parameter estimation;  singular value decomposition;  Progressive generalization of the least squares method;  Box-Jenkins model

V-doped TiO2/activated carbon(AC) photocatalysts were prepared by hydrothermal method under mild conditions. XRD, SEM, diffuse reflectance, infrared and fluorescence spectroscopy were used to characterize the physical and chemical properties of the catalyst. The results show that V-TiO2 still maintains the anatase phase without the diffraction peak of V. Compared with pure TiO2, V-doped samples have higher surface hydroxyl density, lower planter recombination probability, and the absorption spectrum shifts to the visible region. Nanoscale V-TiO2 can be deposited on AC to form micro-nano structures. Under visible light irradiation, V-TiO2/AC catalytically degraded 4-chlorophenol was higher than pure V-TiO2 and P25, which could be attributed to the doping of V and the synergistic effect of AC.