Thermogravimetric And Differential Thermal Analysis Research Articles

Study on mechanical performance and mesoscopic simulation of nano-SiO2 modified recycled aggregate concrete

Utilizing nano-SiO2 (NS) to reinforce the old mortar and the weak interfacial transition zone (ITZ) in recycled coarse aggregate (RCA) is a productive approach to enhance the quality of RCA. Throughout this paper, RCA was immersed in NS solutions with different concentrations (2, 5, 10 and 30 wt%). Subsequently, a systematic evaluation of the crushing index and water absorption of the treated NS modified recycled coarse aggregate (SRCA) was conducted. In addition, the calcium hydroxide (CH) content of RCA before and after modification was analyzed by Thermogravimetric and Differential Thermal Analysis (TG-DTA) curves. This study finds that the performance of SRCA modified with 2% concentration achieves comparable modification effects to other concentrations. Additionally, this paper delves into the impact of NS powder on the slump characteristics and compressive strength of concrete. Considering the above research and economic costs, this study adopts 2% concentration of NS for RCA modification and further investigates the stress-strain relationship of NS modified recycled aggregate concrete (SRAC) with various SRCA replacement ratios. Moreover, this paper establishes mesoscopic models of SRAC for various replacement rates and proposes constitutive models corresponding to these rates. The results indicate that when the SRCA replacement rate is within 60%, the stress-strain curve shape of SRAC closely resembles that of natural aggregate concrete (NAC); when the replacement rate exceeds 60%, the descending segment of the SRAC stress-strain curve becomes more precipitous, showing a higher tendency towards fragility in the concrete.

Synthesis and characterization of porous and photocatalytic geopolymers based on natural clay: Enhanced properties and efficient Rhodamine B decomposition

In this work, the incorporation of anatase TiO2 semiconductor in the geopolymer matrix as catalytic materials has been studied. The most noteworthy results obtained from the synthesis of a novel TiO2/geopolymer nanocomposite as an effective ecological catalyst with high thermal stability and significant porosity is presented. The porous and photocatalytic geopolymers based natural clay rich in pyrophyllite and kaolinite minerals were prepared by simple method, the geopolymerization reaction was able to successfully load TiO2 nanoparticles into the geopolymer surface. Furthermore, the results indicate that the prepared catalyst achieved the best performance to degrade Rhodamine B (RhB) molecules present in aqueous solution under UV light irradiation. The geopolymer matrix proved to be a reusable support for TiO2 nanoparticles during the photocatalytic process, efficiently facilitating the separation of photogenerated charges. Finally, the physicochemical and morphological properties of the samples was characterized by several techniques, namely X-ray Fluorescence (XRF), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetric and Differential Thermal Analysis (TGA/DTA), N2 adsorption/desorption isotherm analysis (BET and BJH methods), UV–Vis Diffuse Reflectance Spectroscopy (DRS), Scanning Electron Microscopy (SEM) coupled to an Energy Dispersive X-ray Spectroscopy (EDS) analyzer and Transmission Electron Microscopy (TEM).

Impact of cation distribution on structural, morphological, optical and low-temperature magnetic properties of Er3+ substituted Cu0.8Cd0.2Fe2O4 nanoparticles

A series of cubic spinel-shaped Cu-Cd ferrites using Er3+ ion doping, Cu0.8Cd0.2ErxFe2-xO4 (x = 000, 0.0010, 0.0015, 0.0020, 0.0025, and 0.0030-CCEF) had been synthesized using the citrate sol-gel auto combustion approach. The structural, optical and magnetic properties of the samples were investigated using a wide range of characterization techniques, such as Thermogravimetric and Differential thermal analysis (TG-DTA), Powder x-ray diffractometer (P-XRD), High-resolution transmission electron microscopy (HR-TEM), UV–VIS, Electron spin resonance (ESR), and Vibrating sample magnetometer (VSM). To obtain an understanding of the existence of hydrated water and comprehend the degradation behavior, the TG-DTA was carried out. The produced powders were then sintered for 240 min at 500 °C. According to X-ray diffraction spectra, the John-Teller ion (Cu2+) causes a tetrahedral deformation for pure Cu-Cd ferrite. Erbium substituted afterwards transformed the tetragonal phase towards the cubic spinel phase including trace amounts of impurity phase. FESEM and HRTEM analysis were employed to investigate the microstructure. These FESEM and HRTEM images' observations demonstrated that nanoparticles have a spherical shape. Furthermore, the findings showed that the as-prepared spinel Cu-Cd ferrite nanoparticles exhibited a determined optical band gap energy in the region of 1.62–1.91 eV, demonstrating the semiconducting properties of the synthesized materials. In order to calculate the spin resonance parameters such as the g-values, peak-to-peak linewidth and resonance field, ESR spectra accumulated with X-band microwave energy have been fitted using the Lorentzian function. At 15 K, an in-depth examination of the ferrite nanoparticles' magnetic characteristics was performed. The prepared sample has shown indications of developing superparamagnetic behavior.

Selective Crystallization of Linkage Isomers, [RhIII(NCS)(SCN)5]3- and [RhIII(SCN)6]3-, to Investigate Structural Trans Influence and Thermal Stability.

Linkage isomers of homoleptic complexes, [RhIII(SCN)6]3- and [RhIII(NCS)(SCN)5]3-, formed in aqueous solution were successfully separated by employing methyltriphenylphosphonium (MePPh3+) and 1-ethylquinolinium (EtQu+) ions as countercations, respectively. The single-crystal X-ray analysis of (MePPh3)3[RhIII(SCN)6] (1) indicated that all of the SCN- ligands coordinate to the RhIII ion by S atoms with an octahedral symmetry, where the average bond length of Rh-S is 2.374(7) Å. On the other hand, the RhIII ion of (EtQu)3[RhIII(NCS)(SCN)5]·H2O (2) is coordinated by five S atoms and one N atom of the SCN- ligands with a C4v symmetry. Structural trans influence was observed in the shorter bond length of Rh-S at the trans position of Rh-N. The Rh-S bond length is 2.3398(13) Å significantly shorter than those of 1 by ca. 0.04 Å, although DFT calculations based on the crystal structures indicated that the effective bond order of Rh-N is higher than those of Rh-S. Thermal stability examination by thermogravimetric and differential thermal analyses (TG/DTA) and IR spectroscopy indicated that the linkage isomerization of [RhIII(SCN)6]3- to [RhIII(NCS)(SCN)5]3- proceeded after melting around 174 °C. These results clearly indicate that [RhIII(NCS)(SCN)5]3- is thermodynamically more stable than [RhIII(SCN)6]3- in solid states, although further linkage isomerization hardly occurs.

Synthesis, crystal growth and characterization of organic 1,2,4-triazole p-nitrophthalic acid (TPNP) single crystal for nonlinear optical (NLO) applications

The novel organic NLO single crystal 1,2,4-Triazole 4-nitrophthalic acid (TPNP) has been synthesised with methanol as a solvent in an equimolar ratio (1:1) by slow evaporation solution technique (SEST). The grown material was characterized for its NLO applications and reported for the first time. TPNP single crystal with the dimension of 10 mm × 5 mm × 4 mm was grown. The grown crystal was analysed through various characterization studies such as structural, optical, thermal, electrical and third harmonic generation (Z-scan) studies. The structural confirmation of the grown TPNP crystals was investigated by Single Crystal X-ray diffraction (SXRD) analysis. The Powder X-ray diffraction (PXRD) was used to identify the (h k l) planes for the purpose of drawing the morphology diagram of the original crystal image. The optical analysis carried out using UV–Vis-NIR study on TPNP crystal showed good optical transparency (80 %) and it can be used for various optical applications. To identify the structure and the functional groups, Fourier transform infrared (FTIR) study was conducted. Thermogravimetric and differential thermal analysis (TG-DTA) revealed the thermal stability of the grown TPNP crystal upto 155 °C. The surface etch pit density of TPNP crystal was carried out using chemical etching analysis. The negative photoconductive nature of title crystal was identified by photoconductivity analysis. The dielectric permittivity and dielectric loss as a function of frequency were measured for grown crystal. Intermolecular interactions and fingerprint plots of TPNP molecules are executed by Hirshfeld surface analysis. LDT of the title crystal was investigated by Q-switched Nd: YAG laser of wavelength 532 nm. Third order NLO parameters and susceptibility were determined using the Z-scan technique. It is concluded that the material can be effectively employed for various optoelectronic and photonic applications.

Enhanced photodegradation of CuCo2O4 nanoflower for the dye degradation of Rhodamine B and Methyl Violet

The investigation examined into the effect of different hydrothermal reaction temperatures and durations on the formation of nanoflower-shaped CuCo2O4 nanostructures (CCO NPs). The structural, morphological, functional, optical, and magnetic properties of the synthesized CCO NPs were thoroughly examined. The optimal calcination temperature was determined using Thermogravimetric and Differential Thermal Analysis (TG/DTA), which identified 400 °C as the ideal temperature. Following X-ray Diffraction (XRD) analysis, pure CuCo2O4 samples were formed, with calculated average crystallite sizes of 27 nm for CCO-A, 48 nm for CCO-B, 30 nm for CCO-C, and 31 nm for CCO-D samples. Fourier Transform Infrared (FTIR) analysis provided additional confirmation of pure CuCo2O4 formation, with characteristic bands in the 665–662 cm-1 and 583–567 cm-1 ranges indicating the presence of CuO and CoO bonds. SEM, High-Resolution SEM (HRSEM) and High-Resolution Transmission Electron Microscopy (HRTEM) all supported the observation of a distinct flower-like structural morphology. The optical properties of an optimized sample were revealed by UV–Visible Diffuse Reflectance Spectroscopy (UV-DRS) analysis, which revealed a band gap of 3.3 eV. According to Vibrating Sample Magnetometer (VSM) results, the magnetic behavior of CCO-D nanostructures at room temperature exhibited paramagnetic characteristics. The saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) values were determined to be 0.26218 emu/g, 2.7214 × 10–3 emu/g and 29.787 Oe, respectively. To evaluate photocatalytic performance, the CCO-D photocatalyst was used to degrade Methyl Violet and Rhodamine B dyes. CCO-D degraded MV dye with greater efficiency (93%) than RhB (85%) when exposed to sunlight. These findings highlight CCO-D's potential as a photocatalyst for the degradation of organic dyes.

Synthesis and characterisation of mesoporous MgAl2O4 hollow spheres as a high-value product in a waste recovery strategy

Micrometre-scale hollow sphere-shaped MgAl2O4 powders were synthesised using a spray-drying method, followed by calcination. An aqueous solution of mixed Mg2+ and Al3+ salts, derived from aluminium slag and serpentine tailings, served as a source of magnesium and aluminium. The secondary raw materials were subjected to acid leaching, and the refined leachates were used to prepare a spray-dried MgAl2O4 precursor, which was heat-treated at temperatures ranging from 550 °C to 1100 °C for 1 h. Characterisation of the resulting MgAl2O4 spinel powders was performed using various physicochemical techniques, including thermogravimetric and differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and physical adsorption using N2 (BET). The prepared MgAl2O4 spinel demonstrated several unique properties, including ultrafine particles with a uniform distribution (1–5 μm) and minimal particle agglomeration, high sintering activity (beginning at 550 °C), high purity, high specific surface area (110 m2 g-1/750 °C), and open porosity with a narrow pore size distribution (3–7 nm). These properties make the prepared MgAl2O4 spinel a highly valuable product for waste recovery strategies. The simplicity, efficiency, and cost-effectiveness of this process also predispose it to large-scale production of functional mixed metal oxides of various compositions for use in industries such as energy storage, sensing, and 3D printing fillers.

Synthesis and characterization of hydrogels from alginate and ora‐pro‐nóbis (Pereskia aculeata Miller) mucilage

AbstractThis study aimed to synthesize and characterize hydrogels prepared with alginate (ALG) and ora‐pro‐nobis mucilage (MOPN) by ionic gelation. The hydrogels were produced from solutions containing 0.5, 0.75, 1.0, and 1.25% (w/v) sodium alginate, 0.25, 0.5, 0.75, 1.0 and 1.25% (w/v) MOPN and 1.5 and 3.0% (w/v) CaCl2. The hydrogels were characterized in terms of mechanical strength, degree of swelling, morphology, chemical groups by Fourier transform infrared spectroscopy (FTIR) and x‐ray diffraction (XRD); and their thermal properties were assessed by differential scanning calorimetry (DSC) and thermogravimetric and differential thermal analysis (TG/DTA). The results indicated that MOPN acted with ALG in chain crosslinking, confirming its ability to interact with other polymers to form gels. The control hydrogel, composed of only ALG (1.5%), showed a more crosslinked and less amorphous structure with greater thermal resistance, while the hydrogel composed of ALG (1.25%) and MOPN (0.25%) showed a more amorphous, porous structure with lumps. However, these treatments were statistically equal in terms of mechanical strength and degree of swelling, indicating that ALG and MOPN hydrogels are an economically viable alternative to ALG‐only hydrogels, where 0.25% (w/v) of the ALG can be replaced by MOPN without significant changes in its mechanical and swelling properties.

CO2 adsorption by ethane periodic mesoporous organosilica at low temperatures and high pressure

In this work, the maximum CO2 adsorption capacity of an ordered mesoporous organosilica with ethylene bridges (PMO-Ethane) was studied. The maximum capture capacity was achieved for the sample at 0 °C and 34 atm (827.8 mg·g-1). This result was better than that obtained by most of the studies on other mesoporous materials found in the literature. Approximately 0.33 g of PMO-Ethane would be sufficient to shrink the concentration of atmospheric CO2 by 1 m3 to preindustrial levels. A study of successive adsorption-desorption cycles has demonstrated the material's potential for use in reversible multicycle CO2 capture processes. The CO2 adsorption curves were fitted using mathematical models: Langmuir, Freundlich, Sips, Toth, DubininRadushkevich and Temkin. Previously, several techniques were used to characterize the material: X-Ray diffraction (XRD), surface area (SBET) and porosity, thermogravimetric and differential thermal analysis (TGA-DTA), particle size, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). These results contribute to the development and use of new materials in GHG capture technologies.

Biopolymer-Capped Pyrazinamide-Loaded Colloidosomes: In Vitro Characterization and Bioavailability Studies.

This study aimed to prepare colloidosome particles loaded with pyrazinamide (PZA). These drug-loaded colloidosomes were prepared using an in situ gelation technique using a central composite design with a shell made of calcium carbonate (CaCO3) particles. Optimal amounts of 150 mg of CaCO3, sodium alginate (2%), and 400 mg of poly(3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV) concentration resulted in the maximum drug loading and efficient release profile. Field emission scanning electron microscopy results showed spherical porous particles with a good coating of the PHBV polymer. Additionally, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric and differential thermal analysis (TGA-DTA), and X-ray diffraction (XRD) analysis showed good compatibility between the drug and excipients. The pharmacokinetic studies demonstrated that the drug-loaded colloidosomes resulted in 4.26 times higher plasma drug concentrations with Cmax values of 32.386 ± 2.744 mcg/mL (PZA solution) and 115.868 ± 53.581 mcg/mL (PZA-loaded colloidosomes) and AUC0-t values of 61.24 mcg-h/mL (PZA solution) and 260.9 mcg-h/mL (PZA-loaded colloidosomes), indicating that colloidosomes have the potential to be effective drug carriers for delivering PZA to the target site.

Investigation on Optical, Electrical, Third Harmonic Generation and Hirshfeld Analysis Characteristics of Novel Organic 3‐Amino‐1H‐1,2,4‐Triazole 3,5‐Dinitrobenzoic Acid Monohydrate (3ATDM) Crystal for Nonlinear Optical (NLO) Applications

AbstractThe organic 3‐amino‐1H‐1,2,4‐triazole 3,5‐dinitrobenzoic acid monohydrate (C9 H10 N6 O7) (H2O) (3ATDM) single crystal is synthesized and grown using the slow evaporation solution technique (SEST), for the first time. Single crystal X‐ray diffraction (SXRD) analysis indicated that the 3ATDM crystal has the characteristics of the noncentrosymmetric Pc space group of the monoclinic crystal system. The crystal have good optical characteristics as observed using UV‐visible‐near infrared (NIR) analysis; the transmittance wavelength region is in the range of 200–1000 nm. Sharp emission peaks are observed in the photoluminescence spectrum; this is indicative of ultraviolet (UV) emission. Thermogravimetric and differential thermal analysis (TG‐DTA) is used to evaluate the thermal behavior. The 3ATDM crystal is thermally stable up to 207 °C; the first endothermic peak appeared at 150 °C. The dielectric loss (tan δ) and dielectric constant (ε') are measured as a function of frequency. Vickers microhardness analysis is used to characterize the mechanical strength of the 3ATDM crystal. The third‐order nonlinear optical properties such as absorption coefficient (β), refractive index (n2), and susceptibility (χ (3)) are evaluated through the Z‐scan technique at 532 nm, using a continuous wave (CW) solid‐state laser.

Effect of nano-SiO2 modified recycled coarse aggregate on the mechanical properties of recycled concrete

Improving the performance of the interface between old mortar and recycled coarse aggregate (RCA) is a hot topic and important to enhance the properties of recycled aggregate concrete (RAC). In this paper, the RCA was soaked by nano-SiO2 (NS-RCA) then the water absorption and crushing index of NS-RCA were investigated. The mechanical properties, such as compressive strength, flexural strength, and elastic modulus of RAC prepared by NS-RCA (NS-RAC) were studied. The Thermogravimetric and Differential Thermal Analysis (TG-DTA) and scanning electron microscopy (SEM) were applied to analyze the properties of the interface transition zone (ITZ) around unmodified RAC and NS-RAC. A modified stress–strain model of NS-RAC was proposed considering the concentration of nano-SiO2 and soaking time. The testing results showed that the concentration of nano-SiO2 and soaking time had significant effects on the strength and durability of RCA and the mechanical properties of RAC. The 2% concentration of nano-SiO2 and 48 h soaking time had the best modification effect on RCA. The compressive strength, flexural strength, and elastic modulus of NS-RAC with best modification were 31.8%, 33.2%, and 89.6% higher than those of unmodified RAC respectively. The TG-DTA and SEM analyses indicated that NS-RAC had the denser microstructure of ITZ. This study is conducive to enrich the knowledge about using NS-RAC and supplying guidance for its mix design.

Facile Preparation of Humins-loaded Graphitic Carbon Nitride with Improved Catalytic Activity on the Thermal Decomposition of Ammonium Perchlorate

Novel g-C3N4/humins (denoted as CNH) composite was synthesized through a simple two-step method. The results indicated that humins nanoparticles with sizes ≤ 200 nm were successfully loaded on the surface of g-C3N4 (CN). The catalytic effect of the as-prepared composite on the thermal decomposition of ammonium perchlorate (AP) was investigated by means of thermogravimetric and differential thermal analyses (TG-DTA). Compared with pure CN, CNH was proved to catalyze the thermal decomposition of AP more effectively. Specifically, the high temperature decomposition step of AP was decreased by 80.9 ◦C, with an increase of the total heat release to 1320 Jg−1. Besides, thepossible catalytic mechanism of AP decomposition was discussed.

Characterization of Argentine dolostones with potential application in the manufacture of refractory materials

The chemical, mineralogical, mechanical, thermal and textural characterization of two samples of dolostones of Argentine origin has been carried out. In this work the samples were: rock fragments approximately 10 cm on a side, rock fragments approximately 1 cm on a side, powder <7200 μm (obtained from rock 1 cm by trituration) and powder <100 μm (obtained from powder <7200 μm by ball mill grinding). For the characterization of the rocks, analytical techniques were used. Particle size distributions were performed by sieving (for the samples <7200 μm) and laser granulometry (for the samples <100 μm) and the specific surface was determined by BET method. The chemical composition was determined by XRF technique. The mineralogical analysis was performed by XRD technique and complemented with Rietveld analysis for the quantification of the mineralogical phases. In addition, the FTIR technique was used to complement the previous spectroscopic technique. The pycnometric density was measured using kerosene as immersion liquid. The bulk density and porosity (open, close and total porosity) of the rocks were carried out on rock fragments 3 cm on a side, using Archimedes method employing kerosene as immersion liquid and complemented with the mercury porosimetry technique. The ceramic texture analysis was carried out by SEM. The mechanical strength to diametrical compression of the rocks was determined on cylindrical specimens, taking into account the ASTM D-3967-16 standard. Finally, the thermal behaviour of the rocks was carried out by thermogravimetric and differential thermal analysis (TGA/DTA); the setting was: 1300 °C in the air atmosphere. The loss on ignition (LOI) was calculated with four thermal techniques: ISO 10058:1992 standard, TGA technique, muffle test (ad hoc method), and a designed method. The results have shown that the rocks studied fall into the classification of “dolostones” with the majority constituent mineral being “dolomite”. The chemical profiles analysed and the content of impurities are within potential range for refractory application.

Porous 8YSZ Ceramics Prepared with Alkali Halide Sacrificial Additives.

8 mol% Y2O3-stabilized ZrO2 (8YSZ) ceramics were prepared with KCl and LiF additions to obtain porous specimens with high skeletal density. Thermogravimetric and differential thermal analyses (TG/DTA) were carried out on 8YSZ and on 8YSZ mixed to 5 wt.% KCl or 5 wt.% LiF as sacrificial pore formers that were thermally removed during sintering. The melting and evaporation of the alkali halides were evaluated by differential thermal analysis. Dilatometric analysis was also carried out following the same TG/DTA temperature profile with results suggesting rearrangement of the 8YSZ particles during LiF and KCl melting. The dilatometric data of 8YSZ green pellets mixed to KCl or LiF exhibited an initial expansion up to the melting of the alkali halide, followed by shrinkage due to sintering evolution with grain growth and pore elimination. The time that the alkali halide molten phase was kept during sintering was found to be an important parameter for obtaining 8YSZ-sintered specimens with specific pore content; bulk density and open porosity could then be tuned by controlling the time the alkali halide remained liquid during sintering. Scanning electron microscopy images of the pellet fracture surfaces showed pores that contributed to increasing the electrical resistivity as evaluated by impedance spectroscopy analysis.

Interfacial effects of Fe2O3@Co3O4 on the thermal decomposition of ammonium perchlorate

Fe2O3Co3O4 composites were fabricated based on hydrothermal process and subsequent annealing treatment and characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The catalytic performances of Fe2O3Co3O4 composites in the thermal decomposition of ammonium perchlorate (AP) were investigated using thermogravimetric and differential thermal analyses (TG-DTA) analysis. The results revealed that Fe2O3Co3O4 composites showed superior catalytic behaviors for AP pyrolysis compared to pure Fe2O3, Co3O4 as well as CoFe2O4 samples, ascribed to the synergistic interactions between Co3O4 and Fe2O3 enhancing electron transfer capability. Especially, the as-obtained Fe2O3@Co3O4 displayed the best catalytic efficiency with the high temperature decomposition (HTD) of AP reducing by 156 °C in the case of 2 wt% addition. Online TG-FTIR was used to detect the decomposed products of AP, and the catalytic mechanism was discussed.

Structural, magnetic and electrical transport properties of the sol-gel derived La1-xCaxMnO3 (0≤x≤0.3) nanoparticles

Sol-gel (SG) prepared calcium doped La1-xCaxMnO3 (0 ≤ x ≤ 0.3) nanoparticles (>35 nm) show a phase transformation from rhombohedral-R3c to orthorhombic-Pnma. The dopant concentration influences the bond length and lattice parameters and their variations as observed from the rietveld refinement. The phase stability and chemical compositions are confirmed using the Thermogravimetric and differential thermal analysis (TG-DTA) and Fourier transform infrared (FTIR) spectroscopy measurements. The latter confirms the presence of dangling bonds from the changes in the characteristic vibrational frequencies and intensities. Field emission scanning electron microscope-energy dispersive X-ray analysis (FESEM-EDAX) confirms the nano-dimension of the particles and good chemical homogeneity of the samples. The Curie temperature Tc, estimated from the field cooled magnetization curve, shifts towards room temperature (Tc = 160–270 K) with the increase of dopant concentration. The samples exhibit a clear metal to insulator transition, the temperature of which shifts to higher values (169–267 K) with increase in dopant content. With the application of an external magnetic field, local ordering of magnetic moments occurs and the evolution of a ferromagnetic metallic phase suppresses the existing paramagnetic insulating phase, decreasing the value of resistivity. Three different temperature ranges demarked in the resistivity curves are studied using different theoretical models. The observed low temperature resistivity upturn is explained on the basis of the Kondo-like model while the ferromagnetic metallic region is studied using different scattering processes like electron – electron, electron – magnon etc. The variable range and small polaron hopping (VRH and SPH) models are used in the high-temperature region data and with the aid of Holstein's relation the non-adiabatic SPH model it is found to be most suitable to understand the conductivity behavior. The temperature dependent evolution of the Griffith's like phase can explain and correlate the electric transport and magnetic properties exhibited by the samples. This highlights the evolution of Mn3+-O2--Mn4+ FM oriented networks, which form conduction channels with the lowering of temperatures. These channels mediate the enhanced conduction and helps set in long-range FM ordering in the samples/

Influence of Molasses on the Explosion and Decomposition Properties of the Coal Dust Deposited in Underground Mines

Coal dust endangers the health and safety of workers in underground coal mines. Therefore, developing coal dust suppressants with dust prevention and explosion-proof properties is critical. The influence of molasses on the explosion and decomposition of the coal dust deposited in underground mines was investigated using 20 L explosion experiments and thermogravimetric and differential thermal analysis (TG-DTA). Findings reveal that, first, molasses can weakly promote the explosion of coal dust at low coal dust concentrations (&lt;400 g/m3) but has no significant effect on the explosion at high coal dust concentrations (≥400 g/m3). Second, the decomposition process of the coal dust mixed with molasses has three stages: the moisture evaporation stage (0–150 °C), the molasses decomposition stage (150–300 °C), and the coal dust decomposition stage (300–500 °C). Molasses oxidation consumes oxygen and releases heat; at low coal dust concentrations, the released heat can promote coal dust decomposition to produce combustible gas, enhancing the coal dust explosion; at high coal dust concentrations, under the co-influence of the heat generation and oxygen consumption, molasses has no effect on the coal dust explosion. This is the mechanism of which molasses influences coal dust explosions.

Valorisation of Water Potabilization Sludges as Precursors for Alkali-Activated Binders: Characterization and Feasibility Study.

Water potabilization sludges (WPS) are a heterogeneous waste generated from the coagulation-flocculation process of drinking water production, whose composition is highly dependent on the geological context of reservoirs, the composition and volume of treated water, and the types of coagulants used. For this reason, any feasible approach for reusing and valorising of such waste cannot be disregarded from the detailed investigation of its chemical and physical characteristics and they have to be evaluated at a local scale. In this study, WPS samples from two plants serving the Apulian territory (Southern Italy) were subjected for the first time to a detailed characterization with a view to evaluating their recovery and reuse at a local scale as a raw material for producing alkali activated binders. WPS samples were investigated by X-ray fluorescence (XRF), X-ray powder diffraction (XRPD) including phase quantification by the combined Rietveld and reference intensity ratio (RIR) methods, thermogravimetric and differential thermal analysis (TG-DTA), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Samples showed aluminium-silicate compositions with up to 37 wt% of Al2O3 and up to 28 wt% of SiO2. Small amounts of CaO were also found (6.8 and 4 wt%, respectively). The mineralogical investigation indicates the presence of illite and kaolinite as clayey crystalline phases (up to 18 wt% and 4 wt%, respectively), in addition to quartz (up to 4 wt%) and calcite (up to 6wt%) and a large amorphous fraction (63 wt% and 76 wt%, respectively). WPS were subjected to heating from 400 °C to 900 °C and mechanical treatment by high energy vibro-milling in order to determine the best pre-treatment condition in view of their use as solid precursors to prepare alkali-activated binders. Alkali activation (8M NaOH solution; room temperature curing) was attempted on untreated WPS, on 700 °C heated and on 10-minute high-energy milled samples, which were considered the most suitable based on the preliminary characterization. Investigations of alkali-activated binders confirmed the geopolymerisation reaction occurrence. Variations in gel features and compositions depended on the amount of reactive SiO2, Al2O3 and CaO available in the precursors. WPS heated at 700 °C led to the most dense and homogeneous microstructures, due to a greater availability of reactive phases. The results of this preliminary study demonstrate the technical feasibility of preparing alternative binders from the investigated Apulian WPS, paving the way for a local reuse of these waste products, leading to economic and environmental benefits.

A comprehensive study on the synthesis and characterization of eco-cementitious binders using different kind of industrial wastes for sustainable development

As it is known that with the urbanization, the demand for Ordinary Portland Cement (OPC) is also increasing. Every year a huge quantity of raw materials are consumed in the manufacturing of cement, which are non-renewable resources such as limestone (70–80%). Almost half of CO2 release from combustion of limestone at high temperature. Therefore, the main purpose of this study is to achieve sustainability and reduced CO2 emission during cement clinker synthesis. This can be achieved by using supplementary fuel to heat the kiln and supplementary raw material instead of natural resources like limestone, sand, clay and iron slag etc. The principal chemical composition of some industrial waste is SiO2, Fe2O3, CaO and Al2O3, which are also major chemical compounds of commercial raw material in cement manufacturing. Therefore, in various literature; the eco-cement clinker was synthesized using minimum natural resources and maximum industrial wastes such as dry sewage sludge, iorn ore tailing, red mud, steel slag, fly ash, ceramic waste etc. As a replacement for commercial raw material. The physio-mechanical properties of the developed eco-cement clinkers were being analyzed followed by isothermal calorimetry, scanning electron microscope, X-Ray Diffraction (XRD) analysis, thermogravimetric and differential thermal analysis (TG-DTA) and then compared with reference cement clinker. Almost all major phases viz.- C3S (Alite), C2S (Belite), C3A (Aluminate) and C4AF (Ferrite), were detected in all eco-cement clinkers. Apart from the literature studies; the ongoing work at Author's Institute, regarding the development of low energy cement clinker is also being presented. In last, on the basis of various research studies, current challenges for utilization of industrial wastes have been examined along with future scope.