Mn-doped carbon-Al₂SiO₅ fibers enable catalytic ozonation for wastewater treatment: Interface modulation and mass...

Heterogeneous catalytic ozonation is an efficient approach to remove hazardous and refractory organic contaminants in wastewater. It is crucial to design an ozone catalyst with high catalytic activity, high mass transfer and facile separation properties. Herein, easily separable aluminosilicate (Al₂SiO₅) fibers were developed as carriers and after interface modulation, Mn-doped carbon-Al₂SiO₅ (Mn-CAS) fibrous catalysts were proposed for catalytic ozonation. The growth of carbon shells on Al₂SiO₅ fiber surface and the introduction of metal Mn provided abundant Lewis acid sites to catalyze ozone. The Mn-CAS fiber/O₃ system exhibited superior reactivity to degrade oxalic acid with a rate constant of 0.034 min^-1, which was about 19 times as high as Al₂SiO₅/O₃. For coal gasification wastewater treatment, Mn-CAS fibers also demonstrated high catalytic activity and stability and the COD removal was over 56%. Computational fluid dynamic simulations proved the high mass transfer properties of fibrous catalysts. Hydroxyl radicals (•OH) were identified as the predominant active species for organic degradation. Particularly, the catalytic pathways of O₃ to •OH on Mn-O₄ sites were revealed by theoretical calculations. This work provides a novel fibrous catalyst with high reactivity and mass transfer as well as easy separation characteristics for catalytic ozonation and wastewater purification.