“…Membrane technologies have been applied successfully in conjunction with enzymatic hydrolysis following steam hydrolysis for processing XOs (Nabarlatz et al 2007;Vegas et al 2008).…”
Xylooligosaccharides (XO), derived from the alkaline (NaOH) extractant of Mikania micrantha, were produced using multiple staged membrane separation and enzymatic xylanolysis. Staged nanofiltration (NMX), ultrafiltration (EUMX), and centrifugation (EMX) processes for the ethanol precipitates were conducted. NMX recovered 97.26% of total xylose and removed 73.18% of sodium ions. Concentrations of total xylose were raised from 10.98 to 51.85 mg/mL by the NMX process. Recovered xylan-containing solids were hydrolyzed by the recombinant Paenibacillus xylanase. 68% XO conversions from total xylose of NMX was achieved in 24 hours. Xylopentaose (DP 5) was the major product from NMX and EMX hydrolysis. Xylohexaose (DP 6) was the major product from EUMX hydrolysis. Results of the present study suggest the applicability for XO production by nanofiltration, as NMX gave higher XO yields compared to those from a conventional ethanol-related lignocellulosic waste conversion process.
“…Membrane technologies have been applied successfully in conjunction with enzymatic hydrolysis following steam hydrolysis for processing XOs (Nabarlatz et al 2007;Vegas et al 2008).…”
Xylooligosaccharides (XO), derived from the alkaline (NaOH) extractant of Mikania micrantha, were produced using multiple staged membrane separation and enzymatic xylanolysis. Staged nanofiltration (NMX), ultrafiltration (EUMX), and centrifugation (EMX) processes for the ethanol precipitates were conducted. NMX recovered 97.26% of total xylose and removed 73.18% of sodium ions. Concentrations of total xylose were raised from 10.98 to 51.85 mg/mL by the NMX process. Recovered xylan-containing solids were hydrolyzed by the recombinant Paenibacillus xylanase. 68% XO conversions from total xylose of NMX was achieved in 24 hours. Xylopentaose (DP 5) was the major product from NMX and EMX hydrolysis. Xylohexaose (DP 6) was the major product from EUMX hydrolysis. Results of the present study suggest the applicability for XO production by nanofiltration, as NMX gave higher XO yields compared to those from a conventional ethanol-related lignocellulosic waste conversion process.
“…Membrane-assisted processing of lignocellulosic hydrolysates has gained importance in fractionation of hemicelluloses in particular from aqueous extracts (Moure et al 2006;Vegas et al 2006;Nabarlatz et al 2007;Sjöman et al 2006Sjöman et al , 2007Al Manarash et al 2012a,b;Sainio et al 2013;Ajao et al 2014;Kallioinen et al 2014). In the pulp and paper industry, membrane technology has already been implemented for recycling chemicals, for cleaning process effluents, and for removing impurities from water circulation systems (Mänttäri et al 1997(Mänttäri et al , 2002Koivula et al 2011Koivula et al , 2012Koivula et al , 2013Krawczyk et al 2013).…”
Section: Fractionation Of Pretreatment Effluentsmentioning
The chemical industry is being forced to evaluate new strategies for more effective utilization of renewable feedstocks to diminish the use of fossil resources. In this literature review, the integration of both acidic and alkaline pretreatment phases of hardwood and softwood chips with chemical pulping is discussed. Depending on the pretreatment conditions, high-volume sulfur-free fractions with varying chemical compositions can be produced. In case of acidic pretreatments, the major products include carbohydrates (mono-, oligo-, and polysaccharides), whereas under alkaline (i.e., aqueous NaOH) pretreatment conditions, the sulfur-free fractions of aliphatic carboxylic acids, lignin, and extractives are primarily obtained. All these fractions are potentially interesting groups of compounds and can be used in a number of applications. Finally, the effects of pretreatments on pulping are also considered. Although it is believed that there are important advantages to be gained by integrating this type of renewable raw material-based production, in particular, with kraft pulping, sulfur-free pulping methods such as soda-AQ and oxygen/alkali delignification processes are also briefly discussed.
“…In addition, the purification of xylo-oligosaccharides for use as low-calorie sweeteners and the removal of monosaccharides and other low molecular weight impurities from rice husk xylan have proved to be feasible using either a 4 kDa MWCO polymeric tubular ultrafiltration membrane or a 1 kDa MWCO ceramic monolithic nanofiltration membrane (Vegas et al 2008). Nabarlatz et al (2007) made successful use of commercial thin-film polymeric ultrafiltration membranes with different MWCOs to purify xylo-oligosaccharides from an autohydrolysis solution of almond shells. They were able to separate the xylo-oligosaccharides into fractions containing narrow and reproducible distributions of molar mass.…”
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