The effects of naturally occurring nickel in hyperaccumulator plants used for phytoremediation of contaminated soils on the microwave (MW) biomass pyrolysis are described for the first time.
Levoglucosenone (anhydrosugar) is one of the most promising chemicalp latforms derived from the pyrolysis of biomass. It is ac hiral building block for pharmaceuticals as wella sa ni ntermediate in the production of solvents and polymers. Therefore, the development of cost-efficient, low-energy production methods is vital for af uture sustainable biorefinery.H ere, a novel, green approach to the production of levoglucosenone was developedb yu sing am icrowave (MW)-assisted pyrolysis of cellulose in the presence of readily available clays. It was shown that natural and pillared clays in the presence of MW irradiation significantly increaset he yield of levoglucosenone from cellulose. Both the water content and the presence of acid centres are critical characteristics that influence the yield and distributiono fc atalysed products.Au nique experiment was designed by using as ynergetic effect between different types of catalysts, which enhanced the levoglucosenone yield to 12.3 wt %with63% purity.Bio-oil is ac omplex organic mixture resultingf rom thermal processing (pyrolysis) of biomass and biowastea nd represents an alternative renewable source for chemicals and fuels. The majority of individual compounds in bio-oil are multifunctional oxygen-containing chemicals. Someofthem are attractive plat-form molecules ready for industrial use without any prefunctionalization. [1] These platform molecules could form the core of as ustainable and efficient biorefinery.C urrently,o ne of the biggest challenges for such ab iorefinery is separation of the complex bio-oil into individual compounds. The direct distillation of the oxygen-containing compounds is impossible, and the applicationo fc hromatography columns is an expensive decision for the large-scale chemical industry.Apossible solution is selectivei nsitu targeting of the desired compounds duringp yrolysis of biomass (which typically contains hemicellulose, cellulose and lignin). At present,m ost of the problems associated with refiningh emicellulose have been addressed, [2] whereas refining crosslinked lignin requires significant further developments;h ence our focus on cellulose. Pyrolysis of cellulose to ac omplex mixture of chemicals is already developed, but ac ontrollable and sustainable production of the platform molecules levoglucosenone( LGO) and 5-hydroxymethylfurfural (5-HMF) is not. Conventional pyrolysis of cellulose proceeds at high temperatures (T > 360 8C), inducing secondary reactions and therefore producing ac omplex mixture of products.One of the ways to increase selectivity during pyrolysis is catalysis. [3] Natural aluminosilicatess uch as zeolitesa re widely reported to preferentially catalyse the conversion of biomass to aromatic compounds. [4,5] However,a lthough cost-efficient and readily available, clays have not attracted significant attention. Pillared clays (a class of swollen clays modified with avariety of large polynuclear hydroxo-complexes) are of particular interest. [6] Another way to improvep yrolysis selectivity is the application...
Bio-oil (pyrolysis oil) is an essential feedstock for the production of renewable fossil-free fuels and valuable chemicals. Enhancement of the pyrolysis oil yield and its quality are significant challenges for an efficient and sustainable biorefinery. Here, we report the microwave (MW)-assisted noncatalytic pyrolysis of cellulose, as a green and controllable alternative to conventional heating, in the presence of eco-friendly Li-, Na-, K-, Mg-, Ca- and Ba-bentonites. The detailed analysis of the MV heating traces demonstrates that the bentonite MW activity significantly depends on the presence of internal water. The intensity of this interaction is controlled by the cation nature reduced in the order: Li+ > Na+ > K+ and Mg2+ > Ca2+ > Ba2+. A unique experimental design for the MW-assisted pyrolysis of cellulose in the presence of Li-doped clays helps to increase the bio-oil yield to 37.8% with high selectivity towards the commercially useful levoglucosan (purity: 39.36%). The combination of an alternative green heating method and environmentally friendly bentonites can be used many times without recycling. We believe that the improved yields of bio-oil are due to: (i) high MW activity of bentonites, which conventionally increases the heating rates of cellulose; and (ii) production of water by hydrophilic clay minerals, favouring depolymerisation of cellulose.
The study of the quantitative and qualitative composition of the soil microbiota, which adequately reflects the degree of anthropogenic load, can be applied as an indicator of assessment of the ecological status of the soil of anthropogenically transformed biogeocoenosis.The aim of the article is to analyze the species composition of micromycetes of drained soils of the Trubizh river Basin as an indicator of the ecological condition of the soil of different degrees of economic activity. For microbiological analysis samples of organogenic (lowland deep and medium peat soils) and mineral (meadow-chernozemic) soils were used. The samples selected from four experimental plots with different degrees of anthropogenic load. In particular, the first plot is a long-term use fallow (more than 15 years) on deep peatlands, the second one is a field with corn for grain on medium peatlands. The third plot is a field with post-harvest soybean residues on medium peatlands and fourth one is fallow with annual and perennial grasses on meadow-chernozemic soils. Soil samples were taken from the root layer at a depth of 0-5, 5-10 and 10-20 cm according to the current DSTU. Isolation of micromycetes was carried out by dilution method of soil with the object of estimation of the concentration (number of colonies, micromycetes). The count of micromycetes was estimated on surface of potato-glucose agar and Chapek's agar plates and was determined by the number of colony forming units (CFU). It was established that in the plot with increased anthropogenic impact (field with corn for grain on medium peatlands) the total number of isolated micromycetes was twice less than in plots of fallow lands and soybean. There was observed very poor species compositions (13 species). 2 species (15%) of Zygomycota, where predominant concentration was Mucor plumbeus in the soil layer 0-20 cm and 11 species (85%) of Ascomycota were found. In all plots, the basis of micromycete complexes was formed by fungi-destructors of plant remains and root secretions of the genus Penicillium. The micromycetes of drained soils of the Trubizh river Basin was presented the biggest phylum Ascomycota (83-95.5%) and the phylum Zygomycota (4.5-17%) also.
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