Tuning synthesis conditions for obtaining innovative eco-friendly solids to degrade glyphosate in contaminated waters

Abstract

This study addresses environmental concerns associated with glyphosate contamination by developing sustainable iron-modified mesoporous catalysts. Key synthesis parameters such as the iron content (Si/Fe) incorporated in the synthesis gel, the nature and proportion of pore-forming agents and the hydrothermal treatment temperature were studied in depth. The materials were characterized by different techniques such as: XRD, Nitrogen Physisorption, TEM, UV-Vis DR and FTIR of Adsorbed Pyridine. The solids synthesized using glyceril monostearate (GM) or glycerol (G) as renewable porogens were catalytically evaluated for glyphosate degradation under mild conditions (ambient temperature and atmospheric pressure). The best catalytic performance (80% of glyphosate degradation with 100% selectivity for the fragmentation into short-chain ions without aminomethylphosphonicacid, AMPA, formation) was found for the solid prepared by direct incorporation with Si/Fe= 10 M ratio, GM as porogen (Si/GM = 5 M ratio) and 85 ◦C of hydrothermal treatment for 3 days. The acidity of catalyst played a crucial role in the activity and selectivity toward the desired products. While strongly acid solids (Fe-M(10)-Si/GM = 5-85 and Fe-M(10)-Si/G = 1/5-85) lead to greater fragmentation of herbicide, those with lower acidity can give rise to the formation of the stable and toxic metabolite AMPA as a degradation product. Thus, the findings of this research open new avenues for developing sustainable and efficient catalystsfor the organic pollutant degradation in aqueous environments.