Impact of Lignin Content on the Properties of Hemicellulose Hydrogels

Abstract

Hemicellulose is a promising renewable raw material for the production of hydrogels. This polysaccharide exists in large amounts in various waste streams, in which they are usually impure and heavily diluted. Several downstream processing methods can be combined to concentrate and purify the hemicellulose. However, such an approach can be costly; hence, the effect of impurities on the formation and properties of hydrogels must be determined. Lignin usually exists in these waste streams as a major impurity that is also difficult to separate. This compound can darken hydrogels and decrease their swellability and reactivity, as shown in many studies. Other properties and effects of lignin impurities are equally important for the end application of hydrogels and the overall process economy. In this work, we examined the feasibility of producing hydrogels from hemicelluloses that originated from sodium-based spent sulfite liquor. A combination of membrane filtration and anti-solvent precipitation was used to extract and purify various components. The influence of the purity of hemicellulose and the addition of lignosulfonates (emulated impurities in the downstream processing) to the crosslinking reaction mixture on the mechanical, thermal, and chemical properties of hydrogels was determined.

On the interaction of softwood hemicellulose with cellulose surfaces in relation to molecular structure and physicochemical properties of hemicellulose

“…The proton NMR resonances in the anomeric region were assigned based on HSQC and confirmed by comparison with literature. 18,19,[59][60][61] The spectra recorded for both samples are similar confirming the similarity of the two samples. Hence, the SP is used as a template to describe assignments of the peaks.…”

Robust, remeltable and remarkably simple to prepare biomass–sulfur composites

“…the constituents used to prepare mAPS x . That lignin and hemicellulose improve one another's thermal stability in such a way has been established for synthetic hydrogels 47 as well as for thermally-treated wood products. [48][49][50][51] The differential scanning calorimetry (DSC) data revealed that all of the materials exhibited cold crystallization peaks but no observable T g (full traces can be found in ESI, ‡ Fig.…”

Analysis of membrane fouling by Brunauer-Emmett-Teller nitrogen adsorption/desorption technique

“…The impact of water to the O-H stretching can be excluded as all of the samples were stored in a desiccator for drying. The areas between the peaks 1320 − cm 1 and 1410 − cm 1 ; 1410 − cm 1 and 1485 − cm 1 as well as 1485 − cm 1 and 1576 − cm 1 are intensified as well and can be attributed to skeletal vibration of phenolic compounds such as lignin 35 . Moreover, a new area around 1650 − cm 1 appeared which can be assigned to carbonyl containing components such as natural lignin or terpenoid extractives.…”