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The present work summarizes the results of an experimental study focused on producing antioxidant additives for biofuels from argan shell lignin. The generation of this waste has noticeably increased in specific regions of Morocco as a result of the upward trend in the production of argan oil. Lignin extracted from argan shells via a semi-chemical pulping process was depolymerized under hydrothermal conditions in a stirred autoclave reactor at a temperature range of 250−350 °C. Lignin conversion to phenolic compounds was conducted in subcritical water together with different reaction medium (H 2 , CO 2 , and HCOOH). The organic fraction in the aqueous liquid product was extracted and blended with biodiesel at a dosage of 1 wt % to evaluate its antioxidant potential. According to the obtained results, the biodiesel oxidation stability time was drastically improved up to 400%. The depolymerization temperature was observed as a critical factor in the antioxidant potential of the additives, showing a maximum value at 300 °C, regardless of the reaction medium. An extensive characterization of the produced additives was performed. The phenolic monomers present in the produced additives were identified using gas chromatography−mass spectrometry, finding a notable presence of catechol, especially in the additives obtained at 300 °C, which led to the best results of biodiesel oxidation stability. Gel permeation chromatography analyses of the additives also showed a well dissolution of relatively big molecules (up to 7000 Da) in biodiesel. More efforts are required to verify the actual antioxidant potential of these types of molecules.

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The production of antioxidant additives via the hydrothermal treatment of lignin from argan shells (agricultural waste) was evaluated in the current study. Specifically, the effect of using a Ni catalyst supported on activated carbon which had been prepared from the same waste (argan shells), has been studied. Adding activated carbon (without Ni load) to the reaction medium slightly improved the additives' production, while no significant effect on its antioxidant activity was observed.

This work proposes a novel population‐balance based model for a bubbling fluidized bed reactor. This model considers two continuum phases: bubble and emulsion. The evolution of the bubble size distribution was modeled using a population balance, considering both axial and radial motion. This sub‐model involves a new mathematical form for the aggregation frequency, which predicts the migration of bubbles from the reactor wall toward the reactor center. Additionally, reacting particles were considered as a Lagrangian phase, which exchanges mass with emulsion phases. For each particle, the variation of the pore size distribution was also considered. The model presented here accurately predicted the experimental data for biochar gasification in a lab‐scale bubbling fluidized bed reactor. Finally, the aggregation frequency is shown to serve as a scaling parameter.

The main objective of this study is to assess the performance of the gasification of Argan’s nutshells with pure oxygen as gasification agent. The results of the experiments gave an important percentage of hydrogen produced, around 20%, and point to this agricultural waste as an interesting material to be gasified.

No abstract

In this work, the production of antioxidant additives via hydrothermal treatment of lignin from argan nutshells (agricultural waste) was evaluated. Specifically, the effect of using a catalyst supported on activated carbon which had been prepared from the same waste (argan nutshells) has been studied.