Characterization of rare-earth Gd-doped iron-carbon materials and their effectiveness in treating waste leachate

• Published in: Environmental science water research & technology 2022-10, Vol.8 (11), p.2775-2785
• Main Authors: Zeng, Yalin, Wu, Lieshan, Huang, Shiwei
• Format: Article
• Language: English
• Subjects: Activated carbon; Analytical methods; Biodegradability; Biodegradation; Catalysts; Colour; Composite materials; Crystals; Degradation; Earth; Electrolysis; Electron microscopy; Fluorescence; Fluorescence spectroscopy; Fourier transforms; Fulvic acids; Functional groups; Gadolinium; High temperature; Humic acids; Hydrothermal reactions; Infrared spectroscopy; Iron; Leachates; Molecular weight; Oxides; Photoelectron spectroscopy; Photoelectrons; Rare earth elements; Removal; Scanning electron microscopy; Spectrum analysis; Temperature; Three dimensional analysis; Total organic carbon; Trace elements; Ultrafiltration; Waste treatment; X ray photoelectron spectroscopy; X rays; X-ray diffraction
• ISSN: 2053-1400; 2053-1419
• DOI: 10.1039/d2ew00355d

Gd/Fe-C composites were prepared by hydrothermal reaction and high-temperature sintering, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) before and after strengthening with rare earth element Gd. The optimum process conditions for the treatment of waste leachate with Gd/Fe-C composites were also investigated, and the organic species in the mixed system were initially characterized by UV-vis analysis, molecular weight cut-off ultrafiltration analysis, and three-dimensional fluorescence spectroscopy to investigate the degradation patterns of organic species, molecular weight and functional groups. The results showed that the rare earth element Gd in the Gd/Fe-C material was mainly present in the form of Gd 3+ and acted as a catalyst in the preparation of the material. The addition of the rare earth element Gd resulted in the appearance of elongated crystals in the material, a more detailed and compact material surface, the inhibition of the formation of Fe-based oxides, a significant increase in the amount of zero-valent iron and activated carbon, and the appearance of more active C-O and C-H functional groups. When the solution pH was 6, the temperature was 25 °C and the solid-liquid ratio between the Gd/Fe-C composite and waste leachate was 6 : 100; the degradation effect on waste leachate was most satisfactory, and the removal rates of COD, TOC and UV 254 were 70.54%, 56.13% and 95.27% respectively, and the removal rate of color was 97.37%. The main components of aged waste leachate are fulvic and humic acids. After treatment, most of the fulvic acid was degraded by the [H] and &z.rad;OH produced by micro-electrolysis, which enhanced the biodegradability of the effluent. Gd/Fe-C composites were prepared by hydrothermal reaction and high-temperature sintering, and characterized by SEM, XRD, FTIR and XPS before and after strengthening with rare earth element Gd.