Solid-state <sup>29</sup>Si NMR and FTIR analyses of lignin-silica coprecipitates

Cabrera, Yohanna; Cabrera, Andrés; Larsen, Flemming H.; Felby, Claus

doi:10.1515/hf-2015-0165

Cited by 29 publications

(15 citation statements)

References 33 publications

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“…The SONE allowed us to analyse organic matter that was intimately associated with the silica (Figure 4 and Figure S1). Our results indicated that the Si atoms are coordinated to oxygen, similarly to silica gel and opal, in agreement with analyses of in planta silica (Yoshida et al, 1959;Casey et al, 2004) and in vitro precipitation with lignin (Cabrera et al, 2016;Soukup et al, 2019). We cannot exclude the existence of Si-O-C bonds as detected by X-ray photoelectron spectroscopy in cell walls extracted from rice cell suspension (He et al, 2015).…”

Section: Discussionsupporting

confidence: 80%

Spectroscopic Discrimination of Sorghum Silica Phytoliths

et al. 2019

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Grasses accumulate silicon in the form of silicic acid, which is precipitated as amorphous silica in microscopic particles termed phytoliths. These particles comprise a variety of morphologies according to the cell type in which the silica was deposited. Despite the evident morphological differences, phytolith chemistry has mostly been analysed in bulk samples, neglecting differences between the varied types formed in the same species. In this work, we extracted leaf phytoliths from mature plants of Sorghum bicolor (L.) Moench. Using solid state NMR and thermogravimetric analysis, we show that the extraction methods alter greatly the silica molecular structure, its condensation degree and the trapped organic matter. Measurements of individual phytoliths by Raman and synchrotron FTIR microspectroscopies in combination with multivariate analysis separated bilobate silica cells from prickles and long cells, based on the silica molecular structures and the fraction and composition of occluded organic matter. The variations in structure and composition of sorghum phytoliths suggest that the biological pathways leading to silica deposition vary between these cell types.

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Section: Discussionsupporting

confidence: 80%

Spectroscopic Discrimination of Sorghum Silica Phytoliths

et al. 2019

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“…Lignin associates with polysaccharides, especially hemicellulose, via covalent bonds to form lignin-carbohydrate complexes. Likewise, silica is hypothesized to have interaction with cellulose and lignin 11 , 12 . The recalcitrant structure of lignocellulosic biomass inhibits bio-refineries such as the fermentation of cellulose for bioethanol, conversion of lignin into value-added chemicals.…”

Section: Introductionmentioning

confidence: 99%

The novel method to reduce the silica content in lignin recovered from black liquor originating from rice straw

Nghị

Pham

et al. 2020

Sci Rep

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Difficulties in the production of lignin from rice straw because of high silica content in the recovered lignin reduce its recovery yield and applications as bio-fuel and aromatic chemicals. Therefore, the objective of this study is to develop a novel method to reduce the silica content in lignin from rice straw more effectively and selectively. The method is established by monitoring the precipitation behavior as well as the chemical structure of precipitate by single-stage acidification at different pH values of black liquor collected from the alkaline treatment of rice straw. The result illustrates the significant influence of pH on the physical and chemical properties of the precipitate and the supernatant. The simple two-step acidification of the black liquor at pilot-scale by sulfuric acid 20w/v% is applied to recover lignin at pH 9 and pH 3 and gives a percentage of silica removal as high as 94.38%. Following the developed process, the high-quality lignin could be produced from abundant rice straw at the industrial-scale.

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“…Results from material science studies show that SiO 2 can covalently bind to lignin (e.g. Strzemiecka et al, 2016) an idea that is strengthened by NMR studies on lignin-silica co-precipitates (Cabrera et al, 2016). The ensuing physical barrier will limit both ion and water permeability, forcing a relatively large proportion to move via the symplast where flux control is far greater.…”

Section: Ion Transportmentioning

confidence: 99%

Is Silicon a Panacea for Alleviating Drought and Salt Stress in Crops?

2020

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Salinity affects around 20% of all arable land while an even larger area suffers from recurrent drought. Together these stresses suppress global crop production by as much as 50% and their impacts are predicted to be exacerbated by climate change. Infrastructure and management practices can mitigate these detrimental impacts, but are costly. Crop breeding for improved tolerance has had some success but is progressing slowly and is not keeping pace with climate change. In contrast, Silicon (Si) is known to improve plant tolerance to a range of stresses and could provide a sustainable, rapid and cost-effective mitigation method. The exact mechanisms are still under debate but it appears Si can relieve salt stress via accumulation in the root apoplast where it reduces "bypass flow of ions to the shoot. Si-dependent drought relief has been linked to lowered root hydraulic conductance and reduction of water loss through transpiration. However, many alternative mechanisms may play a role such as altered gene expression and increased accumulation of compatible solutes. Oxidative damage that occurs under stress conditions can be reduced by Si through increased antioxidative enzymes while Si-improved photosynthesis has also been reported. Si fertilizer can be produced relatively cheaply and to assess its economic viability to improve crop stress tolerance we present a cost-benefit analysis. It suggests that Si fertilization may be beneficial in many agronomic settings but may be beyond the means of smallholder farmers in developing countries. Si application may also have disadvantages, such as increased soil pH, less efficient conversion of crops into biofuel and reduced digestibility of animal fodder. These issues may hamper uptake of Si fertilization as a routine agronomic practice. Here, we critically evaluate recent literature, quantifying the most significant physiological changes associated with Si in plants under drought and salinity stress. Analyses show that metrics associated with photosynthesis, water balance and oxidative stress all improve when Si is present during plant exposure to salinity and drought. We further conclude that most of these changes can be explained by apoplastic roles of Si while there is as yet little evidence to support biochemical roles of this element.

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Solid-state ²⁹Si NMR and FTIR analyses of lignin-silica coprecipitates

Cited by 29 publications

References 33 publications

Spectroscopic Discrimination of Sorghum Silica Phytoliths

Spectroscopic Discrimination of Sorghum Silica Phytoliths

The novel method to reduce the silica content in lignin recovered from black liquor originating from rice straw

Is Silicon a Panacea for Alleviating Drought and Salt Stress in Crops?

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Solid-state 29Si NMR and FTIR analyses of lignin-silica coprecipitates

Cited by 29 publications

References 33 publications

Spectroscopic Discrimination of Sorghum Silica Phytoliths

Spectroscopic Discrimination of Sorghum Silica Phytoliths

The novel method to reduce the silica content in lignin recovered from black liquor originating from rice straw

Is Silicon a Panacea for Alleviating Drought and Salt Stress in Crops?

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Solid-state ²⁹Si NMR and FTIR analyses of lignin-silica coprecipitates