Photocatalytic degradation of salicylic acid with magnetic activated carbon-supported F-N codoped TiO2 under visible light

In this work, magnetically separable F-N co-doped TiO2 were synthesized using a facile sol-gel method grafted on magnetic activated carbon decorated with carbonized chitosan (F-N-TiO2/MAC-CTS). The composite photocatalysts were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), the N2 adsorption/desorption method (BET), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). The usage of hydrofluoric acid (HF) as F precursor could modify the morphology, crystalline size, specific surface area and energy bandgaps of the photocatalysts. Photocatalysts with different molar ratio of F:Ti turned out to show different photocatalytic ability for salicylic acid (SA). The highest degradation rate of 61.99% was achieved for samples with molar ratio (F:Ti) of 0.1 after 3 h visible light irradiation. The rate constant of F0.1-N-TiO2/MAC-CTS was 0.00532 min−1, which was about 2.5 times higher compared with photocatalyst doped with N only. Results of quenching experiment showed that ·OH and h+ played major roles in the photocatalysis. F0.1-N-TiO2/MAC-CTS still remained good photocatalytic activity after 4 times of recycling experiments.