Facile route for fabricating Co(OH)2@WO3 microspheres from scheelite and its environmental application for high-performance peroxymonosulfate activation

The production integration from mineral resources to materials is favorable for reducing the environmental impacts, shortening the production cycle and improving resource utilization. In this work, we developed a facile and eco-friendly method to prepare Co-doped WO3 microspheres from low-grade scheelite, by which the use of chemicals and discharge of wastewater were significantly decreased compared with traditional preparation methods. The as-prepared Co(OH)2@WO3 composite was employed as a peroxymonosulfate (PMS) activator for rhodamine B (RhB) degradation. Density functional theory (DFT) calculation illustrated its adsorption capacity for PMS, and the adsorption effect of Co(OH)2 was more obvious than WO3. Compared with the Co(OH)2, the composites displayed excellent catalytic performance, by which RhB was completely removed within 7 min and a high rate constant of 0.57 min−1 was achieved. This was attributed the lower electrical transfer resistance and better electrical conductivity of the composites confirmed by different electrochemical tests. Quenching experiments revealed that both SO4•− radicals and 1O2 were involved in the reaction system, and 1O2 served as the dominant reactive oxygen species. Furthermore, catalyst stability was assessed by reuse experiments and no significant decrease of degradation efficiency was noticed after five cycles, suggesting good stability of the catalyst. This work might shed new light on preparing efficient catalyst from natural minerals, and the findings would be helpful for the development of the tungsten industry and the improvement of organic wastewater treatment.