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Development and Validation of Chromium Getters for Solid Oxide Fuel Cell Power Systems
Published on: May 26, 2019
From rapid reduction to stable immobilization: A regenerative 4D FeMgAl layered double hydroxide-microbial strategy
Edidiong Okokon Atakpa1, Shirou Cao2, Wu Yukun2
1School of Environment and Resource Management, Southwest University of Science and Technology, Mianyang, Sichuan 621010, China; School of Material Science and Technology, Southwest University of Science and Technology, Mianyang 621010, China; School of Life Sciences and Engineering, Southwest University of Science and Technology, Mianyang 621010, China.
Abstract:
Chromium [Cr(VI)] contamination poses a persistent environmental challenge due to its high toxicity and mobility. Traditional microbial remediation is often limited by pollutant stress and slow kinetics, highlighting the need for strategies that can both accelerate Cr(VI) reduction and ensure long-term stabilization. This study introduces a stimuli-responsive, regenerative, four-dimensional (4D) FeMgAl NO₃- layered double hydroxide (LDH) engineered for advanced Cr(VI) remediation. The LDH features a labile nitrate-intercalated structure and redox-active Fe(II) sites within a macroporous framework that undergoes pH-triggered dissolution-reconstruction cycles, maintaining reactive surface renewal and operational stability. Coupling the LDH with a chromium-reducing bacterial consortium (Priestia aryabhattai PMASS1 and Pseudomonas putida) enabled continuous electron transfer and accelerated Cr(VI) reduction, achieving > 99.9% removal within 60 h, outperforming LDH- or bacteria-only treatments. Mechanistic investigations revealed integrated pathways involving interlayer exchange, chemisorption, microbially-mediated bioreduction, Fe-driven reductive transformation, and coprecipitation into mixed Fe-Cr hydroxide phases. Comparative analyses demonstrated that both macroscopic architecture and interlayer chemistry critically regulate adsorption kinetics, redox accessibility, and reusability. The nitrate-intercalated LDH exhibited superior anion-exchange kinetics relative to the carbonate-intercalated counterpart, while organic and inorganic modifiers modulated redox and adsorption pathways, with citrate yielding the highest Cr(VI) removal through enhanced electron donation and interlayer expansion. Post-remediation characterization indicated gradual transformation of amorphous Cr(III) hydroxides into stable Cr₂O₃-like aggregates, highlighting the system's capacity for long-term chromium stabilization. This adaptive LDH-microbe system offers a promising strategy for rapid detoxification and sustainable immobilization of Cr(VI) under environmentally relevant conditions.
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