preprints.org > environmental and earth sciences > waste management and disposal > doi: 10.20944/preprints202407.2464.v1 (registering DOI)

Preprint Article Version 1 This version is not peer-reviewed

Version 1 : Received: 28 July 2024 / Approved: 30 July 2024 / Online: 30 July 2024 (11:39:43 CEST)

The açaí (Euterpe oleracea Mart.) is a native fruit of the Amazon that is well-known due to its commercial value. Its production chain is centered in the state of Pará, largely supplied by extractivism. The processing of açaí fruits in nature generates huge amount of solid waste, which can pose serious risks to the environment if not used and managed properly. Due to a small number of systhematic studies on the effect of chemical activation by pyrolysis of açaí seeds and fibers, and with the aim of providing a basis for future applications of the waste generated by processing of açaí fruits, the present work proposes a study of the pyrolysis of açaí seeds and fibers and the physicochemical and compositional characterization of the aqueous phase products. In this way, açaí seeds were collected from a local artisan processing facility in the city of Belém, PA. The seeds were dried at 105°C until constant weight, and subsequently, the fibers were separated from the seeds in a rotating drum. The seeds and fibers were impregnated with NaOH solutions at 0.5M, 1.0M, and 2.0M, and then pyrolyzed at a laboratory scale at 450 °C and 1 atm. The liquid products from pyrolysis were characterized through acidity index analysis, Fourier-transform infrared spectroscopy, and gas chromatography. The increase in the concentration of the impregnating agent resulted in an increase in bio-oil yield from both the seeds and fibers, rising from 3.3% (raw seeds) to 6.6% (seeds impregnated with 2M NaOH) and from 1.2% (raw fibers) to 3.7% (fibers impregnated with 2M NaOH). The yield in the aqueous phase after biomass pyrolysis showed an inverse behavior to the bio-oil yield, decreasing from 33.7% (raw fibers) to 21.2% (fibers impregnated with 2M NaOH) and from 41% (raw seeds) to 37.5% (seeds impregnated with 2.0M NaOH). High acidity levels were found in the aqueous phase samples and bio-oils derived from the seeds and fibers, which decreased as the concentration of the impregnating agent increased. The increase in the concentration of the impregnating agent (NaOH) influenced the chemical composition of the obtained liquid products, leading to a decrease in oxygenated compounds and an increase in nitrogenous compounds in both experimental matrices, which was also evidenced by the reduction in acidity.

Biomass wastes; Açaí seeds and fibers; Chemical activation; Pyrolysis process; Characterization of aqueous phase

Environmental and Earth Sciences, Waste Management and Disposal

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