Synthesis of ZnO/ECB (Eichhornia crassipes Biochar) as a Sustainable Efficient Photocatalyst for Photodegradation of Reactive Black-5

Abstract

ZnO/ECB photocatalyst (Eichhornia crassipes Biochar) has been synthesized to be applied as a photocatalyst in the degradation of Reactive Black-5 dye. ZnO/ECB photocatalyst was synthesized by the coprecipitation method with the ratio Zn(NO3)2.6H2O:ECB (M:w) 0.25:1 (0.25MZnO/ECB); 0.45:1 (0.45MZnO/ECB); and 0.6;1 (0.6MZnO/ECB). The characteristics of the ZnO/ECB photocatalyst were tested using X-ray diffraction, Fourier Transforms Infrared (FTIR), and UV Diffuse Reflectance Spectroscopy (UV-DRS) to determine the energy gap of the photocatalyst. The diffractogram pattern showed that the ZnO/ECB crystals were hexagonal wurtzite in shape. The results of the Kubelka-Munk UV-DRS analysis showed that the energy gap of the ZnO/ECB photocatalyst was smaller than that of pure ZnO. The efficiency of the ZnO/ECB catalyst was evaluated through photocatalytic degradation of an aqueous solution of Reactive Black-5 dye. Measurement of photocatalytic activity under UV radiation showed that ZnO/ECB photocatalyst has a higher degradation ability than pure ZnO. The high photocatalytic activity of the ZnO/ECB catalyst was due to the low energy gap of the ZnO/ECB catalyst, thereby reducing the electron and hole recombination rate in the synthesized photocatalyst. Photocatalyst of 0.25ZnO/ECB has the highest photocatalytic activity with degradation efficiency reaching 75.47%.