Effect Of Hydrothermal Pretreatment Research Articles

Extraction of high stearic high oleic sunflower oil (HSHO): Effect of dehulling and hydrothermal pretreatment

The effect of a hydrothermal pretreatment on the solvent extraction of oil and minor compounds (tocopherols) from high stearic high oleic sunflower seeds (HSHO), partially dehulled and undehulled, was analyzed. Samples of sunflower seeds of different origins and oil contents (high oil, 43.0% d.b., and low oil 35.1% d.b.) were used. The oil yield increased significantly due to the hydrothermal pretreatment (p ≤ 0.05) for HSHO samples with high oil content, both partially dehulled and undehulled. The pretreated HSHO samples with low oil content did not show significant differences in oil yield compared to the untreated samples. The effective diffusion coefficients for the hydrothermally pretreated seeds (2.12.10−11 m2 s−1) and the untreated samples (7.07.10−12 m2 s−1) were determined based on the oil extraction from the partially dehulled high oil HSHO samples. For both types of partially dehulled HSHO seeds, a significant increase in tocopherol content in the oils extracted from the pretreated samples was observed.

Effect of Hydrothermal Pre-Treatment on Ferulic Acid Content and Antioxidant Activities of Corn Hydrolysate

Effect of Hydrothermal Pre-Treatment on Ferulic Acid Content and Antioxidant Activities of Corn Hydrolysate

Studies on the effect of hydrothermal pretreatment of sugarcane bagasse for biobutanol production

ABSTRACTThis study deals with the production of butanol using hydrothermally pretreated sugarcane bagasse (SCB) hydrolysate by anaerobic fermentation using Clostridium sporogenes. First, SCB was soaked in water at 30–70°C at a solid to liquid ratio (SLR) of 1:10. Second, SCB was soaked in water and subsequently subjected to thermal treatment at 121°C for 15 min. The effectiveness of pretreatment was evaluated by enzymatic hydrolysis and a maximum glucose yield of 462 mg/g of glucan was obtained from the pretreated biomass. Anaerobic fermentation of the hydrolysate under strict anaerobic condition resulted in the butanol yield of 0.173 g/g. C. sporogenes coculturing with Bacillus subtilis without anaerobic treatment was also investigated.

Effect of hydrothermal pre-treatment (HTP) on poultry slaughterhouse waste (PSW) sludge for the enhancement of the solubilization, physical properties, and biogas production through anaerobic digestion

This study is an assessment of the hydrothermal pre-treatment (HTP) of poultry slaughterhouse waste (PSW) sludge for the enhancement of the solubilization, physical properties, and biogas production through anaerobic digestion. This assessment was carried out to ascertain the optimal HTP temperature. The solubilization and physical properties efficacy was investigated by capillary suction time (CST), time to filter (TTF), and particle size. In addition, the anaerobic digestion was investigated through biochemical methane potential (BMP) tests and subsequent statistical analysis using the modified Gompertz model. HTP was found to have improved the solubilization of the PSW sludge with increasing HTP temperature. In addition, the results of the CST, TTF, and particle size decreased with increasing HTP temperature. These results of the assessment that was conducted in this study confirm that the HTP process indeed modifies the physical properties of PSWs to enhance the solubilization of organic solids. Nevertheless, the results of the BMP tests and the modified Gompertz model analysis show that the optimal HTP temperature of PSWs for anaerobic digestion is 190°C. These findings show that to achieve high conversion efficiency, an accurately designed pre-treatment step must be included in the overall anaerobic digestion process for wastewater treatment.

Effect of hydrothermal pretreatment on the structural changes of alkaline ethanol lignin from wheat straw.

Due to the enormous abundance of lignin and its unique aromatic nature, lignin has great potential for the production of industrially useful fuels, chemicals, and materials. However, the rigid and compact structure of the plant cell walls significantly blocks the separation of lignin. In this study, wheat straw was hydrothermally pretreated at different temperatures (120–200 °C) followed by post-treatment with 70% ethanol containing 1% NaOH to improve the isolation of lignin. Results demonstrated that the content of associated carbohydrates of the lignin fractions was gradually reduced with the increment of the hydrothermal severity. The structure of the lignins changed regularly with the increase of the pretreatment temperature from 120 to 200 °C. In particular, the contents of β-O-4′, β-β′, β-5′ linkages and aliphatic OH in the lignins showed a tendency of decrease, while the content of phenolic OH and thermal stability of the lignin fractions increased steadily as the increment of the pretreatment temperature.

Effect of Hydrothermal Pretreatment on Kitchen Waste for Biodiesel Production Using Alkaline Catalyst

The catalyzed conversion of waste cooking oil by transesterification into biodiesel yields exceptional environmental benefits and is the focus of this study. Sodium methoxide (CH3ONa), an alkaline catalyst, was selected for transesterification. A hydrothermal pretreatment was first applied to heat the kitchen waste to 140–170 °C. The pretreated waste cooking oil was then extracted from kitchen waste after a set time for use as a reactant. The aim of this study was to discuss whether hydrothermal pretreatment affects biodiesel productivity of waste cooking oil by alkali catalyst. Transesterification was conducted following hydrothermal pretreatment. Transesterification conditions were obtained from results of single factor experiments at 60 °C for 80 min, 0.9 wt% sodium methoxide concentration and 5:1 methanol/oil molar ratio. Maximum transesterification productivity reached 80.9 % locating the maximum increment of biodiesel productivity at 2.88 wt% relative to the control obtained under hydrothermal conditions at 160 °C for 80 min and a 1:1 volume ratio of kitchen waste to water. Biodiesel productivity was not impacted by hydrothermal temperature or hydrothermal time and analysis indicates principal properties of the final product complied with the European EN14214 Standard.

Controlled retting of hemp fibres: Effect of hydrothermal pre-treatment and enzymatic retting on the mechanical properties of unidirectional hemp/epoxy composites

The objective of this work was to investigate the use of hydrothermal pre-treatment and enzymatic retting to remove non-cellulosic compounds and thus improve the mechanical properties of hemp fibre/epoxy composites. Hydrothermal pre-treatment at 100kPa and 121°C combined with enzymatic retting produced fibres with the highest ultimate tensile strength (UTS) of 780MPa. Compared to untreated fibres, this combined treatment exhibited a positive effect on the mechanical properties of hemp fibre/epoxy composites, resulting in high quality composites with low porosity factor (αpf) of 0.08. Traditional field retting produced composites with the poorest mechanical properties and the highest αpf of 0.16. Hydrothermal pretreatment at 100kPa and subsequent enzymatic retting resulted in hemp fibre composites with the highest UTS of 325MPa, and stiffness of 38GPa with 50% fibre volume content, which was 31% and 41% higher, respectively, compared to field retted fibres.

The Effect of Hydrothermal Treatment on the Color Stability and Chemical Properties of Birch Veneer Surfaces

The effects of hydrothermal pre-treatment on the color of silver birch veneer were determined. Spectrophotometric and chemical analyses of the veneer by means of extraction were conducted to determine the detailed chemical characteristics of the veneers. Results from spectrophotometric analysis revealed a significant increase in lightness (L*) and a decrease in yellowness (b*) in the veneer produced from a log soaked at 70 °C in short-term. Conversely, the effect of long-term storage resulted in a significant reduction in L* and an increase in b*. Chemical analyses of the veneer extract identified a moderate negative correlation between soluble proanthocyanidins content and treatment temperature. A higher amount of wood extractives, such as lipophilic extractives, free monosaccharides, and other organic substances, were obtained from wood material soaked at 70 °C than at 20 °C, which was most likely due to moderate chemical changes during treatment. Comparison of the results between dried veneers and wet veneers from the water extraction study revealed that the dried veneers had higher amounts of lipophilic matter and less water-soluble organic matter than the wet veneers. Other aspects of the loss of soluble proanthocyanidins in the birch veneer during plywood manufacturing are discussed.

Effect of hydrothermal pretreatment on the properties of moso bamboo particles reinforced polyvinyl chloride composites

Bamboo plastic composites were fabricated from polyvinyl chloride (PVC) and moso bamboo particles (BP). In order to improve the interfacial interaction between BP and PVC, as well as to obtain composites with outstanding mechanical properties, the roles of hydrothermal treating temperatures (120, 140, 160, 180, 200, 220, 240, 260 and 280 °C) on characteristics of BP and properties of the PVC/BP composites were investigated. Results showed that hydrothermal modification improved the surface property of BP and wiped off hemicelluloses and pectin. A uniform dispersion of BP in PVC matrix was observed by SEM with hydrothermal treatment. Tensile strength, tensile modulus and flexural strength of the composites achieved their maximal values of 15.79 MPa, 6702.26 MPa and 39.57 MPa, respectively, with 180 °C hydrothermal treatment. The highest values of elongation at break and flexural deformation were 3.75 ± 0.20% with 200 °C hydrothermal modification and 36.22 ± 2.70% with 140 °C hydrothermal modification, respectively. Due to more decomposition of hemicellulose, the composites expressed lower water absorption and higher thermal stability when the hydrothermal treating temperature exceed 160 °C.

Effects of Hydrothermal Pretreatment on the Content and Structure of Lignin Extracted from Corncob

A systematic hydrothermal pretreatment of corncob has been conducted with an aim to trace the content and property of lignin during the pretreatment process. The result showed that the lowest content of lignin was obtained under the following condition: water-solid ratio is 3:1,180 °C for 90min with 0.4g auxiliary medium. TG and FTIR analysis has been conducted to investigate the thermal stability and structure of lignin, and the result indicated that hydrothermal pretreatment influenced the thermal stability and structure of lignin extracted from corncob.

Effect of Hydrothermal Pretreatment on Convective Drying Characteristics of Paper Sludge

This work concerns the influence of hydrothermal (HT) pretreatment on sludge drying performance. Sludge was dried in an air duct dryer at a temperature of 30.4 ± 0.4 °C with a constant air velocity of 1.34 ± 0.04 m/s and a relative humidity of about 56%. Drying rate curves, defined as the mass flux (kg/(m2 h)) versus the dry basis moisture content (kg/kg), showed that the drying process mainly took place in the falling rate period. HT pretreatment can improve drying speed and shorten drying time. Six classical semi-theoretical drying models, including Lewis, Page, Logarithmic, Henderson and Pabis, Wang and Singh, and Approximation of Diffusion, were evaluated to represent the experimental results in terms of the coefficient of determination (R2), reduced chi-square (χ2), and root means square error (ERMS). The Approximation of Diffusion model was the best one to reproduce the experimental data with R2 close to 1, χ2 around 0.00001–0.00005, and ERMS of 0.00371–0.00686. The HT pretreatment changed the model constants. The expression was MR = 0.4868 exp(−0.0036τ) + 0.5132 exp(−0.0014τ) for the untreated sludge and MR = −0.8945 exp(−0.0071τ) + 1.8945 exp(−0.0045τ) for the HT pretreated sludge. The increase in the effective diffusivity accounted for the improvement in the drying performance.

Effects of hydrothermal pretreatment on subsequent octenylsuccinic anhydride (OSA) modification of cornstarch

Cornstarch granules were hydrothermally pretreated and then esterified with octenylsuccinic anhydride (OSA). The physicochemical properties of cornstarch and hydrothermally pretreated OS-starch (H-OS-starch) were investigated. Results showed that hydrothermal pretreatments significantly increased the degree of substitution (DS) and reaction efficiency (RE) of H-OS-starch compared with the control. The higher the pretreatment temperature was, the more the OSA could go deep into the internal starch granules. The optimal pretreatment temperature for the OSA modification was 60°C. In addition, the OS groups appeared to be distributed throughout the OS-starch granules, especially on the surface, as shown by confocal laser scanning microscopy (CLSM). H-OS-starch had a slightly higher peak viscosity (Pv) and break down (BD) values, but lower pasting temperature (Tp) compared with the control OS-starch.

Effects of hydrothermal pre-treatments on Giant reed (Arundo donax) methane yield

Twelve hydrothermal pre-treatment combinations of temperature (150 and 180 °C), time (10 and 20 min) and acid catalyst (no catalyst; H2SO4 at 2% w/w immediately before steam cooking or in 24-h pre-soaking) were tested to assess their effects on methane yield of Giant reed biomass vs. untreated control. A batch anaerobic digestion was conducted with 4 g VS l(-1) at 53 °C for 39 days. Untreated biomass exhibited a potential CH4 yield of 273 ml g(-1) VS; the four pre-treatments without acid catalyst achieved a 10%, 7%, 23% and 4% yield gain in the respective temperature/time combinations 150 °C/10 min, 150 °C/20 min, 180 °C/10 min and 180 °C/20 min. Conversely, the eight pre-treatments with H2SO4 catalyst incurred a methanogenic inhibition in association with high SO4(2-) concentration in the hydrolysate, known to enhance sulphate reducing bacteria. Furfurals were also detected in the hydrolysate of five strong pre-treatments with H2SO4 catalyst.

Impact of hydrothermal pre-treatment to chemical composition, enzymatic digestibility and spatial distribution of cell wall polymers

The effect of hydrothermal pretreatment on chemical composition, microscopic structure and enzymatic digestibility of wheat straw was studied. Wheat straw was pretreated with increasing severity to obtain series of samples with altered chemistry and structure. The hydrothermal pretreatment caused solubilisation of arabinoxylan and phenolic acids and their dimers in a temperature dependent manner with minor effects on the cellulose and Klason lignin content. In the cell wall level, the pretreatment intensified staining of cellulose and relocalised xylan in the cell walls. The distribution, properties and content of the cell wall phenolic compounds was altered as observed with phloroglucinol and autofluorescence imaging. In the enzymatic hydrolysis, the highest yields were obtained from the samples with a low xylan and diferulate content. On the cell wall structural level, the sample with the highest digestibility was observed to have intensified cellulose staining, possibly reflecting the increased accessibility of cellulose.

Enzyme affinity to cell types in wheat straw (Triticum aestivum L.) before and after hydrothermal pretreatment.

BackgroundWheat straw used for bioethanol production varies in enzymatic digestibility according to chemical structure and composition of cell walls and tissues. In this work, the two biologically different wheat straw organs, leaves and stems, are described together with the effects of hydrothermal pretreatment on chemical composition, tissue structure, enzyme adhesion and digestion. To highlight the importance of inherent cell wall characteristics and the diverse effects of mechanical disruption and biochemical degradation, separate leaves and stems were pretreated on lab-scale and their tissue structures maintained mostly intact for image analysis. Finally, samples were enzymatically hydrolysed to correlate digestibility to chemical composition, removal of polymers, tissue composition and disruption, particle size and enzyme adhesion as a result of pretreatment and wax removal. For comparison, industrially pretreated wheat straw from Inbicon A/S was included in all the experiments.ResultsWithin the same range of pretreatment severities, industrial pretreatment resulted in most hemicellulose and epicuticular wax/cutin removal compared to lab-scale pretreated leaves and stems but also in most re-deposition of lignin on the surface. Tissues were furthermore degraded from tissues into individual cells while lab-scale pretreated samples were structurally almost intact. In both raw leaves and stems, endoglucanase and exoglucanase adhered most to parenchyma cells; after pretreatment, to epidermal cells in all the samples. Despite heavy tissue disruption, industrially pretreated samples were not as susceptible to enzymatic digestion as lab-scale pretreated leaves while lab-scale pretreated stems were the least digestible.ConclusionsDespite preferential enzyme adhesion to epidermal cells after hydrothermal pretreatment, our results suggest that the single most important factor determining wheat straw digestibility is the fraction of parenchyma cells rather than effective tissue disruption.

Calcium-promoted catalytic activity of potassium carbonate for steam gasification of coal char: Effect of hydrothermal pretreatment

Hydrothermal pretreatment of coal with the addition of Ca(OH)2 was found more effective for promoting the K2CO3-catalyzed char gasification than the physical addition way for both JY anthracite coal and HB bituminous coal used. The effect of hydrothermal pretreatment was more remarkable for JY coal which suffers significant catalyst deactivation due to its high mineral content. For this type of coal, employing more severe hydrothermal pretreatment conditions was proven to significantly enhance the gasification rate. It was observed that kaolinite and quartz in coal hydrothermally reacted with calcium forming hydrated calcium aluminosilicates, which, unlike the original minerals, was inactive for the deactivation reactions of potassium. Consequently, the hydrothermal pretreatment allowed more potassium to persist as a water-soluble entity during the gasification. This was a main mechanism underlying the promoted catalytic gasification by the hydrothermal treatment.

Liquefaction process for a hydrothermally treated waste mixture containing plastics

Most landfilled plastic waste is a mixture or is in the form of composites with incombustible wastes such as glass, metals, and ceramics. After hydrothermal treatment, including a steam-explosion process, the separation of mixed waste (MW) into organic and inorganic substances becomes easy. However, the effect of hydrothermal pretreatment on the subsequent liquefaction of organic substances from MW is not obvious. In this study, the effects on the liquefaction of polystyrene and high-density polyethylene are discussed. Moreover, optimum conditions for the liquefaction of organic substances from hydrothermally treated MW are identified. By means of this hydrothermal pretreatment, including the steam-explosion process, polystyrene and high-density polyethylene can be significantly converted to oil by liquefaction at 300°–400°C. In comparison with liquefaction of hydrothermally pretreated mixed waste (HMW) at 300°–400°C with a batch type reactor, the yield of oil increases significantly on liquefaction using a semi-batch type reactor. It is considered that the radical chain and termination reactions among the radicals from HMW were inhibited in the semi-batch type reactor. On liquefaction of HMW in a semi-batch reactor, the conversion of HMW to oil was enhanced on increasing the liquefaction temperature to 350°C and the holding time to 60 min.

Effect of hydrothermal pretreatment on coal structure and the mild gasification process

A suite of coals was pretreated in steam and helium. The effect of this pretreatment on the structure and reactivity of the resulting product was examined by solvent extraction, cross-polarization magic angle spinning nuclear magnetic resonance (CP MAS NMR) spectrometry, Fourier transform infrared (FTIR) spectrometry, and steam reactivity. Hydrothermal pretreatment increased the extractive yield over that of the parent coal, indicating a likely improvement in pyrolysis yield. The effects appeared to be seam-specific rather than rank-specific. Spectral data confirmed that each coal responded differently to the treatment