ZnONPs/covalent triazine frameworks nanocomposite as high-performance photocatalysts for degradation of Congo red under visible light

Herein, we report the construction of novel zinc oxide nanoparticles/covalent triazine frameworks (ZnONPs/CTFs) as a new and active photocatalyst for Congo red degradation under visible light. The deposition of ZnONPs into the CTFs extends the absorption spectrum into the visible range, allowing for photocatalytic degradation of Congo red even with low-energy light under mild conditions. Various amounts of ZnONPs were loaded on as-prepared CTFs, and the photocatalytic effect of ZnONPs/CTFs was studied on Congo red degradation. The deposition of appropriate contents of ZnONPs (0.3 g) on CTFs had the lowest band gap (1.8 eV) and highest photocatalytic activity compared to other ZnONPs/CTFs. The morphology and structure of nanocomposite were characterized by XRD, FTIR, UV–Vis DRS, FESEM, EDS/Map, TEM, TGA, XPS, PL, and BET techniques. Box-Behnken design (BBD) was used to optimize the operating parameters based on response surface methodology (RSM) with design expert software. The highest degradation efficiency (99.97%) of Congo red was achieved according to the optimum conditions as follows: pH 4.03, catalyst mass 0.08 (g), reaction time 149.15 (min), and loading of ZnONPs (0.3g) on CTFs. In addition, ZnONPs/CTFs can be reused six times (6 continuous runs) without an apparent reduction in the photocatalytic operation.