Effects of Ultrasonic Treatments on Cellulose in Cellulosic Biofuel Manufacturing: A Literature Review

Author(s):  
P. F. Zhang ◽  
Z. J. Pei

Cellulosic biofuels are one type of renewable energy, and have been proposed to replace traditional liquid transportation fuels. Cellulosic biomass is the feedstocks in cellulosic biofuel manufacturing. Cellulose accounts for approximately 30% of the total weight in cellulosic biomass. Glucose, one type of monosaccharide convertible to ethanol, can be obtained by hydrolyzing the polymeric structure of cellulose. Currently enzymatic methods are the most common for the hydrolysis of cellulose. However, the low efficiency of enzymatic hydrolysis increases production cost and hinders the large-scale manufacturing of cellulosic biofuels. Ultrasonic treatments applied on cellulosic biomass were found to improve the efficiency of hydrolysis and subsequently increase the sugar yield of hydrolysis. To understand the effects of ultrasonics on cellulose, investigations have been conducted on the effects on cellulose characteristics caused by ultrasonic treatments during hydrolysis. This paper reviews the effects of ultrasonic treatments on cellulose during hydrolysis in terms of sugar yield and some characteristics of cellulose, such as accessibility, crystallinity, degree of polymerization, and morphological structure.

Author(s):  
Qi Zhang ◽  
P. F. Zhang ◽  
Timothy Deines ◽  
Z. J. Pei ◽  
Donghai Wang ◽  
...  

Cellulosic biofuels can be used to replace traditional liquid transportation fuels. Cellulosic biomass is feedstock in manufacturing of cellulosic biofuels. However, the low density of cellulosic biomass feedstock hinders large-scale and cost-effective manufacturing of cellulosic biofuels. Another bottleneck factor in manufacturing of cellulosic biofuels is the low efficiency of the enzymatic hydrolysis of cellulosic biomass materials resulting in a low sugar yield. Ultrasonic vibration-assisted (UV-A) pelleting can increase the density of cellulosic biomass feedstocks via combined effects of mechanical compression and ultrasonic vibration of the tool on the cellulosic biomass. Meanwhile ultrasonic vibration may act as a beneficial pretreatment for enzymatic hydrolysis, which can possibly increase the efficiency of hydrolysis and obtain a higher sugar yield. The pressure and the ultrasonic power are important parameters in UV-A pelleting. Their effects on pellet quality (density, durability, and stability) and sugar yield (after hydrolysis) are experimentally investigated.


Author(s):  
Hera Wu ◽  
Pengfei Zhang ◽  
Qi Zhang ◽  
Z. J. Pei

Cellulosic biofuels are an alternative to petroleum-based liquid transportation fuels. However, manufacturing costs of cellulosic biofuels are high partially due to low density and sugar yield of cellulosic biomass. Previous studies show that UV-A pelleting can increase the density and sugar yield of cellulosic biomass. A hypothesis for UV-A pelleting to increase the density and sugar yield of cellulosic biomass is that UV-A pelleting can reduce biomass particle size. To test this hypothesis, biomass particle sizes before and after UV-A pelleting need to be compared. Soaking pellets in water is an efficient and non-invasive method to separate pellets into particles. However, water soaking itself might change biomass particle size. This paper reports an investigation on effects of water soaking on biomass particle size. The biomass particle sizes before and after water soaking are measured and compared. Results show that effects of water soaking on biomass particle size are dependent on the initial particle size (particle size before water soaking) and time period of water soaking.


Author(s):  
Pengfei Zhang ◽  
Timothy Deines ◽  
Daniel Nottingham ◽  
Z. J. Pei ◽  
Donghai Wang ◽  
...  

Increasing demands and concerns for the reliable supply of liquid transportation fuels make it important to find alternative sources to petroleum based fuels. One such alternative is cellulosic biofuels. However, several technical barriers have hindered large-scale, cost-effective manufacturing of cellulosic biofuels, such as the low density of cellulosic feedstocks (causing high transportation and storage costs) and the low efficiency of enzymatic hydrolysis process (causing longer processing time and low sugar yield). Ultrasonic vibration-assisted (UV-A) pelleting can increase the density of cellulosic materials by compressing them into pellets. UV-A pelleting can also increase the sugar yield of cellulosic biomass materials in hydrolysis. At present, the effects of process variables in UV-A pelleting on pellet quality (density, durability, and stability) and sugar yield have not been adequately investigated. This paper reports an experimental investigation on UV-A pelleting of wheat straw. A 24 factorial design is employed to evaluate the effects of process variables (moisture content, particle size, pelleting pressure, and ultrasonic power) on output variables (pellet density, durability, stability, and sugar yield).


2013 ◽  
Vol 805-806 ◽  
pp. 151-155
Author(s):  
Kang Qi Fan ◽  
Yong Jun Tang ◽  
Yang Fang

Increasing concerns about reliable supplies and envi­ronmental consequences of petroleum-based fuels have made it important to develop sustainable green sources for liquid transportation fuels. One such source is cellulosic biomass. However, high costs associated with transportation and storage of low-density cellulosic biomass has hindered large-scale, cost-effective manufacturing of cellulosic biofuels. Ultrasonic vibration-assisted (UV-A) pelleting can increase biomass density, improve storability, and reduce transportation costs. This paper reviews the state of the art of this technique, covering the effects of different process parameters on pellet quality, pellet charring, pellet crack, and sugar yield. It can be concluded that pellet density increases with an increase in ultrasonic power and pelleting pressure, and with a decrease in biomass moisture content and particle size. However, large ultrasonic power may lead to the charring of cellulosic biomass, which adversely affects the conversion of cellulosic biomass to ethanol. In addition, some problems associated with UV-A pelletingof cellulosic biomass are proposed.


2012 ◽  
Vol 151 ◽  
pp. 245-249 ◽  
Author(s):  
Yong Jun Tang ◽  
Chun Mu Chen ◽  
Guan Wang

Cellulosic biofuels have been proposed to replace part of traditional liquid transportation fuels. Cellulosic biomass is the feedstock in cellulosic biofuel manufacturing. Costs associated with collection and transportation of cellulosic biomass account for more than 80 percent of the feedstock cost. By processing cellulosic biomass into pellets, density and handling efficiencies of cellulosic feedstock can be improved, resulting in reduction of transportation and handling costs. The pellet temperature is one of the most important parameter in Ultrasonic Vibration (UV-A) pelleting. There is very few literature on the pellet temperature of UV-A pelleting. This paper mainly studied how to on-line measure the pelleting temperature, also, the detailed temperature characteristics of the pellet was obtained. The results are valuable for selecting suitable pelleting parameters and controlling the quality of pellet in UV-A pelleting. Also, the accurate measurement of the pellet temperature is helpful to understand pelleting mechanism, charring, and durability issues.


2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Meng Zhang ◽  
Xiaoxu Song ◽  
Pengfei Zhang ◽  
Z. J. Pei ◽  
T. W. Deines ◽  
...  

Increasing demands and concerns for reliable supply of liquid transportation fuels make it important to find alternative sources to petroleum-based fuels. Cellulosic biofuels provide one such alternative in the short to medium term. Size reduction is the first step for converting biomass into biofuels. In the literature, there are inconsistent reports about the effects of particle size and biomass crystallinity on sugar yield (proportional to biofuel yield). An important reason for this inconsistence is that particle formation in current size reduction methods is not well controlled, causing the effects of these two variables confounded. One paper investigating the confounding effects of particle size and biomass crystallinity using a metal-cutting (milling) process was previously published in this journal. This paper presents a follow-up study. In this study, a lathe was used to produce poplar wood particles with the same crystallinity but different sizes, making it possible to study the effects of particle size on biofuel yield independently without being confounded by the effects of biomass crystallinity. Results showed that, for the three levels of particle size used in this study, sugar yield increased as particle size became smaller. This study also revealed future research opportunities to understand the effects of size reduction and biomass crystallinity in cellulosic biofuel manufacturing.


Author(s):  
Meng Zhang ◽  
Xiaoxu Song ◽  
P. F. Zhang ◽  
Z. J. Pei ◽  
T. Deines

Gradual depletion of world petroleum reserves and increasing environmental impact of greenhouse gas emissions make it urgent to develop sustainable alternatives to petroleum-based transportation fuels. Cellulosic biofuels provide one such alternative in the short to medium term. In order to convert cellulosic biomass into biofuels, size reduction is a necessary step. In the literature, there are inconsistent reports about the effects of particle size and biomass crystallinity on sugar yield (proportional to biofuel yield). An important reason for this inconsistence is that particle formation in current size reduction methods is not well controlled, causing the effects of these two variables confounded. This paper presents an experimental study on size reduction of poplar wood using a lathe, where particle formation could be well controlled to prevent the effects of these two variables from being confounded. In this study, particle size was controlled by different numbers of slots cut on the workpiece. Particles with the same crystallinity but different particle sizes were produced. This will make it possible to study the effects of particle size on biofuel yield independently, and reveal future research opportunities to understand the effects of size reduction in cellulosic biofuel manufacturing.


Author(s):  
Qi Zhang ◽  
Pengfei Zhang ◽  
Meng Zhang ◽  
Xiaoxu Song ◽  
Z. J. Pei ◽  
...  

Biofuels made from cellulosic biomass are an alternative to petroleum-based liquid transportation fuels. However, low density of cellulosic biomass causes high costs in biomass transportation and handling in cellulosic biofuel manufacturing. Such costs can be reduced by pelleting processes that can densify cellulosic biomass. Ultrasonic vibration-assisted (UV-A) pelleting and ring-die pelleting are two pelleting methods. A previous study has compared the two pelleting methods in terms of pellet quality and pelleting power consumption. This paper reports an experimental comparison on sugar yields of wheat straw processed by the two pelleting methods under different combinations of pretreatment variables. Results show that wheat straw processed by UV-A pelleting has higher sugar yield than that processed by ring-die pelleting when the higher temperature and longer time are applied in pretreatment. Under other combinations of pretreatment variables, wheat straw processed by UV-A pelleting has lower sugar yield than that processed by ring-die pelleting.


Author(s):  
Elizabeth Kennedy ◽  
Pengfei Zhang ◽  
Qi Zhang ◽  
Z. J. Pei ◽  
Donghai Wang

There are many concerns taking place due to the reliability and sustainability of petroleum-based liquid transportation fuels. The importance of finding an alternative fuel source to the petroleum-based fuels is in high demand. One promising alternative is cellulosic biofuels that offer numerous benefits for the environment. However, there are some obstacles in the way of manufacturing the cellulosic biofuels at a large scale and doing so cost effectively. One obstacle is the low sugar yield of biomass in enzymatic hydrolysis, leading to low efficiency in biomass-biofuel conversion and thus high conversion costs. Pretreatment of biomass is required to achieve high sugar yield in enzymatic hydrolysis. Dilute acid pretreatment and hot water pretreatment can effectively increase the sugar yield, but they usually involve high temperature or excessive use of acid, making pretreatment one of the most costly process in cellulosic biofuel manufacturing. This study investigated effects of ultrasonic vibration-assisted pelleting on the sugar yield of biomass pretreated by the two pretreatment methods. Results showed that, for both pretreatment methods, pellets produces higher sugar yield than particles. Furthermore, at the same pretreatment temperature, the water-pretreated pellets produced higher sugar yield than acid-pretreated particles.


Author(s):  
Q. Zhang ◽  
P. F. Zhang ◽  
X. X. Song ◽  
M. Zhang ◽  
Z. J. Pei ◽  
...  

Biofuels are an alternative to petroleum-based liquid transportation fuels. Cellulosic biomass can be used as feedstocks for befoul manufacturing. Low density of cellulosic feedstocks causes difficulties in handling them during transportation and storage, thus hindering large-scale and cost-effective manufacturing of cellulosic biofuels. Pelleting can increase the density of cellulosic feedstocks by compacting bulky biomass into pellets. Pellet durability, an important quality parameter, measures the ability of pellets to withstand impact and other destructive forces during transportation and handling. ASABE standard S269.4 specifies a procedure to determine pellet durability using 500 grams of pellets. However, it does not provide any justification of choosing this amount of pellets. This paper investigates the feasibility of using a smaller amount of pellets (50 grams) to determine pellet durability. Results show that 50 grams of pellets can generate comparable durability results as 500 grams of pellets.


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