Lignin removal and benzene–alcohol extraction effects on lignin measurements of the hydrothermal pretreated bamboo substrate

Evaluating effects of benzene–ethanol extraction on molecular weight of lignin isolated from pretreated bamboo substrate

“…Degradation reaction lets parts of the lignin fragments dissolve into the solutions, whereas the dissolved lignin fragments tended to condense in acidic medium because of their high reactivity (Leschinsky et al 2008a). As a result, lignin content of the pretreated substrate decreased first and then increased (Ma et al 2014). Additionally, studies confirmed that the dilute acid pretreatment of holocellulose could generate ligninlike substrate, which was termed pseudo-lignin (Sannigrahi et al 2011;Hu et al 2012).…”

“…Additionally, studies confirmed that the dilute acid pretreatment of holocellulose could generate ligninlike substrate, which was termed pseudo-lignin (Sannigrahi et al 2011;Hu et al 2012). The generation of pseudo-lignin made the total lignin content of the biomass rise above the content of the original raw material (Ma et al 2014). The complex behaviors probably make lignin soluble in some solvents even in the biomass state, and it was found that benzene-ethanol mixture could remove some of the lignin degradation fragments and therefore resulted in lower lignin content of the pretreated substrate, including Klason lignin (insoluble lignin) and acid-soluble lignin (Ma et al 2014).…”

“…The bamboo hydrothermal pretreatments were conducted in an oil-bath digester; the apparatus sketch and the pretreatment procedure were described in detail in a previous study (Ma et al 2014). The bamboo chips were subjected to hydrothermal pretreatment at 170°C and liquid/solid ratio 3:1 with various durations (30, 90, and 150 min).…”

“…where Y E is the yield of isolated lignin by CEL method, %; M 1 is the resulting mass of lignin isolated from the pretreated bamboo substrate, g; Y H is the yield of the hydrolysis, %; C L is the Klason lignin content of the pretreated bamboo substrate, %; 100 is the substrate subjected to ball mill and enzymatic hydrolysis, g. Klason lignin content of the substrate was determined by the Tappi standard 222om-06 without BAE (Ma et al 2014). Carbohydrate loss ratio was simplified as efficiency of enzymatic hydrolysis and is shown in Eq.…”

“…The generation of pseudo-lignin made the total lignin content of the biomass rise above the content of the original raw material (Ma et al 2014). The complex behaviors probably make lignin soluble in some solvents even in the biomass state, and it was found that benzene-ethanol mixture could remove some of the lignin degradation fragments and therefore resulted in lower lignin content of the pretreated substrate, including Klason lignin (insoluble lignin) and acid-soluble lignin (Ma et al 2014). The possibility of solvent extraction effects on lignin has been documented elsewhere; for example, large parts of lignin can be extracted from prehydrolyzed wood with organic solvents (Klemola 1968;Lora and Wayman 1978); more than 40 % lignin could be extracted from bioethanol production residue with ethanol at 50°C (Guo et al 2013).…”