Sorption of Glyphosate and AMPA on Mining 2:1 Phyllosilicates: Potential to Mitigate Large Volume of Contaminated Soil and Sediment

Glyphosate is the most widely used herbicide throughout the world. The aim of this study was to evaluate the sorption of glyphosate (GLY) and aminomethyl phosphonic acid (AMPA) on 2:1 mineral extracted from mines to define the potential for mitigating contamination of large volumes of soil, and sediment. Natural samples extracted from mines were characterized as vermiculite (Ve) and regular interstratified illite-smectite (Il-Sm) and the synthetic reference sample as regular interstratified mica-smectite (Mi-Sm). Batch sorption experiments were carried out, and GLY and AMPA chromatographic determination were preceded by derivatization reaction. Specific surface area (SSA) of mining minerals was low (m2 g−1): Ve 0.6 and Il-Sm 7.8. The macroscopic size of Ve (sand content of 841 g kg−1) was determining for SSA reduction. The kinetic qt values of Ve and Il-Sm were low (<0.25 mg g−1) regardless of the analyte (GLY or AMPA) and pH (4.0 and 6.5). This limited sorption was consistent with low accessibility to reactive interlayer sites in the mining minerals. The initial sorption of GLY and AMPA was rapid, with most sorption occurring within the initial stage, followed by slower stabilization. Kinetic modeling indicated possible contributions from intraparticle diffusion and surface heterogeneity to GLY sorption on the mining minerals, while the physicochemical and mineralogical characteristics of the materials provided independent support for differences in sorption behavior. Despite their low sorption capacity, the results suggest that mine-derived 2:1 minerals may have potential for application in the remediation of large volumes of GLY- and AMPA-contaminated soil and sediment, although their practical performance requires confirmation under field conditions.