Co-processing of common plastics with pistachio hulls via hydrothermal liquefaction

Hongthong, Sukanya; Raikova, Sofia; Leese, Hannah S.; Chuck, Christopher J.

doi:10.1016/j.wasman.2019.11.003

Cited by 59 publications

(34 citation statements)

References 68 publications

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“…However, the polyolefins only demonstrated a minor synergistic effect with less than 7% of the polypropylene and polyethylene being converted under HTL conditions when 20% polymer was added. 19 A similar result was seen for the co-liquefaction with macroalgae. 17 …”

Section: Introductionsupporting

confidence: 70%

“…This loading was selected as the highest potential level of PP that would be included in a biorefinery and was demonstrated in previous studies as the optimal loading to still allow the analysis of the breakdown products even under low conversions of the initial polymer. 17 − 19 During hydrothermal liquefaction, the feedstock decomposed quickly to generate biocrude, aqueous residue, solid residue, and a gas phase. Mass balances are shown in Figure 1 where product yields were calculated on the basis of total feedstock input and the mass balance is the sum of the biocrude, solid, gas, and aqueous residue combined.…”

Section: Resultsmentioning

confidence: 99%

“…Pistachio hull was selected as a representative of agriculture waste based on our previous work in this area and the relatively high lipid and protein content of the feedstock. 19 Pistachio hull biomass (3 mm particle size) was sourced as a waste material after pistachio processing from the Wonderful Company, CA. The full characterization is given in the Supporting Information .…”

Section: Methodsmentioning

confidence: 99%

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Valorizing Plastic-Contaminated Waste Streams through the Catalytic Hydrothermal Processing of Polypropylene with Lignocellulose

2020

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Food waste is a promising resource for the production of fuels and chemicals. However, increasing plastic contamination has a large impact on the efficiency of conversion for the more established biological routes such as anaerobic digestion or fermentation. Here, we assessed a novel route through the hydrothermal liquefaction (HTL) of a model waste (pistachio hulls) and polypropylene (PP). Pure pistachio hulls gave a biocrude yield of 34% (w/w), though this reduced to 16% (w/w) on the addition of 50% PP in the mixture. The crude composition was a complex blend of phenolics, alkanes, carboxylic acids, and other oxygenates, which did not change substantially on the addition of PP. Pure PP does not breakdown at all under HTL conditions (350 °C, 15% solids loading), and even with biomass, there is only a small synergistic effect resulting in a conversion of 19% PP. This conversion was enhanced through using typical HTL catalysts including Fe, FeSO 4 ·7H 2 O, MgSO 4 ·H 2 O, ZnSO 4 ·7H 2 O, ZSM-5, aluminosilicate, Y-zeolite, and Na 2 CO 3 ; the conversion of PP reached a maximum of 38% with the aluminosilicate, for example. However, the PP almost exclusively broke down into a solid-phase product, with no enhancement of the biocrude fraction. The mechanism was explored, and with the addition of the radical scavenger butylated hydroxytoluene (BHT), the conversion of plastic reduced substantially, demonstrating that radical formation is necessary. As a result, the plastic conversion was enhanced to over 50% through the addition of the co-solvent and hydrogen donor, formic acid, and the radical donor, hydrogen peroxide. The addition of formic acid also changed the crude composition, including more carboxylic acids and oxygenated species than the conversion of the biomass alone; however, the majority of the carbon distributed to the volatile organic gas fraction producing an array of short-chain volatile hydrocarbons, which potentially could be repolymerized as a polyolefin or combined with the biocrude for further processing. Catalytic HTL was therefore shown to be a promising method for the valorization of polyolefins with biomass under typical HTL conditions.

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Section: Introductionsupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Valorizing Plastic-Contaminated Waste Streams through the Catalytic Hydrothermal Processing of Polypropylene with Lignocellulose

2020

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“…Hongthong et al. 39 found that the oxygen content in bio‐oil decreased from 18 to 10 wt % when adding 10 wt % PE to pistachio hulls, and the HHV increased from 33.6 to 38.0 MJ kg −1 . The reason is that H • radicals from the hydrogen‐rich polyolefin chain can reduce the concentration of oxygen‐containing groups through hydrogenation, dehydration, decarboxylation, and other reactions.…”

Section: Resultsmentioning

confidence: 99%

“…Wu et al [19] studied the co-liquefaction mechanism of Dunaliella alga and polypropylene, and found that the acid content was lower than 100 mg L -1 when the ratio of Dunaliella:polypropylene was 8:2, which was far lower than that of Dunaliella of 18.73 wt %. Hongthong et al [39] found that the oxygen content in bio-oil decreased from 18 to 10 wt % when adding 10 wt % PE to pistachio hulls, and the HHV increased from 33.6 to 38.0 MJ kg -1 . The reason is that H .…”

Section: Interactive Effect On Element Distribution and Hhv Of The Bio-oilmentioning

confidence: 99%

Interactions of the Main Components in Paper‐Plastic‐Aluminum Complex Packaging Wastes during the Hydrothermal Liquefaction Process

Wang

Zhu

et al. 2021

Chem Eng & Technol

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Hydrothermal liquefaction was applied to treat paper-plastic-aluminum (Al-PE-Pa) complex packaging waste for bio-oil production. The interactive effects between the main components of paper fiber, low-density polyethylene (LDPE), and aluminum foil in such complex material were studied. The co-liquefaction of paper fiber and LDPE had a significant synergistic effect. The addition of hydrogen-rich LDPE effectively promoted the removal of oxygen-containing groups. Aluminum foil had only a slight impact on the liquefaction of paper fiber, but it can significantly decrease the oxygen content of the bio-oil, increase the high heating value of the bio-oil, and significantly reduce the ester and phenol contents in the biooil. The co-liquefaction of paper fiber/LPDE/aluminum foil exhibited superimposed effects of paper-plastic synergy and in-situ hydrogenation of Al-H 2 O reaction. A new pathway for the energy utilization of Al-PE-Pa complex packaging waste is provided.

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Co‐Liquefaction of Biomass to Biofuels

Martínez-Narro

Phan

2021

Liquid Biofuels

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Co-processing of common plastics with pistachio hulls via hydrothermal liquefaction

Cited by 59 publications

References 68 publications

Valorizing Plastic-Contaminated Waste Streams through the Catalytic Hydrothermal Processing of Polypropylene with Lignocellulose

Valorizing Plastic-Contaminated Waste Streams through the Catalytic Hydrothermal Processing of Polypropylene with Lignocellulose

Interactions of the Main Components in Paper‐Plastic‐Aluminum Complex Packaging Wastes during the Hydrothermal Liquefaction Process

Co‐Liquefaction of Biomass to Biofuels

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