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Diverse sources of wastewater organic carbon can be microbially funneled into biopolymers like polyhydroxybutyrate (PHB) that can be further valorized by conversion to hydrocarbon fuels and industrial chemicals. We report the vapor-phase dehydration and decarboxylation of PHB-derived monomer acids, 3-hydroxybutyric acid (3HB) and crotonic acid (CA), in water to propylene over solid acid catalysts using a packed-bed continuous-flow reactor. Propylene yields increase with increased Brønsted acidity of catalysts, with amorphous silica–alumina and niobium phosphate yielding 52 and 60 %C (percent feedstock carbon, max 75 %C) of feedstock 3HB and CA, respectively; additional products include CO 2 and retro-aldol products (acetaldehyde and acetic acid). Deactivation studies indicate progressive and permanent steam deactivation of amorphous silica–alumina, while re-calcination partially recovers niobium phosphate activity. Experiments demonstrating sustained reactor operation over niobium phosphate provide a promising technology pathway for increasing valorization of organic-rich wastewater.
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Continuous precision separation of gold using a metal-organic framework/polymer composite
Abstract Critical metals of environmental and economic relevance can be found within complex mixtures, such as mine tailings, electronic waste and wastewater, at trace amounts. Specifically, gold is a critical metal that carries desired redox active properties in various applications, including modern electronics, medicine and chemical catalysis. Here we report the structuring of sub-micron Fe-BTC/PpPDA crystallites into larger 250 μm or 500 μm granules for continuous packed bed experiments for the precision separation of gold. The Structured Fe-BTC/PpPDA is highly crystalline and porous with a BET surface area of 750 m2 g-1. Further, the hybrid nanocomposite material maintains its selectivity for gold ions over common inorganic interferents. The structuring approach reported prevents excessive pressure drop and ensures stability over time and operation in a packed bed column. Further, we demonstrate that the Structured Fe-BTC/PpPDA can concentrate at least 42 wt. % of gold under a dynamic continuous flow operation. These findings highlight the potential of Structured Fe-BTC/PpPDA for practical applications in industry, particularly in the selective capture of gold from complex mixtures.
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- Award ID(s):
- 2151734
- PAR ID:
- 10480402
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Nanotechnology
- ISSN:
- 0957-4484
- Subject(s) / Keyword(s):
- Precision Separations Gold Metal-organic Frameworks/Polymer Composite Continuous Packed Bed Columns Mining Critical Metals
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1088/1361-6528/ad1447
