Pr3+ substituted Mn-Co spinel ferrites as efficient visible light driven magnetic photocatalyst for multi-pollutant degradation

Abstract

Praseodymium-substituted spinel ferrites with general formula Mn_0.1Co_0.9Pr_xFe_2-xO₄ (x = 0.05, 0.1, 0.15, 0.2) was synthesized via self-combustion using glycine. Structural analysis revealed the formation of a secondary PrFe₂O₃ phase, which becomes more prominent with increasing Pr³⁺ content. These materials were evaluated as visible light-driven photo catalysts for the degradation of methylene blue, tetracycline, and ofloxacin achieving maximum degradation efficiency of 99.24 %, 98.99 % and 96.64 % within 40, 120 and 240 min respectively, at pH 3. Hydroxyl radicals were identified as the dominant reactive oxygen species, and the catalysts showed excellent reusability and stability, with magnetic separation enabled by their enhanced magnetic properties. Optical and structural analysis confirmed moderate crystallinity, nanocrystalline morphology, and broad visible light absorption due to lattice strain and moderate bandgap energy, which promote effective charge separation for ROS generation. The Pr³⁺ ions preferentially occupied octahedral B sites, contributing to a mixed spinel structure. MEM electronic structure analysis revealed distinct site-specific bonding characteristics. The 10 % Pr³⁺ substituted sample showed notable interstitial contributions, which negatively impacted photodegradation performance, while the 5 % Pr³⁺ sample exhibited the highest coercivity due to stronger A-O covalent and B-O ionic interactions. These results highlight the promising potential of Pr³⁺ substituted spinel ferrites as efficient, magnetically separable photo catalysts for multi-pollutant degradation under visible light.