Straw lignin degradation by lignin peroxidase from Irpex lacteus cooperated with enzymes and small molecules.

OBJECTIVES: Maximizing the utility value of enzymes was achieved by exploring the effects of small molecules on the efficiency of lignin degradation by lignin peroxidase. METHODS: Using wheat straw as raw material and taking lignin degradation rate as index, it was found that laccase, glucose oxidase, malonic acid, citric acid, ZnSO4, CaCl2 could promote the lignin degradation by the lignin peroxidase from Irpex lacteus, respectively. Moreover, glucose oxidase, malonic acid and CaCl2 had obvious synergy effects on lignin degradation by the lignin peroxidase. RESULTS: The optimal conditions of lignin degradation were obtained by response surface experiment: 4% glucose oxidase, 0.74% malonic acid and 3.29% CaCl2 were added for synergistic degradation at 37 â„ƒ with 50% of water content. After 72 h quickly enzymatic hydrolysis, the degradation rate of lignin was 45.84%. CONCLUSIONS: A new green and efficient method for lignin removal from straw was obtained, which provided a reference for the efficient utilization of straw and lignin peroxidase.

Co-pyrolysis of medical protective clothing and oil palm wastes for biofuel: Experimental, techno-economic, and environmental analyses.

The ongoing global pandemic of COVID-19 has devastatingly influenced the environment, society, and economy around the world. Numerous medical resources are used to inhibit the infectious transmission of the virus, resulting in massive medical waste. This study proposes a sustainable and environment-friendly method to convert hazardous medical waste into valuable fuel products through pyrolysis. Medical protective clothing (MPC), a typical medical waste from COVID-19, was utilized for co-pyrolysis with oil palm wastes (OPWs). The utilization of MPC improved the bio-oil properties in OPWs pyrolysis. The addition of catalysts further ameliorated the bio-oil quality. HZSM-5 was more effective in producing hydrocarbons in bio-oil, and the relevant reaction pathway was proposed. Meanwhile, a project was simulated to co-produce bio-oil and electricity from the co-pyrolysis of OPWs and MPC from application perspectives. The techno-economic analysis indicated that the project was economically feasible, and the payback period was 6.30-8.75 years. Moreover, it was also environmentally benign as its global warming potential varied from -211.13 to -90.76 kg CO2-eq/t. Therefore, converting MPC and OPWs into biofuel and electricity through co-pyrolysis is a green, economic, and sustainable method that can decrease waste, produce valuable fuel products, and achieve remarkable economic and environmental benefits.

Organocatalytic asymmetric syntheses of 3-fluorooxindoles containing vicinal fluoroamine motifs.

An organocatalytic Mannich reaction of 3-fluorooxindoles has been developed. Using a commercially available cinchona alkaloid catalyst, a wide range of 3-fluorooxindoles was successfully reacted with N-sulfonyl aldimines to give biologically important 3-fluorooxindoles containing vicinal fluoroamine motifs with high efficiency and good enantioselectivity. This protocol uses readily available reactants and cheap organocatalysts, and it is operationally simple.

Display of Lignin Peroxidase on the Surface of Bacillus subtilis.

Lignin peroxidase (LiP) has a good application prospect in lignin degradation, environmental treatment, straw feed, and other industries. However, its application is constrained by the high price and low stability of enzyme preparation. In this study, the Escherichia coli-Bacillus subtilis (E. coli-B. subtilis) shuttle expression vector pHS-cotG-lip was constructed and displayed on the surface of Bacillus subtilis spores. The analysis of enzymatic properties showed that the optimal catalytic temperature and pH of the immobilized LiP were 55 °C and 4.5, respectively. Compared with free LiP (42 °C and pH4.0), the optimal reaction temperature increased by 13 °C. After incubation at 70 °C for 1 h, its activity remained above 30%, while the free LiP completely lost its activity under the same conditions. Adding Mn2+, DL-lactic acid, and PEG-4000 increased the CotG-LiP enzyme activity to 313%, 146%, and 265%, respectively. The recyclability of spore display made the fusion protein CotG-LiP retain more than 50% enzyme activity after four cycles. The excellent recycling rate indicated that LiP displayed on the spore surface had a good application prospect in sewage treatment and other fields, and also provided a reference for the rapid and low-cost immobilized production of enzyme preparations.

Study on the detection of water status of tomato (Solanum lycopersicum L.) by multimodal deep learning.

Water plays a very important role in the growth of tomato (Solanum lycopersicum L.), and how to detect the water status of tomato is the key to precise irrigation. The objective of this study is to detect the water status of tomato by fusing RGB, NIR and depth image information through deep learning. Five irrigation levels were set to cultivate tomatoes in different water states, with irrigation amounts of 150%, 125%, 100%, 75%, and 50% of reference evapotranspiration calculated by a modified Penman-Monteith equation, respectively. The water status of tomatoes was divided into five categories: severely irrigated deficit, slightly irrigated deficit, moderately irrigated, slightly over-irrigated, and severely over-irrigated. RGB images, depth images and NIR images of the upper part of the tomato plant were taken as data sets. The data sets were used to train and test the tomato water status detection models built with single-mode and multimodal deep learning networks, respectively. In the single-mode deep learning network, two CNNs, VGG-16 and Resnet-50, were trained on a single RGB image, a depth image, or a NIR image for a total of six cases. In the multimodal deep learning network, two or more of the RGB images, depth images and NIR images were trained with VGG-16 or Resnet-50, respectively, for a total of 20 combinations. Results showed that the accuracy of tomato water status detection based on single-mode deep learning ranged from 88.97% to 93.09%, while the accuracy of tomato water status detection based on multimodal deep learning ranged from 93.09% to 99.18%. The multimodal deep learning significantly outperformed the single-modal deep learning. The tomato water status detection model built using a multimodal deep learning network with ResNet-50 for RGB images and VGG-16 for depth and NIR images was optimal. This study provides a novel method for non-destructive detection of water status of tomato and gives a reference for precise irrigation management.

The effect of torrefaction and ZSM-5 catalyst for hydrocarbon rich bio-oil production from co-pyrolysis of cellulose and low density polyethylene via microwave-assisted heating.

This study aims to investigate the effect of microwave torrefaction and ZSM-5 catalyst for hydrocarbon rich bio-oil production from microwave co-pyrolysis of cellulose and low density polyethylene (LDPE). FTIR analysis displayed remarkable reductions of active hydroxyl and ether groups in microwave torrefied cellulose (MTC), demonstrating that cellulose was less stable than MTC. GC/MS analysis indicated that the hydrocarbons content was ranged from 18.36% to 54.94% in the obtained bio-oils under different conditions, and the maximum hydrocarbons content (54.94%) which also contained the highest aromatic hydrocarbons (19.49%) was obtained from MTC catalytic co-pyrolysis. Microwave-assisted Thermogravimetric analyzer (MW-TGA) analysis showed that MTC catalytic co-pyrolysis apparently shifted the major thermal degradation to a lower temperature area, an evident synergistic effect was observed during MTC catalytic co-pyrolysis. Kinetics study revealed that the activation energy was significantly reduced from 97.87 kJ/mol to 63.86 kJ/mol for co-pyrolysis and MTC catalytic co-pyrolysis, respectively.

Microwave-assisted liquefaction of carbohydrates for 5-hydroxymethylfurfural using tungstophosphoric acid encapsulated dendritic fibrous mesoporous silica as a catalyst.

Tungstophosphoric acid (TPA) encapsulated dendritic fibrous silica KCC-1 was prepared via a microemulsion system with the simple reflux method using cetyltrimethylammonium bromide as a structure-directing agent. The TPA impregnated on KCC-1 (ITPA-KCC-1) was also prepared for comparative. Various physicochemical techniques were used to characterize the synthesized materials and their activity evaluated in the 5-hydroxymethylfurfural (HMF) formation from carbohydrates derivatives of fructose, glucose and cellulose. The effect of various factors such as catalyst to substrate ratio, different solvents and temperature were investigated on the formation of HMF. The resultant encapsulated catalyst was very active in fructose dehydration with the yield of 92% HMF and full conversion of fructose at 120 °C for 30 min under the microwave heating condition without any salt additive in the THF solvent system as well as 95% in MIBK solvent. The HMF yield was achieved by 58% and 16.2% from glucose and cellulose in the DMSO solvent, respectively. The TPA-KCC-1 can be separated easily after reaction from the reaction mixture and reused atleast five times without substantial loss in catalytic activity. This study provides an easy encapsulation method for TPA in dendritic fibrous silica KCC-1 as a heterogeneous catalyst, and it should have great application potential in other biomass valorization processes.

Study on reaction mechanism of superior bamboo biochar catalyst production by molten alkali carbonates pyrolysis and its application for cellulose hydrolysis.

Biochar has attracted wide interest due to its important role in the synthesis of functionalized carbon materials. Molten alkali carbonates (MC) pyrolysis as a novel mean was explored to obtain superior bamboo biochar compared with alkali impregnation pretreating bamboo powder associated with pyrolysis. The properties of biochar produced by MC pyrolysis were enhanced, suggesting an increase in BET surface area of 43.59 m2/g compared with non-pretreat biochar of 5.76 m2/g, and possessed preferable pore structure than the alkali impregnation one of 39.82 m2/g and 16.98 nm for catalyst support. Besides, pyrolysis temperature reinforced the porosity and the degree of carbonization as it rising, however, the optimized temperature for top-grade biochar materials was 450 °C. The MC weakened the hydrogen bonds network in bamboo powder acting a similar role just as alkaline pretreated, meanwhile neutralized the acid produced during pyrolysis process supported by the analysis of FTIR and TGA. The potential pathways of biomass pyrolysis with MC had also been proposed. In addition, the biochar obtained was utilized as a catalyst support of biochar-bearing sulfonic acid groups, which achieved the remarkable yields of TRS and glucose (52.8% and 43.5%) in hydrolysis of cellulose.

Itaconic acid production from undetoxified enzymatic hydrolysate of bamboo residues using Aspergillus terreus.

Itaconic acid (IA) production by fermentation of undetoxified hydrolysate of bamboo residues by Aspergillus terreus was demonstrated. Monosaccharides were obtained by pretreatment and enzymatic hydrolysis of bamboo residues. A. terreus could not grow and synthesize IA in the hydrolysate. The buffer was confirmed to be an inhibitor, and was successfully replaced by deionized water as the suspension, to release equivalent sugar and eliminate the inhibition. Corn steep liquor significantly improved the adaptability of A. terreus to the hydrolysate at 2.0 g/L. The IA titer obtained (19.35 g/L IA) was the highest to be reported for IA production from lignocellulose without detoxification. Simultaneous saccharification and fermentation and fed-batch fermentation increased the titer to 22.43 g/L and 41.54 g/L, respectively. Meanwhile, economic assessment proved that bamboo residues were potential substrates for IA production with economic effectiveness.

Protective effects of resveratrol on acute kidney injury in rats with sepsis.

AIM: To evaluate the protective effects of resveratrol on acute kidney injury (AKI) in septic rats. METHODS: A septic rat model was established by cecal ligation and puncture (CLP). A total of 108 male Sprague Dawley rats were randomly divided into an observation group, a 6 h resveratrol intervention group and a 12 h resveratrol intervention group. Then each group was subdivided into Sham, Sham + Res, CLP and CLP + Res groups. After surgery, the survival and morphological changes in kidney tissues were observed. Serum creatinine and urea nitrogen levels, expression of GRP78, BiP, IRE1 and p65 in kidney tissues, and serum levels of TNF-α, IL-1ß, IL-6 and IL-10 were investigated. RESULTS: The survival rate of CLP + Res group (75.00%) significantly exceeded that of the CLP group (41.67%) (P<0.05). At postoperative 12 h, resveratrol significantly decreased serum creatinine and urea nitrogen levels (P<0.05). Resveratrol evidently relieved renal tubular swelling and luminal narrowing in CLP rats, and significantly reduced the high expressions of GRP78, BiP, phosphorylated IRE1 and p65 proteins (P<0.05). P65 was mainly located in the cytoplasm of Sham, Sham + Res and CLP + Res groups, and in the nucleus of the CLP group. At postoperative 12 h, resveratrol significantly reduced serum levels TNF-α, IL-1ß and IL-6 in CLP rats (P<0.05), whereas elevated that of IL-10 (P<0.05). CONCLUSION: Resveratrol significantly decreased the mortality rate of septic rats and alleviated AKI, probably by attenuating endoplasmic reticulum stress, inhibiting activation of the NF-κB pathway and mitigating the inflammatory response.

Two-stage alkali-oxygen pretreatment capable of improving biomass saccharification for bioethanol production and enabling lignin valorization via adsorbents for heavy metal ions under the biorefinery concept.

Converting lignin into value-added products in current lignocellulosic biorefineries has been challenging, which in turn restricts the commercialization of many lignocellulosic biorefineries. In this work, a two-stage alkali-oxygen assisted liquid hot water pretreatment (AlkOx) was proposed as the first step of biorefinery. This alkali-oxygen pretreatment facilitated biomass fractionation by solubilizing majority of lignin in water-soluble fraction, while remaining most of cellulose and hemicellulose in water-insoluble fraction. As a result, biomass saccharification was significantly improved by selective removal and oxidative modification of lignin through alkali-oxygen pretreatment. Moreover, lignin residues from both pretreatment hydrolysate and enzymatic hydrolysate were shown to be favorable adsorbents for Pb(II) ions, with adsorption capacity of 263.16 and 90.91 mg/g, respectively. Results demonstrated that this integrated process could not only improve biomass saccharification but also enable lignin valorization, which encouraged the holistic utilization of lignin residues as part of an integrated biorefinery.

Integrated process for the coproduction of fermentable sugars and lignin adsorbents from hardwood.

This work proposed an integrated process based on alkali-sulfite (AlkSul) pretreatment to coproduce fermentable sugars and lignin adsorbents from hardwood. Different from conventional liquid hot water (LHW) pretreatment, this pretreatment improved cellulose accessibility through selective lignin removal and modification, resulting in significantly enhanced biomass saccharification. Over 75% of the original cellulose and hemicellulose was released and could be recovered as fermentable sugars after pretreatment and subsequent enzymatic hydrolysis. Meanwhile, lignin residues from pretreatment hydrolysate and enzymatic hydrolysate showed lead ions adsorption capacities of 156.25 and 68.49 mg/g, respectively, indicating both streams of lignin residues were favorable adsorbents for heavy metal ions. The improved adsorption capacity of lignin residues was primarily due to the lignin modification as sulfur-containing functional groups incorporation during the integrated pretreatment. Results demonstrated the integrated alkali-sulfite pretreatment improved biomass saccharification, while coproducing lignin adsorbents for wastewater treatment, which can promote the sustainability of lignocellulosic biorefinery.

Hydrocarbon rich bio-oil production, thermal behavior analysis and kinetic study of microwave-assisted co-pyrolysis of microwave-torrefied lignin with low density polyethylene.

This study aims to enhance the quality of biofuel through microwave torrefaction pretreatment for lignin. Low density polyethylene (LDPE) was added as a hydrogen source during microwave co-pyrolysis along with the microwave-torrefied lignin (MTL). The thermal degradation behavior and kinetic study of MTL co-pyrolysis with LDPE by microwave-assisted heating was investigated as well. The results indicated that the hydrocarbon content in the bio-oil obtained from microwave co-pyrolysis of MTL and LDPE increased significantly (about 80%). It was also noticed that the aromatic hydrocarbon content increased from 1.94% to 22.83% with the addition of LDPE. Thermal behavior analysis and reaction kinetic study showed that the addition of LDPE into MTL had the effect of promoting thermal degradation and improving reaction rate during microwave-assisted pyrolysis.

Thermal decomposition behavior and kinetics for pyrolysis and catalytic pyrolysis of Douglas fir.

In this study, the thermal decomposition behavior and kinetics of pyrolysis and catalytic pyrolysis of Douglas fir (DF) were investigated using thermogravimetric (TG) analysis. It was found that the heating rate was an important factor during the biomass pyrolysis process, it affected the pyrolysis though heat transfer and mass transfer through the biomass particles. The differential thermogravimetric (DTG) curves demonstrated that the role of the catalyst was to slightly reduce the temperature of biomass thermal degradation. We obtained the thermal data including the activation energy, frequency factor and reaction order by Coats-Redfern and Friedman methods. For the Coats-Redfern method, we found that the activation energy of the catalytic pyrolysis was lower than that of the non-catalytic pyrolysis. It means that the ZSM-5 catalyst increased the rate of reaction and reduced the energy required for the decomposition process. Meanwhile, the result from the Friedman method demonstrated that the reaction could be divided into two steps, which were reaction rate between 0.2 and 0.7 and a reaction rate of 0.8 based on parallelism. Addition of the ZSM-5 catalyst reduced the activation energy in the first region then increased it in the second region due to the secondary cracking of intermediate compounds which was highly affected by shape-selective catalysis. Simulation of pyrolysis and catalytic pyrolysis of DF using the obtained kinetic parameters was in good agreement with the experimental data. Py-GC/MS analysis was also carried out and indicated that the ZSM-5 catalyst had a highly positive effect on aromatic hydrocarbon production by significantly reducing oxygen-containing compounds (i.e. acids, esters, ketones/aldehydes and guaiacols) during the catalytic pyrolysis of DF.

Thermal behavior and kinetic study for co-pyrolysis of lignocellulosic biomass with polyethylene over Cobalt modified ZSM-5 catalyst by thermogravimetric analysis.

The thermal behavior and kinetic study of lignocellulosic biomass (rice straw (RS)) and linear low-density polyethylene (LLDPE) pyrolysis over modified ZSM-5 catalyst were investigated using thermo-gravimetric analysis (TGA). Cellulose and lignin were used as model compounds of biomass in order to investigate the reaction mechanism of lignocellulosic biomass and polyethylene co-pyrolysis. Results showed that RS&LLDPE co-pyrolysis was more complicated than that of the individual components. The activation energy (E) of RS, and RS&LLDPE pyrolysis were 79.61kJ/mol and 59.70kJ/mol respectively, suggesting that there was a positive synergistic interaction between RS and LLDPE. The addition of LLDPE with lignin co-pyrolysis obtained a lower apparent activation energy (33.39kJ/mol) compared to raw lignin pyrolysis (53.10kJ/mol). Results indicated that the Cobalt modified ZSM-5 catalyst was able to improve the reaction rate of RS and LLDPE co-pyrolysis; also the addition of Co/ZSM-5 catalyst resulted in a lower apparent activation energy during cellulose and LLDPE co-pyrolysis.

A techno-economic evaluation of anaerobic biogas producing systems in developing countries.

Biogas production has been the focus of many individuals in the developing world; there have been several investigations that focus on improving the production process and product quality. In the developing world the lack of advanced technology and capital has hindered the development of energy production. Renewable energy has the potential to improve the standard of living for most of the 196 countries which are classified as developing economies. One of the easiest renewable energy compounds that can be produced is biogas (bio-methane). Biogas can be produced from almost any source of biomass through the anaerobic respiration of micro-organisms. Low budget energy systems are reviewed in this article along with various feedstock sources. Adapted gas purification and storage systems are also reviewed, along with the possible economic, social, health and environmental benefits of its implementation.

A review of catalytic microwave pyrolysis of lignocellulosic biomass for value-added fuel and chemicals.

Lignocellulosic biomass is an abundant renewable resource and can be efficiently converted into bio-energy by a bio-refinery. From the various techniques available for biomass thermo-chemical conversion; microwave assisted pyrolysis (MAP) seems to be the very promising. The principles of microwave technology were reviewed and the parameters for the efficient production of bio-oil using microwave technology were summarized. Microwave technology by itself cannot efficiently produce high quality bio-oil products, catalysts are used to improve the reaction conditions and selectivity for valued products during MAP. The catalysts used to optimize MAP are revised in the development of this article. The origins for bio-oils that are phenol rich or hydrocarbon rich are reviewed and their experimental results were summarized. The kinetics of MAP is discussed briefly in the development of the article. Future prospects and scientific development of MAP are also considered in the development of this article.

Bio-based phenols and fuel production from catalytic microwave pyrolysis of lignin by activated carbons.

The aim of this study is to explore catalytic microwave pyrolysis of lignin for renewable phenols and fuels using activated carbon (AC) as a catalyst. A central composite experimental design (CCD) was used to optimize the reaction condition. The effects of reaction temperature and weight hourly space velocity (WHSV, h(-1)) on product yields were investigated. GC/MS analysis showed that the main chemical compounds of bio-oils were phenols, guaiacols, hydrocarbons and esters, most of which were ranged from 71% to 87% of the bio-oils depending on different reaction conditions. Bio-oils with high concentrations of phenol (45% in the bio-oil) were obtained. The calorific value analysis revealed that the high heating values (HHV) of the lignin-derived biochars were from 20.4 to 24.5 MJ/kg in comparison with raw lignin (19 MJ/kg). The reaction mechanism of this process was analyzed.

The effects of torrefaction on compositions of bio-oil and syngas from biomass pyrolysis by microwave heating.

Microwave pyrolysis of torrefied Douglas fir sawdust pellet was investigated to determine the effects of torrefaction on the biofuel production. Compared to the pyrolysis of raw biomass, the increased concentrations of phenols and sugars and reduced concentrations of guaiacols and furans were obtained from pyrolysis of torrefied biomass, indicating that torrefaction as a pretreatment favored the phenols and sugars production. Additionally, about 3.21-7.50 area% hydrocarbons and the reduced concentration of organic acids were obtained from pyrolysis of torrefied biomass. Torrefaction also altered the compositions of syngas by reducing CO2 and increasing H2 and CH4. The syngas was rich in H2, CH4, and CO implying that the syngas quality was significantly improved by torrefaction process.