Facile Synthesis of Novel Rare-Earth Elements-Modified SiO2 Films for Effective Cr(VI) Removal from Electroplating Effluent

• Published in: Journal of chemical and engineering data 2019-06, Vol.64 (6), p.2677-2685
• Main Authors: Tu, Wenjun, Cai, Weiquan, Jiang, Yihong, Kong, Fanxin, Zhou, Jiabin
• Format: Article
• Language: English
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/acs.jced.9b00107

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(III) during the in situ reduction process was verified by both macro (optical photographs) and micro (FT-IR and XPS) levels. Importantly, the La/SiO2 film showed high adsorption selectivity and high removal efficiency of 97.4% toward Cr­(VI) from initial concentration of 41.7 mg L–1 to residual concentration of 1.1 mg L–1 in the real electroplating effluent, indicating its potential industrial value for pretreatment of heavy metal wastewater.