RSM-based modeling and optimization of ciprofloxacin oxidative removal from aqueous media using a ternary MWCNT-supported CeO2/LaCoO3 perovskite

Although CeO 2 and MWCNT-supported perovskite catalysts have each shown promise for persulfate (PS)-activated antibiotic degradation, direct multi-technique verification of the electron transfer role of the carbon support in a ternary system has remained largely unexplored. Here, a ternary CeO 2 modified LaCoO 3 perovskite immobilized on multi-walled carbon nanotubes (MWCNTs) was synthesized (co-precipitation) and systematically evaluated for ciprofloxacin (CIP) degradation, combining electrochemical, optical, and process-optimization evidence rarely reported together for this catalyst class. XRD/SEM confirmed 40–60 nm perovskite–ceria particles anchored on MWCNTs; BET analysis showed surface area decreased from 266.9 to 167.4 m 2 g − 1 upon loading, while mesoporosity and active-site accessibility were retained. The optimal catalyst, 25%[15% CeO 2 /LaCoO 3 ]/MWCNT, showed the lowest charge-transfer resistance by EIS, a narrowed band gap of 1.9 eV (vs. 3.2 and 2.1 eV for CeO 2 and LaCoO 3 ), and pronounced PL quenching, confirming enhanced interfacial electron transfer. Response surface methodology gave optimal conditions of pH 5.4, 40.75 °C, and 0.09 g catalyst dosage, achieving 99.8% predicted and 100% experimentally validated CIP removal within 120 min (62.5% TOC mineralization, 180 min), with SO 4 •⁻ identified as the dominant reactive species (removal falling from 99.4% to 41.8% with ethanol). The catalyst retained activity over five cycles with ≤ 0.5% metal leaching. At only 0.09 g L − 1 dosage and ~ 1 mM PS, this system matched or exceeded reported CeO 2 -based photocatalysts (60–87.6%), MWCNT-supported composites (95–96%, light-dependent), and perovskite catalysts (95–98.5%, requiring 0.8–1.0 g L − 1 ), establishing a mechanistically verified, low-dosage, and reusable catalyst for pharmaceutical pollutant remediation.