Enhancing fuel characteristics and combustion performance of cellulose-rich straws through CO2-assisted torrefaction.

Cellulose-rich straws of corn and rice were torrefied under carbon dioxide, and the fuel characteristics and combustion performance of the obtained biochar were investigated. A high severity resulted in surface collapse, greater pore volume, elimination of oxygen, elevated calorific value, and improved hydrophobicity in biochar. Following carbon dioxide torrefaction, the cellulose content in solid biochar experienced a slight decrease when the temperature was raised to 220 °C for longer residence durations. At 300 °C, the cellulose content in the biochar was nearly eliminated, while the relative proportion of non-sugar organic matter in corn stover and rice straw increased to 87.40 % and 77.27 %, respectively. The maximum calorific values for biochar from corn and rice straws were 22.38 ± 0.03 MJ/kg and 18.72 ± 0.05 MJ/kg. The comprehensive combustion indexes of rice and corn straw samples decreased to 1.06 × 10-7 and 1.31 × 10-7 after torrefaction at 300 °C, respectively. In addition, the initial decomposition temperatures increased by 38 °C and 45 °C, while the ultimate combustion temperatures rose by 13 °C and 16 °C for corn and rice straws, respectively. These results imply an extended combustion timeframe for the torrefied samples.

Synthesis of lignin nanoparticle­manganese dioxide complex and its adsorption of methyl orange.

Lignin nanoparticles (LNPs) were synthesized using an anti-solvent method and subsequently loaded with manganese dioxide (MnO2) via potassium permanganate treatment, resulting in the formation of MnO2@LNPs. An extensive investigation was conducted to elucidate the influence of MnO2@LNPs on the decolorization of methyl orange solution. The LNPs were successfully obtained by adjusting the preparation parameters, yielding particles exhibited average sizes ranging from 300 to 600 nm, and the synthesis process exhibited a high yield of up to 87.3% and excellent dispersion characteristics. Notably, LNPs size was reduced by decreasing initial concentration, increasing stirring rate, and adding water. In the acetone-water two-phase system, LNPs self-assembled into spherical particles driven by π-π interactions and hydrogen bond forces. Oxidation modification using potassium permanganate led to the formation of nanoscale MnO2, which effectively combined with LNPs. Remarkably, the resulting MnO2@LNPs demonstrated a two-fold increase in methyl orange adsorption capacity (227 mg/g) compared to unmodified LNPs. The process followed the Langmuir isotherm model and was exothermic.

Freeze-thaw assisted maleic acid pretreatment of eucalyptus to prepare cellulose nanocrystals and degraded lignin.

A green and effective method is proposed for the pretreatment of eucalyptus by freeze-thaw assisted maleic acid tactic, wherein the effects of freeze-thaw, maleic acid concentration, reaction time, and temperature on the fractionation were examined. Results showed that under optimal conditions (60% maleic acid, 120 °C, and 2 h), a remarkable removal of 74.5% lignin and 95.2% hemicellulose was achieved after freeze-thaw treatment. The resulting cellulose-rich solid residues were further processed with maleic acid to prepare cellulose nanocrystals, which displayed uniform sized rod-like structures and high crystallinity (62.51%). Moreover, maleic acid pretreatment resulted in lignin with low molecular weight (2110-2530) and excellent homogeneity (PDI ≤ 1.86), while maintaining a relatively intact structure. The lignin had high ß-O-4 aryl ether bond contents (≥77.5%) and abundant phenolic hydroxyl contents (2.33-3.63 mmol/g). Overall, the process exhibits notable benefits in effectively separating lignocellulose for high valorization.

Experimental evaluation of a hybrid solar dryer with flexible open sorption thermal energy storage unit on demand for burdock root drying.

Solar drying represents an attractive way to implement an efficient and green development strategy. The viability of open sorption thermal energy storage (OSTES) can compensate for the inherent shortcomings of intermittency and instability of solar energy for ensuring the continuity of the drying process. Nevertheless, the existing solar-powered OSTES technologies only allow a batch mode while being severely restricted by sunlight's availability, thereby heavily limiting the flexibility in managing OSTES on demand. Herein, a novel proof-of-concept that a standalone solar dryer integrated with a reversible solid-gas OSTES unit is presented. Using in situ electrothermal heating (in situ ETH) could rapidly release adsorbed water of activated carbon fibers (ACFs) in an energy-efficient manner to achieve a charging process with faster kinetics. Applying electrical power by a photovoltaic (PV) module, particularly during sunlight-absent or insufficient time, allowed multiple OSTES cycles to proceed. Moreover, ACFs cylindrical cartridges can be flexibly interconnected in either series or parallel, forming universal assemblies with well-controlled in situ ETH capacity. The mass storage density of ACFs with a water sorption capacity of 570 mg/g is 0.24 kW·h·kg-1. The desorption efficiencies of ACFs are higher than 90%, corresponding to 0.057 kW·h maximum energy consumption. The resulting prototype can diminish the fluctuation of air humidity along the night and provide a relatively steady and lower air humidity for the drying chamber. The energy-exergy and environment analysis of the drying section for both setups are estimated, respectively.

Optimization of ethanol-extracted lignin from palm fiber by response surface methodology and preparation of activated carbon fiber for dehumidification.

Lignin is a renewable bioresource that can be used for a variety of value-added applications. However, the effective separation of lignin from lignocellulosic biomass remains an ongoing challenge. In this study, lignin was extracted from waste palm fiber and successfully converted into a dehumidifying material. The following four process parameters of lignin extraction from palm fiber were optimized systematically and comprehensively using the response surface methodology: reaction time, extraction temperature, ethanol concentration and solid/liquid ratio. The results revealed that under the optimum processing conditions (111 min of extraction at 174 °C using 73% ethanol at 1/16 g/mL solid/liquid ratio), the extraction yield of lignin was 56.2%. The recovery of ethanol solvent was as high as 91.8%. Further, the lignin could be directly used without purification to produce lignin-based activated carbon fibers (LACFs) with specific surface area and total pore volume of 1375 m2/g and 0.881 cm3/g, respectively. Compared with the commercial pitch-based activated carbon fiber, the LACF has a higher specific area and superior pore structure parameters. This work provides a feasible route for extracting lignin from natural palm fiber and demonstrates its use in the preparation of activated carbon fiber with a remarkable performance as a solid dehumidification agent.

Adsorption equilibrium and kinetics for SO2, NO, CO2 on zeolites FAU and LTA.

In order to develop a single-step process for removing SO(2), NO, CO(2) in flue gas simultaneously by co-adsorption method. Pure component adsorption equilibrium and kinetics of SO(2), NO, and CO(2) on zeolite NaY, NaX, CaA were obtained respectively. Equilibrium data were analyzed by equilibrium model and Henry's law constant. The results suggest that Adsorption affinity follows the trend SO(2)>CO(2)>NO for the same adsorbent. Zeolite with stronger polar surface is a more promising adsorbent candidate. Kinetics behavior was investigated using the breakthrough curve method. The overall mass transfer coefficient and diffusivity factor were determined by a linear driving force model. The results are indicative of micropore diffusion controlling mechanism. NaY zeolite has the minimum resistance of mass transfer duo to the wide pore distribution and large pore amount. CaA zeolite exhibits the highest spatial hindered effect. Finally, co-adsorption effect of SO(2), NO, and CO(2) were investigated by multi-components breakthrough method. SO(2) and NO may form new adsorbed species, however, CO(2) presents a fast breakthrough. Chemical adsorption causes SO(2) transforms to SO(4)(2-), however, element N and C are not detected in adsorbed zeolites.

Gastric and duodenum microflora analysis after long-term Helicobacter pylori infection in Mongolian Gerbils.

BACKGROUND: Long-term Helicobacter pylori infection leads to chronic gastritis, peptic ulcer, and gastric malignancies. Indigenous microflora in alimentary tract maintains a colonization barrier against pathogenic microorganisms. This study is aimed to observe the gastric and duodenum microflora alteration after H. pylori infection in Mongolian Gerbils model. MATERIALS AND METHODS: A total of 18 Mongolian gerbils were randomly divided into two groups: control group and H. pylori group that were given H. pylori NCTC J99 strain intragastrically. After 12 weeks, H. pylori colonization was identified by rapid urease tests and bacterial culture. Indigenous microorganisms in stomach and duodenum were analyzed by culture method. Histopathologic examination of gastric and duodenum mucosa was also performed. RESULTS: Three of eight gerbils had positive H. pylori colonization. After H. pylori infection, Enterococcus spp. and Staphylococcus aureus showed occurrences in stomach and duodenum. Lactobacillus spp. showed a down trend in stomach. The levels and localizations of Bifidobacterium spp., Bacteroides spp., and total aerobes were also modified. Bacteroides spp. significantly increased in H. pylori positive gerbils. No Enterobacteriaceae were detected. Positive colonization gerbils showed a higher histopathologic score of gastritis and a similar score of duodenitis. CONCLUSIONS: Long-term H. pylori colonization affected the distribution and numbers of indigenous microflora in stomach and duodenum. Successful colonization caused a more severe gastritis. Gastric microenvironment may be unfit for lactobacilli fertility after long-term H. pylori infection, while enterococci, S. aureus, bifidobacteria, and bacteroides showed their adaptations.

Effects of four Bifidobacteria on obesity in high-fat diet induced rats.

AIM: To compare the effects of four Bifidobacteria strains (Bifidobacteria L66-5, L75-4, M13-4 and FS31-12, originated from normal human intestines) on weight gain, lipid metabolism, glucose metabolism in an obese murine model induced by high-fat diet. METHODS: Forty-eight Sprague-Dawley rats were randomly divided into six groups. Control group received standard chow, model group received high-fat diet, and intervention groups received high-fat diet added with different Bifidobacteria strains isolated from healthy volunteers' fresh feces. All rats were executed at the 6th weekend. Body weight (BW), obese indexes, oral glucose tolerance test, serum and liver lipid and serum insulin (INS) were tested. Liver lipid deposition was classified pathologically. RESULTS: Compared with the model group, B. M13-4 improved BW gains (264.27 +/- 26.91 vs 212.55 +/- 18.54, P = 0.001) while B. L66-5 induced a decrease in BW (188.47 +/- 11.96 vs 212.55 +/- 18.54, P = 0.043). The rest two strains had no significant change in BW. All the four strains can reduce serum and liver triglyceride and significantly alleviate the lipid deposition in liver. All strains showed a trend of lowing serum and liver total cholesterol while B. L66-5 and B. FS31-12 did so more significantly. In addition, all the four strains showed no significant differences in serum INS and glucose level. CONCLUSION: The response of energy metabolism to administration of Bifidobacteria is strain dependent. Different strains of Bifidobacteria might drive different directions of fat distribution.