Photocatalytic purification of vehicle exhaust using CeO2-Bi2O3 loaded on white carbon and tourmaline.

Photocatalysts are environmentally friendly materials that can be used to degrade vehicle exhaust. CeO2-Bi2O3 loaded on white carbon and tourmaline, as the favorable absorption materials, was prepared respectively for vehicle exhaust photocatalytic purification. Brunauer-Emmett-Teller (BET) adsorption isotherm, scanning electron microscope (SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) were applied to characterize the composite materials. The optimum contents of the loading materials were obtained from the comparison of purification efficiency of vehicle exhaust components after a 60-min photocatalytic reaction under visible and ultraviolet (UV) irradiation, including hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NOx). The results show that the proposed preparation method could improve particle dispersion and distribution uniformity, reduce particle agglomeration, and increase specific surface area. The optical response range of the CeO2-Bi2O3 with loading materials can be extended from UV light to visible light. CeO2-Bi2O3 loaded on tourmaline show excellent photocatalytic purification effect under visible light. The purification efficiency of CeO2-Bi2O3 loaded on tourmaline for HC, CO, CO2, and NOx were 30.8%, 30.6%, 35.3%, and 47.6%, respectively. Moreover, the concentrations of vehicle exhaust components decrease with time, which is well fitted by the Langmuir-Hinshelwood pseudo-first-order kinetics model, and the purification rate constant of CeO2-Bi2O3 composites under visible light is greater than that under UV light. The prepared photocatalytic materials also exhibit the excellent reusability.