Search

This paper briefly introduced the current situation of tailings stockpiling and the associated resource utilization methods of tailings in China. In terms of the low activity of utilizing tailings as building materials, we summarized the research progress made in several activation methods of tailings, including mechanical activation, thermal activation and chemical activation, and the corresponding mechanisms as well as their merits and demerits. We concluded that only integrating multi-methods could achieve the optimal activation. Despite cost-effectiveness, chemical activation still cannot completely substitute other activation methods. If being addressed thoroughly, it would better serve the resource utilization of tailings and remarkably remove the potential environmental issues.

The Late Cretaceous sediments on the margin of the Arabia Plate contain information of tectonics and eustatic fluctuation of the Neo‐Tethys Ocean. The sedimentary association in the north of Saudi Arabia, combined with that from Jordan, Israel, and Egypt, revealed three fourth‐order sedimentary sequences that occurred in the Late Cretaceous and Palaeogene. The evolution of the sequences indicates that a most extensive transgression occurred in the south of Neo‐Tethys Ocean during that time, which deposited phosphorite and carbonate overlying the Devonian sandstone directly. The occurrence of thin and interbedded lithological layers implies vigorous fluctuation of the sea‐level during the transgression. We argue that the transgression is the results of tectonic activities and eustatic fluctuation, but may be closely controlled by the regional subduction and Neo‐Tethys collision. [ABSTRACT FROM AUTHOR]

In this study, coal fly ash supported MnO2 (CFA@MnO2) was synthesized as heterocatalyst for the activation of peroxymonosulfate to degrade Acid Red 73 (AR73). The synthesized catalyst was characterized by X-Ray Fluorescence Spectrometer (XRF), X-ray powder diffraction (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET). The composite of CFA@MnO2 possesses a large surface area of 74.59 m2/g. In the catalytic experiment, CFA@MnO2 exhibits excellent catalytic performance with 99.13% AR73 removed within 40 min with a high kinetic rate constant of 0.124 min−1, 5.49 times higher than that of pure MnO2. The operating parameters of CFA@MnO2-based fenton catalytic system were discussed, including MnO2 loading, solution pH, PMS dosage and temperature. The catalyst maintained a relatively high removal rate (>85%) over 5 cycles and degradation intermediates are detected on the catalyst surface after cycled via XPS analysis. The degradation mechanism was investigated by quenching experiments and Electron Paramagnetic Resonance technology. The surface-bound ·OH and SO4·− are considered as the main active radicals in the degradation process. The composite of CFA@MnO2 provides a low-cost and efficient alternative for the catalytic oxidation of organic pollutants. [ABSTRACT FROM AUTHOR]

In this study, coal fly ash supported MnO 2 (CFA@MnO 2 ) was synthesized as heterocatalyst for the activation of peroxymonosulfate to degrade Acid Red 73 (AR73). The synthesized catalyst was characterized by X-Ray Fluorescence Spectrometer (XRF), X-ray powder diffraction (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). The composite of CFA@MnO 2 possesses a large surface area of 74.59 m 2 /g. In the catalytic experiment, CFA@MnO 2 exhibits excellent catalytic performance with 99.13% AR73 removed within 40 min with a high kinetic rate constant of 0.124 min -1 , 5.49 times higher than that of pure MnO 2 . The operating parameters of CFA@MnO 2 -based fenton catalytic system were discussed, including MnO 2 loading, solution pH, PMS dosage and temperature. The catalyst maintained a relatively high removal rate (>85%) over 5 cycles and degradation intermediates are detected on the catalyst surface after cycled via XPS analysis. The degradation mechanism was investigated by quenching experiments and Electron Paramagnetic Resonance technology. The surface-bound · OH and SO 4 ·- are considered as the main active radicals in the degradation process. The composite of CFA@MnO 2 provides a low-cost and efficient alternative for the catalytic oxidation of organic pollutants.