Adsorption studies of emerging contaminants on Spanish Mg-clays

ROCA JALIL, M.E.; MAGGIO, ANDREA; SANCHEZ, MICAELA; RODRIGUEZ-AMEIJIDE, VANINA; BASCHINI, MIRIA; MUSSO, TELMA BELÉN; PETTINARI, GISELA; GALÁN, ANA BELÉN; VILLA, L.; PÉREZ-ABAD, A.; POZO, MANUEL

Conferencia; 38th lnternational Conference on Geochemistry and Flealth (SEGH 2023); 2023

Emerging contaminants occur in the environment as a consequence of their wide use inveterinary and human health and because water treatment plants are not design to take out thesechemicals. Among the additional processes studied to eliminate these compounds, adsorption iswidely used. Clay minerals, mainly smectites and sepiolite, have shown good adsorptionperformance in the removal of many organic compounds. In this work, after previouscharacterization, eight raw Mg-clays from the Madrid Basin (Spain) were evaluated asadsorbents of two organic compounds in order to establish new applications for them.All materials were assessed as adsorbents of ciprofloxacin (CPX) and lidocaine (LID)considered as emerging contaminants. Adsorption experiments were conducted by batchsorption tests mixing 0.02 g of adsorbent with 8 mL of contaminant solution and stirring at 20°C until equilibrium was reached. Adsorption kinetics studies showed that in all systems theequilibrium is reached within a contact time of 20 min.Adsorbent clays were chosen considering their mineralogical composition and different texturaland physicochemical properties. Four groups were differentiated and identified as: Pal(palygorskite), Sap (saponite), KS (kerolite /stevensite), and Sep (sepiolite). All materialsshowed higher adsorption capacity for CPX than for LID which could be associated with theirmolecular sizes. The higher CPX adsorption capacities were obtained for Pal and Sep (7.76 and5.18 mmol.g-1, respectively) evidencing that fibrous clay minerals favors CPX adsorption. ForLID adsorption, the highest value was obtained for Sap (0.48 mmol.g-1) and followed by Pal(0.41 mmol.g-1) and these results are according to their CEC, suggesting that the adsorptionwould occur mainly by a cation exchange mechanism in this case.The analyzed clays can be good adsorbents of both molecules, evidencing a new application forthem. The obtained results are fundamental when considering them as low-cost geomaterials forenvironmental applications