Preparation and properties of lignin–phenol–formaldehyde resins based on different biorefinery residues of agricultural biomass

.Running title: Tannin inactivation in milled sorghum grain with dilute NaOH 1 Highlights  Steeping milled Type III tannin sorghum in NaOH solution reduces tannin content  NaOH treatment substantially reduces α-amylase inhibition by the tannins  Tannin polymerization was found to be the mechanism of inactivation  NaOH treatment could enable use of Type III tannin sorghum in bioethanol production 2 ABSTRACTSteeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. NaOH steeping substantially reduced assayable total phenols and tannins in both Type III and Type II sorghums and with Type III sorghum caused a 60-80% reduction in α-amylase inhibition compared to a 20% reduction by water steeping. NaOH treatment also reduced starch liquefaction time and increased free amino nitrogen. Type II tannin sorghum did not inhibit α-amylase and consequently the NaOH treatment had no effect. HPLC and LC-MS of the tannin extracts indicated a general trend of increasing proanthocyanin/procyanidin size with increasing NaOH concentration and steeping time, coupled with a reduction in total area of peaks resolved. These show that the NaOH treatment forms highly polymerised tannin compounds, too large to assay and to interact with the α-amylase. NaOH pre-treatment of Type III sorghums could enable their utilization in bioethanol production.

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“…Solid-state NMR would enable detailed characterization of the insoluble highly polymerized tannins (Zhang, Ma, Wang, Li, Zhang, & Chu, 2013).…”

Section: Discussionmentioning

confidence: 99%

Inactivation of tannins in milled sorghum grain through steeping in dilute NaOH solution

2015

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“…Up to 50 %ofthe phenol content in this material can be replaced by lignosulfonate, Kraft, or Organosolv lignin without significantly compromising properties of the resin. [300][301][302] Similarly,K raft lignin may be oxypropylated and then used as apolyol component in the synthesis of rigid polyurethane foams. [303] Lignin may also be employed as af eedstock for high-quality carbon fibres,a t present produced almost exclusively from poly(acrylonitrile).…”

Section: Angewandte Chemiementioning

confidence: 99%

Paving the Way for Lignin Valorisation: Recent Advances in Bioengineering, Biorefining and Catalysis

et al. 2016

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Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine‐tuning of multiple “upstream” (i.e., lignin bioengineering, lignin isolation and “early‐stage catalytic conversion of lignin”) and “downstream” (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a “beginning‐to‐end” analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.

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“…Moreover, from the aesthetic point of view, the dark colour of the adhesive joint is a drawback. So far, a number of research projects have been carried out aimed at increasing the reactivity of phenolic resins through proper selection of substrates, mole ratio of reagents and condensation conditions as well as through introducing modifiers into the resin, which are meant to accelerate the cross-linking process (Park et al 1999;Conner et al 2002;Dukarska and Łęcka 2006;Mirski et al 2008Mirski et al , 2011Zhang et al 2013). Phenolic resins, just like amine resins, join surfaces through adhesion.…”

Section: Introductionmentioning

confidence: 99%

Construction particleboards made from rapeseed straw glued with hybrid pMDI/PF resin

et al. 2016

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Preparation and properties of lignin–phenol–formaldehyde resins based on different biorefinery residues of agricultural biomass

Cited by 237 publications

References 29 publications

Inactivation of tannins in milled sorghum grain through steeping in dilute NaOH solution

Inactivation of tannins in milled sorghum grain through steeping in dilute NaOH solution

Paving the Way for Lignin Valorisation: Recent Advances in Bioengineering, Biorefining and Catalysis

Construction particleboards made from rapeseed straw glued with hybrid pMDI/PF resin

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