다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Soil amendment with biochar is evaluated globally as a means to improve soil fertility and to mitigate climate change. However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties. A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins. However, no studies exist in the soil biologyliterature that recognize the observed largevariations ofbiochar physico-chemical properties. This shortcoming has hampered insight into mechanisms by which biochar influences soil microorganisms, fauna and plant roots. Additional factors limiting meaningful interpretation of many datasets are the clearly demonstrated sorption properties that interfere with standard extraction procedures for soil microbial biomass or enzyme assays, and the confounding effects of varying amounts of minerals. In most studies, microbial biomass has been found to increase as a result of biochar additions, with significant changes in microbial community composition and enzyme activities that may explain biogeochemical effects of biochar on element cycles, plant pathogens, and crop growth. Yet, very little is known about the mechanisms through which biochar affects microbial abundance and community composition. The effects of biochar on soil fauna are even less understood than its effects on microorganisms, apart from several notable studies on earthworms. It is clear, however, that sorption phenomena, pH and physical properties of biochars such as pore structure, surface area and mineral matter play important roles in determining how different biochars affect soil biota. Observations on microbial dynamics lead to the conclusion of a possible improved resource use due to co-location of various resources in and around biochars. Sorption and therebyinactivation of growth-inhibiting substances likelyplaysa rolefor increased abundance of soil biota. No evidence exists so far for direct negative effects of biochars on plant roots. Occasionally observed decreases in abundance of mycorrhizal fungi are likely caused by concomitant increases in nutrient availability,reducing theneedfor symbionts.Inthe shortterm,therelease ofavarietyoforganic molecules from fresh biochar may in some cases be responsible for increases or decreases in abundance and activity of soil biota. A road map for future biochar research must include a systematic appreciation of different biochar-types and basic manipulative experiments that unambiguously identify the interactions between biochar and soil biota.

http://www.css.cornell.edu/faculty/lehmann/pictures/publ/SoilBiolBiochem%2043,%201812–1836,%202011%20Lehmann.pdf

Biochar effects on soil biota – A review

Organic and inorganic contaminants removal from water with biochar, a renewable, low cost and sustainable adsorbent--a critical review.

The forms of alkalis in the biochar produced from crop residues at different temperatures

Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.

Lignocellulosic biomass pyrolysis: A review of product properties and effects of pyrolysis parameters

Thermochemical processing of biomass produces a solid product containing char (mostly carbon) and ash. This char can be combusted for heat and power, gasified, activated for adsorption applications, or applied to soils as a soil amendment and carbon sequestration agent. The most advantageous use of a given char depends on its physical and chemical characteristics, although the relationship of char properties to these applications is not well understood. Chars from fast pyrolysis and gasification of switchgrass and corn stover were characterized by proximate analysis, CHNS elemental analysis, Brunauer-Emmet-Teller (BET) surface area, particle density, higher heating value (HHV), scanning electron microscopy, X-ray fluorescence ash content analysis, Fourier transform infrared spectroscopy using a photo-acoustic detector (FTIR-PAS), and quantitative 13C nuclear magnetic resonance spectroscopy (NMR) using direct polarization and magic angle spinning. Chars from the same feedstocks produced under slow pyrolysis conditions, and a commercial hardwood charcoal, were also characterized. Switchgrass and corn stover chars were found to have high ash content (32–55 wt %), much of which was silica. BET surface areas were low (7–50 m2/g) and HHVs ranged from 13 to 21 kJ/kg. The aromaticities from NMR, ranging between 81 and 94%, appeared to increase with reaction time. A pronounced decrease in aromatic CH functionality between slow pyrolysis and gasification chars was observed in NMR and FTIR-PAS spectra. NMR estimates of fused aromatic ring cluster size showed fast and slow pyrolysis chars to be similar (∼7–8 rings per cluster), while higher-temperature gasification char was much more condensed (∼17 rings per cluster). © 2009 American Institute of Chemical Engineers Environ Prog, 2009

Characterization of biochar from fast pyrolysis and gasification systems

It is clear that the density and porosity of biochar will impact its mobility in the environment, its interaction with the soil hydrologic cycle, and its suitability as an ecological niche for soil microorganisms. However, the wide range of biochar pore sizes complicates biochar porosity characterization, making it challenging to find methods appropriate to connect the fundamental physical properties of density and porosity to environmental outcomes. Here, we report the use of two fast, simple density measurement techniques to characterize biochar density and porosity. We measured biochar skeletal density by helium pycnometry and envelope density by displacement of a dry granular suspension. We found that biochar skeletal density ranged from 1.34 g cm−3 to 1.96 g cm−3, and increased with pyrolysis temperature. Biochar envelope density ranged from 0.25 g cm−3 to 0.60 g cm−3, and was higher for wood biochars than grass biochars—a difference we attribute to plant cell structures preserved during pyrolysis. We compared the pore volumes measured by pycnometry with those measured by nitrogen gas sorption and mercury porosimetry. We show that biochar pore volumes measured by pycnometry are comparable to the values obtained by mercury porosimetry, the current benchmark method. We also show that the majority of biochar pore volume is in macropores, and thus, is not measured by gas sorption analysis. These fast, simple techniques can now be used to study the relationship between biochar's physical properties and its environmental behaviors.

New approaches to measuring biochar density and porosity

One factor limiting the understanding and evaluation of biochar for soil amendment and carbon sequestration applications is the scarcity of long-term, large-scale field studies. Limited land, time, and material resources require that biochars for field trials be carefully selected. In this study, 17 biochars from the fast pyrolysis, slow pyrolysis, and gasification of corn stover, switchgrass, and wood were thoroughly characterized and subjected to an 8-week soil incubation as a way to select the most promising biochars for a field trial. The methods used to characterize the biochars included proximate analysis, CHNS elemental analysis, Brunauer–Emmett–Teller surface (BET) area, photo-acoustic Fourier transform infrared spectroscopy, and quantitative 13 C solid-state nuclear magnetic resonance (NMR) spectroscopy. The soil incubation study was used to relate biochar properties to three soil responses: pH, cation exchange capacity (CEC), and water leachate electrical conductivity (EC). Characterization results suggest that biochars made in a kiln process where some oxygen was present in the reaction atmosphere have properties intermediate between slow pyrolysis and gasification and therefore, should be grouped separately. A close correlation was observed between aromaticity determined by NMR and fixed carbon fraction determined by proximate analysis, suggesting that the simpler, less expensive proximate analysis method can be used to gain aromaticity information. Of the 17 biochars originally assessed, four biochars were ultimately selected for their potential to improve soil properties and to provide soil data to refine the selection scheme: corn stover low-temperature fast pyrolysis (highest amended soil CEC, information on high volatile matter/O–C ratio biochar), switchgrass O2/steam gasification (relatively high BET surface area, and amended soil pH, EC, and CEC), switchgrass slow pyrolysis (higher-amended soil pH and EC), and hardwood kiln carbonization (information on slow pyrolysis, gasification and kiln-produced differences).

https://static.springer.com/sgw/documents/1347843/application/pdf/BioEnergyResearch_Criteria+to+Select+Biochars+for+Field+Studies+based+on+Biochar+Chemical+Properties.pdf

Criteria to Select Biochars for Field Studies based on Biochar Chemical Properties

Jet turbine fuels have not been completely replaced by biomass-derived fuels due, in part, to the lack of the aromatic and cycloalkane hydrocarbons in bio-jet fuels. Such molecules play a critical role in traditional jet fuels for combustion characteristics and material compatibility. To date, this problem has been addressed by blending bio-jet fuel with traditional petroleum-based oils. In order to produce a 100% biomass-derived jet fuel, a suitable bioresource is needed for synthesizing aromatic and cycloalkane fuel compounds. Lignin, the only biomass component rich in aromatic benzene ring structures, is currently underutilized for low-value heat or treated as process waste because of its high chemical resistance. In this review, a four-step pathway of pretreatment, depolymerization, hydrodeoxygenation (HDO), and alkylation to convert lignin into jet-fuel-range aromatic hydrocarbons and cycloalkanes is explored. While many studies about these processes can be found in the literature for biomass and bio-derived molecules, the purposes of those studies were often for something other than lignin valorization. For example, pretreatment processes focus on cellulose and hemicellulose as desired products while lignin is handled as a waste. Most HDO studies focus on the upper phase of bio-oil which contains primarily water and phenolic monomers, ignoring the bottom phase which contains the larger, main components from depolymerization. Many alkylation studies used single, pure components; by comparison, the feedstocks from HDO of lignin-derived bio-oil are mixtures of varying complexity. This review of each process can be used to guide pathway integration and optimization.

Producing jet fuel from biomass lignin: Potential pathways to alkyl-benzenes and cycloalkanes

https://par.nsf.gov/servlets/purl/10081869

Catherine E. Brewer

Papers

Characterization of biochar from fast pyrolysis and gasification systems

New approaches to measuring biochar density and porosity

Criteria to Select Biochars for Field Studies based on Biochar Chemical Properties

Producing jet fuel from biomass lignin: Potential pathways to alkyl-benzenes and cycloalkanes

Hydrothermal liquefaction of high- and low-lipid algae: Bio-crude oil chemistry