resumo
Water hyacinth (Eichornia crassipes) is an invasive aquatic plant that has recently been showed to have a remarkable abundance of stigmasterol in leaves and stalks. The supercritical fluid extraction (SFE) of E. crassipes parts was performed for the first time in this work, covering total yield (eta(total)), stigmasterol yield (eta(stig)), and its concentration in extracts (c(stig)). Several experiments were performed at 200 bar, two temperatures (40 and 60 degrees C), and three cosolvent amounts (0, 5, 10 wt.% ethanol). Moreover, two cumulative extraction curves were measured (200 bar and 40 or 60 degrees C). The results showed that eta(total) ranged from 0.64 to 0.73 wt.% after 6 h of extraction, eventually reaching 1.88 wt.% if the extraction time four times and ethanol is included. For eta(stig), 6 h of SFE yielded 0.20-0.22 wt.% with no noticeable advantage in extending the run time and/or adding ethanol. In comparison to Soxhlet results, the performance of SFE in both eta(total) and eta(stig) fell below dichloromethane results. Nonetheless, when stigmasterol concentration was analyzed, a significant selectivity gain was observed on SFE, which originated extracts up to 3:1 richer in stigmasterol. This was also confirmed after estimating practical stigmasterol selectivities, whose values attained 1.14 at 200 bar and 40 degrees C, while at 60 degrees C they reached ca. 0.90 at most. Modeling suggested intraparticle diffusion as the apparently dominant mass transport mechanism of the process. In the whole, the results encourage the valorization of E. crassipes through a green technology such as SFE. (C) 2015 Elsevier B.V. All rights reserved.
palavras-chave
EUCALYPTUS-GLOBULUS BARK; RESPONSE-SURFACE METHODOLOGY; FLUID EXTRACTION; CARBON-DIOXIDE; EICHHORNIA-CRASSIPES; OPERATING-CONDITIONS; TRITERPENIC ACIDS; BETA-SITOSTEROL; EXPERIMENTAL-DESIGN; MATHEMATICAL-MODEL
categoria
Agriculture
autores
de Melo, MMR; Silva, RP; Silvestre, AJD; Silva, CM
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Carlos Manuel Silva
Professor associado
Marcelo Morais Rodrigues de Melo
Bolseiro de pós-Doutoramento
Rui Pedro Fonseca Ferreira da Silva
Estudante de mestradoagradecimentos
This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by National Funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement.