TG Curves Research Articles

Study of the Pyrolysis of Ayous and Kambala Co-Products: Kinetic Modeling of the Two Species

A kinetic model based on the two-stage semi-global multi-reaction model of Grioui was developed using the TG and DTG curves for the by-products of Kambala and Ayous. These two tropical species are widely used in the Republic of Congo. The TG and DTG curves were obtained through thermogravimetry at five different heating rates (3, 7, 10, and 20 K/min) up to a final temperature of 800 °C under a nitrogen atmosphere. The thermal decomposition of both species started at similar temperatures, but the profiles exhibited notable differences. Kambala showed a distinct profile with two peaks at approximately 500 °C and 700 °C, which upon further investigation were found to correspond to ash decomposition. Additionally, the shoulder present in Ayous between 250 °C and 300 °C, attributed to hemicelluloses degradation, was absent in the DTG curves for Kambala. The kinetic model for Ayous was formulated in three steps, while the model for Kambala consisted of four steps. Both models accurately predicted the thermal degradation of the wood species, and the resulting kinetic parameters aligned with those reported in the literature.

Boron/Difluoroamino (B/NF2) Composites Prepared Through an Energetic Fluorinated-Centerd Surface Modification Strategy to Enhance Their Ignition and Combustion Characteristics

To enhance the ignition and combustion characteristics of boron (B), in this study, a suitable, energetic fluorinated group (NF2) that can improve energy and promote combustion efficiency was utilized and B/NF2 composites (B/PDB) with three different particle sizes (10–20 μm, <5 μm, and 0.5–2 μm) were prepared through energetic fluorinated surface modifications with a PDB layer, a copolymer of difluoroaminomethyl-3-methylethoxybutane and 3,3′-bis(azidomethyl)oxetane, coated on the surface of B. The morphology and structure of B/PDB were characterized via the FTIR, SEM, TEM, and XPS techniques. The results indicate that all B/PDB particle sizes were successfully coated by NF2 on the surfaces of B particles through the PDB layer. The TG curves in the thermal analyses were used to determine the amount of the PDB layer of B/PDB with different particle sizes. Based on the DSC curves, NF2 of composites with better catalysis during ammonium perchlorate (AP) decomposition. Additionally, the effects of NF2 on both B/PDB and B/PDB with AP were investigated through PY-GC/MS, ignition, and combustion. Compared with pure B, NF2 significantly improved the thermal conductivity, thereby decreasing the ignition delay of B/PDB, and the ignition delay of B/PDB with AP. The combustion of B/PDB and AP was more intense, extending the combustion duration, forming volatile fluorine compounds, and increasing combustion reaction efficiency. In general, this energetic fluorinated-centred surface modification has potential applications to enhance the ignition and combustion characteristics in B.

Highly efficient CO2 mineralization: Mechanisms and feasibility of utilizing electrolytic manganese residue as a feedstock and implementing ammonia recycling

Electrolytic manganese residue (EMR) and CO2 emissions from the electrolytic manganese metal (EMM) production process present significant challenges to achieving cleaner production within the industry. Given the high capacity for CO2 sequestration and the stability of the sequestered forms, CO2 mineralization methods utilizing minerals or industrial residues have garnered considerable research interest. The efficacy of such methods is fundamentally dependent on the properties of the materials employed. EMR, due to its calcium sulfate dihydrate (CaSO4·2H2O) content, possesses an intrinsic potential for CO2 solidification. In this study, we propose a novel method for CO2 mineralization utilizing EMR, coupled with NH3·H2O recycling. Experimental results indicated that under conditions of a reaction temperature of 55 °C and a pH of approximately 8, each ton of EMR can sequester 0.16 t of CO2, with equilibrium achieved within 10 min. The mineralization mechanism was elucidated using SEM, TG curves, and XRD analyses, which revealed that Ca2+ ions are initially leached from CaSO4·2H2O in the EMR, subsequently precipitating with CO32− ions to form CaCO3. This CaCO3 layer effectively covers the surface of CaSO4·2H2O, inhibiting further Ca2+ release and stabilizing the reaction equilibrium. Furthermore, the ammonia in the solution is regenerated into NH3·H2O, facilitating its reuse and preventing secondary pollution. The utilization of EMR for CO2 mineralization not only mitigates carbon emissions in the EMM production process but also promotes environmentally sustainable practices in the industry. This study highlights a promising pathway towards achieving carbon neutrality and cleaner production in electrolytic manganese production.

Pyrolysis of Khat waste vs. Coal: Experimental and Aspen plus analysis

This study explores the potential of Khat waste as a biofuel through a detailed analysis of its physical properties and pyrolytic behavior, employing both laboratory and simulation techniques. Biomass, including Khat waste, is a valuable renewable energy source with potential applications in reducing waste and CO2 emissions, especially in rural areas of developing countries like Ethiopia. The physical properties of the Khat waste were thoroughly examined, including moisture content, ash, volatile matter (VM), fixed carbon (FC), and elemental composition. The apparent density of the pyrolyzed khat waste was found to be 0.9688 g/cm³. The TGA results showed a moisture loss of 6.7 %, volatile matter of 4.7 %, fixed carbon of 6.78 %, and ash content of 5.55 %. Notably, Khat waste exhibited unique thermal behavior with a downward shift in TG curves above 220 °C. DTGA identified three decomposition peaks: moisture evaporation at 100 °C, hemicellulose breakdown at 210 °C, and cellulose degradation at higher temperatures. Fourier Transform Infrared Spectroscopy (FTIR) provided insights into the functional groups present in Khat waste, including alkene functional groups and O-H bonds, which are crucial for biofuel properties. Simulation using Aspen Plus software modeled the pyrolysis process, highlighting how varying heating rates affect volatile matter and fixed carbon content. Increasing heating rates decreased volatile matter and moisture but increased fixed carbon content. These findings offer valuable insights for optimizing Khat waste as a biofuel, emphasizing the need for tailored pyrolysis conditions to enhance biofuel production efficiency.

Understanding the kinetics of waste plastic catalytic pyrolysis under microwave irradiation for enhanced resource valorization

The increasing accumulation of ABS plastic waste poses significant environmental challenges, necessitating efficient methods for its disposal and recycling. The pyrolysis of the ABS plastic waste was performed under various heating programs including constant heating rate (27.5, 42.2 and 65 K min−1), and sample-controlled reaction rate (0.01 min−1) to obtain the TG curves using the in-house developed microwave assisted thermogravimetric analyzer. Fe-impregnated SiC was used as thermal and chemical catalyst, while neat SiC played only thermal catalyst role. The modified Sestak-Bergren equation used to model the TG data by Pearson’s linear correlation and associated parameters n = 1.129 and m = 0.27 was achieved. The comparison of normalized form of the conversion function (f (α)/f (0.5)) with the most common models of solid-state reactions showed that random scission model (L2) was the most suitable approach to physically explain the pyrolysis of ABS plastic waste. Furthermore, by applying isoconversional kinetic analysis, the variation of activation energy (Eα) with conversion value was approximately constant. The Eα obtained was 140.5 and 63.7 kJ/mol with SiC and Fe/SiC, respectively. These findings hold practical implications for industrial applications or waste management strategies, particularly when considering the developed microwave-assisted real-time TGA-pyrolysis, which can enhance the efficiency and sustainability of plastic waste recycling processes.

Assessment of sewage sludge as a component for the tire char co-gasification process

The work aimed to assess various sewage sludge (from coking, refinery, and fat-processing plants) as components for tire char co-gasification. The sewage sludge were analysed (basic characteristics, thermal stability, ash characteristics). Then, CO2 gasification and co-gasification measurements of individual materials and their blends (ratio: 70:30, 40:60) were made using the TGA, based on which the process and synergy effect were assessed. Moreover, a detailed analysis of char gasification formed during the pyrolysis was performed (reactivity assessment, kinetic parameters determined using the n-order Coats and Redfern model, and correlation between the individual elements in materials and their reactivity). Co-gasification measurements proved that the addition and increasing sewage sludge share in blends enhanced the process (TG curves were shifted towards lower temperatures, reactivity indicators, and final conversion degrees were improved compared to tire char). The greatest impact on the pyrolysis stage had the sludge from the refinery, while on the gasification stage sewage sludge from coking and fat-processing plants (where the synergy was observed). Moreover, the addition of sewage sludge to tire char reduces the activation energy and, in most cases, the pre-exponential factor. Finally, the correlation between reactivity and the Na, Mg, and P amount in the samples has been proved.

Kinetic investigation of aschalcha heavy oil oxidation in the presence of cobalt biocatalysts during in-situ combustion

The catalytic effect of cobalt tall oil and cobalt sunflower oil catalysts on the oxidation kinetics of heavy crude oil was investigated in this study. Comprehensive kinetic analyses, employing differential scanning calorimetry, thermogravimetric analysis, and kinetic modeling techniques, revealed that the presence of these catalysts significantly influenced the oxidation behavior of heavy oil. The catalysts exhibited pronounced shifts in the DSC and TG curves towards lower temperatures, indicating facilitated initiation of oxidation reactions at lower onset temperatures. Quantitative kinetic parameters, including activation energies and frequency factors, were determined using the Friedman and Kissinger-Akahira-Sunose analyses. The cobalt tall oil catalyst demonstrated superior performance, effectively lowering the activation energy barrier and increasing oxidation rates, particularly at higher conversion degrees. Catalyst characterization techniques, including X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy, revealed the formation of highly crystalline cobalt oxide nanoparticles with optimal dispersion and size distribution, as well as the presence of favorable functional groups for surface interactions. The results elucidated the role of these catalysts in facilitating the oxidation process through the provision of active sites, altered reaction pathways, favorable steric environments, and efficient oxygen activation capabilities. These findings contribute to the development of efficient catalytic systems for heavy oil upgrading processes and offer insights for further optimization of catalyst properties to achieve desired oxidation kinetics behavior.

Pyrolysis kinetic analysis and model constructions of different ranks of coal and validation by GA–BP neural networks

In the current steel industry, environmental pressures are mounting. If the reducing gases generated from coal pyrolysis can be utilized for reducing iron ore, the goal of low-carbon production with controllable costs can be achieved. However, the release of volatile content in coal has a significant impact on the pyrolysis process and final products. Therefore, in this study, the pyrolysis characteristics and gaseous products of four types of coal with different volatile matter content was investigated by thermogravimetry-mass spectrometry (TG-MS) technology. The results showed that coals with higher volatile matter content demonstrated stronger reactivity during pyrolysis. As the volatile matter content in coal increased, the starting temperature for releasing the reducing gases decreased, leading to a significant increase in the released gas volume. In addition, the three kinetic factors were calculated by isoconversional method, distribution of the activation energy model (DAEM) and Coats-Redfern (CR) method respectively, and the pyrolysis reaction mechanism function suitable for all coal types was reconstructed based on common solid reaction models. Finally, a predictive model based on a GA-improved back-propagation neural network (BPNN) was developed, which useing 21 input parameters to predict the TG curves, activation energy (E), lnA and mechanism function (fα) and achieving R2 values above 0.95. This study contributes to a comprehensive understanding of the pyrolysis mechanism of coals with different volatile matter content, providing scientific guidance for effective utilization.

Three-dimensional structural tomography and thermal characterization of the kidney stones and gallstones to know the temperature disintegration

The present study aimed to carry out a structural and thermal characterization of kidney and gallstones to reinforce knowledge aimed at their possible reduction or disintegration. Densities of 36 body stones at different dimensions, obtained by assessments of mass and volume, and structural features of the stones identified by 3D tomographic analysis. The density of kidney stones was greater than that of gallstones, at 0.0025 gr/cm3 > 0.0020 gr/cm3. DTA and TG curves of kidney stones showed minimal structural changes after 200 °C, with initial mass loss and release of carbon dioxide at 458 °C resulting in 66 % mass loss and the transformation of C2H2CaO5. Gallstones are composed mainly of cholesterol (C27H46O). Cholesterol gallstones have a relatively low density and are susceptible to potentially disintegrating within the human body. Kidney stones require high temperatures above 400 °C for their size reduction, which is why partial intracorporeal thermal disintegration may not be feasible.

N,N’-bis(3-dithiocarbamatopropyl) piperazine bridged metallomacrocyclic complexes of Ni(II), Cu(II) and Zn(II): Synthesis, characterization, photophysical, in-silico study and their potential utility in heavy metal ion sensing

Two secondary diamines viz. N,N’-bis{3-(p-methoxybenzylamino)propyl}piperazine (H2L1) and N,N’-bis{3-(p-chlorobenzylamino)propyl}piperazine (H2L2) holding N,N’-bispropylpiperazine linkers have been prepared and subsequently used to derive a new series of N,N’-bis(3-dithiocarbamatopropyl) piperazine bridged metallomacrocyclic complexes [M(II)2-µ2-bis-{(κ2S,S-S2CN(R)C3H6)2piperazine}] wherein R = p-methoxybenzyl, M = Ni(II) 1, Cu(II) 2, Zn(II) 3; R = p-chlorobenzyl, M = Ni(II) 4, Cu(II) 5, Zn(II) 6. The formation and purity of all the metallomacrocyclic dithiocarbamate complexes were verified by microanalysis and standard methods such as HRMS, NMR, IR and UV–Visible absorption spectroscopy and corroborated by density functional theory calculations. The experimental (magnetic susceptibility and UV–Visible) and theoretical calculations suggest a square planar/distorted square planar environment around nickel(II)/copper(II) and tetrahedral/distorted tetrahedral environment around zinc(II) centres in 1–6. Thermogravimetric study was carried out on 1–6 to study their thermal stability and degradation behaviour. Notably, TG curves of compounds 2, 3 and 5 gave a stable residual mass corresponding to corresponding metal sulphides (MS). Notably, the calculated HOMO-LUMO gaps (1.19–1.33 eV) for Cu(II)-dithiocarbamate 2 and 5 indicates their semiconducting nature. The potentials of these metallomacrocycles as a molecular probe for optical sensing of environmentally hazardous heavy metal ions ca Pb(II), Cd(II) and Hg(II) were further examined by using UV–Visible and fluorescence spectroscopies.

Fabrication of ecofriendly silver based composite hydrogel with multifunctional properties as possible wound dressing material

Hydrogels are ideal for creating wound dressings but fabricating such hydrogels with strong antibacterial properties and high biosafety is complex due to their unique properties. Therefore, the present work proposes the preparation of chitosan-silver-moringa gum composite hydrogel (CAM) with excellent bactericidal action. The solvent-free, ecologically friendly, and cost-effective hydrogel sets a new standard for sustainable production. The CAM composite hydrogel showed maximum swelling in distilled water after 24 h. The produced composite hydrogel has a characteristic Fourier Transform Infrared Spectroscopy (FTIR) and x-ray diffraction (XRD) pattern. The CAM composite hydrogel inhibited Hela cell lines by 100 ± 0.56% at 30 μg ml−1 with an IC50 of 13.89 ± 0.8 μg ml−1 via MTT assay. The Scanning Electron Microscope (SEM) showed the hydrogel’s porous structure whereas (EDX) analysis revealed the presence of silver in the hydrogel matrix. Additionally, the DPPH assay showed 82.06 ± 1.39% antioxidant activity at 0.9 mg ml−1 for the composite hydrogel. The in-vitro protein denaturation assay, of composite hydrogel, showed 59.7 ± 2.52% inhibition compared to diclofenac 87.89 ± 0.47% at 1 mg ml−1, indicating anti-inflammatory efficacy. CAM hydrogel showed steady behaviour from 105 to 170 °C with a weight loss of 2.77%, making it suitable for steam sterilisation as a wound dressing material. CAM composite hydrogel has a different glass transition temperature (Tg) curve compared to chitosan and moringa gum, indicating its successful production. The CAM composite hydrogel demonstrated promising antibacterial activity against all tested strains, making it a promising biobased wound dressing material.

Association between blood lipids and diabetes mellitus in older Chinese adults aged 65 years or older: a cross-sectional analysis of residents’ electronic health records

AimThis study aimed to investigate how blood lipids are associated with diabetes among older Chinese adults.Methods3,268,928 older Chinese adults without known diabetes were included. Logistic regression and restricted cubic spline (RCS) models were conducted to study associations between blood lipids (total cholesterol [TC], triglycerides [TG], low-density lipoprotein cholesterol [LDL-C], and high-density lipoprotein cholesterol [HDL-C]) and diabetes.Results202,832 diabetes cases were included. Compared with the lowest quintiles, TC, TG, and LDL-C in the highest quintiles showed a higher diabetes prevalence risk and HDL-C presented a lower risk in multivariate-adjusted logistic regression models. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for the highest quintiles of TC, TG, and HDL-C were 1.39 (1.37–1.41), 2.56 (2.52–2.60), and 0.73 (0.72–0.74), respectively. For LDL-C, 3–5% lower risk was found in the second and third quintiles, and 4–23% higher risk was found in the fourth and fifth quintiles. RCS curves showed a non-linear relationship between each blood lipid parameters and diabetes (P-non-linear < 0.001). TG and HDL-C curves presented monotonically increasing and L-shaped patterns, respectively, whereas TC and LDL-C curves exhibited a J-shaped pattern. When TC < 4.04 mmol/L or LDL-C < 2.33 mmol/L, ORs of diabetes increased with the decrease of corresponding indexes. However, after excluding participants with lower LDL-C, the J-shaped association with TC disappeared.ConclusionsThis study demonstrates non-linear associations between lipids and diabetes. Low cholesterol levels are associated with a high risk of diabetes. The cholesterol paradox should be considered during lipid-lowering treatments.

Can varying activation energy be determined reliably from thermogravimetric experiments?

Solutions of the general isoconversional kinetic equation were generated and compared assuming activation energies, E, which vary with the advance of the reaction, α. Series belonging to 4–5 heating rates were compared. TG curves simulated with highly varying activation energies could approximate well the curves simulated with first-order kinetics and constant E. This observation indicates that the information content of a series of TG curves at constant heating rates is not sufficient for the determination of activation energies that vary with the advance of the studied reactions. The problem proved to be smaller when differential curves were compared in the same way; the uncertainties decreased by factors 0.2–0.5. There is a standard procedure of ASTM International (ASTM E2958-19, 2019. https://doi.org/10.1520/E2958-21) that describes the estimation of E from experiments carried out at a specific modulated temperature program. The reliability of this procedure was also tested and found to be low, though not as low as that of the evaluation of TG curves at linear temperature programs with usual heating rates. The work continues and complements a recent study of the author (Várhegyi in J Therm Anal Calorim 148:12835–12843, 2023).

The Activation Energy Temperature Dependence for Viscous Flow of Chalcogenides

For some chalcogenide glasses, the temperature dependence of the activation energy E(T) of viscous flow in the glass transition region was calculated using the Williams–Landel–Ferry (WLF) equation. A method for determining the activation energy of viscous flow as a function of temperature is proposed using the Taylor expansion of the function E(T) using the example of chalcogenide glasses As-Se, Ge-Se, Sb-Ge-Se, P-Se, and AsSe-TlSe. The calculation results showed that the temperature dependence of the activation energy for the Ge-Se, As-Se, P-Se, AsSe-TlSe, and AsSe systems is satisfactorily described by a polynomial of the second degree, and for Sb-Ge-Se glass by a polynomial of the third degree. The purpose of this work is to compare the values of the coefficients obtained from the Taylor series expansion of E(T) with the characteristics of the E(T) versus (T − Tg) curves obtained directly from the experimental temperature dependence of viscosity. The nature of the dependence E(T) is briefly discussed.

QUANTITATIVE DETERMINATION OF ALUNITE IN ORE AND PRODUCTS OF ITS PROCESSING BY THE DIFFERENTIAL-THERMAL METHOD

The possibility of determining alunite by the derivatographic method according to the area of desulphurization endoeffect on the DTA curve and corresponding to this effect the weight loss on the TG curve has been investigated. It has been proposed to carry out the determination by the calibration curve constructed for standard samples and their area of endoeffect and by the weight loss depending on the content of alunite in the samples, since the dissociation of sulfur bound from 4500C accompanies the whole process. The analysis of samples should be carried out at an intensity of temperature increase of 100C/min, since at an intensity of 300C/min. the peak area increases significantly, and the indicators are not stable. It has been shown that the analyses in an inert medium lead to a twofold loss of sulphur bound, in contrast to the air medium, before desulphurization till the formation of the endoeffect

Reaction mechanism between carbon and CaO–SiO2–Al2O3–Na2O slag system during continuous casting process

The reaction behavior between the carbon and mold fluxes during the heating process is vital for a successful continuous casting process and the high billet quality. A detailed investigation combined with thermogravimetry-mass spectrometry (TG-MS), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM) techniques was carried out to systematically investigate the transformation mechanistic of the macro physicochemical properties, melting behavior, viscosity, crystallization, and heat transfer performance caused by the reaction behavior. The results showed that the mold flux underwent carbonate decomposition (973–1223 K), solid reaction (1273–1573 K), and melting process (1473–1673 K) during the continuous casting process. The carbon-bearing mold flux exhibited an endothermic peak at approximately 1673 K, corresponding to a weight loss ratio of approximately 14.5% on the TG curve, confirming that carbon could react with the middle mineral phases Ca2SiO4, Ca2Al2SiO7, and Na6Ca3Si6O18 to form SiC, increasing the breaking temperature by approximately 293 K. SEM and TEM results indicated that the melting behavior was restrained by the carbon itself and the newly formed components. Besides, the addition of carbon increased the degree of polymerization of molten slag, the thickness of slag film and the proportion of small crystals in slag film, further leading to an increase in crystallization and heat transfer performances. The reaction mechanism between carbon and slag and the subsequent effects on melting point, viscosity, crystallization ratio and heat flux density were clearly understood, which is meaningful for the carbon blending process of the mold flux.

Thermogravimetric investigation of anisotropy of dimensional shrinkage of softwood and hardwood during carbonization

Thermogravimetric analysis (TGA) was performed on five softwood and five hardwood thin wood samples in the longitudinal (L) and radial (R) directions. Dimensional changes were monitored using a charge-coupled device camera under a nitrogen flow. A comparison of the TG and derivative TG (DTG) curves revealed that shrinkage in the R direction began when the weight was reduced to 79–92% at 305–330 °C and 87–96% at 275–290 °C for softwoods and hardwoods, respectively. Hemicellulose is mainly degraded in this temperature range. In contrast, shrinkage in the L direction started at temperatures close to the DTG peaks, i.e., 360–380 °C and 345–370 °C, respectively, at which temperatures cellulose is mainly degraded. In general, the R/L shrinkage anisotropy was greater for hardwoods than for softwoods, but the species variation was large and the magnitude was directly related to the difference in the shrinkage onset temperatures between the R and L directions, regardless of the wood species. Therefore, shrinkage anisotropy can be attributed to the relative reactivity of hemicellulose and cellulose in wood cell walls. The shrinkage mechanism during carbonization is discussed in terms of the cell wall ultrastructure, in which cellulose microfibrils are covered by a hemicellulose–lignin matrix, and the orientation of the cells in the L and R directions.

Pyrolysis and combustion of industrial hemp, coal and their blends for thermal analysis by thermogravimetric analysis/Fourier transform infrared spectrometer.

In this study, the thermal behaviours of Cannabis sativa (CS), coal and their five different blends at a heating rate (β) of 10, 20, 30, 40 and 50°C min-1; the synergistic effects between CS and coal; and the distribution of gases formed during pyrolysis and combustion were investigated by using the thermogravimetric analysis/Fourier transform infrared spectrometer (TGA/FTIR) integrated system. The TG and DTG curves showed that the thermal decomposition of pyrolysis and combustion of all feedstocks at all β values had three main decomposition stages. The synergistic effect was observed for DTGmax, mass loss (ML), or final residue (FR) at least once at a given β of each blend; and the synergy was more effective for DTGmax and ML in pyrolysis than in combustion, whereas the opposite was true for FR. The lowest emissions of CO2, CH4, NOx and SO2 except CO during pyrolysis occurred at the blend of 0% CS + 100% Coal. However, the highest emissions of CO, CH4, NOx and SO2 except CO2 during combustion were observed at the blend of 80% CS + 20% Coal. The emissions of CO, CO2, NOx and SO2 from all samples during pyrolysis were lower than that of combustion, indicating that pyrolysis can be preferred due to its lower emission to the environment. Different structural properties of CS, coal and their blends caused different thermal behaviours, synergistic effects and gas products during pyrolysis and combustion by TGA/FTIR, suggesting detailed further investigation for upper-scale pyrolysis and combustion applications.

Structure, Antioxidant Activity and Antimicrobial Study of Light Lanthanide Complexes with p-Coumaric Acid.

This paper presents the results of a study of the effects of the lanthanide ions Ce3+, Pr3+, Nd3+ and Sm3+ on the electronic structure and antioxidant and biological (antimicrobial and cytotoxic) properties of p-coumaric acid (p-CAH2). Structural studies were conducted via spectroscopic methods (FTIR, ATR, UV). Thermal degradation studies of the complexes were performed. The results are presented in the form of TG, DTG and DSC curves. Antioxidant properties were determined via activity tests against DPPH, ABTS and OH radicals. The reducing ability was tested via CUPRAC assays. Minimum inhibitory concentrations (MICs) of the ligand and lanthanide complexes were determined on E. coli, B. subtilis and C. albicans microorganisms. The antimicrobial activity was also determined using the MTT assay. The results were presented as the relative cell viability of C. albicans, P. aeruginosa, E. coli and S. aureus compared to controls and expressed as percentages. In the obtained complexes in the solid phase, lanthanide ions coordinate three ligands in a bidentate chelating coordination mode through the carboxyl group of the acid. Spectroscopic analysis showed that lanthanide ions increase the aromaticity of the pi electron system of the ligand. Thermal analysis showed that the complexes are hydrated and have a higher thermal stability than the ligand. The products of thermal decomposition of the complexes are lanthanide oxides. In the aqueous phase, the metal combines with the ligand in a 1:1 molar ratio. Antioxidant activity tests showed that the complexes have a similar ability to remove free radicals. ABTS and DPPH tests showed that the complexes have twice the ability to neutralise radicals than the ligand, and a much higher ability to remove the hydroxyl radical. The abilities of the complexes and the free ligand to reduce Cu2+ ions in the CUPRAC test are at a similar level. Lanthanide complexes of p-coumaric acid are characterised by a higher antimicrobial capacity than the free ligand against Escherichia coli bacteria, Bacillus subtilis and Candida albicans fungi.

Conductive nano-Al/polyaniline composites prepared via mechanical milling

The conductive nano-Al/polyaniline composites were prepared by the milling method in the solid state. Here, aluminum nanostructures were prepared in two different mechanical methods, wire drawing and wire milling in the presence of lubricant oil. The effects of the preparation methods on the structures and morphologies of aluminum nanostructures were investigated by XRD and FESEM. The results show that the shape and size of aluminum nanoparticles in the preparation by the wire drawing method are significantly different than the wire milling method. The aluminum nanostructures were prepared by milling method have flake-like nanosheets while the wire drawing method leads to the formation of spherical ultrafine nanoparticles, which particles size are in the range of 30–60 nm. Then, polyaniline was produced using a solid-state polymerization process by the chemical reaction between aniline hydrochloride and potassium peroxydisulfate. Finally, nano-Al/polyaniline composites were prepared by mechanical milling at room temperature. The quantitative analysis was carried out with the materials analysis using diffraction (MAUD) method and weight fraction for aluminum and PANI were calculated 6.66% and 93.34%, respectively. Electrical conductivity measurements show the conductivity (1.2 × 10−2 S cm−1 at 25 °C) for polyaniline emeraldine salt and (1.02 × 10−3 S cm−1 at 25 °C) in nanocomposite respectively. The results show that by adding aluminum nanoparticles to the polymer the conductivity of nanocomposite (Al/PANI-ES) is lower than that for pure (PANI-ES). Thermogravimetry and differential thermal analysis curves show pure (PANI-ES) and nanocomposite (Al/PANI-ES) have a similar thermal degradation process. The total weight loss in TG curve of pure PANI-ES, in the temperature range 45–800 °C is 46.28% but, total weight loss observed in nanocomposite is 38.67%. Therefore, nanocomposite has higher thermal stability than that of the pure PANI-ES.