1. Spherical Cu2O-Fe3O4@chitosan bifunctional catalyst for coupled Cr-organic complex oxidation and Cr(VI) capture-reduction
- Author
-
Deli Wu, Fang Li, Yanbiao Liu, Chensi Shen, Yuezhong Wen, Yaopeng Zhang, Feng Zhao, and Hao Li
- Subjects
General Chemical Engineering ,Radical ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial and Manufacturing Engineering ,0104 chemical sciences ,Bifunctional catalyst ,law.invention ,Catalysis ,Chitosan ,chemistry.chemical_compound ,Chromium ,Adsorption ,Catalytic oxidation ,chemistry ,law ,Environmental Chemistry ,0210 nano-technology ,Electron paramagnetic resonance ,Nuclear chemistry - Abstract
Unlike the removal of chromium (Cr) ions, the efficient treatment of Cr complexes with organic ligands is a challenging issue in wastewater treatment. The generation and accumulation of highly toxic Cr(VI) species should be minimized. In this study, well-dispersed Cu2O and Fe3O4 nanoparticles inlaid in chitosan beads were prepared. This catalyst demonstrated dual functions, i.e., catalytic oxidation of Cr(III)-organic complexes and efficient inhibition of Cr(VI) accumulation in the presence of H2O2. More than 85% of the Cr(III)-organic complexes were removed in a wide pH range and a negligible amount of Cr(VI) remained in solution in the presence of 20 mmol/L H2O2. The synergistic effect of Cu2O, Fe3O4, and the chitosan matrix was the key factor for the ligand disruption and Cr removal. X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) analysis were used to determine the underlying mechanism. The results showed that the generated Cu+ species of Cu2O transferred electrons to accelerate the Fe(III)/Fe(II) cycle during the Fenton reaction, which favored the production of OH radicals. The generated Cr(VI) in the Fenton-like reaction was efficiently adsorbed by chitosan and reduced to Cr(III) by chitosan and Cu2O. The reduced Cr(III) was then incorporated into the surface structure of Fe3O4 and generated a stable complex oxides of Fe and Cr(III). Overall, this paper demonstrated a new method for the treatment of Cr(III)-organic complexes from wastewater.
- Published
- 2020
- Full Text
- View/download PDF