http://sourcedb.xtbg.cas.cn/zw/lw/201312/P020131220579561830195.pdf

Ultrasound-enhanced conversion of biomass to biofuels

Lignocellulosic materials, such as forest, agriculture, and agroindustrial residues, are among the most important resources for biorefineries to provide fuels, chemicals, and materials in such a way to substitute for, at least in part, the role of petrochemistry in modern society. Most of these sustainable biorefinery products can be produced from plant polysaccharides (glucans, hemicelluloses, starch, and pectic materials) and lignin. In this scenario, cellulosic ethanol has been considered for decades as one of the most promising alternatives to mitigate fossil fuel dependence and carbon dioxide accumulation in the atmosphere. However, a pretreatment method is required to overcome the physical and chemical barriers that exist in the lignin-carbohydrate composite and to render most, if not all, of the plant cell wall components easily available for conversion into valuable products, including the fuel ethanol. Hence, pretreatment is a key step for an economically viable biorefinery. Successful pretreatment method must lead to partial or total separation of the lignocellulosic components, increasing the accessibility of holocellulose to enzymatic hydrolysis with the least inhibitory compounds being released for subsequent steps of enzymatic hydrolysis and fermentation. Each pretreatment technology has a different specificity against both carbohydrates and lignin and may or may not be efficient for different types of biomasses. Furthermore, it is also desirable to develop pretreatment methods with chemicals that are greener and effluent streams that have a lower impact on the environment. This paper provides an overview of the most important pretreatment methods available, including those that are based on the use of green solvents (supercritical fluids and ionic liquids).

Current Pretreatment Technologies for the Development of Cellulosic Ethanol and Biorefineries

Pretreatment of lignocellulose has received considerable research globally due to its influence on the technical, economic and environmental sustainability of cellulosic ethanol production. Some of the most promising pretreatment methods require the application of chemicals such as acids, alkali, salts, oxidants, and solvents. Thus, advances in research have enabled the development and integration of chemical-based pretreatment into proprietary ethanol production technologies in several pilot and demonstration plants globally, with potential to scale-up to commercial levels. This paper reviews known and emerging chemical pretreatment methods, highlighting recent findings and process innovations developed to offset inherent challenges via a range of interventions, notably, the combination of chemical pretreatment with other methods to improve carbohydrate preservation, reduce formation of degradation products, achieve high sugar yields at mild reaction conditions, reduce solvent loads and enzyme dose, reduce waste generation, and improve recovery of biomass components in pure forms. The use of chemicals such as ionic liquids, NMMO, and sulphite are promising once challenges in solvent recovery are overcome. For developing countries, alkali-based methods are relatively easy to deploy in decentralized, low-tech systems owing to advantages such as the requirement of simple reactors and the ease of operation.

/pdf/chemical-pretreatment-methods-for-the-production-of-ugnli341dq.pdf

Chemical Pretreatment Methods for the Production of Cellulosic Ethanol: Technologies and Innovations

The conversion of lignocellulosic biomass for biofuels and biorefinery applications is limited due to the cost of pretreatment to separate or access the biomass’s three main usable components, cellulose, hemicellulose, and lignin. After pretreatment, each component may be utilized via chemical conversion, hydrolysis, and/or fermentation. In this review we aim first, to identify the current status-quo of knowledge of the parametric effects of ultrasound, second, to evaluate the potential of ultrasound as a pretreatment and fractionation method of lignocellulose, and last, to identify the challenges that this technology faces. Ultrasound produces chemical and physical effects which were both found to augment the pretreatment of lignocellulose via delignification and surface erosion. The magnitudes of these effects are altered when the ultrasonic field is influenced by parameters such as solvent, ultrasonic frequency, and reactor geometry and type. Therefore, the implementation of ultrasound for the pretreat...

Effect of Ultrasound on Lignocellulosic Biomass as a Pretreatment for Biorefinery and Biofuel Applications

Insight into progress in pre-treatment of lignocellulosic biomass

Ultrasound-assisted compatible in situ hydrolysis of sugarcane bagasse in cellulase-aqueous–N-methylmorpholine-N-oxide system for improved saccharification

The invention discloses an extraction method of 1-desoxynojirimycin in mulberry leaf, which comprises the following steps: 1. fermentation: adding mulberry leaf into a cellulase generation strain seed liquid, carrying out constant temperature shake culture to obtain a fermentation liquid; 2. extraction: centrifuging the fermentation liquid (centrifuging after carrying out constant temperature extraction on the understratum precipitate and a hydrochloric acid water solution), taking the supernatant extracting solution, repeating the operations above on the understratum precipitate, and merging the extracting solutions; and 3. purification: removing impurities with macroporous resin, eluting 1-desoxynojirimycin with anhydrous alcohol, carrying out vacuum distillation to remove the anhydrous alcohol, and carrying out freeze-drying to obtain the finished 1-desoxynojirimycin product. The extraction method disclosed by the invention has the advantages of high extraction efficiency and low cost.

Extraction method of 1-desoxynojirimycin in mulberry leaf

The invention discloses a method for extracting mulberry branch bark pectin. The method comprises the following steps of: (1) treating mulberry branch bark by using a greenhouse ionic liquid to separate pectin in the branch bark from cellulose and the like; (2) after treating with the greenhouse ionic liquid, adding water for dissolving the pectin in the mulberry branch bark pectin into water, and precipitating components such as cellulose, hemicellulose, lignin and the like out; (3) taking an upper layer liquid, adding cellulose for treating, and removing cellulose impurities; and (4) decolorizing a supernatant, adding ethanol for precipitating the pectin out, washing with absolute ethanol, drying, and grinding into powder to obtain mulberry branch bark pectin. In the method, the ionic liquid is taken as a treating agent for extracting mulberry branch bark pectin, so that pectin can be extracted effectively, ionic liquid treatment is only required to be performed for 20-50 minutes, the final yield of pectin can be up to about 11 percent, and the pectin extracting efficiency of the mulberry branch bark is increased.

Method for efficiently extracting mulberry branch bark pectin

The invention discloses a method for preparing biodiesel by directly using cellulose through mixed fermentation. The mixed fermentation is performed by using a plant fiber degrading strain and a grease producing strain, and ethanol is produced by directly using natural plant fiber such as straws. The method comprises the following steps of: designing a culture medium for the mixed fermentation by optimization methods such as a response surface method, and optimizing to obtain the fermentation conditions such as the optimum temperature of mixed fermentation, optimum mixing proportion of strains and optimum mixing time of the strains by utilizing the methods such as orthogonal test and response surface methodology; according to the optimized fermentation conditions, by using the plant fiber as a carbon source, degrading the cellulose into fermentable sugar by using a cellulase producing strain, and adding grease-producing microorganisms into the culture system for the mixed fermentation; and by using the sugar which is produced by the constant enzymolysis of the plant fiber as the carbon source, fermenting to produce grease by using the grease producing strain, and performing methyl esterification reaction of the microbial grease to obtain the biodiesel.

Method for preparing biodiesel by directly using cellulose through mixed fermentation

The invention discloses a method for producing cellulase for high-efficiency hydrolysis of a special vegetable fiber. The method comprises the steps of: activating and culturing cellulase-producing bacteria; inoculating the cellulase-producing bacteria into a cellulase-producing culture medium, and inducing the cellulase by using a natural vegetable fiber such as bagasse as a substrate; fermenting to produce the cellulase; taking fermentation liquor out; and filtering the fermentation liquor, performing salting-out, and dialyzing to form a crude cellulase solution. According to different compositions of different natural vegetable fibers, the cellulase produced by induction of different natural vegetable fibers has different cellulase composition and different degrading capabilities on different natural vegetable fibers. For example, the cellulase produced by induction of the bagasse has a high degrading capability on the bagasse and a relatively low degrading capability on other natural vegetable fibers. The method for producing the cellulase for high-efficiency hydrolysis of the special vegetable fiber provided by the invention has the advantages of simplicity and convenience in operation and simplicity in process, and can provide a guiding principle for the industrial production of the natural vegetable fiber degrading cellulase.

Fei Juanjuan

Papers

Ultrasound-assisted compatible in situ hydrolysis of sugarcane bagasse in cellulase-aqueous–N-methylmorpholine-N-oxide system for improved saccharification

Extraction method of 1-desoxynojirimycin in mulberry leaf

Method for efficiently extracting mulberry branch bark pectin

Method for preparing biodiesel by directly using cellulose through mixed fermentation

Method for producing cellulase for high-efficiency hydrolysis of special vegetable fiber