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 1 O 2 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.
Methodologies for simple and rapid identification of gas compounds are needed in the fields of environmental and security. Here, a new and simple method for the discrimination of gas compounds was designed through an interesting transient cataluminescence (TRCTL) phenomenon on the highly efficient MgO materials. The flowerlike MgO with high CTL activity was controllably synthesized via a facile and time-saving aqueous precipitation route and characterized by scanning electron microscopy, powder X-ray diffractometry, high-resolution transmission electron microscopy, and N2 adsorption measurements, etc. With flowerlike MgO working as the sensing material, the newly developed CTL gas sensor exhibited highly active, ultrafast, and characteristic responses toward many analytes; the TRCTL curves thus were obtained and 10 VOCs have been successfully identified. Parallel experimental results show that the controllable synthesis of flowerlike MgO can greatly enhance the discrimination capacities for VOCs. Further, the TRCTL of CHCl3 and C2H5OC2H5 were taken as typical examples to illustrate the possible sensing mechanism, which could contribute to explaining processes of catalytic oxidations. We expect this novel TRCTL concept will be of practical importance for applications including gas detection, gas discrimination, and research of chemical kinetics processes.
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