Magnetic CuFe2O4 nanoparticles immobilized on mesoporous alumina as highly efficient peroxymonosulfate activator for enhanced degradation of tetracycline hydrochloride

Nanoscaled magnetic copper ferrite (CuFe2O4) is widely used as a peroxymonosulfate (PMS) activator but suffers from agglomeration owing to its inherent magnetic properties and high surface energy. In this work, spinel structured CuFe2O4 anchored on mesoporous alumina (denoted as CFO@AO) were synthesized, characterized, and applied as a PMS activator for the removal of tetracycline hydrochloride (TC·HCl). Approximately 97.5 % of TC·HCl was decomposed within 10 min in 30 %–CFO@AO (0.2 g/L)/PMS (0.3 g/L) system, and the corresponding kinetic rate constant of 30 %–CFO@AO/PMS (0.417 min−1) was around 1.57 times higher than that of CuFe2O4/PMS (0.266 min−1), which indicating that the existence of synergistic catalysis between CuFe2O4 and Al2O3 enhanced the degradation of TC·HCl. Moreover, nano-sized CuFe2O4 were successfully anchored on the surface of Al2O3 because of FeOAl bond, which could account for the enhanced catalytic activity, superior pH flexibility, and high chemical stability and reusability of 30 %–CFO@AO. Quenching experimentals, electron paramagnetic resonance, and methyl phenyl sulfoxide (PMSO) chemical probe assays confirmed that both radical oxidation (OH) and non-radical oxidation (1O2 and Fe(IV)O) were proposed in the developed CFO@AO/PMS system, and OH played a key role in the process. Meanwhile, the PMS activation mechanism by CFO@AO composite was also analyzed based on the results of adsorption energy, which was calculated via DFT. Based on UPLC–MS technique, a possible degradation pathway for TC·HCl destruction in 30 %–CFO@AO/PMS system was proposed. The toxicity assessment showed that the catalytic degradation of TC·HCl in 30 %–CFO@AO/PMS system reduced the toxicity of most of degradation intermediates. Present work proved that CuFe2O4@Al2O3 composite is an efficient, environment-friendly, and recyclable heterogeneous catalyst for practical wastewater treatment via PMS activation.