Characteristics of Hydrochars Prepared from Cassava Residues Using Different Aqueous Media
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This study presents the synthesis and physicochemical characterization of functionalized carbon-based materials prepared from cassava residues (Manihot esculenta). Cassava residues were obtained from a local market, washed, dried and ground to small particle size. This powder was mixed with different aqueous media: diluted sulfuric acid (0.2 M), nejayote and deionized water. These mixtures were treated in an autoclave at 200 °C for 4 h. The physicochemical characteristics of samples were studied by SEM, TGA, FTIR, XPS and elemental analysis. The chemical composition of C:O was similar among groups, but TGA suggested that the hydrochar prepared with sulphuric acid presented a better thermal stability, with a decomposition peak at 435 °C, which was 80 °C higher than samples prepared with deionized water. The acid sample also had lower mass loss (47.3%). The SEM images showed that sulphuric acid promoted the formation of small needle-like structures, while samples prepared using nejayote and water showed agglomerates with a few spherical shapes. The proximate analysis indicated that there was a carbon enrichment from 41% from the original sample to 62% after the hydrothermal process.
KeywordsHydrochars Cassava Nejayote Waste biomass
The authors appreciate the LENERSE-254667 and Problemas Nacionales 2266 grants. XPS measurements were performed at LANNBIO Cinvestav Mérida, under support from projects FOMIX-Yucatán 2008-108160 CONACYT LAB-2009-01-123913, 292692, 294643, 188345, 204822, 292692, and 294643. Technical help is acknowledged to Ing W Cauich. Support to BEM through the Programa de Cátedras—CONACYT is acknowledged.
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