Synthesis of Highly Active Doped Graphitic Carbon Nitride using Acid-Functionalized Precursors for Efficient Adsorption and Photodegradation of Endocrine-Disrupting Compounds

Abstract

A highly active non-metallic doped bulk graphitic carbon nitride (g-C3N4) was synthesized via acid-functionalized melamine decomposition. Specifically, melamine was treated with acetic acid, sulfuric acid, and phosphoric acid to obtain oxygen, sulfur, and phosphorus-doped g-C3N4 derivatives. Sulfur-doped g-C3N4 exhibited remarkable photocatalytic activity to degrade two environmentally harmful hormones, 17β-estradiol, and 17α-ethinylestradiol, due to its narrow energy bandgap and high surface area. The hormones were removed entirely in 30–45 min by adsorption in the dark, followed by photodegradation under visible light (430 nm). Furthermore, the pseudo-second-order kinetic model fitted the adsorption kinetics well, and photocatalytic degradation followed the exponential decay model. LC–MS identified the intermediate products for the photodegradation of 17β-estradiol (E2). This study provides a simple one-step method to synthesize highly reactive metal-free doped bulk g-C3N4 photocatalysts to remove harmful water pollutants.