The influence of pH, temperature and hydrolyzate concentration on the removal of volatile and nonvolatile compounds from sugarcane bagasse hemicellulosic hydrolyzate treated with activated charcoal before or after vacuum evaporation

Abstract

This paper analyzes the influence of pH, temperature and degree of hydrolyzate concentration on the removal of volatile and nonvolatile compounds from sugarcane bagasse hemicellulosic hydrolyzate treated with activated charcoal before or after the vacuum evaporation process. Furfural and 5-Hydroxymethylfurfural were almost totally removed in all the experiments, irrespective of pH and temperature and whether the charcoal was added before or after the vacuum evaporation process. Adding activated charcoal before the vacuum evaporation process favored the removal of phenolic compounds for all values of pH. Acetic acid, on the contrary, was most effectively removed when the activated charcoal was added after the vacuum evaporation process at an acid pH (0.92) and at the highest degree of hydrolyzate concentration (f=4). However, addition of activated charcoal before or after vacuum evaporation at an acid pH (0.92) and at the highest degree of hydrolyzate concentration (f=4) favored the removal of both acetic acid and phenolic compounds

Inhibitory effect of acetic acid on bioconversion of xylose in xylitol by Candida guilliermondii in sugarcane bagasse hydrolysate

“…The concentrations of sugars and toxic compounds were quantified by chromatography as described by Rodrigues et al (14). Xylose, glucose, arabinose, xylitol and acetic acid were determined by HPLC Shimadzu (Kyoto, Japan) provided with a refractive index (RI) detector and Bio Rad (Hercules, CA) Aminex HPX-87H column (300x7.8mm) at 45ºC, using 0.01N H2SO4, a flow rate of 0.6mL.min -1 , and a sample injector volume of 20mL.…”

“…Next, it was submitted to treatment consisting in pH adjustment to 7.0 with CaO (commercial grade) and to 5.5 with H3PO4, followed by the addition of 2.4% w/v activated charcoal (refined powder), for 1h, under agitation (200rpm, 30ºC). The precipitate formed as a result of this treatment was removed by vacuum filtration, and then the hydrolysate was autoclaved at 111ºC, 0.5atm and used for medium preparation (14).…”

Evaluation of microorganisms performance in hemicellulosic hydrolyzate detoxification and sugarcane bagasse lignin removal for ethanol production

“…A slightly increase (1.25 times) in the furfural concentration was observed, whereas HMF concentration did not suffer any variation (Table 5-2). As long as acetic acid, furfural and HMF are volatile compounds, this fact can be explained by the easiness with which they are dragged by vapors, and by the boiling point drops due to the vacuum, regardless the temperature applied to the process (RODRIGUES et al, 2001). Those results are in accordance to Parajo; Domínguez; Dominguez (1996) who observed partially removal of volatile compounds and increase of nonvolatile products of hemicellulosic hydrolyzate after vacuum evaporation process.…”

Avaliação da biomassa de sorgo forrageiro para produção biotecnológica de xilitol

“…Frutose 1,6-difosfato (FELIPE et al, 1997a;SENE et al, 2000;RODRIGUES et al, 2001;SILVA et al, 2004b). Já em fermentador de bancada a utilização de um coeficiente É importante considerar ainda que os hidrolisados contêm, além de açúcares, compostos tóxicos como fenóis, ácido acético, furfural e 5-hidroximetilfurfural, os quais interferem nesse bioprocesso, em função das concentrações em que se encontram no meio (FELIPE et al, 1996;ALVES et al, 1998;RODRIGUES et al, 2001;MARTON et al, 2003;VILLARREAL et al, 2006).…”

“…As concentrações de furfural e hidroximetilfurfural (HMF) foram determinadas também por cromatografia líquida (RODRIGUES et al, 2001), porém empregando-se as seguintes condições: coluna Hewlett-Packard RP18 mantida a 25ºC; detector de ultravioleta SPD-10A UV-VIS; eluente, solução de acetonitrila/água (1:8) com 1% de ácido acético; fluxo de 0,8 mL/min; volume da amostra injetada 20 µL.…”