scholarly journals Effect of Low Temperatures and Residence Times of Pretreatment on Glucan Reactivity of Sodium Hydroxide-Pretreated Rice Straw

2017 ◽  
Vol 15 (4) ◽  
pp. 313-323
Author(s):  
Supaporn SOPHONPUTTANAPHOCA ◽  
Kontawan SIRIGATMANEERAT ◽  
Kulphaphorn KRUAKRUT
Keyword(s):  
Sodium Hydroxide ◽  
Rice Straw ◽  
Elevated Temperatures ◽  
Total Solid ◽  
Future Research ◽  
Residence Times ◽  
Simple Method ◽  
Lignin Removal ◽  
Pretreatment Time ◽  
Pretreatment Conditions

Alkaline pretreatment of lignocellulosic biomass is an approach to enhance the susceptibility of the biomass that is subsequently converted into fermentable sugars. The efficacy of the sodium hydroxide pretreatment of rice straw RD41 was evaluated in terms of total solid removal, lignin removal, glucan recovery, and glucan conversion yields. The pretreatment conditions were 50, 60, 70, 80, and 100 °C, and each temperature kept for 1 to 5 h. The effect of pretreatment temperatures was more pronounced than that of the pretreatment times. The elevated temperatures caused higher total solid removal and lignin removal. The highest total solid removal (52.5 to 55.8 %) was found in the pretreatment at 100 °C. At this temperature, the highest lignin removal (~87 %) could be obtained regardless of the residence times of the pretreatment. Most of the glucan (~80 to 100 %) was preserved in the pretreated rice straw. Lower temperatures (50 and 60 °C) favored higher glucan preservation (> 90 %) in the pretreated solids. Glucan conversion of the 3 h pretreatment time samples of each pretreatment temperature revealed that more than 80 % of glucan conversion could be accounted for in samples pretreated at 70 to 100 °C within 24 h of saccharification. The lower temperatures required a prolonged pretreatment time to reach a higher glucan conversion (~90 %), as found in the 50 °C, 5 h pretreated rice straw. The optimal conditions of this simple method are economically feasible, and can be applied to testing the reactivity of herbaceous lignocellulose in future research.

scholarly journals Changes in the Material Characteristics of Maize Straw during the Pretreatment Process of Methanation

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Yongzhong Feng ◽  
Xiaoling Zhao ◽  
Yan Guo ◽  
Gaihe Yang ◽  
Jianchao Xi ◽  
...  
Keyword(s):  
Sodium Hydroxide ◽  
Ph Value ◽  
Total Solid ◽  
Biogas Slurry ◽  
Volatile Solid ◽  
Chemical Reagents ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio ◽  
Pretreatment Conditions ◽  
Pretreatment Technology

Pretreatment technology is important to the direct methanation of straw. This study used fresh water, four bacterium agents (stem rot agent, “result” microbe decomposition agent, straw pretreatment composite bacterium agent, and complex microorganism agent), biogas slurry, and two chemical reagents (sodium hydroxide and urea) as pretreatment promoters. Different treatments were performed, and the changes in the straw pH value, temperature, total solid (TS), volatile solid (VS), and carbon-nitrogen ratio (C/N ratio) under different pretreatment conditions were analyzed. The results showed that chemical promoters were more efficient than biological promoters in straw maturity. Pretreatment using sodium hydroxide induced the highest degree of straw maturity. However, its C/N ratio had to be reduced during fermentation. In contrast, the C/N ratio of the urea-pretreated straw was low and was easy to regulate when used as anaerobic digestion material. The biogas slurry pretreatment was followed by pretreatments using four different bacterium agents, among which the effect of the complex microorganism agent (BA4) was more efficient than the others. The current study is significant to the direct and efficient methanation of straw.

scholarly journals Chemical Kinetics of Alkaline Pretreatment of Napier Grass (Pennisetum purpureum) Prior Enzymatic Hydrolysis

2018 ◽  
Vol 12 (1) ◽  
pp. 36-56 ◽  
Author(s):  
Samuel Eshorame Sanni ◽  
Olasubomi Akinrinola ◽  
Esther Ojima Yusuf ◽  
Omololu Oluwatobi Fagbiele ◽  
Oluranti Agboola
Keyword(s):  
Waste Material ◽  
Napier Grass ◽  
Pennisetum Purpureum ◽  
Lignin Removal ◽  
Pretreatment Time ◽  
Reaction Orders ◽  
Pretreatment Conditions ◽  
Kinetics Of ◽  
Vast Area ◽  
Total Lignin

Background:Napier grass is a naturally abundant waste material that can be cultivated over a vast area of land which makes it a viable source for sugar and bioethanol production.Introduction:The presence of lignin in the biomass makes cellulose inaccessible for conversion to useful products, however, in order to provide for efficient utilization of the waste material, reagent and energy, a study on the kinetics of lignin removal from Napier grass was carried out in this work using 1 and 3 w/w % NaOH at temperatures between 80 and 120°C.Materials & Methods:Based on the investigation, there was increased lignin removal for increased NaOH concentration. Kinetic parameters were also determined and it was observed that, the reaction of lignin in Napier grass with NaOH obeys a pseudo-zero or pseudo-fractional order kinetics. Furthermore, the orders of the reaction for the pretreatment conditions of 3 w/w% NaOH at 100°C and those of 3 and 1 w/w NaOH at 120°C gave close reaction orders of 0.2, 0.22 and 0.24 respectively after 110 minutes, which implies that, for the three cases, the residual lignin in the extract was almost the same at the pretreatment conditions while slight differences are evident in their pseudo rate constants. Also, it was observed that, the activation energy of the reaction reduced significantly as the concentration of NaOH increased from 1w/w - 3 w/w%.Conclusion:Based on the AIL and the total lignin (i.e.AIL + ASL) in the Napier grass, the recorded delignification efficiencies at the optimum pretreatment time of 17.5 h are 90 and 76% respectively. In addition, the adopted Differential Technique (DT) combined with the Ostwald Method of Isolation (OMI) can be accurately used to study the kinetics of lignin removal from Napier grass.

scholarly journals A study on alkali pretreatment conditions of sorghum stem for maximum sugar recovery using statistical approach

2014 ◽  
Vol 20 (2) ◽  
pp. 261-271 ◽  
Author(s):  
Maryam Nikzad ◽  
Kamyar Movagharnejad ◽  
Farid Talebnia ◽  
Ghasem Najafpour ◽  
Farahi Hosein
Keyword(s):  
Sorghum Bicolor ◽  
Alternative Energy ◽  
Solid Loading ◽  
Bioethanol Production ◽  
Alkali Pretreatment ◽  
Model Predictions ◽  
Pretreatment Time ◽  
Pretreatment Conditions ◽  
Energy Production System ◽  
Central Composite

Bioethanol production from lignocellulosic biomass provides an alternative energy-production system. Sorghum bicolor stem is a cheap agro-waste for bioethanol production. In this study, response surface methodology (RSM) was used to optimize alkali pretreatment conditions for sorghum bicolor stem with respect to substrate concentration, NaOH concentration and pretreatment time based on a central composite rotary design. The main goal was to achieve the highest glucose and xylose yields after enzymatic hydrolysis. Under optimum conditions of pretreatment i.e. time 60.4 min, solid loading 4.2%, and NaOH concentration 1.7%, yields of 98.94% g glucose/g cellulose and 65.14% g xylose/g hemicelluloses were obtained. The results of a confirmation experiment under the optimal conditions agreed well with model predictions. Pretreatment of sorghum bicolor stem at the optimum condition increased the glucose and xylose yields by 7.14 and 3.02 fold, respectively. Alkali pretreatment showed to be a great choice for the pretreatment of sorghum bicolor stem.

scholarly journals “Adherent” versus Other Isolation Strategies for Expanding Purified, Potent, and Activated Human NK Cells for Cancer Immunotherapy

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Senthamil R. Selvan ◽  
John P. Dowling
Keyword(s):  
Nk Cells ◽  
Large Scale ◽  
Mononuclear Cells ◽  
Adoptive Cell Therapy ◽  
Cost Effective ◽  
Future Research ◽  
Peripheral Blood Mononuclear ◽  
Simple Method ◽  
Antitumor Potential ◽  
Healthy Donors

Natural killer (NK) cells have long been hypothesized to play a central role in the development of new immunotherapies to combat a variety of cancers due to their intrinsic ability to lyse tumor cells. For the past several decades, various isolation and expansion methods have been developed to harness the full antitumor potential of NK cells. These protocols have varied greatly between laboratories and several have been optimized for large-scale clinical use despite associated complexity and high cost. Here, we present a simple method of “adherent” enrichment and expansion of NK cells, developed using both healthy donors’ and cancer patients’ peripheral blood mononuclear cells (PBMCs), and compare its effectiveness with various published protocols to highlight the pros and cons of their use in adoptive cell therapy. By building upon the concepts and data presented, future research can be adapted to provide simple, cost-effective, reproducible, and translatable procedures for personalized treatment with NK cells.

High-Temperature Dielectric Materials for Electrical Energy Storage

2018 ◽  
Vol 48 (1) ◽  
pp. 219-243 ◽  
Author(s):  
Qi Li ◽  
Fang-Zhou Yao ◽  
Yang Liu ◽  
Guangzu Zhang ◽  
Hong Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Power Systems ◽  
Oil And Gas ◽  
Elevated Temperatures ◽  
Temperature Stability ◽  
Electrical Energy ◽  
Dielectric Materials ◽  
Future Research ◽  
Capacitive Energy Storage

The demand for high-temperature dielectric materials arises from numerous emerging applications such as electric vehicles, wind generators, solar converters, aerospace power conditioning, and downhole oil and gas explorations, in which the power systems and electronic devices have to operate at elevated temperatures. This article presents an overview of recent progress in the field of nanostructured dielectric materials targeted for high-temperature capacitive energy storage applications. Polymers, polymer nanocomposites, and bulk ceramics and thin films are the focus of the materials reviewed. Both commercial products and the latest research results are covered. While general design considerations are briefly discussed, emphasis is placed on material specifications oriented toward the intended high-temperature applications, such as dielectric properties, temperature stability, energy density, and charge-discharge efficiency. The advantages and shortcomings of the existing dielectric materials are identified. Challenges along with future research opportunities are highlighted at the end of this review.

scholarly journals Optimization of alkali pretreatment of wheat straw to be used as substrate for biofuels production  

2013 ◽  
Vol 59 (No. 12) ◽  
pp. 537-542 ◽  
Author(s):  
K. Jaisamut ◽  
L. Paulová ◽  
P. Patáková ◽  
M. Rychtera ◽  
K. Melzoch
Keyword(s):  
Response Surface Methodology ◽  
Enzymatic Hydrolysis ◽  
Sodium Hydroxide ◽  
Wheat Straw ◽  
Response Surface ◽  
Fermentable Sugars ◽  
Alkali Pretreatment ◽  
The Media ◽  
Pretreatment Conditions ◽  
Expert Designer

Alkali pretreatment of wheat straw was optimized by response surface methodology to maximize yields of fermentable sugars in subsequent enzymatic hydrolysis and to remove maximum lignin in order to improve rheological attributes of the media. The effects of pretreatment conditions on biomass properties were studied using the Expert Designer software. Concentration of sodium hydroxide and temperature were the factors most affecting pretreatment efficiency. At the optimum (80°C, 39 min, 0.18 g NaOH and 0.06 g lime per g of raw biomass), 93.1 ± 1.0% conversion of cellulose to glucose after enzymatic hydrolysis and 80.3 ± 1.2% yield of monosaccharides (glucose plus xylose and arabinose) from cellulose and hemicellulose of wheat straw were achieved.

scholarly journals Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4990
Author(s):  
Petr Pokorný ◽  
Jiří Kolísko ◽  
David Čítek ◽  
Michaela Kostelecká
Keyword(s):  
Bond Strength ◽  
High Performance ◽  
Elevated Temperatures ◽  
High Performance Concrete ◽  
Future Research ◽  
Ultra High Performance Concrete ◽  
Negative Effect ◽  
Laboratory Investigations ◽  
Increasing Temperature ◽  
Positive Effect

The study explores the effect of elevated temperatures on the bond strength between prestressing reinforcement and ultra-high performance concrete (UHPC). Laboratory investigations reveal that the changes in bond strength correspond well with the changes in compressive strength of UHPC and their correlation can be mathematically described. Exposition of specimens to temperatures up to 200 °C does not reduce bond strength as a negative effect of increasing temperature is outweighed by the positive effect of thermal increase on the reactivity of silica fume in UHPC mixture. Above 200 °C, bond strength significantly reduces; for instance, a decrease by about 70% is observed at 800 °C. The decreases in compressive and bond strengths for temperatures above 400 °C are related to the changes of phase composition of UHPC matrix (as revealed by X-ray powder diffraction) and the changes in microstructure including the increase of porosity (verified by mercury intrusion porosimetry and observation of confocal microscopy) and development cracks detected by scanning electron microscopy. Future research should investigate the effect of relaxation of prestressing reinforcement with increasing temperature on bond strength reduction by numerical modelling.

scholarly journals Short Communication: Humans and the missing C-sink: erosion and burial of soil carbon through time

2013 ◽  
Vol 1 (1) ◽  
pp. 45-52 ◽  
Author(s):  
T. Hoffmann ◽  
S. M. Mudd ◽  
K. van Oost ◽  
G. Verstraeten ◽  
G. Erkens ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Soil Carbon ◽  
Short Communication ◽  
Future Research ◽  
Residence Times ◽  
Fluvial System ◽  
Anthropogenic Soil ◽  
Atmospheric Carbon ◽  
Gain Change

Abstract. Is anthropogenic soil erosion a sink or source of atmospheric carbon? The answer depends on factors beyond hillslope erosion alone because the probable fate of mobilized soil carbon evolves as it traverses the fluvial system. The transit path, residence times, and the resulting mechanisms of C-loss or gain change significantly down-basin and are currently difficult to predict as soils erode and floodplains evolve – this should be a key focus of future research.

The Flammability Limits of Hydrogen and Methane in Air at Moderately Elevated Temperatures

1997 ◽  
Author(s):  
B. B. Ale ◽  
I. Wierzba
Keyword(s):  
Residence Time ◽  
Initial Temperature ◽  
Elevated Temperatures ◽  
Hydrogen Oxidation ◽  
Initial Mixture ◽  
Spark Ignition ◽  
Stainless Steel Surface ◽  
Flammability Limits ◽  
Simple Method ◽  
The Rich

The flammability limits of hydrogen and methane in air were determined experimentally at elevated initial mixture temperatures up to 350°C at atmospheric pressure for upward flame propagation in a conventional steel test tube apparatus. Additionally the extent to which a prolonged exposure (i.e., residence time) of the mixture to elevated temperatures before spark ignition and, consequently, the existence of pre-ignition reactions that may influence the value of the lean and rich flammability limits was also investigated. It was shown that the flammability limits for methane widened approximately linearly with an increase in the initial mixture temperature over the whole range of temperatures tested. These limits were not affected by the length of the residence time before spark ignition. Different behaviour was observed for flammability limits of hydrogen. They were also widened with an increase in the initial temperature but only up to 200°C. In this initial temperature range the limits were not affected by the length of the residence time. However, at initial temperature exceeding 200°C the flammability limits, especially, the rich limits narrowed with an increase in the temperature and were significantly affected by the residence time before spark ignition. The results of detailed chemical kinetic simulation showed that the gas phase reactions of hydrogen oxidation could not be responsible for the substantial drop in the value of the rich limit. It was therefore, suggested that this drop in the value of the rich limit with the increase in the residence time was caused by the relatively low temperature catalytic reactions on the stainless steel surface of the flame tube. Simple method for calculating the hydrogen conversion to water was proposed. The results of calculations are in fair agreement with the experimental evidence.

Bioethanol Production from Rice Straw in the MAFF Research Project, Japan

2009 ◽  
Vol 1219 ◽  
Author(s):  
Ken Tokuyasu
Keyword(s):  
Heat Treatment ◽  
Saccharomyces Cerevisiae ◽  
Rice Straw ◽  
Enzymatic Saccharification ◽  
Bioethanol Production ◽  
Chemical Pretreatment ◽  
Simple Method ◽  
Herbaceous Biomass ◽  
Free Glucose ◽  
Simultaneous Saccharification

AbstractRice straw is among the most abundant herbaceous biomass, and regarded as the central feedstock for bioethanol production in Japan. We found that significant amounts of soft carbohydrates (SCs), defined as carbohydrates readily recoverable by mere extraction from the biomass or brief enzymatic saccharification, exist in rice straw in the form of free glucose, free fructose, sucrose, starch, and β-1,3-1,4-glucan. Based on the finding, we proposed a simple method for bioethanol production from rice straw samples with SCs, by a heat treatment for sterilization and starch gelatinization, followed by simultaneous saccharification/fermentation with Saccharomyces cerevisiae. This method would offer an efficient process for bioethanol production without the aid of harsh thermo/chemical pretreatment step.

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