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A robust prediction of U(VI) sorption on Fe3O4/activated carbon composites with surface complexation model

Sun, Yubing, Peng, Dingkun, Li, Ying, Guo, Han, Zhang, Ning, Wang, Huihui, Mei, Peng, Ishag, Alhadi, Alsulami, Hamed, Alhodaly, Mohammed Sh
Environmental research 2020 v.185 pp. 109467
Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, activated carbon, adsorption, carbonates, coprecipitation, ionic strength, iron, iron oxides, magnetism, moieties, nitrogen, pH, prediction, uranium, wastewater
A robust prediction of U(VI) on Fe₃O₄/activated carbon (Fe₃O₄/AC, fabricated by co-precipitation method under N₂ conditions) under different pH was developed via diffuse layer model, in accordance with FI-IR, XRD and XPS analysis. No influence of ionic strength onto U(VI) adsorption by Fe₃O₄/AC under ambient conditions suggested the inner-sphere surface adsorption, which was attributed to abundant surficial functional groups according to FT-IR and XPS analysis. The batch experiments indicated Fe₃O₄/AC with fast adsorption rate (equilibrium within 60 min), high adsorption capacity (56 mg/g at pH 4.0) towards U(VI). The adsorbed U(VI) was partly reduced by Fe²⁺ of Fe₃O₄/AC by XPS analysis. Surface complexation modeling showed that a single set of monodentate and mononuclear species (SOUO₂⁺) cannot predict U(VI) adsorption at high pH, whereas the robust prediction of U(VI) adsorption over wide pH range was observed by adding the other binuclear and tridentate species ((SO)₂UO₂(CO₃)⁶⁻). These findings revealed that magnetic AC as a candidate for immobilization and/or preconcentration of radioactive wastewater in environment management.