Large-scale and green synthesis of flower-like MgO from waste magnesite activated PMS for oxidation of doxycycline

Large quantities of MgO materials have been obtained by roasting waste magnesite. Compared with the traditional MgO synthesis method, the preparation method in this paper is simple, inexpensive, environmentally friendly, and can be produced on a large scale. XRD and XPS results show that the main component of the magnesite roasted product is MgO. The SEM results show that after hydration treatment and secondary roasting, the morphology of MgO changed from granular to flower-like. XRD and XPS before and after the reaction showed that a hydration reaction (Mg(OH)₂) could take place when MgO activates PMS. The activity results showed that MgO was able to remove 96 % of the doxycycline within 30 min, which was significantly higher than that of the conventional MOF materials and comparable to the ZIF-67 activity of the cobalt-based MOF materials. In addition, MgO has superior catalytic activity for Congo red (90.59 %), methyl orange (40.04 %), and tetracycline (98.85 %). Quenching experiments revealed ¹O₂ as the main active species. The material has good potential for practical applications as shown by anion interference experiments, pH and cycling experiments. The optimum reaction condition is when the MgO content is 0.6 g/L and the PMS content is 0.6 g/L.