A theoretical and experimental approach for photocatalytic degradation of caffeic acid using BiOBr microspheres

Highlights: • BiOBr microspheres were synthesized via solvothermal and varying the bromide source. • Optimal conditions (pH and catalyst dose) were optimized by design of experiments. • Maximum degradation of caffeic acid was achieved at pH 6.7 and 344 mg L⁻¹ of catalyst. • BiOBr synthesized with ionic liquids showed the highest degradation yields. This study describes theoretical and experimental considerations to optimize the photocatalytic degradation of caffeic acid in water using 3D-BiOBr based materials under visible light irradiation. Three BiOBr materials were synthesized through the solvothermal method using different bromide sources, namely potassium bromide (KBr) and the ionic liquid (IL) 1-butyl-3-methylimidazolium bromide. Morphological and chemical changes were observed in IL based 3D-BiOBr materials. The theoretical optimization of the experimental conditions in heterogeneous photocatalysis tests (pH and dose of catalyst) were simulated using the MODDE 12.0.1 software. A central composite design (CCD) was applied to obtain a response surface to elucidate the optimal conditions. This model predicted that the maximum photocatalytic degradation can be achieved at pH of 6.7 and a photocatalyst dose of 344 mg L⁻¹. The optimal experimental conditions were tested using the three synthesized 3D-BiOBr materials. The results showed that the highest degradation efficiency and mineralization yield were obtained using the BiOBr microspheres synthesized with the IL at 145 °C.