Fast and efficient photocatalytic degradation of Brilliant blue dye, under solar light irradiation, with bismuth doped ZnO.

Abstract

Brilliant blue dye (BB) is being extensively used in textile and cosmetic industries. Recently BB has been reported to be carcinogenic and asthma causing agent. Hence, its use has been banned in several European countries. During the current study ZnO and Bi-ZnO were synthesized by using sol-gel method. The synthesized catalysts were characterized by x-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy dispersive x-ray spectroscopy (EDX), and Brunauer-Emmett-Teller surface area analysis (BET). Both ZnO and Bi-ZnO were used for the photocatalytic degradation of BB under solar light irradiation. Different parameters affecting the photocatalytic degradation of BB like contact time, dye concentration, catalyst concentration, and pH were evaluated and optimized. Both catalysts degraded BB efficiently but Bi-ZnO displayed better degradation potential (maximum 92 %) than ZnO (maximum 76 %). The band gap for ZnO and Bi-ZnO was found to be 3.10 and 2.95 eV, respectively. Surface area and pore size for ZnO and Bi-ZnO were determined to be 104.03 m /g and 199 nm, and 114.67 m /g and 203 nm, respectively. Kinetics analysis of the experimental data revealed that the photocatalytic degradation of BB followed pseudo-first-order kinetics (R = 0.9581). The value of first order rate constant (k ) was found to be 3.14 x 10 min . The results of the scavenging studies indicated that superoxide radicals ( O ) and hydroxyl radicals ( OH) produced by Bi-ZnO are mainly responsible for the degradation of BB. Finally, the current field challenges are presented, along with widely applied recommendations and detailed concluding remarks.