Porous Mn₂O₃/ pSiO₂Nanocomposites on Bio-scaffolds for Tetracycline Degradation

In this study, manganese sesquioxide (Mn₂O₃) nanoparticles (NPs) were inserted into porous silica (pSiO₂) and thus a mosaic-like porous composite of Mn₂O₃/pSiO₂was constructed by a bio-templating route. Structure and morphology analyses reveal the successful assembly and high dispersion of Mn₂O₃NPs on the matrix of porous SiO₂. Because of the presence of a porous structure and high number of accessible active sites, the resulting Mn₂O₃/pSiO₂exhibits both large adsorption capacity and remarkable catalytic activity for the removal of tetracycline (TC, 80 mg·L^-1) from aqueous solutions. With the assistance of H₂O₂, Mn₂O₃/pSiO₂could synergistically degrade TC with a total removal efficiency (RE) of 80%, which is much greater than those of pSiO₂(13%) and nMn₂O₃(63%). Meanwhile, Mn₂O₃/pSiO₂possesses a wide pH application range (3.0-11.0, RE > 83%), quite good efficiency (64%) for highly concentrated TC (240 mg·L^-1), and excellent reusability (RE = 70% after four cycles). Radical-trapping tests and electrochemical measurements reveal that a direct electron transfer pathway plays the dominant role in this TC-Mn₂O₃/pSiO₂-H₂O₂catalytic system. This study provides a convenient and effective strategy to design porous composite adsorbents/catalysts for the remediation of antibiotic wastewater.