Visible light photodegradation of blue basic 41 using cobalt doped ZnO: Box–Behnken optimization and DFT calculation

Co x Zn 1− x O system (0 ≤ x ≤ 0.2) was synthesized using the solution combustion method with urea as a fuel source. Photocatalytic tests were performed under visible light to assess the Basic Blue 41 (BB41) conversion. Various characterization techniques, including XRD, FT-IR analysis, SEM, EDS, XRF, BET-surface area, and DRS were used to investigate the composition, structure, and morphology of the synthesized catalysts. In addition, the density functional theory calculation was used in order to study the electronic properties of the ZnO structure. The Box–Behnken model was valid for describing the degradation of BB41 dye according to the analysis of variances results. A maximum conversion of 100% for BB41 dye has been reached with high mineralization and important removal of chemical oxygen demand. The optimum conditions for BB41 conversion are reported. On the other hand, the reuse tests of the best catalyst showed high-performance stability after five cycles. Furthermore, the activity of superoxide ions (O 2 ·− ) and hydroxyl radicals (OH . ) as the spices responsible for BB41 dye conversion was well confirmed by the free radicals scavenging tests. The use of Box–Behnken optimization and DFT calculation applied to the synthesized catalysts proves to be a very suitable procedure to establish the operating conditions under which the synthesis strategy of the Co x Zn 1− x O catalyst in its activity in the visible region performs an excellent efficiency for the degradation of organic dyes and makes contributions to the current literature related to the field of environmental technology.