Solid-state Thermal Decomposition Research Articles

NiO/vermiculite composites prepared for photocatalytic degradation of methanol-water solution and hydrogen generation

A novel eco-friendly NiO/Vm clay based photocatalysts were synthesized from two vermiculites (Vm1 and Vm2) and nickel(II) nitrate hexahydrate (Ni(NO3)2·6H2O salt precursor by the chemical precipitation without and with the sodium hydroxide (NaOH) or ammonium hydroxide (NH4OH, 28% NH3 in H2O) as precipitation agents (Synthesis A) in comparison with the solid-state thermal decomposition (Synthesis B) at 600 °C. Structural properties of all specimens were characterized by X-ray fluorescence, scanning electron microscopy, X-ray diffraction, infrared (IR) and Raman spectroscopy. The photocatalytic performance of NiO/Vm composites was evaluated under UV radiation (λ = 254 nm) for decomposition of methanol-water to hydrogen over 4-h and the stable yield of hydrogen over the 24-h periods. The NaOH and NH4OH affected the NiO crystallite size and therefore the photocatalytic activity during 4 h. Different 2:1 layer charge of Vm1 (0.82 e−) and Vm2 (0.40 e−) and the specific surface area of Vm1 (about 43 m2/g) and Vm2 (about 34 m2/g) supported H2 yield of 628.2 μmol/gcat. and 596.8 μmol/gcat., close to 657.0 μmol/gcat. produced in the presence of commercial photocatalyst TiO2 Evonik P25. Crystalline NiO precipitated and anchored in NiO/Vm composites contained smaller crystallites than those in free NiO. Vermiculite silica surface supports coverage of NiO by hydrogen bonding to Si-OH groups influencing the geometry of the NiO crystal structure (disorder NiO(X)). The heterojunction with Si-O-Ni bonding, at which electrons transfer from Vm to NiO cause enriching electron density in NiO and favoring its photocatalytic activity. Photocatalytic hydrogen generation from methanol–water mixture at the presence of all specimens indicated the main product H2 and minimum by-products CH4 and CO. The stable hydrogen production for 24 h was confirmed only in the presence NiO/Vm1–24 while maintaining the NiO(X) in small crystallites. The thermal solid-state procedure provided the gradual dehydration of vermiculites and Ni(NO3)2·6H2O to the same amount and crystallinity of NiO in NiO/Vm1 and NiO/Vm2 composites. The results of this work confirm that vermiculites mixed layer structures with different negative layer charge play a dominant role as semiconductors for anchored NiO. The photocatalytic activity of NiO/vermiculite composites can be harnessed to treat wastewater containing organic contaminants.

Influence mechanism of ZnCdS solid solution composition regulation on its energy band and photocatalytic hydrogen performance

The regulation of the band structure is crucial for the improvement of the photocatalytic performance, but the relationship between the composition of solid solution catalyst and their band structure is still unclear. Herein, the solid solution catalysts ZnxCd1-xS (1 > x > 0) were designed and synthesized using a handy solid-phase thermal decomposition strategy. It is interesting that the band structure and photocatalytic hydrogen production (PHP) performance of the obtained solid solution catalyst can be cleverly regulated by controlling the atomic ratio of the solid solution. Among the obtained series of ZnxCd1-xS solid solution catalysts, the optimal solid solution catalysts Zn0.5Cd0.5S exhibits the best PHP activity and favorable cycle stability: the corresponding PHP rate is 41211.2 μmol·h−1·g−1 and the QE value is 7.7 % at 400 nm. The outstanding photocatalytic hydrogen production performance is the result of significantly narrowing the band gap of sulfide solid solution. Additionally, the effective separation and transfer rate of photogenerated carrier has also been improved effectively. The construction of bimetallic sulfide solid solution photocatalyst via an ingenious solid-state thermal decomposition strategy in this work provided a new idea for improving the photocatalytic performance of bimetallic catalysts.

Facile Synthesis and Multiple Application of Ultralong-Afterglow Room Temperature Phosphorescence Aggregate Carbon Dots from Simple Raw Materials.

Owing to the ultralong afterglow, room temperature decay phosphorescence nanomaterials have aroused enough attention. In the work, by simple one-pot solid-state thermal decomposition reaction, aggregate carbon dots (CDs) was prepared from trimesic and boric acid. Based on the intermolecular hydrogen bonds and intramolecular π-π stacking weak interaction from precursors, CDs was encapsulated in boron oxide matrix and formed aggregation. The aggregate state of CDs facilitated the triplet excited states (Tn), which could induce the room temperature decay phosphorescence properties. By careful investigation, under different excitation wavelengths at 254 and 365nm, the aggregate CDs showed > 15s and > 3s room temperature phosphorescence emission in the naked eye, which was associated with 1516.12 ms and 718.62 ms lifetime respectively. And the aggregate CDs exhibited widespread application in encoding encryption, optical anti-counterfeiting and fingerprint identification etc. The interesting aggregate CDs revealed unexpected ultralong-afterglow room temperature decay phosphorescence properties and the work opened a window for constructing ultralong-afterglow room temperature decay phosphorescence aggregate CDs nanomaterials.

The “Periodic Table” of 1-methylbenzotriazole: Zinc(II) Complexes

In an attempt to fill in the empty Zn position in the “Periodic Table” of 1-methylbenzotriazole (Mebta), reactions between Zn(II) sources and this ligand were carried out. The detailed synthetic studies provided access to complexes [ZnX2(Mebta)2] (X = Cl, 1; X = Br, 3; X = I, 4), (MebtaH)2[ZnCl4] (2), tet-[Zn(NO3)2(Mebta)2] (5), oct-[Zn(NO3)2(Mebta)2] (6), and [Zn(Mebta)4](Y)2 [Y = ClO4, 7; Y = PF6, 8]. Solid-state thermal decomposition of 2 leads to 1 in quantitative yield. The structures of 3, 4, 5, 6, and 7 were determined by single-crystal crystallography. The structures of the remaining complexes were proposed based on spectroscopic evidence. In all compounds, Mebta behaves as monodentate ligand using the nitrogen of the position 3 as donor. Complexes 1–4, 7, and 8 are tetrahedral. Complexes 5 and 6 are isostoichiometric and their preparation in pure forms depends on the reaction conditions; in the former the ZnII atom has a tetrahedral geometry, whereas in the latter the metal ion is octahedral. This case of rare isomerism arises from the monodentate (in 5) vs. bidentate (in 6) coordination of the nitrato groups. Extensive π–π stacking interactions and non-classical H bonds build interesting 3D architectures in the structurally characterized complexes. The compounds were characterized by IR, far-IR, and Raman spectroscopies in the solid state, and the data were interpreted in terms of the structures (known or proposed) of the complexes and the coordination modes of the organic and inorganic ligands involved. The solid-state structures of the complexes are not retained in solution, as proven by NMR (1H, 13C[1H]) spectroscopy and molar conductivity data. The thermal decomposition study of 1 and 3 leads to stable intermediates with 1:1 stoichiometry, i.e., ZnX2(Mebta). Based on far-IR spectra, polymeric tetrahedral structures are possible with simultaneous presence of terminal and bridging X− groups. Liquid-phase ab initio (MP2) and gas-phase DFT calculations, performed on Mebta and the nitrato complexes, respectively, shed light on the tendency of Mebta for N3-coordination, and the existence and relative stabilities of 5 and 6.

Effect of Substitution at the Di- and Trivalent Sites of {N[n- C4H9]4]FeIIFeIII[C2O4]3]}∞ on the Nature of Solid State Decomposition Reaction Leading to Various Metal Oxides

Background: Oxalate ligand-based metal complexes have long been used for the thermal synthesis of metal oxides. Polymeric homo/heterometallic oxalate-based molecular materials of the general formula, {A]MIIMIII[C2O4]3]}∞, [A = organic cation, MII/MIII: di/trivalent transition metal ion; C2O4: oxalate ligand] provides a molecular source to prepare metal oxides through solid state thermal decomposition primarily due to the potential to tune the materials’ outcome by adjusting the molecular stoichiometry and composition. Objective: The study aims to explore the effect of mixing at the di- and trivalent metal sites of {N[n-C4H9]4]FeIIFeIII[C2O4]3]}∞ which decomposes to hematite, on the nature of thermal decomposition reaction as well as the nature of the obtained decomposed materials. Methods: Two series of materials {N[n-C4H9]4]FeII 1-xZnII xFeIII[C2O4]3]}∞ and {N[n- C4H9]4]FeIIFeIII 1-xCrIII x[C2O4]3]}∞ were prepared as precursors for non-isothermal thermogravimetry [TG] study. Model-free integral isoconversional method is employed to calculate the activation energy of decomposition, and hence the most probable reaction mechanism, as well as the reaction rate of thermal decomposition, was determined. Based on the kinetic parameters, the important thermodynamic parameters such as the changes of entropy, enthalpy, and Gibbs free energy are estimated for the activated complex formation from the precursors. Powder X-ray diffraction studies were made to identify the decomposed materials. Results: For materials with 0 < x ≤ 1 well-defined two-step and one-step decomposition process were observed for {N[n-C4H9]4]FeII 1-xZnII xFeIII[C2O4]3]}∞ and {N[n- C4H9]4]FeIIFeIII 1-xCrIII x[C2O4]3]}∞, respectively. For each series of materials, a systematic dependence of the activation energy on the extent of conversion indicates a systematic change in the reactivity. The thermal decomposition strongly depends on the extent of mixing at the di- and trivalent sites and proceeds through different reaction mechanisms at different rates. On the decomposition of these series of materials, a range of metal oxides was obtained. Possibly, during such extent of mixing dependent reactions, the reactant particles go through modifications in their reactivity by several factors. Conclusion: Present work may invoke interest in solid state synthesis of different metal oxides under controlled thermal decomposition by identifying the rate controlling the process through reaction kinetics study for better synthesis and manoeuvring.

Spectral, Structural, and Antibacterial Study of Copper(II) Complex with N2O2 Donor Schiff Base Ligand and Its Usage in Preparation of CuO Nanoparticles

A new Schiff base complex, Cu(H2L)2 (H3L: 6,6 ′ -((1E,1 ′ E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol)), through the reaction of ligand H3L with Cu(NO3)2 3H2O, in the ratio of 2 : 1 in methanol solvent was prepared. The obtained ligand (H3L) was characterized by FT-IR, 13C NMR, 1H NMR and elemental analyses. Then its copper(II) complex was prepared and characterized by FT-IR spectroscopy, thermal studies, elemental analyses and single crystal X-ray diffraction. The X-ray crystallography revealed that the two H3L ligands in bidentate fashion coordinated to one copper center for producing Cu(H2L)2 complex. We used copper(II) Schiff base complex, Cu(H2L)2, for the preparation of CuO nanoparticles via solid-state thermal decomposition. The crystalline structure of the product was studied by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). XRD indicated that the new product was copper oxide. SEM image showed that the size of CuO nanoparticles was between 46 and 53 nm, and they had uniform shape. The antibacterial properties of the complex and ligand were also investigated. The results revealed that Schiff base complex showed higher biological activity than Schiff base ligand.

ZnCo2O4/ZnO nanocomposite: Facile one-step green solid-state thermal decomposition synthesis using Dactylopius Coccus as capping agent, characterization and its 4T1 cells cytotoxicity investigation and anticancer activity

Although, using plant extracts for the green synthesis of various nanoparticles attracted the attention of researchers and scientists due to easy availability and wide distribution of plants as well as their safety to use, in the present work, ZnCo2O4/ZnO nanoparticles synthesized via the green chemistry technique using Dactylopius Coccus, the scale insect. Dactylopius Coccus plays the role of an active reducing and capping agent for synthesis of NPs with well-organized biological properties. Various formulations synthesized in order to investigate the effect of different calcination time and temperatures on the morphology of NPs. The synthesized NPs were characterized by several techniques like XRD, SEM, TEM, HRTEM, and VSM. The XRD result revealed that the particle size of the NPs prepared was in the range of 40 ± 2 nm that was confirmed through HRTEM analysis. Moreover, the cytotoxicity of the NPs was investigated to determine its anti-proliferative impact against 4T1 cancer cell lines. Effective in-vitro and in-vivo death induction in breast cancer cells in the presence of magnetic nanostructures was discussed. The results confirmed that the NPs significantly decreased the percentage of 4T1 cells survival with an IC50 of 0.3 mg/ml. Finally, the dominant mechanism of cell death was investigated that is apoptosis along with an increase in cellular oxidative stress.

Novel thiosemicarbazone complexes as single coordinated precursors for noble metal modified nickel oxide nanophotocatalysts

Pd2+, Pt2+, Ni2+ and Cu2+ complexes of N-ethyl-2-(2-hydroxybenzylidene) hydrazine-1-carbothioamide (H2L) have been prepared and fully characterized via SCXRD, FTIR, CHNS, UV–Vis, GC-MS, TGA and NMR. Ni2+, Pd2+ and Pt2+ complexes were used as novel single precursors for the preparation of noble metal/metal oxide nanoparticles via solid state thermal decomposition method based on their thermal characteristics. For the first time, one pot preparation of Pd/NiO and Pt/NiO nanoparticles (NPs) was achieved via this method. The prepared nanoparticles were characterized using XRD, TEM, XPS and UV–Vis analytical techniques. The photocatalytic activities of bare and noble metal modified NiO NPs were assessed toward the photodegradation of Methylene Blue dye (MB) under natural solar radiation. The tight contact between noble metals and NiO in addition to the lack of aggregation gave preference to this method. The nanoparticles demonstrated high photocatalytic activities with the following trend Pt/NiO (91.3%)˃Pd/NiO(84.5%)˃NiO (45.0%). The enhanced photocatalytic efficiency in the presence of noble metals was attributed to lower charge carrier's recombination rate and the fermi level energies of noble metal nanoparticles. Total organic carbon (TOC) analysis was performed to assess the mineralization ability of the Pt/NiO nanoparticles (90.7% TOC Removal). For in-depth understanding the reasons behind Pt/NiO nanoparticles photo-reactivity, the revealing of reactive oxidative species (ROS) was achieved through scavenging trapping experiments.

Mononuclear Copper(I) Schiff Base Complex Cu((Cl-NO2-ba)2en)I(CH3CN): Synthesis and Crystal Structure

New mononuclear copper(I) Schiff base complex Cu((Cl-NO2-ba)2en)I(CH3CN) (1) containing a bidentate Schiff base ligand (Cl-NO2-ba)2en = 2,4-dichloro-5-nitro-benzylidene-1,2-diaminopropane, was prepared in an acetonitrile solution and characterized by elemental analyses (CHN), FT-IR and UV-Vis spectroscopy. Suitable dark-orange single crystals were obtained by slow evaporation of solvent at 5 ºC for several days. Crystal structure of the title compound 1 was determined by single-crystal X-ray diffraction. The complex 1 crystallizes in orthorhombic space group Pna21, a = 16.8634 (5) Å, b = 8.4460 (5) Å, c = 17.4786 (2) Å, V = 2489.45 (17) Å3 and Z = 4. In addition, the title compound 1 was used as new precursor for the synthesis of copper(II) oxide nanoparticles via solid state thermal decomposition. The as prepared CuO product was characterized by FT-IR, XRD and SEM.

Mononuclear Copper(I) Schiff Base Complex Cu((Cl-NO2-ba)2en)I(CH3CN): Synthesis and Crystal Structure

New mononuclear copper(I) Schiff base complex Cu((Cl-NO2-ba)2en)I(CH3CN) (1) containing a bidentate Schiff base ligand (Cl-NO2-ba)2en = 2,4-dichloro-5-nitro-benzylidene-1,2-diaminopropane, was prepared in an acetonitrile solution and characterized by elemental analyses (CHN), FT-IR and UV-Vis spectroscopy. Suitable dark-orange single crystals were obtained by slow evaporation of solvent at 5 and#186;C for several days. Crystal structure of the title compound 1 was determined by single-crystal X-ray diffraction. The complex 1 crystallizes in orthorhombic space group Pna21, a = 16.8634 (5) and#197;, b = 8.4460 (5) and#197;, c = 17.4786 (2) and#197;, V = 2489.45 (17) and#197;3 and Z = 4. In addition, the title compound 1 was used as new precursor for the synthesis of copper(II) oxide nanoparticles via solid state thermal decomposition. The as prepared CuO product was characterized by FT-IR, XRD and SEM.

Mononuclear Copper(I) Schiff Base Complex Cu((Cl-NO2-ba)2en)I(CH3CN): Synthesis and Crystal Structure

New mononuclear copper(I) Schiff base complex Cu((Cl-NO2-ba)2en)I(CH3CN) (1) containing a bidentate Schiff base ligand (Cl-NO2-ba)2en = 2,4-dichloro-5-nitro-benzylidene-1,2-diaminopropane, was prepared in an acetonitrile solution and characterized by elemental analyses (CHN), FT-IR and UV-Vis spectroscopy. Suitable dark-orange single crystals were obtained by slow evaporation of solvent at 5 and#186;C for several days. Crystal structure of the title compound 1 was determined by single-crystal X-ray diffraction. The complex 1 crystallizes in orthorhombic space group Pna21, a = 16.8634 (5) and#197;, b = 8.4460 (5) and#197;, c = 17.4786 (2) and#197;, V = 2489.45 (17) and#197;3 and Z = 4. In addition, the title compound 1 was used as new precursor for the synthesis of copper(II) oxide nanoparticles via solid state thermal decomposition. The as prepared CuO product was characterized by FT-IR, XRD and SEM.

Mononuclear Copper(I) Schiff Base Complex Cu((Cl-NO2-ba)2en)I(CH3CN): Synthesis and Crystal Structure

New mononuclear copper(I) Schiff base complex Cu((Cl-NO2-ba)2en)I(CH3CN) (1) containing a bidentate Schiff base ligand (Cl-NO2-ba)2en = 2,4-dichloro-5-nitro-benzylidene-1,2-diaminopropane, was prepared in an acetonitrile solution and characterized by elemental analyses (CHN), FT-IR and UV-Vis spectroscopy. Suitable dark-orange single crystals were obtained by slow evaporation of solvent at 5 and#186;C for several days. Crystal structure of the title compound 1 was determined by single-crystal X-ray diffraction. The complex 1 crystallizes in orthorhombic space group Pna21, a = 16.8634 (5) and#197;, b = 8.4460 (5) and#197;, c = 17.4786 (2) and#197;, V = 2489.45 (17) and#197;3 and Z = 4. In addition, the title compound 1 was used as new precursor for the synthesis of copper(II) oxide nanoparticles via solid state thermal decomposition. The as prepared CuO product was characterized by FT-IR, XRD and SEM.

Mononuclear Copper(I) Schiff Base Complex Cu((Cl-NO2-ba)2en)I(CH3CN): Synthesis and Crystal Structure

New mononuclear copper(I) Schiff base complex Cu((Cl-NO2-ba)2en)I(CH3CN) (1) containing a bidentate Schiff base ligand (Cl-NO2-ba)2en = 2,4-dichloro-5-nitro-benzylidene-1,2-diaminopropane, was prepared in an acetonitrile solution and characterized by elemental analyses (CHN), FT-IR and UV-Vis spectroscopy. Suitable dark-orange single crystals were obtained by slow evaporation of solvent at 5 ºC for several days. Crystal structure of the title compound 1 was determined by single-crystal X-ray diffraction. The complex 1 crystallizes in orthorhombic space group Pna21, a = 16.8634 (5) Å, b = 8.4460 (5) Å, c = 17.4786 (2) Å, V = 2489.45 (17) Å3 and Z = 4. In addition, the title compound 1 was used as new precursor for the synthesis of copper(II) oxide nanoparticles via solid state thermal decomposition. The as prepared CuO product was characterized by FT-IR, XRD and SEM.

Physico-chemical and thermal studies of newly developed phenolic copolymer resin and its antibacterial activities

A new random copolymer derived from 8-hydroxyquinoline, vanillin, 4-hydroxyacetophenone and formaldehyde was synthesized using conventional condensation polymerization. This copolymer further characterized by FT-IR, 1H NMR, 13C NMR, 13C NMR-DEPT, GPC, BET, DSC and TG-DTG. The apparent activation energy of resin by using Friedman methods and Kissinger-Akahira-Sunose (KAS) were 19.8 and 16.3 kJ mol−1, respectively. The three-dimensional diffusion (D3) decomposition mechanisms for the solid state thermal decomposition of copolymer have been observed from the Craido method and master plots. The copolymer resin could be used in the prevention of infections linked to medical devices.

Band gap modified zinc oxide nanoparticles: an efficient visible light active catalyst for wastewater treatment

The use of photocatalysis in wastewater treatment using low cost photocatalyst plays a vital role in thwarting the enigma of water pollution. In this work, we report synthesis of metal- and non-metal-doped zinc oxide (ZnO) nanostructures via solid state, solvent and surfactant-free microwave-assisted thermal decomposition method. HRTEM images confirm the formation of highly crystalline nanorod morphology in the case of sodium-doped ZnO. The photocatalytic activity of the synthesized samples initially assessed by the degradation of methylene blue under visible light illumination suggests that SZO-3 (15wt% Na-doped) with admirable degradation rate (95% in 180 min with apparent rate constant of 1.69 × 10–2 min−1) and tenacious photostability envisages its potential applications in water treatment processes. The coalescence of ultrasound, visible light and catalyst resulted in augmented degradation (99.5%) in 60 min.

Copper oxide derived from copper(I) complex of 2-acetylpyridine-N(4)-(methoxy phenyl)thiosemicarbazone as an efficient catalyst in the reduction of 4-nitrophenol

A copper(I) complex of 2-acetylpyridine-N(4)-(methoxy phenyl)thiosemicarbazone was successfully synthesized and structurally characterized using Fourier transform infrared (FTIR), Ultraviolet-visible (UV-Vis) and nuclear magnetic resonance (NMR) spectroscopies, thermal gravimetric analysis (TGA) and CHN elemental analyses. The complex was converted into copper oxide in a simple, efficient, and cheap method via solid state thermal decomposition. Test of the catalytic performance of the copper(I) complex and copper oxide were in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) shows that copper oxide has a higher catalytic activity (98.7%) compared to the copper(I) complex (78.2%). Optimization of the catalyst loading revealed that 1.0 mol% of catalyst was the most optimized amount with the highest conversion (98.7%) than any other amounts, 0.5 mol% (96.8%), 1.5 mol% (95.4%) and 2.0 mol% (89.6%). Recyclability and reproducibility tests of copper oxide prove that this catalyst was very efficient, exhibit excellent reproducibility with consistent catalytic performances and could be reused four times without significant decrease in the catalytic activities.

Fractional kinetics on thermal analysis: application to lumefantrine thermal decomposition.

The fractional derivative concept to treat non-isothermal solid state thermal decomposition was employed in this work. Simulated data were compared with the exact solutions for the method validation. Calculated fractional kinetics data for four heating rates were initially considered and the Kissinger-Akahira-Sunose (KAS) method demonstrate that, although the activation energy is not retrieved, it can be useful to determine a single or multistep process. Experimental thermal decomposition data of lumefantrine heated at 5, 10 ,15, and 20 oC min- 1 were fitted for a single-step process. The kinetic parameters were retrieved for integer and fractional kinetics, considering some ideal and general models. Application of the KAS method to these data demonstrated an activation energy dependent on the conversion rate, indicating a multistep process. Five data subintervals were fitted separately using the general model with variable derivative order. It was found a process that occours with integer order derivative until α = 0.3 and fractional order for α > 0.3 with combination of simultaneous reactions, since the parameters do not correspond to any ideal model. The determined activation energies showed the same increasing behavior observed in the KAS approach. The results for multistep process presented an error 102 times smaller if compared with the best result, considering a single-step process. Therefore, the fractional kinetic model presents a powerful extension to the usual thermal data analysis.

Master-eğriler kinetik yönteminin izotermal olmayan selüloz pirolizine uygulanması ve piroliz işleminin termodinamik analizi

Kinetic modeling of thermochemical conversion methods such as pyrolysis is one of the most challenging issues for bio-refineries. It is known that cellulose together with hemicellulose and lignin mainly affect the characteristics of biomass pyrolysis. However, there is still limited knowledge about the thermal behaviors of biopolymers that go into complex multi-phase pyrolysis reactions in the literature. Therefore, cellulose pyrolysis kinetics and thermodynamics were investigated in this study. Kinetic parameters of the pyrolysis process were calculated by a combined method of master-plots and Friedman method. Active pyrolysis of cellulose is found to occur between 263 and 455 °C. Applied Friedman method was perfectly fitted with the experimental data and activation energy of the thermochemical conversion process was found between 150.8 and 190.2 kJ/mol while the mean activation energy was calculated as 164.3 kJ/mol. The comparison of kinetic models used of solid-state thermal decomposition processes indicated that the cellulose pyrolysis mechanism is a diffusion-controlled (D3) degradation process at lower conversions (0<α<0.5) and the process can be explained by reaction-based mechanisms at higher conversion degrees.

Effect of polymorphic phase transitions on stability of energetic compounds. Thermal transformations of 2,4,6-tris(2,2,2-trinitroethylnitramino)-1,3,5-triazine

The kinetics of thermal transformations of the energetic compound 2,4,6-tris(2,2,2- trinitroethylnitramino)-1,3,5-triazine (1) and products of this reaction were studied by differential scanning calorimetry, thermogravimetry, IR spectroscopy, single-crystal X-ray diffraction, and powder X-ray diffraction. The kinetic and activation parameters of the decomposition of compound 1 were determined. The polymorphic phase transformation α-1 → β-1 was observed at 105 °C. The kinetics of the solid-state thermal decomposition of compound β-1 was found to be described by the same Arrhenius equation as the decomposition kinetics of 1 in the melt, i.e., the inhibitory effect of the crystal lattice is absent. The factors responsible for this anomaly are discussed.

A facile route for the synthesis of new 1D copper(II) coordination polymer as precursors for preparation of nano structures: Crystallography and Hirshfeld surface analysis

The purpose of the present study was to investigate a simple approach for synthesis of new 1D copper (II) coordination polymer as a precursor for preparation of nano-structures based on crystallography and Hirshfeld surface analysis method. In doing so, A novel 1D copper(II) coordination polymer compound of [Cu(tp)(phen)]n(1) (tp = 1,4-benzendicarboxylic acid and phen: 1,10-Phenanthroline) was synthesized using two different methods, such as branched-tube and sonochemical methods. The X-Ray Diffraction (XRD) results revealed that with applying both methods, the produced compounds have a same crystalline phase. A Single crystal X-ray analysis of produced compound 1 using the branched-tube method showed that Cu2+ ions are 6-coordinated. The contribution of intermolecular interactions in compound 1 were studied by Hirshfeld Surface Analysis method. The role of sonication power, reaction time, concentrations of reactants, temperature on the growth and final morphology of the obtained nanostructures were studied by the sonochemical method. While, the concentrations of reactants and reaction time directly affected the final size of nano-structures of compound 1, the sonication power and temperature showed an inverse impact. Compound 1 was used as a new precursors for preparation of Cu(II) oxide structures via solid-state thermal decomposition process. The nano-structures of compound 1 were further analyzed by IR spectroscopy, powder X-ray diffraction (PXRD) and Scanning Electron Microscopy (SEM).