• Treated plastic waste good at grabbing c

    From ScienceDaily@1:317/3 to All on Tue Apr 5 22:30:40 2022
    Treated plastic waste good at grabbing carbon dioxide
    Turning hard-to-process trash into carbon-capture master

    Date:
    April 5, 2022
    Source:
    Rice University
    Summary:
    Rice University chemists treat waste plastic to absorb carbon
    dioxide from flue gas streams more efficiently than current
    processes.



    FULL STORY ========================================================================== Here's another thing to do with that mountain of used plastic: make it
    soak up excess carbon dioxide.


    ==========================================================================
    What seems like a win-win for a pair of pressing environmental problems describes a Rice University lab's newly discovered chemical technique
    to turn waste plastic into an effective carbon dioxide (CO2) sorbent
    for industry.

    Rice chemist James Tour and co-lead authors Rice alumnus Wala Algozeeb, graduate student Paul Savas and postdoctoral researcher Zhe Yuan reported
    in the American Chemical Society journal ACS Nanothat heating plastic
    waste in the presence of potassium acetate produced particles with nanometer-scale pores that trap carbon dioxide molecules.

    These particles can be used to remove CO2 from flue gas streams,
    they reported.

    "Point sources of CO2 emissions like power plant exhaust stacks can
    be fitted with this waste-plastic-derived material to remove enormous
    amounts of CO2 that would normally fill the atmosphere," Tour said. "It is
    a great way to have one problem, plastic waste, address another problem,
    CO2 emissions." A current process to pyrolyze plastic known as chemical recycling produces oils, gases and waxes, but the carbon byproduct is
    nearly useless, he said.

    However, pyrolyzing plastic in the presence of potassium acetate produces porous particles able to hold up to 18% of their own weight in CO2 at
    room temperature.



    ==========================================================================
    In addition, while typical chemical recycling doesn't work for polymer
    wastes with low fixed carbon content in order to generate CO2 sorbent, including polypropylene and high- and low-density polyethylene, the
    main constituents in municipal waste, those plastics work especially
    well for capturing CO2 when treated with potassium acetate.

    The lab estimates the cost of carbon dioxide capture from a point source
    like post-combustion flue gas would be $21 a ton, far less expensive
    than the energy-intensive, amine-based process in common use to pull
    carbon dioxide from natural gas feeds, which costs $80-$160 a ton.

    Like amine-based materials, the sorbent can be reused. Heating it to
    about 75 degrees Celsius (167 degrees Fahrenheit) releases trapped
    carbon dioxide from the pores, regenerating about 90% of the material's
    binding sites.

    Because it cycles at 75 degrees Celsius, polyvinyl chloride vessels
    are sufficient to replace the expensive metal vessels that are normally required.

    The researchers noted the sorbent is expected to have a longer lifetime
    than liquid amines, cutting downtime due to corrosion and sludge
    formation.

    To make the material, waste plastic is turned into powder, mixed with
    potassium acetate and heated at 600 C (1,112 F) for 45 minutes to
    optimize the pores, most of which are about 0.7 nanometers wide. Higher temperatures led to wider pores. The process also produces a wax byproduct
    that can be recycled into detergents or lubricants, the researchers said.

    Co-authors of the paper are Rice alumnus Zhe Wang and research scientist
    Carter Kittrell, and graduate student Jacklyn Hall and Praveen Bollini,
    an assistant professor of chemical and biomolecular engineering, both
    of the University of Houston. Tour is the T.T. and W.F. Chao Chair in
    Chemistry as well as a professor of materials science and nanoengineering.

    The Department of Energy (DE-F0031794) and Saudi Aramco supported the
    research.


    ========================================================================== Story Source: Materials provided by Rice_University. Original written
    by Mike Williams. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Wala A. Algozeeb, Paul E. Savas, Zhe Yuan, Zhe Wang, Carter
    Kittrell,
    Jacklyn N. Hall, Weiyin Chen, Praveen Bollini, James
    M. Tour. Plastic Waste Product Captures Carbon Dioxide in Nanometer
    Pores. ACS Nano, 2022; DOI: 10.1021/acsnano.2c00955 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220405143537.htm

    --- up 5 weeks, 1 day, 10 hours, 50 minutes
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)