Preface

Bergman, David J.; LaTorraca, Gerald A.

doi:10.1016/s0950-1401(02)80001-5

Cited by 52 publications

(70 citation statements)

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“…NMR relaxation data were analyzed by Inverse Laplace transform (ILT), resulting in distributions of transverse relaxation times ( T 2 -distributions) [37-39]. Figure 5 shows the T 2 -distributions obtained for bagasse samples that were submitted to the drying procedure being stack plotted for different relative humidities.…”

Section: Resultsmentioning

confidence: 99%

Nuclear magnetic resonance investigation of water accessibility in cellulose of pretreated sugarcane bagasse

Tsuchida

Rezende

Oliveira‐Silva

et al. 2014

Biotechnol Biofuels

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BackgroundEnzymatic hydrolysis is a crucial step of biomass conversion into biofuels and different pretreatments have been proposed to improve the process efficiency. Amongst the various factors affecting hydrolysis yields of biomass samples, porosity and water accessibility stand out due to their intimate relation with enzymes accessibility to the cellulose and hemicellulose fractions of the biomass. In this work, sugarcane bagasse was subjected to acid and alkali pretreatments. The changes in the total surface area, hydrophilicity, porosity and water accessibility of cellulose were investigated by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR).ResultsChanges in chemical and physical properties of the samples, caused by the partial removal of hemicellulose and lignin, led to the increase in porosity of the cell walls and unwinding of the cellulose bundles, as observed by SEM. 1H NMR relaxation data revealed the existence of water molecules occupying the cores of wide and narrow vessels as well as the cell wall internal structure. Upon drying, the water molecules associated with the structure of the cell wall did not undergo significant dynamical and partial moisture changes, while those located in the cores of wide and narrow vessels kept continuously evaporating until reaching approximately 20% of relative humidity. This indicates that water is first removed from the cores of lumens and, in the dry sample, the only remaining water molecules are those bound to the cell walls. The stronger interaction of water with pretreated bagasse is consistent with better enzymes accessibility to cellulose and higher efficiency of the enzymatic hydrolysis.ConclusionsWe were able to identify that sugarcane bagasse modification under acid and basic pretreatments change the water accessibility to different sites of the sample, associated with both bagasse structure (lumens and cell walls) and hydrophilicity (lignin removal). Furthermore, we show that the substrates with increased water accessibility correspond to those with higher hydrolysis yields and that there is a correlation between experimentally NMR-measured transverse relaxation times and the efficiency of enzymatic hydrolysis. This might allow for semiquantitative estimates of the enzymatic hydrolysis efficiency of biomass samples using inexpensive and non-destructive low-field 1H NMR relaxometry methods.

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Section: Resultsmentioning

confidence: 99%

Nuclear magnetic resonance investigation of water accessibility in cellulose of pretreated sugarcane bagasse

Tsuchida

Rezende

Oliveira‐Silva

et al. 2014

Biotechnol Biofuels

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“…The measured NMR relaxation signal M(t) is constituted by superposition of all signal-contributing pores in a rock sample (e.g., Coates et al, 1999;Dunn et al, 2002):…”

Section: Nmr Response For Triangular Capillariesmentioning

confidence: 99%

Understanding NMR relaxometry of partially water-saturated rocks

Mohnke

Jorand

Nordlund

2015

Hydrol. Earth Syst. Sci.

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Abstract. Nuclear magnetic resonance (NMR) relaxometry measurements are commonly used to characterize the storage and transport properties of water-saturated rocks. Estimations of these properties are based on the direct link of the initial NMR signal amplitude to porosity (water content) and of the NMR relaxation time to pore size. Herein, pore shapes are usually assumed to be spherical or cylindrical. However, the NMR response at partial water saturation for natural sediments and rocks may differ strongly from the responses calculated for spherical or cylindrical pores, because these pore shapes do not account for water menisci remaining in the corners of desaturated angular pores. Therefore, we consider a bundle of pores with triangular cross sections. We introduce analytical solutions of the NMR equations at partial saturation of these pores, which account for water menisci of desaturated pores. After developing equations that describe the water distribution inside the pores, we calculate the NMR response at partial saturation for imbibition and drainage based on the deduced water distributions.For this pore model, the NMR amplitudes and NMR relaxation times at partial water saturation strongly depend on pore shape, i.e., arising from the capillary pressure and pore shape-dependent water distribution in desaturated pores with triangular cross sections. Even so, the NMR relaxation time at full saturation only depends on the surface-to-volume ratio of the pore. Moreover, we show the qualitative agreement of the saturation-dependent relaxation-time distributions of our model with those observed for rocks and soils.

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“…NMR relaxation data were analyzed by Inverse Laplace transform (ILT), resulting in distributions of transverse relaxation times (T 2 -distributions) [37][38][39]. Figure 5 shows the T 2 -distributions obtained for bagasse samples that were submitted to the drying procedure being stack plotted for different relative humidities.…”

Section: Nuclear Magnetic Resonance Relaxationmentioning

confidence: 99%

“…Although these log-Gaussians may overlap each other along the T 2 -distributions; this fitting procedure allows us to quantitatively estimate how each region of the T 2 -distribution varies as a result of water saturation [37][38][39].…”

Section: Nuclear Magnetic Resonance Relaxationmentioning

confidence: 99%

1 H NMR investigation of water accessibility in cellulose of pretreated sugarcane bagasse

Tsuchida

Rezende

Oliveira‐Silva

et al. 2014

Biotechnol Biofuels

View full text Add to dashboard Cite

Background: Enzymatic hydrolysis is a crucial step of biomass conversion into biofuels and different pretreatments have been proposed to improve the process efficiency. Amongst the various factors affecting hydrolysis yields of biomass samples, porosity and water accessibility stand out due to their intimate relation with enzymes accessibility to the cellulose and hemicellulose fractions of the biomass. In this work, sugarcane bagasse was subjected to acid and alkali pretreatments. The changes in the total surface area, hydrophilicity, porosity and water accessibility of cellulose were investigated by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). Results: Changes in chemical and physical properties of the samples, caused by the partial removal of hemicellulose and lignin, led to the increase in porosity of the cell walls and unwinding of the cellulose bundles, as observed by SEM.

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Preface

Cited by 52 publications

References 0 publications

Nuclear magnetic resonance investigation of water accessibility in cellulose of pretreated sugarcane bagasse

Nuclear magnetic resonance investigation of water accessibility in cellulose of pretreated sugarcane bagasse

Understanding NMR relaxometry of partially water-saturated rocks

1 H NMR investigation of water accessibility in cellulose of pretreated sugarcane bagasse

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