Location and size regulation of manganese oxides within mesoporous silica for enhanced antibiotic degradation

Refractory antibiotics in domestic wastewater are hard to be completely eliminated by conventional methods, and then lead to severe environmental contamination and adverse effects on public health. In present work, advanced oxidation processes (AOPs) are adopted to remove the antibiotic of sulfachloropyridazine (SCP). Nanosized Mn₂O₃ was fabricated on the SBA-15 material to catalytically activate potassium peroxydisulfate (PDS) to generate reactive oxygen radicals of ∙OH and SO₄^•− for SCP degradation. The effects of location and size of Mn₂O₃ were explored through choosing either the as-made or template-free SBA-15 as the precursor of substrate. Great influences from the site and size of Mn₂O₃ on the oxidation activity were discovered. It was found that Mn₂O₃ with a large size at the exterior of SBA-15 (Mn-tfSBA) was slightly easier to degrade SCP at a low manganese loading of 1.0–2.0 mmol∙g⁻¹; however, complete SCP removal could only be achieved on the catalyst of Mn₂O₃ with a refined size at the interior of SBA-15 (Mn-asSBA). Moreover, the SO₄^•− species were revealed to be the decisive radicals in the SCP degradation processes. Exploring the as-made mesoporous silica as a support provides a new idea for the further development of environmentally friendly catalysts.