Effective use of raw, chemically, and thermally modified clay-rich materials to remove amoxicillin from aqueous environments

Amoxicillin (AMX) is widely released into natural ecosystems, posing serious environmental and health concerns. This study aims to evaluate three raw, base-/acid-activated, and calcined clay-rich materials (AM, HJ1, and HJ2), sampled from the Maknessy-Mazzouna basin (central Tunisia), to remove AMX from water. The clay-rich materials were analyzed in detail using several computational techniques to understand the AMX adsorption processes and the molecular interactions with the various minerals present in these clay-based adsorbents. Acid-treatment enhanced the adsorbent’s BET surface, thereby raising the removal yield, since the acid-activated samples constantly exhibited the highest adsorption capacities, particularly HJ1 (HJ1+HCl), which achieved a maximum adsorption of 98.7% when 1000 µmol L −1 AMX were added, and with a mean desorption rate of 0.6%. Furthermore, HJ1+HCl exhibited the best regeneration performance (adsorption always above 95%), highlighting its superior efficiency as an AMX adsorbent compared to the remaining samples. Conversely, base treatment was less effective than acid activation in enhancing adsorption performance, yet base-treated adsorbent samples exhibited higher overall AMX retention (45.4–94.2%), irrespective of adsorbent type or initial antibiotic concentration, compared with raw (33.8–82.9%) and calcined samples (27.2–84.5%). Generally, the weaker adsorption capacities of the calcined clay-rich materials compared to the raw and acid-/base-activated ones are possibly due to their lower porosity. Overall, the results underscore the efficacy of the studied Tunisian clay-rich materials as eco-friendly adsorbents for antibiotic removal and environmental preservation.