Researchers at São Paulo State University (UNESP) in Brazil have devised an innovative approach to eliminate glyphosate, one of the world’s most commonly used herbicides, from water sources. Their method draws inspiration from the circular economy concept and revolves around sugarcane bagasse, a byproduct generated by sugar and ethanol plants.
Maria Vitória Guimarães Leal, the lead author of a study published in the journal Pure and Applied Chemistry, explained, “Isolated and chemically modified sugarcane bagasse fibers serve as an effective adsorbent material. Glyphosate molecules adhere to its surface and can be efficiently removed from water through processes like filtration, decantation, or centrifugation.”
Glyphosate, despite its widespread use due to its affordability and potential to enhance crop yields, has raised concerns regarding its potential human health risks, including a possible link to cancer. Several countries, such as Austria, Bulgaria, Colombia, Costa Rica, Denmark, El Salvador, Germany, and Greece, have imposed restrictions or bans on glyphosate-containing products. In stark contrast, Brazil continues to annually use an average of 173,150.75 metric tons of such products, some of which find their way into rivers, wells, and aquatic ecosystems due to runoff.
Researchers from UNESP’s School of Sciences and Technology (FCT) in Presidente Prudente, led by postdoctoral fellow Guilherme Dognani and Professor Aldo Eloizo Job, have discovered a promising method to combat glyphosate contamination in water sources.
How it works
Dognani elaborated on the process, stating, “We begin by breaking down the sugarcane bagasse, isolating the cellulose from the hemicellulose and lignin components. Next, we modify the cellulose fibers by introducing quaternary ammonia groups onto their surfaces, giving them a positive charge. These positively charged cationic cellulose microfibers readily bind with glyphosate.”
Leal emphasized the significance of specific conditions, with a focus on pH variation, as a central aspect of their study. He explained, “By altering the pH levels, both the adsorbent material and the glyphosate exhibit varying molecular configurations. The pH level that fosters the most effective interaction between them, resulting in the highest adsorption and optimal removal, is pH 14.”
To assess the adsorption capacity, the researchers prepared different fractions of a glyphosate solution with pH levels of 2, 6, 10, and 14, meticulously measured using a pH meter. They then introduced identical quantities of functionalized cellulose microfibers into each fraction.
The flasks containing the glyphosate-contaminated solution mixed with cellulose were agitated for a 24-hour period. Following a procedure outlined in scientific literature, the mixtures were subsequently heated in a water bath until the desired reaction occurred, then cooled to room temperature and analyzed using visible light spectrophotometry. The researchers calculated the removal efficiency by comparing the initial and final glyphosate levels in each sample, while adsorption capacity was determined based on the varying pH levels.
Source: FAPESP