Key role of hydrochar in heterogeneous photocatalytic degradation of sulfamethoxazole using Ag3PO4-based photocatalysts

Abstract

To overcome the practical application limitations of Ag₃PO₄ such as photocorrosion and relatively low efficiency of photogenerated carrier seperation, Ag₃PO₄ particles were loaded onto hydrochar. The particles in the composite had a smaller crystallite size and different phase structure with more edges than pure Ag₃PO₄ particles. The as-prepared composite catalyst exhibited a different photocatalytic performance for sulfamethoxazole (SMX) degradation when varying the mass ratio of hydrochar and Ag₃PO₄. In addition to higher SMX degradation efficiency, the composite exhibited much higher TOC degradation efficiency, recycling stability, and less-toxic intermediate production. The composites enhanced visible light response, and accelerated electron transfer and photogenerated carrier separation as well. The addition of H₂O₂ to the photocatalytic system enhanced the photocatalytic activity of the composite catalyst. According to a mechanistic examination, the hole (h⁺) is the dominant reactive species for SMX degradation. This study provides new insight into high-efficiency, low cost, and easily prepared photocatalysts for pollution removal from water.