Effect Of Pretreatment Temperature Research Articles

Alkali pretreatment-assisted catalytic pyrolysis of waste cellulose acetate for selective preparation of levoglucosenone

With the increasing demand for cellulose acetate (CA) in industrial and daily applications, the disposal of its waste has emerged as an environmental concern. In this study, a novel and sustainable method for value-added utilization of waste CA was proposed, which involved NaOH pretreatment and subsequent catalytic pyrolysis using phosphoric acid-activated carbon (PAC) to prepare levoglucosone (LGO). The effects of pretreatment temperatures and NaOH concentrations on the physicochemical characteristics of CA were thoroughly investigated. Furthermore, the pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were conducted to methodically assess the impacts of both pretreatment and pyrolysis conditions on the production of LGO. The results indicated that NaOH pretreatment could effectively hydrolyze the ester bonds in CA, leading to the removal of acetyl groups and a decrease in thermal stability. At a pretreatment temperature of 40 °C, a NaOH concentration of 0.5 mol/L, a catalyst/sample ratio of 1/3, and a pyrolysis temperature of 400 °C, the LGO yield could reach 11.52 wt%, much higher than that obtained from catalytic pyrolysis of CA (2.70 wt%). This study provides an efficient method for treating waste CA and demonstrates its potential for conversion into high-value chemicals, laying a solid foundation for the green recycling of waste plastics.

Effect of pretreatment temperature and time on fat bonding and fat reduction in deep-fried surimi

Deep frying (DF) is a popular cooking technique resulting in desirable sensory quality. However, DF also results in negative perception related to increased fat uptake and thus poor nutritional quality. In this study, a development of a novel strategy for fat reduction in DF surimi without additives and coatings was attempted. Novel pre-baking and pre-roasting were applied to surimi prior to DF. This novel pre-treatment strategy for DF surimi has not been reported in literature. Total, free, and bonded fat contents and corresponding fat reductions in DF surimi were determined. Cook and moisture losses as well as water holding capacity, expressible moisture, in addition to color and texture were also investigated. Fat uptake during DF of surimi was reduced (P < 0.05) by ≥ 25 % with pre-baking. Pre-baking improved (P < 0.05) or did not (P > 0.05) affect cook and moisture losses, water holding capacity, expressible moisture, color, and texture. However, pre-roasting increased (P < 0.05) fat content and adversely affected most quality parameters. Pre-baking of surimi at lower-temperature (116 °C) for longer-time (12–15 min) followed by DF at lower-temperature (170 °C) for longer-time (4 min) was most optimal for fat reduction, cook and moisture losses, water holding capacity, expressible moisture, color, and texture of surimi.

A comprehensive study on flocculation of anionic dyes using the bioflocculant produced by Bacillus thuringiensis: Kinetics, affecting factors, and perspectives.

Bioflocculants have received more and more attention as alternatives to chemical flocculants because of their innocuousness, environmental friendliness, and high effectiveness. This study aims to investigate various factors that influence the performance of the novel bioflocculant produced by Bacillus thuringiensis (BF-TWB10) and analyze its adsorption kinetics to optimize its flocculation performance for real applications. The best-fit kinetic model was pseudo-second order with R2 = 0.999. The effects of pretreatment temperature, pH, and the presence of cations on flocculation were assessed. Further investigations of flocculation, including zeta potential analysis and particle size analysis, were also conducted. Thermal pretreatment of BF-TWB10 or the presence of divalent cations could stimulate the decolorization efficiency of the bioflocculant. BF-TWB10 manifested outstanding dye removal performances with over 90% for all tested anionic dyes at pH2 and 3. Its decolorization efficiency on anionic dyes decreased with the increase of pH values. Zeta potential analysis revealed that the electrostatic repulsion between anionic dyes decreased after the addition of BT-TWB10 and further diminished by adjusting the reaction mixture to pH2 before flocculation, suggesting the occurrence of adsorption bridging and charge neutralization. These findings proposed that BF-TWB10 might be a promising bioflocculant for the removal of dyes in textile wastewater. PRACTITIONER POINTS: Bioflocculant BF-TWB10 shows outstanding performance in flocculation. Adsorption process follows pseudo-second-order kinetic model. Flocculation process is pH-responsive. High-temperature pretreatment or divalent cations enhance its flocculation performance. The analyses suggest the occurrence of charge neutralization and adsorption bridging.

Microwave-assisted two-stage hydrothermal liquefaction of Spirulina to produce high-quality bio-oil with low-carbon ketones

Due to the aggravation of environmental pollution and the massive consumption of fossil fuels, exploring renewable resources has become an important research topic. It is one of the research hotpots to convert algae into bio-oil by hydrolysis. This study studies the preparation of bio-oil with high content of low-carbon ketones by typical algae (Spirulina) using microwave-assisted heating through two-stage hydrothermal liquefaction (HTL). The effects of pre-treatment temperature, pre-treatment time, reaction temperature, reaction time, and reaction environment on the content of low-carbon ketones in the hydrolysate were discussed by setting up the orthogonal experiments. The changes of algae caused by pre-treatment were observed by elemental analysis, TEM and SEM. The samples obtained from the experiment were analyzed by gas chromatography/mass spectrometry (GC/MS) to find the best experimental conditions. Through the research in this study, it is found that the pre-treatment temperature of 80 °C is conducive to the formation of the target product (low-carbon ketones). The pre-treatment time of 20 min is more favorable. At the same time, it is found through experiments that the reaction temperature of 180 °C and the reaction time of 30 min are more conducive to the formation of the ketones. In addition, the weak acid solution environment significantly increases the relative content of the ketones. This study provides the basis for algae to prepare high-quality bio-oil and scientific support for the energy utilization of abundant algae resources.

Optimization of Vibration Pretreatment Microwave Curing in Composite Laminate Molding Process.

Vibration pretreatment microwave curing is a high-quality and efficient composite out-of-autoclave molding process. Focusing on interlaminar shear strength, the effects of pretreatment temperature, pretreatment time and vibration acceleration on the molding performance of composite components were analyzed sequentially using the orthogonal test design method; a scanning electron microscope (SEM) and optical digital microscope (ODM) were used to analyze the void content and fiber-resin bonding state of the specimens under different curing and molding processes. The results show that the influence order of the different vibration process parameters on the molding quality of the components was: vibration acceleration > pretreatment temperature > pretreatment time. Within the parameters analyzed in this study, the optimal vibration pretreatment process parameters were: pretreatment temperature of 90 °C, pretreatment time of 30 min, and vibration acceleration of 10 g. Using these parameters, the interlaminar shear strength of the component was 82.12 MPa and the void content was 0.37%. Compared with the microwave curing process, the void content decreased by 71.8%, and the interlaminar shear strength increased by 31.6%. The microscopic morphology and mechanical properties basically reached the same level as the standard autoclave process, which achieved a high-quality out-of-autoclave curing and molding manufacturing of aerospace composite components.

Development of lutetium oxide continuous fibers with excellent mechanical properties

The difficulty of reducing the diameter of lutetium oxide (Lu₂O₃) continuous fibers below 50 μm not only limits the flexibility of the sample but also seriously affects their application and development in high-energy lasers. In this work, a Lu-containing precursor with high ceramic yield was used as raw material, fiberized into precursor fibers by dry spinning. The pressure-assisted water vapor pretreatment (PAWVT) method was creatively proposed, and the effect of pretreatment temperature on the ceramization behavior of the precursor fibers was studied. By regulating the decomposition behavior of organic components in the precursor, the problem of fiber pulverization during heat treatment was effectively solved, and the Lu₂O₃ continuous fibers with a diameter of 40 μm were obtained. Compared with the current reported results, the diameter was reduced by about 50%, successfully breaking through the diameter limitation of Lu₂O₃ continuous fibers. In addition, the tensile strength, elastic modulus, flexibility, and temperature resistance of Lu₂O₃ continuous fibers were researched for the first time. The tensile strength and elastic modulus of Lu₂O₃ continuous fibers were 373.23 MPa and 31.55 GPa, respectively. The as-obtained flexible Lu₂O₃ continuous fibers with a limit radius of curvature of 3.5–4.5 mm had a temperature resistance of not lower than 1300 ℃, which established a solid foundation for the expansion of their application form in the field of high-energy lasers.

Application of Methylene Blue Adsorption Technique in the Determination of Specific Surface Area of Termite Feathers

Methylene Blue (MB) adsorption technique was employed in the measurement of the Specific Surface Area (SSA) of Termite Feathers (TF). The adsorption study was carried out at 25°C and 270 rpm after which the residual concentration of MB was determined spectrophotometrically at a wavelength of 660 nm. The adsorption data was found to conform to the Langmuir model within the concentration range studied and Langmuir constants were determined for TF. The specific surface area was then calculated from the Langmuir isotherm constant ‘b’. Effect of pre-treatment temperature on SSA was also considered at 30, 40, 50 and 60OC. The specific surface area was found to be 58.85 m2/g for the raw TF with values of 60.34, 78.52, 99.64 and 118.26 m2/g for the samples pre-treated at 30, 40, 50 and 60OC respectively. Finally, the specific surface area value obtained by MB adsorption technique was then compared with those obtained by Orth phenanthroline (OP) and p-nitrophenol (PNP) adsorption

Starch and protein recovery from brewer’s spent grain using hydrothermal pretreatment and their conversion to edible filamentous fungi – A brewery biorefinery concept

This study aimed at recovering a highly concentrated starch and protein stream from the brewer’s spent grain (BSG). The effect of pretreatment temperature and retention time on the solubilization of starch and protein; and the generation of fermentation inhibitors were studied. Then, the application of recovered streams for fungal cultivation was evaluated using different edible fungi Aspergillus oryzae, Neurospora intermedia, and Rhizopus delemar. The hydrothermal pretreatment resulted in the highest solubilized starch concentration, 43 g/L, corresponding to 83% solubilization of initial BSG starch content. The highest protein concentration was 27 g/L (48% solubilization of initial BSG protein content). Cultivation with Neurospora intermedia on the recovered streams from the two best pretreatment conditions, 140 ℃ for 4 h and 180 ℃ for 30 min, resulted in pure fungal biomass with the highest protein content 59.62% and 50.42% w/w, respectively. Finally, a brewery biorefinery was proposed for the valorization of BSG.

Effects of LAT on chemical structure and enzymatic hydrolysis of crop straw

Objective This study aims to investigate the effects of liquid ammonia treatment (LAT) pretreatment on the hydrolysis resistance of biomass and the enzymatic hydrolysis rate of lignocellulosic biomass. Method Four different types of lignocelluloses biomass, namely wheat straw (Triticum aestivum), alfalfa (Lotus corniculatus), sorghum straw (Sorghum bicolor), and their mixture (mass ratio 1∶1∶1), were pretreated by LAT method, and the effect of LAT on their chemical structure changes was studied by using thermo gravimetric analysis (TGA), Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), and scanning electron microscope (SEM). Then, the effect of pretreatment temperature and enzymatic hydrolysis time on the enzymatic hydrolysis conversion rates of glucan and xylan in the four raw materials was investigated. Result LAT had a significant effect on the chemical structure of biomass materials. After this pretreatment, the relative content of glucan, xylan, and arabinan in four types of lignocelluloses biomass slightly decreased. The relative content of O and H decreased because some functional groups containing O and H dropped off. The crystallinity decreased slightly, while the surface pore structure significantly increased, and the availability of enzymes in the chemical structure of biomass increased. The optimum pretreatment temperature of wheat straw and mixture was 90 ℃, while that of alfalfa and sorghum straw was 110 ℃. The enzymatic hydrolysis rates of glucan and xylan increased with the increase of enzymatic hydrolysis time. Among the four types of lignocelluloses biomass, the highest enzymatic hydrolysis rate of glucan obtained at the optimal enzymatic hydrolysis condition was wheat straw, followed by the mixture, sorghum straw, and alfalfa. The enzymatic hydrolysis rate of xylan ranging from large to small was sorghum straw, wheat straw, the mixture, and alfalfa. Conclusion LAT can improve the enzymatic hydrolysis efficiency of lignocellulosic biomass, especially that of wheat straw and sorghum straw. [Ch, 8 fig. 2 tab. 24 ref.]

Co-production of xylooligosaccharides and activated carbons from Camellia oleifera shell treated by the catalysis and activation of zinc chloride

Camellia oleifera shell (COS) is a worthy byproduct in woody edible oil production enriched in hemicellulose and lignin. This paper aims to explore the high-value transformation of COS for the production of xylooligosaccharides (XOS) with main degree of polymerization (DP) of 2–5 by the catalysis of ZnCl2. The effect of pretreatment temperature, reaction time and ZnCl2 concentration on the contents and DP distributions of XOS were analyzed. Moderate reaction conditions tended to achieve high content XOS, and the maximum value 61.38% and 14.39 g/L of XOS yield and concentration, respectively, peaked at 170 °C for 30 min using 0.5% (w/w) ZnCl2. The first time the solid residues derived from the production process of XOS were used as the precursor for the co-production of activated carbons (AC). The maximum iodine values and BET surface area were 5623.94 mg/g and 1244.46 m2/g, respectively, using 2.20 M ZnCl2 as the activating agent.

Effects of pretreatment temperature on the analysis of size‐fractionated aerosol particles using ToF‐SIMS

Size‐fractionated aerosol particles were collected with a MOUDI 10‐stage cascade impactor from an urban roadside place in a downtown area of Hong Kong. Fine aerosol particulate samples from stage 6 (aerodynamic particle diameter between 0.56 and 1 μm) and stage 9 (aerodynamic particle diameter between 0.10 and 0.18 μm) were pretreated at a chosen temperature, including −100°C, −50°C, 25°C, and 60°C, in a load lock chamber and then analyzed using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) at the same temperature (−100°C). Principal component analysis (PCA) was applied to further analyze ToF‐SIMS spectra of aerosol particles with different pretreatment temperatures from two selected stages. ToF‐SIMS results showed that the intensities of aliphatic hydrocarbon ions such as C4H7+ and C4H9+ and amine ions such as C2H8N+ and C4H12N+ decreased with an increase of the pretreatment temperature under ultrahigh vacuum conditions. We have shown that analyses of this type of aerosol particles using ToF‐SIMS should not be conducted at ambient temperature but at low temperature (eg, −50°C). In addition, we also developed a procedure that can be used to analyze aerosol particle samples under ultrahigh vacuum environment.

Enhanced cellulase accessibility using acid-based deep eutectic solvent in pretreatment of empty fruit bunches

Deep eutectic solvents (DESs) are new and rapid emerging green solvents that have been gaining much attention lately. In this work, DES was prepared by mixing choline chloride with lactic acid with the molar ratio of 1:10 to pretreat empty fruit bunches. The effects of pretreatment temperature, pretreatment time and solid-to-solvent ratio were investigated. A maximum reducing sugars yield of 51.1% was obtained at the operating conditions of 100 °C for 1 h with solid-to-solvent ratio of 1:10 (w/v). The reducing sugars yield obtained for DES pretreatment was higher than dilute acid, alkaline and organosolv pretreatment suggesting DES pretreatment is a promising alternative to conventional pretreatment techniques. Furthermore, there was no reducing sugar loss during DES pretreatment. The outstanding DES pretreatment performance was further confirmed by both Fourier-transform infrared spectroscopy and scanning electron microscopy indicated that DES pretreatment was effective in altering biomass structure by disrupting the hydrogen bonding interactions within the chains of cellulose molecules and lignin extraction.

Effect of pre-treatment temperatures on the film-forming properties of collagen fiber dispersions

Collagen fiber dispersions were formed and the influence of pre-treatment temperatures on the fiber structure and film-forming properties was investigated. A pre-transition at 33.0 °C and a main denaturation transition at around 42.8 °C were observed according to the dynamic temperature sweep of the dispersions. Accordingly, the dispersions were pre-treated at specific temperatures to obtain different structure of collagen fiber. The storage modulus and loss modulus of dispersions decreased sharply at > 39 °C. Also, the viscosity had a similar trend and the power law exponent n became larger. Microstructure and SDS-PAGE analysis showed that high temperature (≥45 °C) destroyed the fiber network and more low molecular weight fragments dissolved in dispersions. The tensile strength and elongation at break of films all decreased with the increase of temperature while the water solubility increased, attributing to the degeneration of collagen. The film hydrophilicity also increased due to more collagen turning into gelatin. However, the water vapor permeability and oxygen permeability of collagen fiber films were improved with the increase of temperature, indicating that suitable heating could improve their barrier properties. Moreover, the layered fiber network in films gradually disappeared with the increase of pre-treatment temperature. All films had typical characteristic infrared peaks of collagen and the values of AIII/A1450 gradually decreased from 1.2976 to 1.0802, indicating reduced contents of triple helix. The intensity of the XRD peaks at ~8° also decreased and higher temperatures promoted the stripping of collagen molecules from collagen fiber, where collagen molecular chains closely contact with each other.

Flame combustion of single wet-torrefied wood particle: Effects of pretreatment temperature and residence time

In this work, combustion behaviors of single wet-torrefied wood particle in a high temperature flame reactor (1226 °C, 4.2 vol% O2) simulating suspension biomass fired combustion were studied. 4 mm schima wood spheres were pretreated at various wet torrefaction (WT) conditions (at 175, 200, 225, 250 °C, for 5, 30, 60 min). For the WT pretreated particle has less mass than the raw feedstock, linear regressions were performed to fit ignition, devolatilization and char burnout time with R2 higher than 0.961, 0.995 and 0.988 respectively. The slopes of the fitting lines, indicating the conversion rates, were then used to assess the combustion time on the basis of per sample mass. All three combustion stages, i.e., ignition, devolatilization and char combustion, are prolonged after WT, which is related to the severity of the torrefaction conditions and the diminished AAEMs content. The largest variation lies in the char combustion behavior: the wet-torrefied wood particle produces significantly less char (accumulated char yield reduced from 8.2% to as low as 2.8% after WT), but the char combustion rate decreases up to a factor of 2.4–4.6. The reduced char reactivity is also confirmed by the TGA analysis.

Improvement of sugar recovery from Sida acuta (Thailand Weed) by NaOH pretreatment and application to bioethanol production

Sida acuta, a common type of weed in Thailand, contains relatively high cellulose (42.7%) content. We pretreated NaOH to improve glucose recovery from S. acuta. The effect of pretreatment temperature and NaOH concentration was fundamentally investigated based on hydrolysis efficiency with recovery of solid fraction. The pretreatment condition was determined to be 3% NaOH at 60 °C for 9 h, which showed the highest glucose recovery. The hydrolysates obtained by enzymatic hydrolysis of S. acuta were applied to the fermentation of Saccharomyces cerevisiae K35, and a theoretical yield of 97.6% was achieved at 18 h. This indicated that the hydrolysates medium without detoxification had no negative effects on the fermentation. The production of biomass into bioethanol was evaluated based on the material balance of 1,000 g basis. Following this estimation, approximately 28 g and 110 g bioethanol could be produced by untreated and pretreated S. acuta, respectively, and this production was improved about 3.9-fold by NaOH pretreatment. These results again show the importance of pretreatment in biorefinery process.

Retraction Notice: Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis

On 3rd March 2018, the Editorial Board of the Mongolian Journal of Chemistry decided to retract the article entitled "Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis" because of an authorship dispute. The article was originally published in Vol.17 No.43 2016 pp.38-41. DOI: http://dx.doi.org/10.5564/mjc.v17i43.745

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

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 (&gt; 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.

Aggravated fine particulate matter emissions from heating-upgraded biomass and biochar combustion: The effect of pretreatment temperature

Heat pretreatment is a promising method for biomass upgrading. However, PM formation from the combustion of such pretreated biomass has not been fully evaluated. In this work, the effect of pretreatment temperature on PM emission of the upgraded biomass and biochar combustion was studied in an entrained flow reactor. The physical and chemical properties of upgraded biomass, biochar and PMs at varied pretreatment temperatures were obtained to illustrate the PM formation mechanism. Results show that pretreatment temperature significantly affects the concentration and particle size distribution of PM emissions, through changing the char yield and K/Cl contents in char. With increase in pretreatment temperature, the PM1.0 emission of upgraded biomass and biochar combustion first increases, reaches maximum at 500°C, and then decreases. A linear relationship between the PM1.0 emission and Cl content in upgraded biomass and biochar was found. This result indicates that the combustion of upgraded biomass and biochar produced at moderate temperatures of 250–500°C result in aggravated fouling and PM emissions.

Investigation of the calcination temperature effect on the interaction between Au nanoparticles and the catalytic support α-Fe 2 O 3 for the low temperature CO oxidation

Abstract Au/α-Fe2O3 catalysts were prepared by deposition-precipitation, and subjected to thermal pretreatment at 150, 200 and 300 °C, and non-calcination (dried at 110 °C). The effect of pretreatment temperature on the catalytic performance was investigated by subtracting the effect of any modifications of the FeOx support structure. The structural, morphological and redox properties of Au/α-Fe2O3 samples were analysed and catalytic activity toward CO oxidation was tested. The size of gold nanoclusters ranged between 3.8 and 6.7 nm. The results showed that the Au-Fe2O3 interface perimeter length and the OSC were minimum within the series for the only dried sample. However, it showed the maximum TOF in CO oxidation (0.163 s−1 at 75 °C). It was found that the content of surface Au1+ species was maximum for this sample. Thus, a better stabilization of AuO-species could be deduced. Also, it exhibited a higher concentration of lattice defects and surface OH− groups. Our results suggest that the amount of oxygen vacancies, which determines the amount of adsorbed oxygen species, and an adequate ratio of Au1+/Au0 (i.e. maximum activity was observed for a value of 0.12) are the predominant features leading to the superior low temperature CO oxidation activity of the non-calcined Au/α-Fe2O3 catalyst.

RETRACTED: Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis

On 3rd March 2018, the Editorial Board of the Mongolian Journal of Chemistry decided to retract the article entitled "Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis" because of an authorship dispute. The article was originally published in Vol.17 No.43 2016 pp.38-41. DOI: http://dx.doi.org/10.5564/mjc.v17i43.745