Mesoporous tubular g-C3N4 as an efficient metal-free photocatalyst with peroxymonosulfate to degrade carbamazepine

Abstract

In advanced oxidation processes with metal-containing catalysts, metal dissolution usually leads to reduced efficiency and biotoxicity. Therefore, it is very important to find efficient non-metallic materials. In this work, a metal-free mesoporous tubular g-C3N4 was fabricated using melamine and urea mixed according to the mass ratios of 1:12 (TPCN12) by a facile one-step thermal polymerization method. Mesoporous tubular TPCN12 was proved to be successfully synthesized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Then the degradation of carbamazepine (CBZ) by activating peroxymonosulfate (PMS) of TPCN12 under visible light was investigated. It was found that degradation rate constant of CBZ in TPCN12/Vis/PMS system (0.0939 min−1) exhibited great superiority over that in TPCN12/Vis system (0.0149 min−1) and in TPCN12/PMS system, which indicated TPCN12, Vis and PMS had a synergistic effect. The dominant role of the electron transfer and the primary contribution of the holes (h+) and •O2− reactive species were revealed in TPCN12/Vis/ PMS system. Furthermore, the system showed sufficient advantages over a wide pH range and high resistance to inorganic anions. In general, the TPCN12/Vis/PMS system was capable of high stability and recyclability. This metal-free mesoporous tubular catalyst was proposed to achieve efficient and green elimination of pharmaceutical organic pollutants.