Browsing by Author "Tang, Yang"

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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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    Highly efficient capture of mercury from complex water matrices by AlZn alloy reduction-amalgamation and in situ layered double hydroxide
    (Taylor & Francis, 2023-02-23) Fang, Yetian; Li, Fangyuan; Chao, Jingbo; Tang, Yang; Coulon, Frederic; Krasucka, Patrycja; Oleszczuk, Patryk; Hu, Qing; Yang, Xiao Jin
    Mercury pollution is a critical, worldwide problem and the efficient, cost-effective removal of mercury from complex, contaminated water matrices in a wide pH range from strongly acidic to alkaline has been a challenge. Here, AlZn and AlFe alloys are investigated and a new process of synergistic reduction-amalgamation and in situ layered double hydroxide (SRA-iLDH) for highly efficient capture of aqueous Hg(Ⅱ) is developed using AlZn alloys. The parameters include the pH values of 1-12, the Hg(II) concentrations of 10-1000 mg L-1, and the alloy’s Zn concentrations of 20, 50 and 70% and Fe concentrations of 10, 20 and 50%. The initial rate of Hg(Ⅱ) uptake by AlZn alloys decreases with increasing Zn concentration while the overall rate is not affected. Specifically, AlZn50 alloy removes >99.5% Hg(Ⅱ) from 10 mg L-1 solutions at pH 1-12 in 5 min at a rate constant of 0.055 g mg-1 min-1 and achieves a capacity of 5000 mg g-1, being the highest value reported so far. The super-performance of AlZn alloy is attributed to multiple functions of chemical reduction, dual amalgamation, in situ LDH’s surface complexation and adsorption, isomorphous substitution and intercalation. This study provides a simple and highly efficient approach for removing Hg(Ⅱ) from complex water matrices.
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    Improving the biodegradability of rice straw by electrochemical pretreatment
    (Elsevier, 2022-08-23) Sun, Shaohua; Zhang, Yuanyuan; Yang, Zhaoyang; Liu, Chunmei; Zuo, Xiaoyu; Tang, Yang; Wan, Pingyu; Liu, Yanping; Li, Xiujin; Coulon, Frederic; Hu, Qing; Yang, Xiao Jin
    The efficacy of NaOH, alkaline hydrogen peroxide (NaOH-H2O2), electrochemically produced NaOH-H2O2 (eNaOH-H2O2) and electrohydrolysis (EH) pretreatments was investigated for anaerobic digestion of rice straw. The cumulative biogas production was enhanced by 8%, 22% and 14% in the NaOH-H2O2, eNaOH-H2O2 and EH relative to conventional NaOH pretreatment. The chemical and electrochemical pretreatments decreased the crystallinity of cellulose and created a porous surface vein. Electrochemical NaOH-H2O2 pretreatment is efficient to promote microbial degradation of lignocellulose for biogas production while the risks associated with the transportation and storage of H2O2 are avoided. EH reduces the pretreatment time significantly and is a promising approach for utilizing rice straw biomass to produce renewable energy.
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    In situ nanoconfinement catalysis for highly efficient redox transformation
    (American Chemical Society, 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.