A Sustainable Approach on Spruce Bark Waste Valorization through Hydrothermal Conversion

In the context of sustainable use of resources, hydrothermal conversion of biomass has received increased consideration. As well, the hydrochar (the solid C-rich phase that occurs after the process) has caused great interest. In this work, spruce bark (Picea abies) wastes were considered as feedstock and the influence of hydrothermal process parameters (temperature, reaction time, and biomass to water ratio) on the conversion degree has been studied. Using the response surface methodology and MiniTab software, the process parameters were set up and showed that temperature was the significant factor influencing the conversion, while residence time and the solid-to-liquid ratio had a low influence. Furthermore, the chemical (proximate and ultimate analysis), structural (Fourier-transform infrared spectroscopy, scanning electron microscopy) and thermal properties (thermogravimetric analysis) of feedstock and hydrochar were analyzed. Hydrochar obtained at 280 °C, 1 h processing time, and 1/5 solid-to-liquid ratio presented a hydrophobic character, numerous functional groups, a lower O and H content, and an improved C matter, as well as a good thermal stability. Alongside the structural features, these characteristics endorsed this waste-based product for applications other than those already known as a heat source.

Theoretical calculation of nitro-1-(2,4,6-trinitrophenyl)-1H-azoles energetic compounds

In order to study the properties of new energetic compounds formed by introducing nitroazoles into 2,4,6-trinitrobezene, the density, heat of formation and detonation properties of 36 nitro-1-(2,4,6-trinitrobenzene)-1H-azoles energetic compounds are studied by density functional theory, and their stability and melting point are predicted. The results show that most of target compounds have good detonation properties and stability. And it is found that nitro-1-(2,4,6-Trinitrophenyl)-1H-pyrrole compounds and nitro-1-(2,4,6-trinitropenyl)-1H-Imidazole compounds have good thermal stability, and their weakest bond is C-NO2 bond, the bond dissociation energy of the weakest bond is 222 kJ mol-1-238 kJ mol-1 and close to TNT (235 kJ mol-1). The weakest bond of the other compounds may be the C-NO2 bond or the N-N bond, and the strength of the N-N bond is related to the nitro group on azole ring.

Computational Envision of Structural, Electronic, Mechanical and Thermoelectric Properties of PdXSn (X=Zr, Hf) half Heusler compounds

Half heusler compounds have gained attention due to their excellent properties and good thermal stability. In this paper, using first principle calculation and Boltzmann transport equation, we have investigated structural, electronic, mechanical and thermoelectric properties of PdXSn (X=Zr,Hf) half Heusler materials. These materials are indirect band gap semiconductors with band gap of 0.52 (0.44) for PdZrSn (PdHfSn). Calculations of elastic and phonon characteristics show that both materials are mechanically and dynamically stable. At 300K the magnitude of lattice thermal conductivity observed for PdZrSn is 15.16 W/mK and 9.53 W/mK for PdHfSn. The highest ZT value for PdZrSn and PdHfSn is 0.32 and 0.4 respectively.

Membranes adsorber from oil palm empty fruit branches (OPEFB): preparation and fabrication

Oil Palm empty fruit branches (OPEFB) are solid waste that are numerous produced from palm oil mills. OPEFB is economically and potentially used as membrane adsorber material due to has good thermal stability, chemical resistance and biodegradability. The objectives of this work is to preparate and fabricate the OPEFB membrane adsorber which is activated by physical activation. The OPEFB has been cleaned and dried, subsequently heated at 500 °C for 30 min via pyrolysis. The activated OPEFB was sieved using 200-400 mesh and followed by the addition of 2-propanol, NH4Cl, polyvinyl alcohol (PVA) and polyethylene glycol (PEG) to become a mixture. The activated OPEFB ratio were varied in the mixtures to obtain the best composition in order to produce a good membrane adsorber texture for casting. FTIR shows on wavenumber at 1082 cm−1 indicates that there is O-H stretching functional groups and bands at 943 cm−1 correspons to C=O functional group. It is concluded that the membrane mixtures can be employed as membrane adsorber due to carbon content which creates strong matrix applied for gas separation.

Fluorescent Indolo[2,3-b]quinoxalin-2-yl)(Phenyl)methanone Dyes: Photophysical, Aie Activity, Electrochemical, and Theoretical Studies

Herein, we have synthesized four indolo[2,3-b]quinoxalin-2-yl)(phenyl)methanone derivatives 1−4 by cyclocondensation. The photophysical studies of dyes in various solvents and neat solid film exhibit typical electronic spectra with inbuilt intramolecular charge transfer (ICT) (λmax: 397‒490 nm) confirming donor-acceptor architecture. Herein, dyes fluoresce in the blue-orange region (λEmax: 435–614) on excitation at their ICT maxima in toluene, ethyl acetate, chloroform, DMSO, and neat solid film. 1 and 2 which exhibit good emission intensity in all mediums, were studied for aggregation-induced emission (AIE) effect. Electrochemical studies indicate 1−4 possess relatively low lying LUMO (‒3.65 to ‒3.98 eV) comparable to reported n-type/electron-transporting materials. The HOMO and LUMO energy levels in 1−4 were evaluated by DFT and TD-DFT calculations. TGA analysis shows 1−4 exhibit good thermal stability. The characteristic optoelectronic properties and thermal stability signify these dyes are potential candidate for their application in optoelectronics.

Stabilizing the Exotic Carbonic Acid by Bisulfate Ion

Carbonic acid is an important species in a variety of fields and has long been regarded to be non-existing in isolated state, as it is thermodynamically favorable to decompose into water and carbon dioxide. In this work, we systematically studied a novel ionic complex [H2CO3·HSO4]− using density functional theory calculations, molecular dynamics simulations, and topological analysis to investigate if the exotic H2CO3 molecule could be stabilized by bisulfate ion, which is a ubiquitous ion in various environments. We found that bisulfate ion could efficiently stabilize all the three conformers of H2CO3 and reduce the energy differences of isomers with H2CO3 in three different conformations compared to the isolated H2CO3 molecule. Calculated isomerization pathways and ab initio molecular dynamics simulations suggest that all the optimized isomers of the complex have good thermal stability and could exist at finite temperatures. We also explored the hydrogen bonding properties in this interesting complex and simulated their harmonic infrared spectra to aid future infrared spectroscopic experiments. This work could be potentially important to understand the fate of carbonic acid in certain complex environments, such as in environments where both sulfuric acid (or rather bisulfate ion) and carbonic acid (or rather carbonic dioxide and water) exist.

Silica-Based Core-Shell Nanocapsules: A Facile Route to Functional Textile

In this work, we present a surfactant-free miniemulsion approach to obtain silica-based core-shell nanocapsules with a phase change material (PCM) core via in-situ hydrolytic polycondensation of precursor hyperbranched polyethoxysiloxanes (PEOS) as silica shells. The obtained silica-based core-shell nanocapsules (PCM@SiO2), with diameters of ~400 nm and silica shells of ~14 nm, reached the maximum core content of 65%. The silica shell had basically no significant influence on the phase change behavior of PCM, and the PCM@SiO2 exhibited a high enthalpy of melt and crystallization of 123–126 J/g. The functional textile with PCM@SiO2 has been proposed with thermoregulation and acclimatization, ultraviolet (UV) resistance and improved mechanical properties. The thermal property tests have shown that the functional textile had good thermal stability. The functional textile, with a PCM@SiO2 concentration of 30%, was promising, with enthalpies of melting and crystallization of 27.7 J/g and 27.8 J/g, and UV resistance of 77.85. The thermoregulation and ultraviolet protection factor (UPF) value could be maintained after washing 10 times, which demonstrated that the functional textile had durability. With good thermoregulation and UV resistance, the multi-functional textile shows good prospects for applications in thermal comfort and as protective and energy-saving textile.

Solvothermal Synthesis of Flower-Flakes Like Nano Composites of Ni-Co Metal Organic Frameworks and Graphene Nanoplatelets for Energy Storage Applications

Solvothermal synthesis of Ni-Co-MOF/graphene nanoplatelets (GNPs) nanocomposites was done for their potential application as electrode material in energy storage devices. Addition of GNPs and metallic precursors together with 2-methylimedazole in the same autoclave reactor produced smooth-nanoflakes like Ni-Co-MOF/GNPs nanocomposites as evaluated by SEM. XRD analysis showed the presence of GNPs where GNPs do not affect the growth of MOF crystals and Ni-Co-MOF crystalline phases remain unaffected in the composite structure. FTIR analysis confirmed the presence of organic links forming nickel-cobalt metal cations framework. Electrochemical testing(CV,EIS,GCD) of the produced composites demonstrated that GNPs addition can enhance the charge storage performance of MOFs nanocomposites. The largest cycle area and most discharge time have been shown by Ni-Co-MOF/GNP-50 composite electrode that delivered the highest specific capacity values (313 Cg-1@1 Ag-1), good reversibility and low internal resistance and charge transfer resistance. Moreover, Ni-Co-MOF/GNP-50 composite exhibited good thermal stability with 28% weight loss during thermogravimetric analysis. The electrochemical evaluations performed on asymmetric supercapacitor real device expressed a specific capacity of 136.5 [email protected] Ag-1, maximum energy density of 32.2 Whkg-1@425 Wkg-1 and maximum power density of 17000 [email protected] Whkg-1. Moreover, the device showed a stability performance of 92.5%@10 Ag-1 after 5000 CD cycles.

Dragon Fruit Foliage: An Agricultural Cellulosic Source to Extract Cellulose Nanomaterials

In this report, we focus our effort to extract cellulose nanomaterials (CNs) from an agricultural cellulosic waste, Dragon Fruit foliage (DFF). DFF was first pretreated by several mechanical treatments and then bleached by chemical treatment to obtain bleached DFF. CNs were then produced from the hydrolysis of the bleached DFF catalyzed by sulfuric acid. We obtained CNs with a small diameter (50 to 130 nm) and length (100 to 500 nm) and a height of 3 to 10 nm. The CNs have a high crystallinity (crystallinity index 84.8%), high −COOH content (0.74 mmol. g−1), good thermal stability and a good Cu (II) adsorption capacity with an adsorption maximum of ~103 mg. g−1. These findings demonstrated the great potential of converting many agricultural cellulosic wastes into valuable cellulose nanomaterials.