Immobilized Co2+ and Cu2+ induced structural change of layered double hydroxide for efficient heterogeneous degradation of antibiotic

In this study, MgMn-layered double hydroxide (MgMnLDH) exhibited excellent remediation functionality for heavy metals-antibiotics combined pollution. On the one hand, Co2+ and Cu2+ was efficiently immobilized on MgMnLDH with maximum quantity of 4.30 and 10.65 mmol g(-1), respectively. A series of characterizations reflected the changes in structure and physicochemical properties of MgMnLDH after the immobilization. Density functional theory calculations (DFT) confirmed that the binding modes were lattice substitution for Co2+ and surface precipitation for Cu2+. On the other hand, the immobilized heavy metals enhanced the heterogeneous degradation for sulfamethoxazole (SMX) by peroxymonosulfate (PMS) activation. Complete degradation was achieved within 10 min in MgMnLDH-Co-4/PMS system and 60 min in MgMnLDH-Cu/PMS system, while only 20% in MgMnLDH/PMS system. The pH adaptability, reusability, stability and activation mechanism of two systems were systematically compared. The superior degradation performance of MgMnLDH-Co-4 benefited from the intense Co/Mn synergism and abundant oxygen vacancies, which could accelerate electron transfer during PMS activation process. The applicability of two catalysis system was confirmed in purifying other antibiotics and actual wastewater. The results highlight the importance of structural control in heterogeneous catalysis and provide new idea for environmental remediation.

Automated summary

This study found that MgMnLDH has excellent remediation functionality for heavy metals-antibiotics pollution, efficiently immobilizing Co2+ and Cu2+ and enhancing SMX degradation. MgMnLDH-Co-4 exhibited superior degradation performance due to intense Co/Mn synergism and abundant oxygen vacancies accelerating electron transfer.