Synthesis and characterization of nano Co3O4- B co-doped g-CN heterojunction for photocatalytic degradation of textile dye wastewater under sunlight

Abstract

Photocatalysis is the best method for organic dye removal process due to non-toxicity of the final products. Hetero-junction photocatalysis has become a hot topic in removal of organic pollutants from the wastewater under sunlight. In this study the photocatalytic activity of the boron doped graphitic carbon nitride (BCN) and tricobalt tetroxide (Co3O4) was used to produce visible light active Co3O4/BCN heterojunction photocatalyst. Graphitic carbon (g-C3N4) and B co- doped BCN with 0.5-10 (w/w) % was synthesized according to literature. 5% BCN has the lowest band gap energy of 2.64 eV. Different weight percentages Co3O4 (10-75 (w/w) %) was used to synthesize hetero-junctions catalyst. The 50 (w/w) % Co3O4-BCN showed the best band gap energy for the photocatalysis (2.34 eV, 530.0 nm). The photocatalysts were characterized by using FT– IR spectroscopy (809, 1237, 1317, 1407, 1555, 1631, 3000-3500 cm-1for g-C3N4 and 656 cm-1for Co3O4). Reactive black 5 dye (RB5) 50 ppm solution was used for the catalysis. The best photocatalyst dosage 0.3 g of g-C3N4 was found from 0.1- 0.4 g and 0.4 g of 50% (w/w) Co3O4-BCN from 0.1- 0.4 g was the best dosage at pH=4. Under sunlight, g-C3N4 was found the best photocatalyst. RB5 dye degradation reached 100% in 100 minutes under sunlight irradiation. Degradation efficiency was enhanced with the pH = 4 up to 100 % efficiency within 80 minutes.