LAUSR

The rare-earth elements (La, Ce, and Y)-modified SiO2 films for effective Cr(VI) removal from electroplating effluent were synthesized by a convenient sol–gel method successfully. X-ray diffraction, Fourier transform infrared spectra (FT-IR), scanning electron microscope, energy-dispersive system, and X-ray photoelectron spectroscopy (XPS) were applied to characterize their physicochemical properties. The adsorption isotherms showed that the adsorption capacity of SiO2 modified by La3+ (64.43 mg g–1) is the best, followed by Ce3+ (53.45 mg g–1) and Y3+ (47.83 mg g–1) because of the different ion-exchange capacities of La/Ce/Y–(OH), whereas that of SiO2 film without modification is only 38.54 mg g–1. Their adsorption processes could be well depicted by the pseudo-second-order kinetic model. The thermodynamics study showed that the adsorption process of the La/SiO2 film is spontaneous. The adsorption mechanism includes the ion exchange and electrostatic effect. Furthermore, the conversion of Cr(VI) to Cr(II...