Characterization of the water-insoluble pyrolytic cellulose from cellulose pyrolysis oil

Water-insoluble pyrolytic cellulose with similar appearance to pyrolytic lignin was found in cellulose fast pyrolysis oil. The influence of pyrolysis temperature on pyrolytic cellulose was studied in a temperature range of 300–600 °C. The yield of the pyrolytic cellulose increased with temperature rising. The pyrolytic cellulose was characterized by various methods. The molecular weight distribution of pyrolytic cellulose was analyzed by gel permeation chromatography (GPC). Four molecular weight ranges were observed, and the M_w of the pyrolytic cellulose varied from 3.4 × 10³ to 1.93 × 10⁵ g/mol. According to the elemental analysis (EA), the pyrolytic cellulose possessed higher carbon content and lower oxygen content than cellulose. Thermogravimetric analysis (TGA) indicated that the pyrolytic cellulose underwent thermo-degradation at 127–800 °C and three mass loss peaks were observed. Detected by the pyrolysis gas chromatography–mass spectrometry (Py-GC/MS), the main pyrolysis products of the pyrolytic cellulose included saccharides, ketones, acids, furans and others. Fourier transforms infrared spectroscopy (FTIR) also demonstrated that the pyrolytic cellulose had peaks assigned to CO stretching and glycosidic bond, which agreed well with the Py-GC/MS results. The pyrolytic cellulose could be a mixture of saccharides, ketones, and their derivatives.     

Quality variations of poultry litter biochar generated at different pyrolysis temperatures

Producing biochar and biofuels from poultry litter (PL) through slow pyrolysis is a farm-based, value-added approach to recycle the organic waste. Experiments were conducted to examine the effect of pyrolysis temperature on the quality PL biochar and to identify the optimal pyrolysis temperature for converting PL to agricultural-use biochar. As peak pyrolysis temperature increased incrementally from 300 to 600 °C, biochar yield, total N content, organic carbon (OC) content, and cation exchange capacity (CEC) decreased while pH, ash content, OC stability, and BET surface area increased. The generated biochars showed yields 45.7–60.1% of feed mass, OC 325–380 g kg⁻¹, pH 9.5–11.5, BET surface area 2.0–3.2 m² g⁻¹, and CEC 21.6–36.3 cmol_c kg⁻¹. The maximal transformation of feed OC into biochar recalcitrant OC occurred at 500 °C, yet 81.2% of the feed N was lost in volatiles at this temperature. To produce agricultural-use PL biochar, 300 °C should be selected in pyrolysis; for carbon sequestration and other environmental applications, 500 °C is recommended.     

One-step synthesis of hollow structured Si/C composites based on expandable microspheres as anodes for lithium ion batteries

Si/C composites of carbon hollow structures loaded with Si nanoparticles (NPs) (Si/C-HSs) were prepared by one-step pyrolysis of a mixture of Si NPs and expandable microspheres (EMs). For the Si/C-HSs, hollow carbon shells with rough surfaces were formed by directly carbonizing the polymer shells of EMs, and the Si NPs fell into the void space or were loaded on the rough surfaces of the carbon shells. The EM-based carbon shells accommodated the volume expansion of the Si NPs and improved the electrical conductivity of the composites. As a result, the Si/C-HSs exhibited a high capacity (initial reversible capacity: 854.4 mAh g^− 1 at 300 mA g^− 1), stable cycling performance (capacity retention: 80% after 50 cycles), and excellent rate capability.     

Life test of DMFC using poly(ethylene glycol)bis(carboxymethyl)ether plasticized PVA/PAMPS proton-conducting semi-IPNs

A novel, low-cost proton-conducting semi-IPN has been successfully prepared from PVA/PAMPS blends by incorporating poly(ethylene glycol)bis(carboxymethyl)ether (PEGBCME) as a novel plasticizer. Although, the polymer is based on a relatively low content of PAMPS as a component of ion conducting sites, the resulting semi-IPN exhibited high proton conductivity (0.1 S cm⁻¹) at 25 °C, which afforded a higher power density of 51 mW cm⁻² at 80 °C. A striking feature is that a long-term initial performance is achieved with a 130 h of stable fuel cell operation in DMFC mode due to effectively suppressed methanol crossover. This is a new record for a fully hydrocarbon membrane in DMFC, seeing that the PVA–PAMPS proton-conducting semi-IPNs are made simply of aliphatic skeletons.     

Thermal degradation and evolved gas analysis: A polymeric blend of urea formaldehyde (UF) and epoxy (DGEBA) resin

A polymeric blend has been prepared using urea formaldehyde (UF) and epoxy (DGEBA) resin in 1:1 mass ratio. The thermal degradation of UF/epoxy resin blend (UFE) was investigated by using thermogravimetric analyses (TGA), coupled with FTIR and MS. The results of TGA revealed that the pyrolysis process can be divided into three stages: drying process, fast thermal decomposition and cracking of the sample. There were no solid products except ash content for UFE during combustion at high temperature. The total mass loss during pyrolysis at 775 °C is found to be 97.32%, while 54.14% of the original mass was lost in the second stage between 225 °C and 400 °C. It is observed that the activation energy of the second stage degradation during combustion (6.23 × 10⁻⁴ J mol⁻¹) is more than that of pyrolysis (5.89 × 10⁻⁴ J mol⁻¹). The emissions of CO₂, CO, H₂O, HCN, HNCO, and NH₃ are identified during thermal degradation of UFE.     

Characteristics of inclusions in topaz from Serrinha pegmatite (Medina granite,Minas Gerais State,SE Brazil) studied by Raman spectroscopy

Eastern Brazilian Pegmatite Province includes many topaz-bearing pegmatitic bodies. Residual melts from the Fe–K-rich alkaline Medina granite (ca. 500 Ma) formed the Serrinha pegmatite—a system of branched thin pegmatite veins hosted by pink facies of the parent granite. The colourless topaz from Serrinha pegmatite contains both mineral and fluid inclusions. Microcline (513, 476, 456 cm⁻¹), albite (507, 479, 457 cm⁻¹), topaz (926, 858, 267, 239 cm⁻¹), quartz (463 cm⁻¹), rutile (610, 444 cm⁻¹), wolframite (884 cm⁻¹) and uranophane (968, 788 cm⁻¹) represent solid inclusions formed by fluid-induced processes from the pneumatolytic (∼600–400 °C) to hydrothermal (<400 °C) stages of pegmatite crystallization. Fluid inclusions are mainly liquid or liquid-gas, which contain CO₂ (marker bands ∼1388 cm⁻¹ and ∼1285 cm⁻¹) and traces of methane (2917 cm⁻¹). They are mainly of primary and pseudo-secondary origin, indicating tectonic quiescence during and after topaz crystallization (in agreement with the post-collisional nature of the parent granite). Topaz crystallized in high temperature conditions of the pneumatolytic stage at a depth around 8.5–10.0 km.     

Proton-conducting membranes based on poly(2,5-benzimidazole) (ABPBI) and phosphoric acid prepared by direct acid casting

We report the preparation of phosphoric acid doped poly(2,5-benzimidazole) (ABPBI) membranes for PEMFC by simultaneously doping and casting from a poly(2,5-benzimidazole)/phosphoric acid/methanesulfonic acid (MSA) solution. The evaporation of MSA yields a very homogeneous membrane having a better controlled composition, avoiding the use of solvent-intensive procedures. Membranes have been prepared with contents of up to 3.0H₃PO₄ molecules per ABPBI repeating unit. These membranes achieve a maximum conductivity of 1.5 × 10⁻² S cm⁻¹ at temperatures as high as 180 °C in dry conditions. These ABPBI membranes are more conveniently prepared than those conventionally formed and doped in separate steps while featuring comparable conductivities (ABPBI × 2.7H₃PO₄ prepared by the soaking method showed a conductivity of 2.5 × 10⁻² S cm⁻¹ at 180 °C in dry conditions).     

Preparation of activated carbon from Turbinaria turbinata seaweeds and its use as supercapacitor electrode materials

Turbinaria turbinata brown seaweeds were tested as carbon electrode material in symmetric, electrochemical supercapacitors. The electrochemical properties of the carbon materials were characterised for their application as supercapacitors using cyclic voltammetry, galvanostatic charge/discharge method and electrochemical impedance spectroscopic analyses. Our initial results showed that the optimal behaviour was obtained for the sample prepared by pyrolysis at 800 °C. The average surface area of the carbon was 812 m²/g. Electrochemical tests with an organic electrolyte gave the following interesting results: a capacitance of 74.5 F/g, a specific series resistance of 0.5 Ω cm² and an ionic resistivity of 1.3 Ω cm². These results show the promising capacitive properties of carbon derived from seaweeds and their application in electrochemical supercapacitors.     

Evaluation of the porous structure development of chars from pyrolysis of rice straw: Effects of pyrolysis temperature and heating rate

The effects of pyrolysis temperature and heating rate on the porous structure characteristics of rice straw chars were investigated. The pyrolysis was done at atmospheric pressure and at temperatures ranging from 600 to 1000 °C under low heating rate (LHR) and high heating rates (HHR) conditions. The chars were characterized by ultimate analysis, field emission scanning electron microscope (FESEM), helium density measurement and N₂ physisorption method. The results showed that temperature had obvious influence on the char porous characteristics. The char yield decreased by approximately 16% with increasing temperature from 600 to 1000 °C. The carbon structure shrinkage and pore narrowing occurred above 600 °C. The shrinkage of carbon skeleton increased by more than 22% with temperatures rising from 600 to 1000 °C. At HHR condition, progressive increases in porosity development with increasing pyrolysis temperature occurred, whereas a maximum porosity development appeared at 900 °C. The total surface area (S_total) and micropore surface area (S_micro) reached maximum values of 30.94 and 21.81 m²/g at 900 °C and decreased slightly at higher temperatures. The influence of heating rate on S_total and S_micro was less significant than that of pyrolysis temperature. The pore surface fractal dimension and average pore diameter showed a good linear relationship.     

A porous polymer electrolyte based on P(VDF-HFP) prepared by a simple phase separation process

A polymer electrolyte with interconnected pores based on poly(vinylidene difluoride-co-hexafluoropropylene) [P(VDF-HFP)] copolymer was prepared by a simple phase separation process using water as both non-solvent and pore inducer. The prepared porous membrane was characterized by SEM, XRD and DSC. With a narrow pore size distribution and low crystallinity, the resulting polymer electrolyte shows a high ionic conductivity up to 1.76 × 10⁻³ S cm⁻¹ at room temperature and exhibits low apparent activation energy of 10.35 kJ mol⁻¹ for the transportation of ions. Its low cost and environmentally friendliness provide great promise for the practical application in polymer lithium-ion batteries.     

Novel core–shell SDC/amorphous Na2CO3 nanocomposite electrolyte for low-temperature SOFCs

Novel core–shell SDC (Ce_0.8Sm_0.2O_1.9)/amorphous Na₂CO₃ nanocomposite was prepared for the first time. The core–shell nanocomposite particles are smaller than 100 nm with amorphous Na₂CO₃ shell of 4–6 nm in thickness. The nanocomposite electrolyte shows superionic conductivity above 300 °C, where the conductivity reaches over 0.1 S cm⁻¹. Such high conductive nanocomposite has been applied in low-temperature solid oxide fuel cells (LTSOFCs) with an excellent performance of 0.8 W cm⁻² at 550 °C. A new potential approach of designing and developing superionic conductors for LTSOFCs was presented to develop interface as ‘superionic highway’ in two-phase materials based on coated SDC.     

A cobalt-free electrode material La0.5Sr0.5Fe0.8Cu0.2O3 − δ for symmetrical solid oxide fuel cells

Cobalt-free perovskite oxide La_0.5Sr_0.5Fe_0.8Cu_0.2O_3 − δ (LSFC) was applied as both anode and cathode for symmetrical solid oxide fuel cells (SSOFCs). The LSFC shows a reversible transition between a cubic perovskite phase in air and a mixture of SrFeLaO₄, a K₂NiF₄-type layered perovskite oxide, metallic Cu and LaFeO₃ in reducing atmosphere at elevated temperature. The average thermal expansion coefficient of LSFC in air is 17.7 × 10^− 6 K^− 1 at 25 °C to 900 °C. By adopting LSFC as initial electrodes to fabricate electrolyte supported SSOFCs, the cells generate maximum power output of 1054, 795 and 577 mW cm^− 2 with humidified H₂ fuel (~ 3% H₂O) and 895, 721 and 482 mW cm^− 2 with humidified syngas fuel (H₂:CO = 1:1) at 900, 850 and 800 °C, respectively. Moreover, the cell with humidified H₂ fuel demonstrates a reasonable stability at 800 °C under 0.7 V for 100 h.     

Cobalt-free cathode material SrFe0.9Nb0.1O3−δ for intermediate-temperature solid oxide fuel cells

A cobalt-free cubic perovskite oxide, SrFe_0.9Nb_0.1O_3?δ (SFN) was investigated as a cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). XRD results showed that SFN cathode was chemically compatible with the electrolyte Sm_0.2Ce_0.8O_1.9 (SDC) for temperatures up to 1050 °C. The electrical conductivity of SFN sample reached 34–70 S cm^?1 in the commonly operated temperatures of IT-SOFCs (600–800 °C). The area specific resistance was 0.138 Ω cm² for SFN cathode on SDC electrolyte at 750 °C. A maximum power density of 407 mW cm^?2 was obtained at 800 °C for single-cell with 300 μm thick SDC electrolyte and SFN cathode.     

Electrochemical performances of LaBaCuFeO5+x and LaBaCuCoO5+x as potential cathode materials for intermediate-temperature solid oxide fuel cells

Layered perovskite-structure oxides LaBaCuFeO_5+x (LBCFO) and LaBaCuCoO_5+x (LBCCO) were prepared and the electrical conductivity and electrochemical performance were investigated as potential cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The electrical conductivity of LBCCO is much higher than that of LBCFO. Area specific resistances of LBCFO and LBCCO cathode materials on Ce_0.8Sm_0.2O_1.9 (SDC) electrolyte are as low as 0.21 Ω cm² and 0.11 Ω cm² at 700 °C, respectively. The maximum power density of the LBCFO/SDC/Ni-SDC and LBCCO/SDC/Ni-SDC cells with 300 μm thick electrolytes attains 557 mW cm^?2 and 603 mW cm^?2 at 800 ^oC, respectively. Preliminary results demonstrated that the layered perovskite-structure oxides LBCFO and LBCCO are very promising cathode materials for application in IT-SOFCs.     

Raman spectroscopic study on boron-doped silicon nanoparticles

Raman analyses were performed on thin films prepared from B-doped Si nanoparticles with an average diameter of 15 nm using the spin-coating method. The resulting spectrum exhibited a broad band with a peak near 520 cm⁻¹. The band was decomposed into three bands corresponding to the crystalline, grain boundary (GB), and amorphous regions by the least-squares band-fitting method based on the three Voigt bands. The fractions of the crystalline, GB, and amorphous regions were 37%, 35%, and 28%, respectively. A spherical particle exhibited an ordered crystalline core surrounded by a disordered shell in a transmission electron microscope (TEM) image. The crystalline fraction of the 15-nm B-doped Si nanoparticle film was much lower than that of the 19-nm P-doped Si nanoparticle film. This result suggested that the B-doping mechanism was different from that of P-doping. The temperature of the sample was estimated from the ratio of the peak intensities of anti-Stokes to Stokes Raman bands (I^AS/I^S) observed near 520 cm⁻¹. The temperature of the B-doped Si nanoparticle film upon irradiation at a power density of 4.6 kW/cm² was 298 °C, whereas the temperature of the P-doped Si nanoparticle film was 92 °C. The B-doped Si nanoparticle films were capable of producing light-induced heat.     

Sulfur tolerant redox stable layered perovskite SrLaFeO4 − δ as anode for solid oxide fuel cells

Redox stable K₂NiF₄ type layered perovskite SrLaFeO_4 − δ(SLFO_4 − δ) has been prepared and evaluated as anode for solid oxide fuel cell (SOFC). The SLFO_4 − δ shows linear thermal expansion behavior with TEC of 14.3 × 10^− 6 K^− 1. It also demonstrates excellent catalytic activity for various fuels. A scandia stabilized zirconia (ScSZ, 180 μm) electrolyte supported SOFC with the anode achieves maximum power densities (P_max) of 0.93, 0.76, 0.63, and 0.46 Wcm^− 2 at 900–750 °C, respectively, in wet H₂. P_maxs of cells supported by 250 μm ScSZ reach 0.57, 0.60 and 0.50 Wcm^− 2 in H₂, H₂ + 50 ppm H₂S and propane, respectively, at 800 °C. Moreover, the cells show stable power output during ~ 100 h operation at 800 °C under 0.7 V in various fuels. The P_max at 800 °C in wet H₂ even increases by ~ 11% in the subsequent two thermal cyclings, indicating that SLFO_4 − δ is a promising anode candidate for SOFC with good electro-catalytic activity, high stability and resistance to sulfur and coking.     

Microstructural modifications in swift ion irradiated PET

Polyethylene terephthalte (PET) was irradiated with carbon (70 MeV) and copper (120 MeV) ions to analyze the induced modifications with respect to optical, structural and thermal properties. In the present investigation, the fluence for carbon irradiation was varied from 1×10¹¹ to 1×10¹⁴ ions cm⁻², while that for copper beam was kept in the range of 1×10¹¹ to 1×10¹³ ions cm⁻². UV–vis, FTIR, XRD and DSC techniques were utilized to study the induced changes. The analysis of UV–vis absorption studies reveals that there is decrease of optical energy gap up to 10% on carbon ion irradiation (at 1×10¹⁴ ions cm⁻²), whereas the copper beam (at 1×10¹³ ions cm⁻²) leads to a decrease of 49%. FTIR analysis indicated the formation of alkyne end groups along with the overall degradation of polymer with copper ion irradiation. X-ray diffraction analysis revealed that the semi-crystalline PET losses its crystallinity on swift ion irradiation. It was found that the carbon beam (1×10¹⁴ ions cm⁻²) decreased the crystallite size by 16% whereas this decrease is of 12% in case of the copper ion irradiated PET at 1×10¹³ ions cm⁻². The loss in crystallinity on irradiation has been supported by DSC thermograms.     

Chiral separation of trans-stilbene oxide through cellulose acetate butyrate membrane

An enantioselective membrane was prepared using cellulose acetate butyrate as a membrane material. The flux and permselective properties of membrane using 50% ethanol solution of (R,S)-trans-stilbene oxide as feed solution were studied. The top surface and cross-section morphology of the resulting membrane were examined by scanning electron microscopy. The resolution of over 92% enantiomeric excess was achieved when the enantioselective membrane was prepared with 15 wt % cellulose acetate butyrate and 30 wt % N,N-dimethylformamide in the casting solution of acetone, 10 °C temperature of water bath for the gelation of the membrane, and the operating pressure and the feed concentration of the trans-stilbene oxide were 3 kgf/cm² and 5.2 mmol/L, respectively. Since the cellulose acetate butyrate contained a large amount of asymmetric carbons on the backbone structure, it was possible to form helical structure, this was considered to be the reason for the enantioselectivity of the membrane.     

Electronic and vibrational spectra of tourmaline – The impact of electron beam irradiation and heat treatment

Irradiation and heat treatment were performed on tourmalines of various colors from Antandrokomby, Madagascar. The samples were irradiated with 10 MeV electrons to fluencies of 2 ×10¹⁷ cm⁻² for 1 h and were heated at 550 °C for 3 h in air. Their electronic and vibrational spectra were investigated by UV–vis, mid-infrared, and WD-XRF spectroscopy for comparison to pristine samples. Changes in the Mn³⁺ ions after irradiation resulted in darker pink tourmalines, which had absorption peaks at 390 and 520 nm. These samples became colorless after subsequent heat treatment. After irradiation, colorless, light blue and yellow tourmalines displayed a new absorption band at 365 nm. Alteration of the stretching absorption bands and wavenumber after irradiation could be explained by the following reactions:OH⁻ + e⁻ beam irradiation → O⁻ + H°,Mn²⁺ + e⁻ beam irradiation → Mn³⁺ + e⁻ andFe²⁺ + e⁻ beam irradiation → Fe³⁺ + e⁻.Stretching vibration of the BO₃ structure occurred at 1330 cm⁻¹, while the SiO vibration absorption bands were assigned to around 1100 cm⁻¹. Colorless, green, and yellow tourmalines showed high-intensity peaks around 3608 and 3505 cm⁻¹ after irradiation. Pink and dark green tourmalines showed low-intensity peaks at 3605 and 3585 cm⁻¹, respectively. The combination modes of stretching and bending in the range of 4600–4300 cm⁻¹ were split after irradiation and heat treatment, and different color changes occurred after irradiation.     

Ni infiltrated Sr2Fe1.5Mo0.5O6-δ-Ce0.8Sm0.2O1.9 electrode for methane assisted steam electrolysis process

It is an effective way to substitute air to methane in the anode of solid oxide electrolysis cells to reduce the electrical consumption for simultaneously producing H₂ and high-quality syngas. In the methane assisted mode, the thermodynamic properties and Nernst potential exhibit one order of magnitude reduction of applied voltage to produce comparable electrolysis current. Ni catalysts are infiltrated to the SFM-SDC anode to improve the catalytic properties for methane assisted steam electrolysis. After Ni infiltration, surface oxygen exchange coefficient is effectively accelerated from 3.03 × 10^− 5 to 2.20 × 10^− 4 cm s^− 1, and the current density is significantly enhanced from − 487 to − 1022 mA cm^− 2 at 850 °C and 0.5 V.