Porous Mn2O3/pSiO2 Nanocomposites 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/pSiO2 was constructed by a bio-templating route. Structure and morphology analyses reveal the successful assembly and high dispersion of Mn2O3 NPs on the matrix of porous SiO2. Because of the presence of a porous structure and high number of accessible active sites, the resulting Mn2O3/pSiO2 exhibits 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/pSiO2 could 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/pSiO2 possesses 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–H2O2 catalytic system. This study provides a convenient and effective strategy to design porous composite adsorbents/catalysts for the remediation of antibiotic wastewater.