Comparison of the activities of C2N and BCNO towards Congo red degradation

An n-type organic carbon nitride semiconductor, C2N, was synthesized by the pyrolysis of uric acid, and its properties were investigated by scanning electron and transmission electron microscopies, X-ray powder diffraction, and vibrational, UV-visible and X-ray photoelectron spectroscopies. This novel material, composed of crystalline flakes, featured a broad absorption centered at 700¿nm, possibly due to charge transfer, and a 2.49¿eV band gap. Its catalytic performance was assessed for the treatment of effluents with the diazo dye Congo red, comparing it with that of boron carbon nitrogen oxide, BCNO. Both wide band gap semiconductors exhibited decolorizing activity in the dark, although the mechanisms were different and were not photocatalytic: BCNO was more effective towards the adsorption-coordination due to the presence of B-O, while C2N was effective towards the adsorption and the advancement of the oxidation reaction. Their kinetic constants (0.19 and 0.02 min-1 for BCNO and C2N, respectively) were comparable to those of intermetallic compounds studied for azo dyes degradation in dark conditions. In view of the high color removal efficiency (97% after 20¿min) and good reusability of BCNO, this study suggests a potential application of this catalyst for wastewater treatment, alone or in combination with C2N

Green Ag/AgCl as an Effective Plasmonic Photocatalyst for Degradation and Mineralization of Methylthioninium Chloride

A green synthesis of Ag/AgCl with an exceptional SPR and photocatalysis property is greatly benefit to the environmental application especially pollutant removal. In this work, a novel green plasmonic photocatalysis of Ag/AgCl nanocatalyst using aqueous garlic extract (Allium Sativum L.) was successfully synthesized. The allicin and organosulfur compounds in the garlic can act as reducing agents in the green synthesis process. The nanocatalyst properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffractometer. The light-harvesting property was investigated by UV-vis absorption spectra which reveals its visible light absorption capability owing surface plasmon resonance behavior of Ag nanoparticles. The degradation and mineralization of methylthioninium chloride (MC) using this photocatalyst were evaluated under visible light and natural solar irradiation. Surface plasmon resonance of Ag nanoparticles and the presence of organosulfur from the garlic extract facilitated adsorption of MC onto the particle surface, promoting greater degradation. The photocatalytic reaction under visible light can be explained by the pseudo first-order pattern with the highest reaction rate of 0.5829 mg L−1 min−1 at pH 10. The photocatalytic activity of the Ag/AgCl under the natural sunlight reached 90% and 75% for MC and total organic carbon (TOC), respectively. The intermediate products detected during MC degradation under sunlight irradiation before final transformation to CO2, H2O, HNO3, and H2SO4 were also reported. The simplicity of Ag/AgCl green synthesis with the photocatalysis properties under visible light and sunlight can offer the convenience of applying these nanoparticles for pollutant removal in water treatment processes