1. Selective capacitive removal of Pb(II) ions from industrial wastewater using NF/Mn2CoO4@MoO2 electrodes.
- Author
-
Tang, Changbin, Li, Yanrong, Yu, Yongqi, Shi, Yuzhu, Xu, Hongjiao, Zhang, Yujie, Xue, Juanqin, and Zheng, Nan
- Subjects
- *
NEGATIVE electrode , *MOLECULAR dynamics , *INDUSTRIAL wastes , *DENSITY functional theory , *METAL ions , *DEIONIZATION of water , *BINDING energy , *WATER purification - Abstract
[Display omitted] • A NF/Mn 2 CoO 4 @MoO 2 electrode was prepared for Pb2+-targeted removal via CDI technology. • SCR of the electrode relies on preferential adsorption and sluggish desorption for Pb2+. • Synergistic effects of Mn 2 CoO 4 and MoO 2 are beneficial for Pb2+ capacitive removal. • Theoretical calculations confirm SCR is due to stronger bonding between Pb2+ and MoO 2. • Electrodepositing loaded MoO 2 onto NF/Mn 2 CoO 4 for 60 min achieved optimum capacitance. To achieve targeted removal of Pb2+ from industrial wastewater, a NF/Mn 2 CoO 4 @MoO 2 composite electrode, synthesised using the hydrothermal method combined with electrodeposition technology, was employed to construct an asymmetric capacitive deionization (CDI) system to selectively electro-adsorb and desorb Pb2+ ions. The electrode exhibited pseudocapacitive characteristics in solutions containing Pb2+, facilitating rapid and reversible redox reactions. The asymmetric CDI system, utilising graphite paper as the positive electrode and NF/Mn 2 CoO 4 @MoO 2 as the negative electrode, displayed exceptional adsorption performance at 1.4 V for 1 h, decreasing the Pb2+ concentration from 50 ppm to 4 ppb, achieving an adsorption capacity of 156.24 mg g−1, and displaying outstanding cyclic stability. Moreover, the electrode demonstrated preferential adsorption of Pb2+ in mixed solutions containing multiple heavy metal ions, with relative removal coefficients of 4.48 − 19.86 compared with other ions. Analysis of the adsorption mechanism indicated that during the adsorption process, Pb2+ was embedded between MoO 2 layers, disrupting the electron cloud symmetry and triggering an oxidation reaction. Octahedral MoO 2 then lost electrons and transformed into tetrahedral [MoO 4 ]2-, forming PbMoO 4 with embedded Pb2+ between the layers, and achieving effective removal of Pb2+ with high selectivity. Molecular dynamics simulations and density functional theory (DFT) calculations confirmed the high selectivity of the prepared electrode for Pb2+ ions based on stronger binding of Pb2+ to MoO 2 than other ions. The electrode has application potential for the capacitive removal of Pb2+ from industrial effluent through CDI technology. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF