Uniformly dispersed TiO in indole-based porous polymer for efficient wastewater degradation through synergistic adsorption and photocatalysis.

Titanium dioxide (TiO), functioning as an inorganic photocatalyst, often encounters aggregation issues and lacks sufficient pollutant enrichment, leading to reduced photocatalytic performance. To address these challenges, by employing cation-π interaction, titanium ions (Ti) were effectively driven and induced to disperse uniformly around the indole ring plane of the indole-based porous polymer (PTIMK), which served as a carrier. Subsequently, through an in-situ reaction, a titanium dioxide/indole-based porous composite material (PTIMK/TiO-C) with exceptional TiO dispersion was prepared. Utilizing trinitrotoluene (TNT) as a model pollutant, a pronounced synergistic effect between the photocatalysis of TiO and the adsorption of PTIMK was observed, highlighting the outstanding capability of PTIMK/TiO-C in degrading TNT-containing wastewater. Specifically, TiO catalyzed the degradation of TNT and the aromatic intermediates generated during this process, while PTIMK adsorbed TNT and these aromatic molecules. Notably, the adsorbed TNT, its degraded aromatic molecules, and TiO were concentrated around the indole groups of PTIMK, effectively shortening the diffusion distance between the adsorbed pollutants and TiO and enhancing the degradation efficiency of PTIMK/ TiO-C. The composite achieved purification of a 50 mg/L TNT solution within 1.16 h and reduced the chemical oxygen demand (COD) of the TNT solution to 18 mg/L within 6.50 h, meeting the national Class III water standard. Furthermore, PTIMK/ TiO-C demonstrated notable effectiveness in degrading various other organic pollutant-containing wastewaters including methylene blue (a dye), acetylsalicylic acid (a pharmaceutical ingredient), and trichlorophenol (a phenolic compound). This work not only provides an effective method for preparing porous composite materials with uniform TiO dispersion but also introduces a novel strategy combining the photocatalytic capability of TiO with the adsorption capacity of a porous polymer for the degradation of wastewaters containing organic pollutants.