Adsorption of antibiotics using fly ash-based NaP1 zeolite modified with lanthanides via ion exchange and wet impregnation

The increase in global population, extended life expectancy, and the potential of pandemic occurrence substantially elevate antibiotics consumption, thereby exacerbating concerns related to drug resistance and their toxic effects on ecosystems. Consequently, developing effective materials capable of removing antibiotics from water has attracted significant attention. This research focused on lanthanum and cerium modifications of fly ash-based NaP1 zeolite via ion exchange and wet impregnation, aiming to enhance its performance as an adsorbent for ciprofloxacin and tetracycline. Lanthanum and cerium were selected as modifiers due to their low toxicity, abundance, and cost-effectiveness. Their incorporation into NaP1 material was confirmed by structural and compositional changes. The results showed that using lanthanum for modification is more beneficial than cerium, and ion-exchanged samples yielded greater effectiveness compared to wet-impregnated ones. According to EDS elemental mapping, ion exchange promoted a homogeneous distribution of lanthanides, implying uniform formation of active sites. The adsorption of antibiotics occurred through electrostatic and cation-π interactions, ion exchange, hydrogen bonding, and coordination complexes formation. The highest sorption capacities were attained for the sample modified with lanthanum via ion exchange (235 and 190 mg g-1 for ciprofloxacin and tetracycline), which can be attributed e.g., to faster adsorption rates of La-modified adsorbents. The reusability tests showed that materials can be used five times, which is important for minimizing secondary pollution and enhancing sustainability. These findings highlight the potential of lanthanide modification of fly ash-based zeolite as an effective approach for reducing antibiotic contamination, helping to ensure environmental safety and public health protection.