Plastic Waste Product Captures Carbon Dioxide in Nanometer Pores

Abstract

Plastic waste (PW) and increasing atmospheric carbon dioxide (CO 2 ) levels are among the top environmental concerns presently facing humankind. With an ambitious 2050 zero-CO 2 emissions goal, there is a demand for economical CO 2 capture routes. Here we show that the thermal treatment of PW in the presence of potassium acetate yields an effective carbon sorbent with pores width of 0.7−1.4 nm for CO 2 capture. The PW to carbon sorbent process works with single or mixed streams of polyolefin plastics. The CO 2 capacity of the sorbent at 25 °C is 17.0 ± 1.1 wt % (3.80 ± 0.25 mmol g −1 ) at 1 bar and 5.0 ± 0.6 wt % (1.13 ± 0.13 mmol g −1 ) at 0.15 bar, and it regenerates upon reaching 75 ± 5 °C. The CO 2 capture cost from flue gas via this technology is estimated to be <$21 ton −1 CO 2 , much lower than competing CO 2 capture technologies. Hence, this PW-derived carbon material should find utility in the capture of CO 2 from point sources of high CO 2 emissions while providing a use for otherwise deleterious PW.

Structure-oriented conversions of plastics to carbon nanomaterials

“…On the other hand, the backbone of charring plastics (including PET, PVC, and PS) experiences cyclization, aromatization, and crosslinking instead of being decomposed into small molecular gases, and then carbon material frames will be constructed. This is beneficial for the production of carbon nanosheets and porous carbon but is detrimental to the formation of smooth carbon spheres (Algozeeb et al 2022 ; Sawant et al 2013 ). Most waste plastics are mixed plastics and consist of additives and contaminants, so the influences of the three factors should be critical for the carbonization and reutilization of plastics, and deserve more attention in future research.…”

“…Due to its high specific surface area, low cost, adjustable pore structure, and good electrical conductivity, porous carbon has been widely applied in CO 2 capture (Algozeeb et al 2022 ; Song et al 2022 ), solar steam evaporation (Zhang et al 2019a ), supercapacitor (Cheng et al 2015 ; Ma et al 2020b ; Min et al 2019 ; Zhang et al 2021a ), and battery (Min et al 2020 ). Thus, the carbonization of waste plastics to porous carbons is beneficial for wide applications.…”

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Fig. 7 a Scheme of the formation of 3D porous hollow carbon spheres/porous carbon flakes, inset is the TEM image of HCl washed product, reproduced with permission from Min et al (Min et al 2020 ), copyright 2020 The Royal Society of Chemistry; b Scheme of PET carbonization using ZnCl 2 /NaCl eutectic salts, reproduced with permission from Zhang et al (Zhang et al 2019a ), copyright 2019 The Royal Society of Chemistry; c TEM images of porous carbon synthesized before and after KOH treatment, reproduced with permission from Ma et al (Ma et al 2020b ), copyright 2020 Elsevier; d SEM image of porous carbon synthesized with HDPE and KOAc, reproduced with permission from Algozeeb et al (Algozeeb et al 2022 ), copyright 2022 American Chemical Society

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“…KOAc is another option as a carbon activator. Compared with KOH, KOAc is less corrosive, making it safer to use in scale-up productions (Algozeeb et al 2022 ). Surface areas of products enlarged when the ratio of KOAc to plastics increased.…”

Materials from waste plastics for CO2capture and utilisation

“…J. Name., 2022, 00, 1-3 This journal is © The Royal Society of Chemistry 20xxPlease do not adjust margins Please do not adjust margins demonstrated that pyrolysis of HDPE, LDPE and PP in the presence of potassium acetate salt could yield porous carbons with pore widths of 0.7-1.4 nm for CO 2 capture, instead of valueless carbon char 72. Single or mixed polyolefin feedstock could afford sorbents with CO 2 capacities of 3.80 mmol g -1 (1 bar CO 2 , 25 o C), and could be easily regenerated at approximately 75 o C.…”