Carbon-Rich g-C₃N₄ Nanotubes with Highly Dispersed Cobalt as a Catalyst to Degrade Sulfamethoxazole in the Vis-PMS System: Nonradical Oxidation Role

Abstract

As one of the typical antibiotics, sulfamethoxazole (SMX) has attracted widespread attention because of its nonbiodegradability and persistence. Here, a novel carbon-rich graphite carbon nitride nanotube with nitrogen vacancies and highly dispersed cobalt doping (Co-CN) was prepared based on porous tubular carbon nitride (PTCN) by a simple one-step thermal polymerization method employing urea, melamine, and cobalt(II) phthalocyanine as raw materials. Characterization results showed that highly distributed Co atoms were evenly doped in the CN ring of g-C 3 N 4 . Under visible light irradiation with the assistance of peroxymonosulfate (PMS) (the Vis-PMS system), the best Co-CN catalyst showed a rate of 0.222 min −1 to SMX degradation, which was 31 times that of PTCN/Vis-PMS, with only 0.020 mg/L cobalt leaching. Further investigation showed that nonradical 1 O 2 was predominantly responsible for the SMX degradation, and h + , O 2•− , and high-valent cobalt species also made certain contributions. Therefore, neither the pH nor the anion of the solution had much of an effect on the degradation process. Moreover, the degradation pathways of SMX were proposed, and an assessment of the ecotoxicity of the resulting byproducts was also conducted. In general, this work developed a new photocatalyst for potential applications to remove organic pollutants from water and wastewater.■ HIGHLIGHTS 1. Catalyst preparation was simple and easy one-step thermal polymerization. 2. Co-CN-20 showed excellent photocatalytic performance with ultralow cobalt ions leaching. 3. The reaction mechanism dominated by nonradical oxidation made degradation almost independent of the pH and anions.

Design and Synthesis of Mosaic ZnO/g-C3N4 Heterojunction Materials with Excellent Anticorrosion Performance

“…g-C 3 N 4 (CN) is rapidly gaining attention as a prospective contender for metallic protection, attributed to its effective shield, high stability, eco-friendliness, ease of synthesis, and advantageous energy band structure. − However, challenges, such as strong Coulombic forces, limited visible light response range, and the recombination phenomenon of the separated electron–hole pairs, can go against the prospective property of the CN materials. − The energy bands of CN and ZnO can be well matched, which is supposed to provide electrochemical protection for alloys by forming heterojunctions to make highly efficient use of the solar energy to generate photoelectrons. The charge transfer path of the heterojunction structure would ensure unidirectional and rapid electron transfer while maintaining the powerful reduction capability of electrons, which significantly improves photocathodic protection.…”