Facile preparation of manganese sand-based monolithic catalysts with excellent catalytic performance and reusability for activation of peroxymonosulfate: The key role of pre-calcination

Abstract

The construction of monolithic catalysts for peroxymonosulfate (PMS) activation with excellent performance and reusability holds great promise in environmental remediation. In this work, manganese‑cobalt bimetallic oxide (MC) loaded manganese sand (MS) monolithic catalysts (0.5MC/800MS) with enhanced catalytic performance were obtained by modulating the interaction between manganese‑cobalt bimetallic oxides and manganese sand. The calcination of MS results in a partial reduction of the manganese and iron fractions, in particular in the decomposition of MnO₂ to form Mn₂O₃. The changes in the chemical properties of Mn in MS greatly enhance the activity of Co in MC. 0.5MC/800MS exhibited a remarkably higher efficacy for PMS activation than 0.5MC/MS. The effects of several reaction parameters (i.e., PMS dosage, catalyst dosage, reaction temperature, initial pH value, and inorganic ions) on tetracycline (TC) removal were comprehensively investigated by batch catalytic experiments. 0.5MC/800MS can effectively activate PMS in the pH range of 3–9 to generate sulfate radical (SO₄⁻) for TC degradation. In continuous catalytic experiments, the instantaneous and delayed removal of TC was 71.3 % and 84.9 %, respectively, after 21 L of simulated wastewater flowed through the fixed-bed reactor. Especially, when 6 L of actual industrial cleaning wastewater was treated, the TOC removal ratio of about 85 % could be maintained. This study provides new insights into optimizing the interaction of manganese sands with surface spinel for the development of novel macroscopic Fenton-like catalysts.