Steam Explosion Treatment Research Articles

Steam explosion pretreatment of willow grown on phytomanaged soils for bioethanol production

A steam explosion (SE) process was evaluated as a pretreatment method to achieve simultaneously the pretreatment and the decontamination of trace elements (TE) from woody biomass for bioethanol applications. The willow biomass used in this study was obtained from short rotation coppice phyto-managed plots harvested on a TE-contaminated soils (Zn, Mn). The influence of the SE reaction severity on the composition of the cellulosic pulp and on the TE extraction in the water effluent was investigated. SE performed at 220 °C after a 2% sulfuric acid presoaking allowed an extraction of ̴ 80% of Mn and Zn in the water effluent. The enzymatic hydrolysis of the resulting pulps was examined. A cellulose-to-glucose conversion of ˜80% was obtained after 75 h of incubation of the pulp obtained after a SE treatment performed at 180 °C. The subsequent fermentation into ethanol using Saccharomyces cerevisiae was successfully performed. No significant influence of TEs on the action of the biocatalysts (enzymes and yeast) was observed.

Combination of steam explosion pretreatment and anaerobic alkalization treatment to improve enzymatic hydrolysis of Hippophae rhamnoides

The optimum condition of steam explosion pretreatment was screened for hippophae, and anaerobic calcium oxide (CaO) alkalization was further used to improve its enzymatic hydrolysis. Steam-exploded hippophae reached the lowest pH value (4.01) and the maximal hemicellulose removal (77.16%) at pressure 1.5 MPa and residence time 20 min. Lignocellulosic fractions of hippophae was remarkably reduced by CaO alkalization or steam explosion treatment, and enzymatic sugar yield was increased from 66 mg/g DM (untreated material) to 270 and 300 mg/g DM, respectively. The sequent pretreatment of steam explosion and CaO alkalization achieved a sugar yield of 330 mg/g DM, where 2% CaO loading rate was high enough. Besides, SEM, FTIR, and XRD analyses validated structural and physicochemical changes of hippophae. In conclusion, the sequent pretreatment of steam explosion at pressure 1.5 MPa for 20 min and anaerobic CaO alkalization at 2% loading rate could remarkably improve enzymatic hydrolysis of hippophae.

Modification of Zhaotong Lignite by Steam Explosion Treatment: Pore Structure and Oxygen-Containing Functional Groups

The pore structure and oxygen-containing functional groups of lignite play an important role in drying behavior, spontaneous combustion characteristics, and other applications of lignite. In this p...

Evaluation of different methods for extraction of nanocellulose from yerba mate residues

In this work, we evaluate the production of nanocellulose from yerba mate sticks (YMS) using soft chemical and steam explosion treatments. The nanocellulose is characterized by chemical characterization, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The main results showed that after the chemical treatment and steam explosion, the YMS fiber reached diameters of 11–15 nm and aspect ratios (L/D) of 12–24. The XRD results showed that there is an increase in the index of crystallinity of up to 35% when compared to raw YMS. We discover that it is possible to obtain cellulose nanofibers (CNF) from the YMS without the use of alkaline treatment, which reduces the generation of liquid waste. Thus, the production of CNF by means of acid hydrolysis, bleaching and steam explosion represents an alternative route.

Steam explosion modification on tea waste to enhance bioactive compounds' extractability and antioxidant capacity of extracts

In this work, steam explosion (SE) was introduced to modify physicochemical features of tea waste to intensify bioactive compounds’ extraction and antioxidant capacity of extracts. Modification effects of SE on chemical composition, multi-scale structure and solubilization of tea waste were investigated to confirm that cell wall composition and porous network of tea waste were destroyed and restructured, resulting in the increased solubility after SE. Effects of SE on distribution and diffusion rules of four typical bioactive compounds in tea extracts revealed that SE enhanced their extraction efficiency by raising the maximum extraction yield and diffusion coefficient. After SE treatment, the extraction yields of tea polyphenols, caffeine, saponin and water soluble sugars were maximally increased by 15.5%, 14.1%, 28.8% and 74.8%, respectively. Most of them experienced a balance of dissolution and degradation during SE, showing a firstly increasing and then decreasing tendency with increasing SE severity. The availability of tea waste facilitated by SE led to at least 20% improvement of antioxidant capacity including Ferric reducing antioxidant power (FRAP) and OH, O2- radical scavenging activity of tea extracts.

Effect of Water-impregnation on Steam Explosion of Pinus densiflora

This study addresses the biorefinery feedstock from Pinus densiflora. This raw material is a major tree species in the Republic of Korea; it is renewable, has cost-effective, and is readily available. In this study, steam explosion of P. densiflora was performed in a reactor at 225 °C and with 1 to 13 min reaction times with or without previous water impregnation. The combined severity factor (Ro), which is an expression relating the reaction temperature and reaction time used in the steam explosion treatment, ranged from 3.68 to 4.79. The influence of both impregnation and steam explosion conditions were investigated by examining color variations, chemical composition, and mass balance on the pretreated solids. The results showed that steam-exploded P. densiflora that was not impregnated with water exhibited significantly darker color (chroma 28.8-41.4) than water-impregnated and steam-exploded P. densiflora (chroma 18.8-37.3). The increased α–cellulose and lignin contents were detected as the severity factor increased. Furthermore, the α–cellulose and lignin contents in the non-impregnated/steam-exploded P. densiflora were higher than those in the water-impregnated/steam-exploded P. densiflora. However, the decreased holocellulose content was detected as the severity factor increased. In mass balance, the holocellulose yield from water-impregnated/steam-exploded P. densiflora was higher than that from the non-impregnated P. densiflora.

Effect of steam explosion on dietary fiber, polysaccharide, protein and physicochemical properties of okara

Okara is the byproduct of tofu and soymilk industries. A large amount of okara is produced annually in the world, but only a small amount is fully utilized. The effect of steam explosion (SE) treatment on dietary fiber, protein and physiochemical properties of okara was investigated in this paper. The results showed that untreated okara contained 76.38% total dietary fiber (TDF) and 18.10% protein, but the content of soluble dietary fiber (SDF) was only 1.34%. After SE treatment, SDF content increased significantly. When the SE strength was 1.5 MPa for 30s, SDF content increased to 36.28%, higher by 26 times compared to the control okara. However, the contents of TDF and SDF both decreased when the SE strength enhanced further. Gel filtration chromatography showed that molecular weight of okara polysaccharides were distributed from 55 KDa to 2087 KDa. With the increase of SE strength, the ratio of low molecular weight polysaccharides increased and the molecular weight range of polysaccharides became narrower. Okara protein showed two molecular weight peaks. After SE treatment, the area of high molecular weight peak decreased and low molecular weight peak increased. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that okara protein appeared in five bands: 73.7 KDa, 55 KDa, 41.1 KDa, 32.7 KDa and 20.2 KDa. After SE treatment, the bands of 73.7 KDa, 55 KDa and 41.1 KDa weakened markedly, indicating high SE strength can dissociate macromolecular protein aggregates. Water solubility of okara increased significantly, while swelling capacity, oil and water holding capacities decreased after SE treatment. Scanning electron microscopy (SEM) demonstrated that the loose sheet structure of okara surface was destroyed into small fragments after SE treatment and the internal nucleated structure was disintegrated into small particles at high SE strength. The change in morphological structure also produced important influences on physiochemical properties of okara. This study suggested that SE treatment is an effective method for improving SDF content and quality of okara, so as to expand its development and utilization.

The effects of henequen cellulose treated with polyethylene glycol on properties of polylactic acid composites

Cellulosic henequen fibers were subjected to steam explosion and impregnated with polyethylene glycol (PEG) to improve fiber-matrix compatibility in polylactic acid (PLA) composites. Through Fourier-transform infrared spectroscopy (FTIR) it was shown that the hydroxyl, methyl, and ether functional groups were increased after the steam explosion treatment. Changes in the cellulose morphology caused by the steam explosion and impregnation with PEG were observed via scanning electron microscopy (SEM). Good adhesion of the treated cellulose and the PLA matrix was observed through improvement of the tensile strength and Young’s modulus of the PLA composite. The PEG impregnated into the fiber plasticized the PLA matrix and reduced the Tg from 59 °C to 52 °C. The increase in crystallinity confirmed the cellulose fibers induced nucleation of the PLA, which resulted in greater rigidity of the PLA composites.

Effect of steam explosion treatments on the functional properties and structure of camellia (Camellia oleifera Abel.) seed cake protein

The effect of steam explosion on the functional properties of camellia seed protein (CSP) was investigated, and the structural properties after the modified treatment were evaluated by fourier transform infrared spectroscopy (FTIR), near-UV circular dichroism (CD), thermogravimetric (TG), differential scanning calorimeter (DSC), glycosylation fluorescence, zeta potential (ζ) measurement and particle size measurement. After the steam explosion treatment, the content of simple sugars and free amino acids in the camellia seed cake (CSC) decreased, and the lightness of the CSP was reduced. The result showed that the solubility of treated CSP was significantly higher than those of untreated CSP in different pHs. The foaming and emulsifying properties of the treated CSP were higher than that of native CSP. Moreover, FTIR and DSC indicated a small change in the protein secondary structure after steam explosion, with a decrease in α-helix, random coil, β-turn contents and an increase in β-sheet content, the change of CSP tertiary structure has been confirmed by near-UV CD. In addition, steam explosion reduced the particle size and the zeta potential. Changes in protein glycosylation indicated Maillard reaction has been activated during steam explosion. These results concluded that CSP can be treated by steam explosion to modify the functional properties.

Microcrystalline Cellulose from Lignocellulosic Material Activated by Steam Explosion Treatment and Mathematical Modeling of the Processes Accompanying its Preparation

In this paper we propose a mathematical model and an algorithm for calculating the processes accompanying the hydrolysis of a lignocellulosic material activated by steam explosion treatment, the purpose of which is to obtain microcrystalline cellulose (MCC). The calculation of the process is implemented in MathCad and CurveExpert software environments. The obtained modeling results will allow to control the technological processes of continuous delignification and hydrolysis of lignocellulosic material activated by steam explosion treatment and also to automate them.

Physical and chemical characteristics of pretreated slash pine sawdust influence its enzymatic hydrolysis

The aim of this work was to evaluate the effect of different pretreatments applied to industrial slash pine sawdust (Pinus elliottii) on its enzymatic hydrolysis. NREL laboratory analytical procedures for standard biomass analysis were used to characterize the thirty one fibrous materials produced. Eight pretreated materials were selected considering both the chemical composition and the enzymatic hydrolysis yield to further evaluate crystallinity and porosity, determined by X-ray diffraction and thermoporosimetry, respectively. Diluted acid, steam explosion, and slight alkali treatments revealed to be not effective to enhance enzymatic hydrolysis of resinous pines since a maximum yield value of only 25% was achieved. On the contrary, strong alkali treatments promoted the lignin removal, thus increasing the accessibility of the material for enzymatic hydrolysis. In accordance, the highest values of the cellulose crystallinity (about 75–76%) were also obtained. No correlation was found between the porosity and the enzymatic hydrolysis yield. It was concluded that to enhance enzymatic hydrolysis the lignin content of the pretreated material should below. As for the hemicelluloses content, only its interaction with the lignin content is significant, as revealed by the regression model obtained.

Bit coir fiber and sugarcane bagasse fiber reinforced eco-friendly polypropylene composites: Development and property evaluation thereof

Waste natural fibers, bit coir fiber residue of traditional coir industries, and sugarcane bagasse fibers were subjected to chemical modifications via alkaline steam explosion treatments toward the extraction of reinforcing fibers with better compatibility and reinforcing characteristics in the polymer matrix. The treated fibers were utilized in the fabrication of composites with polypropylene (PP) as the base polymer with the aid of maleic anhydride–grafted PP as the compatibilizer. Percent composition of fiber in the composites was decided to facilitate maximum replacement of the matrix and further applicability in large-scale continuous polymeric production processes. Mechanical, thermal, and morphological characterization of the composites reveals the best composition to be of 30% composition, in the added view of maximum replacement of polymer matrix with the reinforcing filler, retention of requisite properties, reduced cost of manufacture and inventory, and reduction in the carbon footprint per unit dimensions in comparison with the wholly polymer component. The thermal properties of coir fiber-reinforced composites showed good improvement up to 134.5°C increase in onset degradation temperature while retaining matrix properties for sugarcane bagasse-reinforced composites.

Fractionation of Pinus radiata wood by combination of steam explosion and organosolv delignification

This work proposes a sequential combination of steam explosion and organosolv delignification for Pinus radiata fractionation. An efficient pretreatment to fully optimize the use of lignocellulosic materials is the key to make a biorefinery profitable, especially for softwoods, known to be more recalcitrant than other lignocellulosic raw materials. Steam explosion has a dual effect on biomass as morphological and chemicalchanges are introduced. A delignifying stage has been stated to be necessary in order to ease hydrolytic enzymes accessibility to cellulose while avoiding non-productive bonds with the lignin present. Three steam explosion conditions were tested (170°C, 5 min; 180°C, 10 min; 170°C, 5+5 min) followed by an organosolv delignification stage, carried out at two different conditions (170°C, 60 min; 170°C, 90 min). All treatmentyields, delignification extent, and hydrolysis yields were determined to evaluate each stage. The steam explosion treatment did not produce high delignification extent. Maximum global delignification (50,4%) was achieved when combining the two-cycle steam explosion with the most severe post-treatment condition tested. Enzymatic hydrolysis of the cellulosic residue improved after organosolv delignification; however, hydrolysisyields did not exceed 35%. The chemical changes undergone by softwood lignins are presumably responsible for the low digestibility.

Optimization of the Steam Explosion Pretreatment Effect on Total Flavonoids Content and Antioxidative Activity of Seabuckthom Pomace by Response Surface Methodology.

Steam explosion pretreatment was conducted on seabuckthom pomace. Response surface methodology was used to optimize the treatment conditions of steam explosion, including steam pressure, duration and particle size. After this, the content of total flavonoids and the antioxidant capacity of total flavonoids were investigated. Results showed that when the steam pressure was 2.0 MPa, duration was 88 s and a sieving mesh size was 60, the total flavonoids content in seabuckthorm reached a maximum of 24.74 ± 0.71 mg CAE/g, an increase of 246% compared with that without steam explosion treatment (7.14 ± 0.42 mg CAE/g). Also, DPPH and ·OH free radical scavenging ability showed significant improvement, with an IC50 decrease to 13.53 μg/mL and 4.32 μg/mL, respectively, far lower than that in original samples. Through the scanning electron microscope, the surface of seabuckthom pomace after steam explosion was crinkled, curly, and holey. Our study showed that the content of total flavonoids in seabuckthom pomace could be obviously promoted and the antioxidant capacity of total flavonoids also improved significantly, after applying steam explosion pretreatment to seabuckthom pomace, making this approach meaningful for the reuse of seabuckthom pomace resources.

Study on structural and thermal properties of cellulose microfibers isolated from pineapple leaves using steam explosion

In Thailand, pineapple leaves are one of the most common agricultural wastes after cultivation. The aim of this research was to understand effects of the steam explosion treatment conditions (steam pressure and treatment cycle) on properties of cellulose microfibers extracted from pineapple leaves. The fibers were steam exploded at pressure of 16 and 20 kgf cm−2 between 1 and 5 cycles. The steam explosion technique could partially eliminate hemicellulose and lignin and increase the cellulose content, leading to improvement of the thermal properties and crystallinity of the treated fibers. With increasing the steam pressure and treatment cycles, changes of the fiber morphology were observed. Smaller widths and shorter lengths of the treated fibers could be obtained. Microfibers with widths of 3 μm and lengths of 93 μm were extracted from fiber bundles with widths of 45.8 μm and lengths of ∼2 cm with the pressure of 20 kgf cm−2 for 5 cycles. Also, the steam explosion method could possibly fibrillate cellulose nanofibers. With more cycles of the steam explosion treatment, large amounts of cellulose nanofibers could be found.

Microcrystalline Cellulose Based on Cellulose Containing Raw Material Modified by Steam Explosion Treatment

Today’s methods for producing powdered celluloses, in particular microcrystalline cellulose (MCC), from various plant raw materials, while applying new highly efficient methods for the isolation of cellulose are of a great interest. One of these methods is the production of MCC from lignocellulosic material activated by steam explosion treatment. The material obtained by this method from wood has a high reactivity, low content of residual lignin, a high specific surface, which allows to subject it successfully and efficiently to accelerated delignification or hydrolytic breakdown (degradation). This ability of the lignocellulosic material, activated by steam explosion, is the basis of this study, which provides the results of an experimental evaluation of the component and dispersion analysis of MCC, obtained from this material.

Physical and Chemical Properties of Activated Lignocellulose and its Areas of Application

In this paper we present the results of a study of the physical and chemical properties of activated lignocellulose obtained in the process of steam explosion treatment of various breeds of wood. It is shown that fibrous material has a high potential for scientific and commercial use: in the field of production of pulp for paper and cardboard production in a more efficient way, to obtain microcrystalline cellulose by hydrolysis, to produce coarse lignocellulosic fibers for the production of construction and insulation boards with new properties. The scope of activated lignocellulose is not limited only to these directions, but can be significantly expanded due to the competent use of its physical and chemical properties.

Environmentally-Friendly Extraction of Cellulose Nanofibers from Steam-Explosion Pretreated Sugar Beet Pulp.

Cellulose nanofibers (CNFs) with an average diameter of 22 nm were prepared from sugar beet pulp (SBP) via an environmentally-friendly method. Steam-explosion pretreated SBP was treated with hydrogen peroxide (H2O2) bleaching, high-speed blending, and ultrasonic treatment. Thermogravimetric analysis showed that hemicellulose was partially hydrolyzed in the steam-cooking stage, pectin was removed in the explosion stage, and lignin was removed by H2O2 bleaching. The removal of non-cellulosic components was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. Morphological analysis showed that steam-explosion pretreatment largely extracted the binder materials of hemicellulose and pectin. This exposed the microfibrillated cellulosic fibers, which promoted subsequent nanofibrillation. X-ray diffraction showed that the CNFs had a crystallinity index of 62.3%. The CNFs had good thermal stability, and thus have potential for use as fillers in polymer matrices. The only chemical reagent used in this green method was H2O2. Combining H2O2 bleaching with steam explosion, high-speed blending, and ultrasonic treatment reduced the overall energy consumption and increased the efficiency of the CNFs extraction. The method, therefore, has potential application in industrial processes.

Isolation and characterization of cellulosic fibers from kenaf bast using steam explosion and Fenton oxidation treatment

Degumming is the dominant method to isolate cellulosic fibers in the textile industry. High content of lignin is the principle obstacle in bast-fibers degumming. In order to remove lignin efficiently, the treatment using steam explosion coupled with Fenton oxidation was conducted on kenaf bast in this study. The influence and mechanism of the combined treatment of steam explosion and Fenton oxidation were studied. Fiber microstructure, composition proportion and distribution, cellulose Segal crystallinity and polymerization as well as residual lignin structure were analyzed. The results showed that the pretreatment of steam explosion could sufficiently extract most of the hemicellulose from kenaf bast. Also, the Fenton oxidation followed by alkaline boiling could effectively remove the lignin from the fiber, especially from the fiber surface. The refined dry fibers produced only remained 8.82% of hemicellulose and 9.36% of lignin. And the whole treatment process didn’t change the cellulose crystalline structure but could gradually degrade hemicellulose, lignin and other amorphous gummy matter as well as disordered areas in cellulose, leading to the increase of fiber Segal crystallinity from 62.02 to 70.12%. Part of cellulose was damaged with the increase of degumming intensity, resulting in the decrease of the polymerization degree of cellulose. Meanwhile, the structure of residual lignin changed during the degumming stages of steam explosion, Fenton oxidation and alkaline boiling. All the results revealed that the treatment of combined steam explosion and Fenton oxidation is significantly effectual for isolating bast-fibers.

A green degumming process of ramie

Ramie provides the longest and strongest natural fiber in textile industry, but its traditional degumming process is costly and requires a large amount of alkali, which causes serious environmental concerns. In the current work, a steam explosion (STEX) treatment followed by sodium percarbonate (SP) soak degumming process was investigated. Microstructure, chemical composition and mechanical properties of the refined ramie fibers were comprehensively characterized. The residual gum content was below 5%, the fineness was higher than 1600 Nm (6.25 dtex), the breaking tenacity was 5.4 cN/dex, and the whiteness was above 50%. All of the properties met the requirements of Chinese national standard, and the breaking tenacity and whiteness were notably better than those of the fibers degummed traditionally. In addition, environmental impacts of the new degumming process were evaluated. Only 50% chemicals were needed for the new process, and chemical oxygen demand (COD) of the waste reduced to 35% of the traditional method. Therefore, the new method was more environment-friendly and economically feasible. It has great potential for industry applications.