Nitrogen and sulfur co-doped porous carbon derived from polypyrrole-polythiophene for efficient peroxydisulfate activation towards degradation of aniline

To enhance the catalytic activity of carbon materials and streamline their synthesis process, it is necessary to optimize the doping of heteroatoms and reduce the dependence on organic solvents. This can be achieved by utilizing carbonized Polypyrrole-Polythiophene (C(Ppy-Pth)), which is obtained through simultaneous and in-situ co-doping of N and S. This material can serve as an effective activator of peroxydisulfate (PDS) for the degradation of aniline (AN). The results showed that Ppy-Pth could be efficiently synthesized by using cetyltrimethyl ammonium bromide, pyrrole, thiophene, FeCl₃, and H₂O₂ in water. Based on the price, self-decomposition and oxidation efficiency, the performance of PDS activated by C(Ppy-Pth) was superior to that of peroxymonosulfate (PMS) in degrading AN. The optimum conditions for catalyzing PDS and degrading 30 mg/L AN by C(Ppy-Pth) were 0.10 g/L C(Ppy-Pth)-1000-1/1, 2.10 mM PDS, and pH₀ = 3.00, which resulted in 86.69% AN removal in 30 min. Carbonation temperature, N/S ratio and pyridine N content are the key factors affecting the catalytic activity of C(Ppy-Pth). Quenching, probe, and electrochemical experiment revealed that in the catalytic PDS system with C(Ppy-Pth)-1000-1/1 (pH₀ = 3.00), the oxidation of AN mainly occurred through the generation of hydroxyl radical (·OH), superoxide anion (O₂^·-), and electron transfer on the C(Ppy-Pth)-1000-1/1 surface. The steady-state concentration of ·OH and O₂^·- were 2.65 × 10^-14 M and 1.97 × 10^-13 M, respectively, and the contribution rate of ·OH oxidation was 31.28%. The oxidation of AN by sulfate radical (SO₄^·-) and singlet oxygen (¹O₂) could be neglected. This study provides a promising strategy for the construction of PDS catalyst and wastewater treatment.