Fast and efficient photocatalytic degradation of Brilliant blue dye,
under solar light irradiation, with bismuth doped ZnO.
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 2/g and 199 nm, and
114.67 m 2/g and 203 nm, respectively. Kinetics
analysis of the experimental data revealed that the photocatalytic
degradation of BB followed pseudo-first-order kinetics (R
2 = 0.9581). The value of first order rate constant (k
1) was found to be 3.14 x 10 -3 min
-1. The results of the scavenging studies indicated
that superoxide radicals ( •O 2
−) 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.