Synthesis of Fe(III)-g-C3N4 and Applications of Synergistic Catalyzed PMS with Mn(VII) for Methylene Blue Degradation

Refractory organic pollutants pose a great threat to public health in water bodies due to their toxicity and low biodegradability. Developing a method of activating persulfate efficiently and in an environmentally friendly way has become a popular topic of research in current advanced oxidation water treatment technologies. Fe(III)-g-C3N4 was prepared by the calcination method. Fe(III) was anchored on the framework of g-C3N4. The characterization analysis indicated that Fe(III) was successfully loaded on g-C3N4. The best effect for MB degradation was Fe(III)-g-C3N4 (0.1 g/L) dosed with 30 µmol/L KMnO4 for synergistic catalyzed PMS (0.1 g/L), where the degradation rate could reach 95.4%. The optimum temperature for MB degradation was determined to be 10 °C. The optimum pH range of Fe(III)-g-C3N4/Mn(VII) synergistic catalyzed PMS for MB degradation was pH 4.4–6.6 under acidic conditions, and the optimum pH range for MB degradation was pH 8–10 under alkaline conditions. The Fe(III)-g-C3N4/Mn(VII) synergistic catalyzed PMS system was also tested for the degradation of methyl orange and rhodamine b, and good degradation results were obtained with the degradation rates of 87.37% and 84%, respectively. It facilitates the reduction in pollutant emissions, improves water quality and will have a positive impact on the sustainability of the environment.