CETMIC   05378
CENTRO DE TECNOLOGIA DE RECURSOS MINERALES Y CERAMICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Argentinian soils/montmorillinite-carbon systems: adsorption behaviour against two pesticides
Autor/es:
E. ZELAYA-SOULE; SUAREZ-GARCÍA F; FERNANDEZ M.A; TORRES SANCHEZ R.M.; MONTES M.L.; DIEZ TASCÓN J.M
Lugar:
Granada
Reunión:
Congreso; XVI International Clay Conference; 2017
Institución organizadora:
Sociedad Española de Arcillas
Resumen:
The addition of pesticides to the soil to maintain the yield in the agricultural production generates concern about the soils and waters contamination. Among the remediation techniques, amendments with activated carbons have been used with success to restore soils contaminated [1]. The adsorption capacity of montmorillonite combined with that of carbon, can be considered as an economic and alternative system to activated carbon that can be used for same purpose. Among the pesticides utilized in Argentina, in fruit production, thiabendazole (TBZ) and chlorpyrifos (CPF) are applied in the greatest quantity and their behaviour in cultivated soils as well as in montmorillonite carbon systems (MCS) has not been evaluated.In this work, thiabendazole and chlorpyrifos sorption on nine different surface soils and MCS were studied. Characterization of the product obtained by both pesticides and MCS was conducted in order to understand the sorptionsurface sites involved. The MCS synthesis was performed using a similar procedure to that reported by Martın-Jimeno et al. [2]. An Argentine montmorillonite from Rio Negro province was used as a carbon support (from 10and 25 mg/L of dextrose). A suspension of 10 mg/L of montmorillonite was prepared and then 5, 10 or 25 mg/L of dextrose was added. The obtained suspension was sonicated by 3 h and then maintained at 180oC during 16 hon hydrothermal reactor. The resultant material (MCS-5, MCS-10 and MCS-25) was washed and dried at 60oC.MCS sorbents were characterized by BET, XRD and SEM. Some soil characteristics, as clay content, surface area and organic carbon (OC) were also determined by conventional methods. MCS sorbents with the adsorbed pesticides were characterized by IR measurements.Sorption studies were performed at room temperature in batch conditions, using 25 mg/L of TBZ or CPF, ratio solid-solution = 0.8 g/l, pH = 6 and 24 h of contact time. The TBZ or CPF adsorbed were determined as the differencebetween the initial concentration and that at equilibrium determined by HPLC.Surface area for all MCS samples was around 1m2/g. XRD showed that montmorillonite structure of all MCS samples was not modified, while SEM analysis indicated laminar structures without presence of free dextrose.Soils showed a clays range between 17 and 54%, specific surface area between 12 and 39 m2/g, and OC between 1 and 5%.TBZ sorption percentage on the different soils varied between 5 and 68% and the sorption capacity was positively correlated with the clay content (Pearson correlation coefficient = 0.88). Similar results were observed for CPFsorption, obtaining a Pearson correlation coefficient = 0.73). No correlation was observed between soil OC content and pesticides sorption capacity of the soils. Relatively high sorption percentages of TBZ on the MCS sampleswere obtained (around 95%).The FTIR spectra of the adsorbed pesticides showed peaks corresponding to TBZ and CPF in the MCS.These preliminary results indicated the capacity of MCS sorbents to retain the pesticides studied and their potential use as soil amendments.[1] Bes, C., & Mench, M. (2008). Remediation of copper-contaminated topsoils from a wood treatment facility using in situ stabilisation.Environmental Pollution, 156(3), 112