Browsing by Author "Zhang, Jingqi"

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    Groundwater remediation using Magnesium–Aluminum alloys and in situ layered doubled hydroxides
    (Elsevier, 2021-10-22) Zhang, Jingqi; Hu, Hanjun; Chao, Jingbo; Tang, Yang; Wan, Pingyu; Yuan, Qipeng; Fisher, Adrian C.; Coulon, Frederic; Hu, Qing; Yang, Xiao Jin
    In situ remediation of groundwater by zerovalent iron (ZVI)-based technology faces the problems of rapid passivation, fast agglomeration, limited range of pollutants and secondary contamination. Here a new concept of Magnesium–Aluminum (Mg–Al) alloys and in situ layered double hydroxides on is proposed for the degradation and removal of a wide variety of inorganic and organic pollutants from groundwater. The Mg–Al alloy provides the electrons for the chemical reduction and/or the degradation of pollutants while released Mg2+, Al3+ and OH- ions react to generate in situ LDH precipitates, incorporating other divalent and trivalent metals and oxyanions pollutants and further adsorbing the micropollutants. The Mg–Al alloy outperforms ZVI for treating acidic, synthetic groundwater samples contaminated by complex chemical mixtures of heavy metals (Cd2+, Cr6+, Cu2+, Ni2+ and Zn2+), nitrate, AsO33-, methyl blue, trichloroacetic acid and glyphosate. Specifically, the Mg–Al alloy achieves removal efficiency ≥99.7% for these multiple pollutants at concentrations ranging between 10 and 50 mg L−1 without producing any secondary contaminants. In contrast, ZVI removal efficiency did not exceed 90% and secondary contamination up to 220 mg L−1 Fe was observed. Overall, this study provides a new alternative approach to develop efficient, cost-effective and green remediation for water and groundwater.
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    In situ nanoconfinement catalysis for highly efficient redox transformation
    (American Chemical Society (ACS), 2024-11-13) Chen, Yuhan; Tan, Jisheng; Chao, Jingbo; Zhang, Jingqi; Tang, Yang; Liu, Yanping; Hu, Qing; Coulon, Frederic; Yang, Xiao Jin
    The rapid reduction of Cr(VI) across a wide pH range, from acidic to alkaline pH conditions to stable Cr(III) species for efficient remediation of Cr(VI) pollution, has long been a challenge. Herein, we propose a new concept of in situ nanoconfinement catalysis (iNCC) for highly efficient remediation of Cr(VI) by growing nanosheets of in situ layered double hydroxide (iLDH) on the surface of Al-Mg-Fe alloy achieving chemical reduction rates of >99% in 1 min from pH 3 to 11 for 100 mg L-1 Cr(VI) with a rate constant of 201 h-1. In stark contrast, the reduction rate is less than 6% in 12 h with a rate constant of 0.77 h-1 for the pristine Al-Mg-Fe alloy. The ultrafast reduction of Cr(VI) is most likely attributed to the synergistic catalysis of Al12Mg17 and Al13Fe4 and nanoconfinement of MgAlFe-iLDH and superstable mineralization of Cr(III) by MgAlCrIII- and MgFeCrIII-iLDHs. This study demonstrates the potential of in situ nanoconfinement catalysis on redox transformation for environmental remediation.
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    Production of high‐purity hydrogen and layered doubled hydroxide by the hydrolysis of Mg‐Al alloys
    (Wiley, 2021-02-24) Zheng, Tong; Zhang, Jingqi; Tang, Yang; Wan, Pingyu; Yuan, Qipeng; Hu, Hanjun; Coulon, Frederic; Hu, Qing; Yang, Xiao Jin
    Hydrogen is becoming an important clean energy and layered doubled hydroxide (LDH) is of great interest for many applications, including water treatment, environmental remediation, and chemical catalysis. The production of high‐purity hydrogen and LDH by the hydrolysis of Mg‐Al alloys is reported. The effects of initial pH, reaction temperature, reaction time, and alloy's Mg/Al mass ratio on the rate of hydrogen generation and the purity of LDH are evaluated and the solid hydrolysis products are characterized by different techniques. The initial rate of hydrogen generation increases with decreasing initial pH and increasing reaction temperature and Mg/Al ratio while the purity of LDH increases with Mg/Al ratio, reaction temperature and time. This study may provide a new, green, and sustainable approach for storage of hydrogen and material for water treatment.
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    Production of hydrogen, active zerovalent iron and ferroferric oxide octahedron by alkaline etching Al–Fe alloys
    (Elsevier, 2021-06-02) Zheng, Tong; Li, Mingcong; Chao, Jingbo; Zhang, Jingqi; Tang, Yang; Wan, Pingyu; Hu, Qing; Coulon, Frederic; Bardos, Paul
    Hydrogen is becoming important clean energy while zerovalent iron (ZVI) and ferroferric oxide are of great interest to many applications including environmental remediation and chemical catalysis. Here, we report production of hydrogen, zerovalent iron and ferroferric oxide octahedron by etching Al–Fe alloys using NaOH solutions. The rate of hydrogen generation increased with increasing NaOH concentration and the alloy's particle size and decreasing the alloy's Fe concentration. Alkaline etching Al–Fe alloy particles of 425–850 μm produced 19–53 μm ZVI particles, which had paralleled ravines of 0.2–0.3 μm wide on the surface and possessed specific surface areas of 30–70 m2/g. The microscale ZVI was highly active for the removal of a model pollutant acid orange 7 from water. After 3–6 h ageing in the alkaline etching solution, the microscale ZVI particles were transformed to octahedral ferroferric oxide with saturation magnetization of 68.2 emu/g and residual magnetization of 13.2 emu/g and a coercive force of 330 Oe. This study provides a new approach for a facile synthesis of highly active ZVI and octahedral ferroferric oxide along with on-board generation of hydrogen from Al–Fe alloys.
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    Rapid and effective removal of copper, nitrate and trichloromethane from aqueous media by aluminium alloys
    (Elsevier, 2023-12-12) Zhang, Jingqi; Song, Ying; Chao, Jingbo; Huang, Hai; Liu, Dazhi; Coulon, Frederic; Yang, Xiao Jin
    Zero-valent iron (ZVI) has been extensively studied for its efficacy in removing heavy metals, nitrate, and chlorinated organic compounds from contaminated water. However, its limited effectiveness due to rapid passivation and poor selectivity is prompting for alternative solutions, such as the use of aluminium alloys. In this study, the efficacy of five distinct aluminium alloys, namely Al–Mg, Al–Fe, Al–Cu, and Al–Ni, each comprising 50 % Al by mass at a concentration of 10 g/L, was assessed using copper, nitrate and trichloromethane (TCM) as model contaminants. Results show that chemical pollutants reacted immediately with Al–Mg. On the contrary, the remaining three alloys exhibited a delay of 24 h before demonstrating significant reactivity. Remarkably, Al–Mg alloy reduced nitrate exclusively to ammonium, indicating minimal preference for nitrate reduction to N2. In contrast, the Al–Cu, Al–Ni, and Al–Fe alloys exhibited N2 selectivity of 3 %, 5 %, and 19 %, respectively. The removal efficiency of copper, nitrate and TCM reached 99 % within 24 h, 95 % within 48h and 48 % within 48h, respectively. Noteworthy findings included the correlation between Fe concentration within the Al–Fe alloy and an increased N2 selectivity from 9.3 % to 24.1 %. This resulted in an increase of Fe concentration from 10 % to 58 % albeit with a concurrent reduction in reactivity. Cu2+ removal by Al–Fe alloy occurred via direct electron transfer, while the removal of nitrate and TCM was facilitated by atomic hydrogen generated by the alloy's hydrolysis. Intriguingly, nitrate and TCM suppressed Cu2+ reduction, whereas Cu2+ improved nitrate reduction and TCM degradation. These findings demonstrate the great potential of Al–Mg and Al–Fe alloys as highly efficient agents for water remediation.