Photocatalytic decomposition of Congo red under visible light irradiation using MgZnCr-TiO₂ layered double hydroxide

The new nanophotocatalyst MgZnCr-TiO₂ was prepared by co-precipitation under different molar ratio of metals (Zn:Cr) and the loaded amount of TiO₂. And it was characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy et al. Langmuir model fitted well the adsorption isotherm with the value of R² 0.9765, the maximum adsorption capacity was 526.32 mg g^-1, the adsorption followed pseudo second order kinetic by MgZnCr-TiO₂ (1:1:2-0.05). The photocatalytic oxidation of Congo red was used to determine the photocatalytic performance of MgZnCr-TiO₂ (1:1:2-0.05) under visible light irradiation, and the removal rate reached 98% after reaction for 40 min. The degradation mechanism of Congo red also was proposed, and the MgZnCr-TiO₂ (1:1:2-0.05) was stable after five cycles. Compared to the adsorption, Congo red was removed fundamentally by photocatalysis and it is expected to be an effective way to eliminate Congo red.