulose and lignin. The cellulose fibers are then functionalized by adding quaternary ammonia groups to their surface so that the material becomes positively charged. The resulting cationic cellulose Microfibers easily bind with glyphosate,” she said.
Leal said there are some favorable conditions, such as pH variation, which was the focus of the study. “When the pH varies, both the adsorbent material and glyphosate exhibit different molecular configurations. The most efficient level for the interaction between them, inducing the most adsorption and therefore optimal removal, is pH 14,” They said.
To evaluate the adsorption capacity, the researchers prepared fractions of glyphosate solution with pH 2, 6, 10 and 14, which were measured using a pH meter. They then added equal amounts of functional cellulose microfibers to each fraction.
The flask containing the solution contaminated with glyphosate plus cellulose was shaken for 24 hours. According to the procedure described in the literature, they were heated in a water bath until the reaction occurred, cooled to room temperature and analyzed by visible light spectrophotometry. Removal efficiency was calculated as the ratio of the initial to final glyphosate level in each sample, and adsorption capacity was calculated as a function of pH.
more information:
Maria Vitória Guimaraes Leal et al, pH dependence of glyphosate adsorption from aqueous solution using cationic cellulose microfiber (CCMF) biosorbent, pure and applied chemistry (2023). DOI: 10.1515/PAC-2022-1205
Citation : Brazilian researchers develop method to purify water contaminated by glyphosate (2023, 22 September) Retrieved 22 September 2023
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Source: phys.org