The bidirectional matter transfer in adsorption-promoted photocatalytic ozonation system derived by triazine nanosheets-heptazine nanotubes homojunction composite biochar

Abstract

Heterogeneous catalytic ozonation (HCO) process is an efficiency and eco-friendly solution to the growing challenge of water purification, yet is challenging by O₃ utilization, pollutants selectivity, and matter transfer resistance. Herein, adsorption-promoted photocatalytic ozonation (HCO/PO_AP) system was constructed derived by triazine nanosheets-heptazine nanotubes homojunction carbon nitride composite Enteromorpha prolifera derived biochar (CN_Th-St/EpC) to provide a targeted solution for the refractory organic pollutants treatment. In the HCO/PO_AP system, the adsorption sites predominantly reside on EpC, while the catalytic sites are primarily located on CN. The construction of efficient transport channels is facilitated by the induction of triazine structures from amorphous C, N compounds along the edges of heptazine. This leads to the independent yet closely interconnected process of inward transfer of pollutants and outward transfer of active species, confining reactions to a bidirectional transfer channel. This strategic confinement significantly amplifies the performance of HCO/PO_AP system. Specifically, the removal rates are 80 % for TC and 94 % for PNP in 30 min with almost entirely harmless or non-toxic degradation products, and mark a 56 % and 77 % enhancement over O₃ system, respectively. Moreover, the HCO/PO_AP system demonstrates exceptional efficacy in treating dissolved organic matter, chemical oxygen demand (COD), and ultraviolet absorbance at 254 nm (UV₂₅₄) in diverse actual wastewater. This study highlights the potential of HCO/PO_AP process in efficient water purification, and provides mechanistic insights into the bidirectional matter transfer during the contaminants remove.