Generalized two-dimensional correlation infrared spectroscopy to reveal the mechanisms of lignocellulosic biomass pyrolysis

As the initial stage of combustion, pyrolysis plays a significant role in the combustion of biomass, a typical solid fuel that contains higher volatile contents than other solid fuels. To better understand the pyrolysis mechanism, we herein employed generalized two-dimensional correlation infrared spectroscopy (2D-PCIS) to analyze the functional group evolution in bamboo chars between 250 and 600 °C, and by combination of the volatile release properties, the biomass pyrolysis process mechanism was speculated. We found that below 250 °C, the hydrogen bonding network within the biomass macromolecular structure was broken, while at 250–300 °C, the branched structures were broken during hydration and decarboxylation reactions, resulting in the formation of H₂O, acetic acids, and CO₂. The subsequent formation of various phenols between 300 and 350 °C mainly originated from rupture of the ether bridges in the lignin structure. In addition, molecular rearrangement of the intermediates from the decomposition of holocellulose resulted in aromatic ring formation. Interestingly, analysis by 2D-PCIS demonstrated that the aromatic rings bearing adjacent substituents easily formed double active sites following breakage of the branched structures. These structures then easily produced fused ring systems below 400 °C, while dehydrogenation and polycondensation at?>?400 °C promoted the formation of fused rings from aromatic rings without adjacent substituents.     

Investigation of growth responses in saprophytic fungi to charred biomass

We present the results of a study testing the response of two saprophytic white-rot fungi species, Pleurotus pulmonarius and Coriolus versicolor, to charred biomass (charcoal) as a growth substrate. We used a combination of optical microscopy, scanning electron microscopy, elemental abundance measurements, and isotope ratio mass spectrometry (¹³C and ¹⁵N) to investigate fungal colonisation of control and incubated samples of Scots Pine (Pinus sylvestris) wood, and charcoal from the same species produced at 300 °C and 400 °C. Both species of fungi colonise the surface and interior of wood and charcoals over time periods of less than 70 days; however, distinctly different growth forms are evident between the exterior and interior of the charcoal substrate, with hyphal penetration concentrated along lines of structural weakness. Although the fungi were able to degrade and metabolise the pine wood, charcoal does not form a readily available source of fungal nutrients at least for these species under the conditions used in this study.     

Catalytic cracking of tar derived from the pyrolysis of municipal solid waste fractions over biochar

The tars derived from the pyrolysis of four typical municipal solid waste fractions at 600 °C, namely pine wood (PW), tryptone (TP), polyethylene (PE) and polyvinyl chloride (PVC), were characterized and then catalytically cracked by activated biochar catalyst (ABC) at 700–900 °C. The ABC was produced from the pyrolysis of pine wood at 800 °C for 1 h, then activated by CO₂ at 900 °C for 20?min. The results showed that O-containing species, N-containing species, chain hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were the main products in the raw tar from the pyrolysis of PW, TP, PE and PVC, respectively. The tar cracking efficiency by ABC was ordered as PW>TP>PE>PVC, which indicated that the biomass tars were easier to be converted by ABC than plastic tars. The highest tar conversion of 98.7% was achieved for PW at 900 °C. Besides, N-containing tars were more stable than O-containing tars. The coke deposition on the ABC was more serious after the cracking of plastic tars (PE and PVC) than that of biomass tars (PW and TP). After the catalytic cracking of TP and PVC tars at 900 °C, the nitrogen and chlorine contents in ABC increased by 3 times and 10.5 times, respectively.     

Rapid pyrolysis of biochar prepared from slow and fast pyrolysis: The effects of particle residence time on char properties

This paper investigates the evolution of char properties with particle residence time during rapid pyrolysis of biochar under conditions pertinent to pulverized fuel (PF) applications. Two biochar samples were considered, prepared via slow (S-BC) and fast (F-BC) pyrolysis of mallee wood (150–250 µm) at 500 °C and two different heating rates (10 °C/s and ∼400 °C/s), respectively. The biochar samples were then subjected to rapid pyrolysis at 1300 °C using a novel drop-tube furnace (DTF), which enables direct determination of char yield experimentally. The evolution of char yield, the release of alkali and alkaline earth metallic (AAEM) species, and particle size and shape during rapid pyrolysis are investigated as a function of particle residence time (0.45 s to 1.4 s). The results show that char yields decrease from ∼77% to 75% when particle residence time increases from 0.45 s to 1.4 s. Rapid pyrolysis of F-BC has slightly higher char yields, due to the higher ash content of F-BC. More Cl in F-BC facilitates the release of Na during rapid pyrolysis, leading to the lower retention of Na in FC than in SC. Nevertheless, the retentions of K (∼90%), Mg (∼85%), and Ca (∼90%) are higher in FC, which can be ascribed to its higher contents of oxygen after rapid pyrolysis. The investigation of particle size and shape shows that biochar particles exhibit little changes after rapid pyrolysis, indicating their strong resistance to shrinkage and deformation even at high temperature.     

The iron mineral changes occurring in lignite coal during gasification

Representative lignite and gasified material samples were retrieved form a cooled down gasifier. The samples were taken at various heights in the gasifier that operated on lignite, under stable conditions. The proximate analyses, ash composition and temperature in the gasifier were determined according to standard procedures. The main minerals found in the present investigation were bassanite, illite, quartz, kaolinite, calcite and the only iron bearing mineral was found to be pyrite. The trend in the estimated particle surface temperature profile shows an increase in the drying, pyrolysis, gasification and combustion zones from about 300 °C to just over 900 °C. About 1/3 down the gasifier, an average particle temperature of about 400 °C and particle surface temperature of about 600 °C was measured where pyrite conversion started. About 2/3 down the gasifier, where an average temperature of about 700 °C and particle surface temperature of about 900 °C was measured, all the pyrite was converted and in the bottom part of the gasifier, oxidation of the iron started to play a role and hematite and an iron containing glass formed at an average temperature of > 800 °C and surface temperature of 900 °C.     

Mechanical properties of pyrolysed wood: a nanoindentation study

The present work focuses on changes of mechanical properties in pyrolysed spruce wood as a function of temperature up to 2400°C. Nanoindentation tests are used for the determination of mechanical properties at the scale of single wood cell walls. Hardness, indentation modulus and elasto-plastic/brittle behaviour of the carbonaceous residues are derived as function of pyrolysis temperature. Hardness values increase continuously by more than one order of magnitude to 4.5?GPa at 700°C. The indentation modulus shows complex changes with a minimum of 5?GPa around 400°C and a maximum of 40?GPa around 1000°C. The deformation induced by the indenter is largely visco-plastic in native wood, but it is almost purely elastic in the carbonaceous residue, with particular low values of the indentation ductility index around 700°C. A low density and a strongly cross-linked carbon structure may explain the mechanical behaviour at these intermediate temperatures. A final decrease of the modulus and a slight decrease of ductility for temperatures above 2000°C can be attributed to a continuous structural transition of the material towards graphite-like stacking of carbon sheets and to preferred carbon orientation along the wood cell axis.     

The polarization of MeV neutrons elastically scattered from 4He

The analyzing power of ⁴He for neutron elastic scattering has been measured at four angles between 20° and 80° (lab) throughout the energy range 1.5–6.0 MeV using a doublescattering method. The intense flux of polarized neutrons was generated via the reactions Pb(γ, n) → ¹²C(n, $\text{n}$)¹²C, and the magnitude of the polarization of the neutron beam measured absolutely in a separate double-scattering experiment. Neutron energies were determined with a nanosecond time-of-flight spectrometer, and the generalized neutron spin-precession method was used to minimize systematic uncertainties.     

Influence of ceramide on the internal structure and hydration of the phospholipid bilayer studied by neutron and X-ray scattering

Small angle neutron scattering (SANS), neutron diffraction and X-ray powder diffraction were used to investigate influence of N-stearoyl phytosphingosine (CER[NP]) and α-hydroxy-N-stearoyl phytosphingosine (CER[AP]) on the internal structure and hydration of DMPC membrane in fully and partly hydrated states at T = 30 °C. Application of Fourier analysis for diffraction data and model calculations for the SANS data evidence that addition of both CER[NP] and CER[AP] in small concentrations promotes significant changes in the organization of DMPC bilayers, such as the increase of the hydrophobic core region. SANS data evidence a decrease in the average radius and polydispersity of the vesicles that can be ascribed to hydrogen bonds interactions that favor tight lipid packing with a compact, more rigid character.     

In-process ZnO thin films alloying during pulsed laser deposition

Alloyed ZnO:Al thin films were prepared by a pulsed laser deposition by the altering of two pure targets (ZnO and Al) during the deposition process. Two deposition temperatures (?197 °C and 400 °C) were applied and differences of diffusion dynamics were compared. As-grown layered films were annealed and aluminium distribution was homogenized. The results revealed that the amorphous structure (samples grown at ?197 °C) of ZnO provide more positive conditions for efficient Al diffusion in comparison with crystalline structure (samples grown at 400 °C). A detailed investigation by SIMS depth profiling confirmed a homogeneous chemical composition of annealed and recrystallized films which exhibited a porous nature and wurtzite crystalline structure.     

Effect of electrode material on the photoconduction behaviour of ion-irradiated kapton-H polyimide

Photoconduction behaviour of 75 MeV oxygen ion-irradiated (fluence: 1.8×10¹³ ions/cm²) kapton-H polyimide film in the visible region has been investigated for different electrode materials at various operating temperatures ranging 40–250 °C and at different electric fields (40–400 kV/cm). A photoinduced exciton formation is the major source for providing charge carriers through thermolization and field-assisted dissociation processes. A decrease in the photocurrent in ion-irradiated samples when compared with pristine samples has been associated with the enhancement in the trapping sites, which may deplete the charge carriers and a loss in the photoactive groups owing to radiation-induced demerization. The evidence of Schottky type conduction (based on Schottky's coefficient estimation) mechanism in irradiated samples is observed at moderate temperatures (80–160 °C). A strong dependence of photocurrent on temperature in irradiated samples reconfirms the thermal ionization process of exciton for photogeneration of charge carriers.     

Study of structural and electrical properties of thin NiO<Subscript>x</Subscript> films prepared by ion beam sputtering of Ni and subsequent thermo-oxidation

Nickel oxide thin films were prepared by thermal annealing of thin Ni films (thickness ca 47?nm) deposited by ion beam sputtering. The thermal annealing was performed at 350 °C and 400 °C with elected time (1–7 hours) in a quartz furnace opened to air. During annealing the samples underwent structural changes, as well as changes of their electrical properties. The structural properties (surface morphology and occurrence of crystalline phases) were analyzed by the AFM and XRD methods, O and Ni depth concentration profiles by the NRA method, and electrical properties (sheet resistance) by the van der Pauw 4-point technique. The sheet resistance (R _S ) of the as-deposited sample was found to be 12.03 Ω/□; after open air thermal annealing at 350 °C for 1 h the value was found to be almost the same, 11.67 Ω/□. After 2 h of annealing, however, a sharp increase in the sheet resistance (R _S = 1.46 MΩ/□) was observed. At this stage the deposit formed largely oxidized Ni layer with a distinct polycrystalline structure. The sharp increase of sheet resistance was ascribed to the oxidation of the Ni layer, leaving only a smaller amount of isolated Ni particles unoxidized. Almost complete oxidation was found after 7 h of annealing at 350 °C. At 400 °C was almost complete oxidation recorded already after 1 h of annealing.     

Study of an anisotropic ferrimagnetic bioactive glass ceramic for cancer treatment

For the hyperthermia therapy of cancer, ferrimagnetic glass ceramics are a potential candidate. Ferrimagnetic zinc-ferrite-containing bioactive glass ceramics were prepared by quenching the glass ceramics from sintering temperature. Then the samples were heated to 600°C and cooled in an aligning magnetic field of 1 Tesla to cause anisotropy. The magnetically aligned samples were compared with non-aligned samples. Vibrating sample magnetometry measurements at 10 kOe showed that the magnetic properties were enhanced by the aligning magnetic field and it led to an enhancement of the magnetic heat generation under a magnetic induction furnace operating at 500 Oe and 400 kHz for 2 min. Data showed that the maximum specific power loss and temperature increase after 2 min were 31.5 W/g and 45°C, respectively, for the aligned sample of maximum zinc-ferrite crystalline content. The glass ceramics were immersed in simulated body fluid for 3 weeks. X-ray diffraction and Fourier transform infrared and atomic absorption spectroscopy results indicated the growth of precipitated hydroxyapatite, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to living tissues in physiological environment.     

Neutron-transmutation doping of GaAs — as studied by ESR

Neutron (n⁰) transmutation doping of GaAs has been monitored by electron spin resonance (ESR). Strong evidence was obtained that, apart from fast neutron impact, As_Ga antisite defects are also created by the γ- and β-emissions following thermal n⁰-capture. The As_Ga defects, forming deep midgap states, anneal out at 500°C.     

Bound Energy of Water in Hard Dental Tissues

Abstract

Enamel and dentin are composed, respectively, of 3 wt% and 10 wt% of water, which exhibits different features in the tissues: loosely and tightly bound water. The objective of this study is to clarify by infrared spectroscopy, the different features of the water in heated (100–1000°C) hard dental tissues (enamel and dentin). The water band between 3800 cm^?1 and 2500 cm^?1 was analyzed by infrared spectroscopy. The area dependence of the water band with temperature was compared with the Arrhenius equation in two regions (100–400°C and 700–1000°C). The activation energy was determined for these two regions, and similar values were observed for both tissues. For enamel we obtain ?4.1±0.2 kJ/mol at 100–400 °C and ?63±9 kJ/mol at 700–1000°C; for dentin ?4.1±0.2 kJ/mol at 100–400°C and ?60±11 kJ/mol at 700–1000°C. The water loss changes the color of the tissues, hydroxyapatite crystallographic parameters, and produce ESR signals. These changes were discussed and compared with the results observed in this work and after laser irradiation. We conclude that these two activation energies could be assigned to the adsorbed (loosely bound) and trapped (tightly bound) water.     

Continuous catalytic pyrolysis of oily sludge using U-shape reactor for producing saturates-enriched light oil

Continuous catalytic pyrolysis of oily sludge was carried out in a special U-shape reactor for producing saturates-enriched light oil. The sludge underwent thermal pyrolysis first and then catalytic pyrolysis. During the thermal pyrolysis, chain hydrocarbons were first cracked and further polymerized into aromatics. The effect of temperatures (400–800 °C) on the products was investigated and the maximum liquid yield (67.7%) was obtained at 500 °C. High temperature promoted polymerization, thus the distribution of aromatics in the liquid product was increased and was more concentrated in polyaromatics at 800 °C. In the catalytic upgrading stage, dolomite was used as catalyst and aromatics were adsorbed on it, either aggregated or decomposed. As a result, a light oil product with 57.0% saturates was obtained at the residence time of 8.9?s due to the conversion of aromatics and heavy hydrocarbons into light aliphatic hydrocarbons such as straight chain hydrocarbons. Compared with the oil phase in the raw sludge sample, the content of saturates was increased by 45.0% and that of the asphaltenes was reduced by 88.5%. Meanwhile, the inherent moisture in the oily sludge could participate in the steam reforming reaction, promoting the decomposition of aromatics and leading to an increase in the H₂ generation. Moreover, the release of H₂S was reduced from 0.132 to 0.005?mol per kg sludge and the sulfur content of the oil product was also decreased in the presence of dolomite. The deactivation of dolomite can be attributed to the carbonization of CaO and deposition of polyaromatic coke on the catalyst surface.     

Neutron polarizations from the9Be(d,n)10B and11B(d,n)12C reactions

Neutron polarization angular distributions were measured for the⁹Be(d,n)¹⁰B and¹¹B(d,n)¹²C reactions for deuteron energies of 5.47 and 5.34 MeV, respectively. Using neutron time-of-flight techniques, polarizations to eight states in¹⁰B and to six states in¹²C have been measured. Neutron polarization energy excitation functions for both reactions were measured for deuteron energies from 3.0 to 5.5 MeV in 0.25 MeV steps at 30° (lab). Distorted wave method calculations carried out to compare theoretical calculations against experimental results were not in good agreement with the data.     

Neutron irradiation-induced enhancement of electronic carrier transport in ZnO

Irradiation of ZnO single crystals by thermal neutrons with a dose up to 7×10¹⁷ cm^?2 and subsequent annealing at 400 °C for 1 h leads to a significant increase in majority carrier mobility and concentration in this material, with the corresponding decrease of its sheet resistance. Additionally, cathodoluminescence spectra taken before and after neutron irradiation are consistent with the growing carrier lifetime. The observed effects are attributed to irradiation-induced formation of electrically active species of interstitial Zn and improvement of lattice crystallinity due to annealing.     

EPR and Magnetization Studies of Polymer-Derived Fe-Doped SiCN Nanoceramics Annealed at Various Temperatures: Blocking Temperature,Superparamagnetism and Size Distributions

X-band EPR spectra on SiCN ceramics, doped with Fe(III) ions, annealed at 800 °C, 1000 °C, 1100 °C, 1285 °C, and 1400 °C have been simulated to understand better their magnetic properties, accompanied by new magnetization measurements in the temperature range of 5–400 K for zero-field cooling (ZFC) and field cooling (FC) at 100C. The EPR spectra reveal the presence of several kinds of Fe-containing nanoparticles with different magnetic properties. The maxima of the temperature variation of ZFC magnetization were exploited to estimate (i) the blocking temperature, which decreased with annealing temperature of the samples and (ii) the distribution of the size of Fe-containing nanoparticles in the various samples, which was found to become more uniform with increasing annealing temperature, implying that more homogenous magnetic SiCN/Fe composites can be fabricated by annealing at even higher temperatures than 1400 °C to be used as sensors. The hysteresis curves showed different behaviors above (superparamagnetic), below (ferromagnetic), and about (butterfly shape) the respective average blocking temperatures, 〈T_B〉. An analysis of the coercive field dependence upon temperature reveals that it follows Stoner–Wohlfarth model for the SiCN/Fe samples annealed above 1100 °C, from which the blocking temperatures was also deduced.     

Thermopower of beech wood biocarbon

This paper reports on measurements of the thermopower S of high-porosity samples of beech wood biocarbon with micron-sized sap pores aligned with the tree growth direction. The measurements have been performed in the temperature range 5–300 K. The samples have been fabricated by pyrolysis of beech wood in an argon flow at different carbonization temperatures (T _carb). The thermopower S has been measured both along and across the sap pores, thus offering a possibility of assessing its anisotropy. The curves S(T _carb) have revealed a noticeable increase of S for T _carb < 1000°C for all the measurement temperatures. This finding fits to the published data obtained for other physical parameters, including the electrical conductivity of these biocarbons, which suggests that for T _carb ∼ 1000°C they undergo a phase transition of the insulator-(at T _carb < 1000°C)-metal-(at T _carb > 1000°C) type. The existence of this transition is attested also by the character of the temperature dependences S(T) of beech wood biocarbon samples prepared at T _carb above and below 1000°C.     

Effect of thermal annealing on disorder and optical properties of Cr/Si bilayer thin films

Chromium/silicon bilayers are deposited by sequential electron beam evaporation on quartz substrates. The bilayers consisting of Cr and Si layers of 50 and 400 nm thicknesses, respectively, are subjected to post-deposition annealing at temperatures from 200 to 700 °C. The thermal annealing results in the interdiffusion between Cr and Si, as evidenced by cross-section scanning electron micrographs and the line profiles obtained from energy-dispersive X-ray spectroscopy. It is inferred from the compositional line profiles that the films are a combination of silicon-rich oxide, chromium oxide and unreacted Cr up to 500 °C. Chromium disilicide forms at temperatures greater than 500 °C with decrease in chromium oxide content. The refractive index value and extinction coefficient values are 2.1 and 0.12 in the as-deposited case which increase to 3.5 and 0.24 at 400 °C. These values decrease to 2.1 and 0.12 at 500 °C. At the same temperatures, the band gap values are 2.21, 2.40 and 2.28, respectively. Thus, the refractive index, absorption coefficient and the optical band gap of the films peak at an annealing temperature of 400 °C and decrease thereafter. Significantly, this is accompanied by increase in Urbach energy which is an indication of increase in disorder in the system. There is decrease in Urbach energy as well as the optical constants at temperatures >400 °C.