Thermogravimetric Differential Thermal Analysis Research Articles

Date palm (Phoenix dactylifera L.) pollen-based microgel and its promising medical and environmental applications

Pollen, a natural bi-layered porous microcapsule, plays a crucial role in plant reproduction by protecting the plant's genetic material. Due to its unique properties, it has garnered attention for medical and environmental applications. Recent studies have focused on transforming the pollen's rigid structure to soft, gel-like matter, enabling the creation of pollen-based products such as paper and sponge. The main factor in the gelation process involves pectin-to-pectate conversion within the pollen's inner layer. Previously, claimed that this transformation is restricted to eudicot plants, and some others, such as monocot plant pollens do not exhibit this gelation phenomenon. In this study, we successfully produced microgel from date palm (Phoenix dactylifera L.) pollen (DPP), challenging this assertion. A significant portion of these monocot plant pollens exceeds the requirement of date production, presenting an opportunity for large-scale production without environmental concerns. Here, we have prepared pollen-based microgel, paper, and sponge and conducted a comprehensive analysis using various techniques such as optical and fluorescence microscopy, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), elemental CHN analysis, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric differential thermal analysis (TGA/DTA), rheological measurements, mechanical analysis, pH-sensitivity tests, swelling analysis, and oil absorption capacity. By discerning the specific physicochemical properties of these materials, we propose potential medical and environmental applications for further investigation.

Thermoanalytical and Kinetic Studies for the Thermal Stability of Emerging Pharmaceutical Pollutants Under Different Heating Rates

Emerging pharmaceutical pollutants like ciprofloxacin (CIP) and ibuprofen (IBU) are frequently detected in aquatic environments, posing risks to ecosystems and human health. Since pollutants rarely exist alone in the environment, understanding the thermal stability and degradation kinetics of these compounds, especially in mixtures, is crucial for developing effective removal strategies. This study therefore investigates the thermal stability and degradation kinetics of CIP and IBU, under different heating rates. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were employed to examine the thermal behavior of these compounds individually and in mixture (CIP + IBU) at heating rates of 10, 20, and 30 °C/min. The kinetics of thermal degradation were analyzed using both model-fitting (Coats–Redfern (CR)) and model-free (Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Friedman (FR)) methods. The results showed distinct degradation patterns, with CIP decomposing between 280 and 550 °C and IBU between 152 and 350 °C, while the mixture exhibited multistep decomposition in the 157–500 °C range. The CR model indicated first-order kinetics as a better fit for the degradation (except for IBU). Furthermore, CIP exhibits higher thermal stability and activation energy compared to IBU, with the KAS model yielding activation energies of 58.09 kJ/mol for CIP, 11.37 kJ/mol for IBU, and 41.09 kJ/mol for CIP + IBU mixture. The CIP + IBU mixture generally showed intermediate thermal properties, suggesting synergistic and antagonistic interactions between the compounds. Thermodynamic parameters (ΔH°, ΔG°, ΔS°) were calculated, revealing non-spontaneous, endothermic processes for all samples (except in the FWO method) with a decrease in molecular disorder and positive ΔG° values across all models and heating rates. The study found that higher heating rates led to less thermodynamically favorable conditions for degradation. These findings provide important information concerning the thermal behavior of these pharmaceutical pollutants, which can inform strategies for their removal from the environment and the development of more effective waste-treatment processes.

Synthesis and Properties of a Red Na5Zn2Gd1−x(MoO4)6: xEu3+ Phosphor

Novel Eu3+-doped Na5Zn2Gd(MoO4)6 triple molybdate phosphors were fabricated by the sol-gel method. The structure, morphology, and luminescent properties have been characterized by X-ray diffraction (XRD), thermogravimetric differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), FTIR spectroscopy, and luminescence spectroscopy. The results indicated that the synthesized Na5Zn2Gd1−x(MoO4)6: xEu3+ phosphor consisted of a pure phase with monoclinic structure. Under excitation at 465 nm, the Na5Zn2Gd1−x(MoO4)6: xEu3+ phosphor exhibits an intensive red emission band around 610 nm corresponding to the transition of 5D0→7F2 which is much higher than that 5D0→7F1 at 594 nm, which was appropriate for a blue LED. According to the influence of the synthesis conditions, the phosphors showed the highest emission intensity when the doping concentration of Eu3+ was 25 mol.% and the molar ratio of citric acid to metal ions was 2:1. Na5Zn2Gd0.75(MoO4)6: 0.25 Eu3+ with the color coordinates (x = 0.658, y = 0.341) is a more stable red phosphor for blue-based white LEDs than the commercial Y2O2S: Eu3+ red phosphor (0.48, 0.50) due to its being closer to the NTSC standard values (0.670, 0.330).

Plant-mediated synthesis, characterization, and evaluation of a copper oxide/silicon dioxide nanocomposite by an antimicrobial study

Abstract This study presents an innovative, environmentally friendly method for biosynthesizing copper oxide–silica (Cu2O/SiO2) nanocomposites (CSNCs) utilizing an aqueous leaf extract of Callistemon viminalis (C. viminalis). The goal of this work is to fabricate CSNCs using a less hazardous and sustainable synthesis approach. Copper acetate and sodium metasilicate were used as precursors, whereas the C. viminalis green leaf extract was used as the reducing and stabilizing agent. Analysis of the plant extract using Fourier transform infrared spectroscopy indicated the presence of polyphenolic compounds, primarily phenolic acids, which functioned as both reducing and stabilizing agents in the synthesis of CSNCs. A combination of energy dispersive X-ray spectroscopy and scanning electron microscopy was used to study the formation of spherical copper–silica hybrid nanostructures. Powder X-ray diffraction analysis revealed the successful integration of silica with copper(i) oxide (Cu2O) through the presence of distinct Cu2O peaks and a broad amorphous SiO2 peak at 2θ = 22.77°. The thermal stability of the nanocomposites (NCs) was assessed using thermogravimetric analysis and differential thermal analysis under a nitrogen atmosphere. The biogenic NCs also successfully inhibited pathogenic strains of Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans); however, S. aureus was found to be more susceptible to the biocidal activity of the NCs than P. aeruginosa. These findings suggest that this simple, cost-effective, and eco-friendly method for producing biologically active hybrid nanomaterials holds significant promise for future applications in both biological and materials sciences.

Quantitatively characterization of rare earth ore by terahertz time-domain spectroscopy

The Bayan Obo deposit is the world’s largest polymetallic associated minerals deposit of rare earths, iron and niobium, and the rarity of its physical properties restrict the knowledge and understanding of its laws. Taking the high-grade mixed rare earth concentrate of Bayan Obo as the research object, terahertz time-domain spectroscopy (THz-TDS) has been adopted for the systematic investigation of high-grade rare earth concentrate base on the traditional X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric-differential thermal analysis (TG-DTA). The absorption coefficient and refractive index of high-grade rare earth ores and their associated minerals of fluorite and dolomite, are all investigated by terahertz time-domain spectroscopy. The terahertz spectral response is affected by the type of mineral and its content. The acquired rare earth terahertz spectral data are processed by correlation analysis. Three machine learning algorithms, Partial Least Squares Regression (PLSR), Random forest (RF) and Multilayer Perceptron (MLP), are used to achieve quantitative detection of their concentrations and components with the coefficient of determination R2 of the absorption coefficient of the optical parameter reaching up to 0.975, 0.992 and 0.984, respectively. This work promotes the growing understanding of terahertz transmission spectroscopy of rare earth-bearing minerals, which can be used to help guide the search for minerals, and to detect, identify as well as quantify them in geology. Terahertz time-domain spectroscopy supplies a new method for study of rare earth resources, and the comprehensive development and utilization of resources in the Bayan Obo deposit.

Removal of acetyl-rich impurities from chitosan using liquefied dimethyl ether

Chitosan, recognized for its excellent biodegradability, biocompatibility, and antibacterial properties, has several potential applications, particularly in the biomedical field. However, its widespread use is hindered by inherent limitations such as low mechanical strength and safety concerns arising from a low degree of deacetylation and the presence of impurities. This study aimed to introduce an innovative purification method for chitosan via liquefied dimethyl ether (DME) extraction. The proposed technique effectively addresses the challenges associated with chitosan by facilitating deacetylation and impurity removal. Liquefied DME is emerging as the extraction solvent of choice owing to its advantages, such as low boiling point, safety, and environmental sustainability. The degree of deacetylation of chitosan was extensively evaluated using thermogravimetric–differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, intrinsic viscosity measurements, solid-state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy, and elemental analysis. The solubility of chitosan in liquefied DME was investigated using Hansen solubility parameters. This study contributes to the improvement of the safety profile of chitosan, thereby expanding its potential applications in various fields. The use of liquefied DME as an extraction solvent proved to be efficient in addressing the existing challenges and is consistent with the principles of safety and environmental sustainability.

An experimental insight into a promising novel organic nonlinear optical single crystal Guanidinium 2,4-dichlorobenzoate (G24DCB)

Guanidinium 2,4-dichlorobenzoate (G24DCB), a new chloro substituted benzoic acid based organic single crystal is synthesized, grown and added to the guanidinium family of single crystals. Such G24DCB crystal was obtained by a versatile slow evaporation solution growth technique. The analysis of single crystal X-ray diffraction examined the phase identification and determination of lattice parameters for the synthesized compound. The G24DCB crystal has monoclinic system and adopts space group P21/c. Powder X-ray diffraction explores the studied crystal's crystalline characteristics. The study of Fourier Transform-Infrared (FTIR) spectroscopy examined the necessary vibrational assignments for the formation of the structure of G24DCB. The UV–Visible-NIR analysis entails the determination of the cut-off wavelength of the G24DCB compound from its transmittance spectrum and the computation of other related optical parameter values. Photoluminescence analysis was employed to investigate the studied crystal's emission characteristics. The thermal stability of the G24DCB crystal was examined through thermogravimetric analysis and differential thermal analysis. The laser-induced damage threshold of the crystal was determined using a Nd:YAG laser. The various mechanical attributes exhibited by the synthesized compound were elucidated by microhardness studies and it corresponds to a soft material type. The various third order nonlinear optical characteristics were probed by Z scan study. The positive results of the aforementioned studies suggest the emerging significance possessed by the novel title crystal Guanidinium 2,4-dichlorobenzoate in nonlinear optical applications.

Evaluating the thermal stability of hazelnut oil in comparison with common edible oils in Turkey using ATR infrared spectroscopy

Hazelnut oil (HO), a high-quality nutrient rich in monounsaturated fatty acids and antioxidants, is not commonly used due to a lack of awareness of its nutritional benefits. The purpose of the current study is to evaluate the stability of HO during the heating process in comparison with Riviera olive, sunflower and corn oils, the most commonly used edible oils in Turkey, by using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR). The oils were heated at 180 °C for 24h, divided into 8-h periods over the course of three days and the measurements were performed on oil samples taken every 2h. Thermogravimetric analysis-differential thermal analysis (TGA-DTA) and the measurement of the specific absorbance of conjugated dienes and trienes by using UV-visible spectroscopy were also performed to confirm the ATR-FTIR data. The spectroscopic results showed that the heating process led to an increase in the amount of primary and secondary oxidation products, a decrease in the amount of cis fatty acids and an increase in the amount of trans fatty acids in all oils. Based on the results of linear regression analysis, HO has the lowest slope value for all parameters, indicating that it is the most resistant to thermal oxidation. Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) and TGA-DTA results confirmed that HO has a higher thermal stability than the other oils. These findings revealed that HO has the highest thermal stability among the oils compared and can be utilized as a healthy alternative for cooking. This study also showed that ATR-FTIR spectroscopy holds significant promise in oil analysis, competing with routine quality control techniques.

A facile synthesis procedure for Engelhard titanosilicate (ETS-4) and its Cs+ and Sr2+ ion exchange properties

This manuscript reports an environmentally benign method for the synthesis of Engelhard titanosilicate (ETS-4) using titanium isopropoxide or anatase as titanium source and citric acid as complexing agent. Slow release of Ti from the hydroxide or oxide precursors through the citric acid complex plays crucial role in formation of titanosilicate. Characterizations of the prepared material were carried out by powder X-ray diffraction (XRD), Scanning Electron Microscope – Energy Dispersive X-ray spectroscopy (SEM-EDS), Thermogravimetric – Differential Thermal Analysis (TG-DTA) and ion exchange studies. Caesium and strontium exchange capacities of the synthesised ETS-4 were found to be 220 mg/g and 76.2 mg/g, respectively. The saturation exchange equilibrium was attained within 60 min.

Enhanced morphological and thermal properties of epoxy composites reinforced with Palm and Prosopis Juliflora fibers

Abstract This study investigates the fabrication and characterization of a hybrid epoxy matrix composite reinforced with Palm and Prosopis Juliflora fibers fabricated using the hand layup technique. Three composite samples were prepared with varying weight percentages of palm and Prosopis Juliflora fiber reinforcements: 5% (Sample A), 10% (Sample B), and 15% (Sample C). Sample B having 10 weight percentage each of Palm fiber and Prosopis Juliflora fiber and 80 weight percentage of Epoxy matrix, exhibited superior performance with a tensile strength of 45.5 MPa and a hardness of 86.5 Shore D. Thermal analysis revealed Sample B’s exceptional thermal stability, with distinct decomposition stages observed through Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA). Void content analysis indicated Sample C had the lowest void content at 4.5%. Energy Dispersive x-ray (EDX) Analysis confirmed homogeneous fiber distribution and strong fiber-matrix adhesion, supported by carbon and oxygen peaks. Fourier-transform infrared spectroscopy (FTIR) spectra showed interactions between functional groups, including alcohols, carboxylic acids, and carbonyl compounds. These findings underscore the composite’s potential for high strength, toughness, and thermal stability applications.

Phase evolution and heavy metal solidification of cement desulphurized electrolytic manganese residue composite cementitious system under steam curing conditions based on thermodynamic simulation

The mechanical properties and microstructure of desulphurized electrolytic manganese (D-EMR) cement mortar under steam curing at 80 °C for 7 h and 7 days and standard curing for 3 days and 28 days were studied. The hydration products, microstructure and pore distribution were studied by Quantitative X-ray diffraction analysis (QXRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), thermogravimetric-differential thermal analysis (TG-DTA) and backscattered electron (BSE). At the same time, the evolution of hydration products with age and the existence form of heavy metals under different curing conditions were simulated by GEMS thermodynamics. The results show that steam curing can promote the hydration reaction of cement and the secondary hydration of D-EMR. With the extension of steam curing time, the mechanical properties of the early stage are significantly improved. At a D-EMR content of 15 %, the compressive strength of D-EMR cement mortar after steam curing for 7 days is 1.15 times that of the control group under the same conditions, and the content of calcium hydroxide (CH) is 65.91 % of the control group. Steam curing can significantly improve the degree of C3S hydration of cement clinker and the secondary hydration of D-EMR, and increase the degree of polymerization of hydrated calcium silicate (C-S-H) gel. In addition, thermodynamic simulation showed that when the pH value was greater than 7.5, Mn2+ was mainly stable in the form of Mn(OH)2, MnOOH and Mn3O4, and there was no leaching risk. This will provide theoretical support for the use of D-EMR as a new type of supplementary cementitious material (SCM).

Research on the mechanism of natural antibacterial properties of Calotropis gigantea fiber

This research explores the antibacterial mechanism of Calotropis gigantea (CG) fiber through systematic antimicrobial testing and microstructural characterizations on different types of dried CG fibers. Different temperatures and light exposure times were employed to prepare a series of fiber samples. Standard antimicrobial tests were conducted, revealing that both light exposure time and drying temperature significantly influenced the fiber's antibacterial properties against Escherichia coli. Prolonged light exposure time and drying temperatures notably suppressed the antibacterial efficacy. Chemical composition, surface morphology, and thermal stability were further investigated using various techniques, including laser microscopy, Raman, FTIR, and X-ray photoelectron spectroscopies, as well as thermogravimetric-differential thermal analysis. The results revealed a minor role of surface profile and lignin in the variation of antibacterial properties of CG fiber, which should mainly be associated with the alteration of flavonoids, despite the presence of distinct mass losses and decomposition temperature shifts after fiber drying. This study not only unveils and confirms the resource and mechanism of the antimicrobial activity of Calotropis gigantea fiber but also provides insights to guide future optimization of processes and control of microstructure. These findings hold promise for the development of Calotropis gigantea fiber applications in antibacterial products.

Synergistic modification of hydrolyzed keratin-based rigid polyurethane foam with zinc stannate and aluminum hypophosphite to improve its thermal stability and flame retardant properties

Abstract Zinc stannate (ZS) was prepared for flame retardant modified rigid polyurethane foam (RPUF). The flame retardancy and thermal stability performance of the modified RPUFs were investigated by limiting oxygen index (LOI), cone calorimeter (CONE), smoke density (Ds) test and thermogravimetric (TG) differential thermal analyzer. The LOI of RPUF5-7.5 AL/7.5 ZS with 5 wt% hydrolyzed keratin (HK), 7.5 wt% aluminum hypophosphate (AL) and 7.5 wt% ZS increased from 26.1 % to 27.2 %. At 50 kW/m2 radiant intensity, RPUF5-7.5 AL/7.5 ZS had the lowest peak heat release rate (PHRR) and heat release rate (THR), which were 108.17 kW/m2 and 2.56 MJ/m2, respectively. In addition, RPUF5-7.5 AL/7.5 ZS had the highest initial decomposition temperature of 191.24 °C and the largest activation energy (E) of 148.16 kJ/mol. Under flameless condition, the maximum Ds of RPUF5-7.5 AL/7.5 ZS was 31.25, and its light transmittance was also the highest, i.e., 57.89 %. Therefore, ZS/AL was selected as a synergistic flame retardant system to modify the RPUF, and promotes the development of high-performance building materials.

Investigation of Host-Guest Inclusion Complex of Mephenesin with α-Cyclodextrin for Innovative Application in Biological System.

The goal of this study was to use coevaporation to look into how polyether compounds like mephenesin (MEP) can be encapsulated into the host molecule α-cyclodextrin's nanohydrophobic cage. Fourier transform infrared spectroscopy (FT-IR) investigations, powder X-ray diffraction (PXRD), and 1H NMR were among the spectroscopic techniques used to describe the inclusion complex. Additionally, Job's plot has been utilized to illustrate how MEP is encapsulated with α-cyclodextrin (α-CD) at a 1:1 molar ratio. The thermal stability of MEP increased after encapsulation according to thermogravimetric analysis (TGA) and differential thermal analysis (DTA) experiments. Mephenesin fits into the cavity of α-cyclodextrin in a 1:1 ratio, as observed by molecular docking for the inclusion complex to find the most appropriate orientation. This observation is further supported by the Job plot. Furthermore, a comparison was carried out based on a cell viability study between the medication and its inclusion complex.

A comprehensive study of laser irradiated hydrothermally synthesized 2D layered heterostructure V2O5(1−x)MoS2(x) (X = 1–5%) nanocomposites for photocatalytic application

Abstract It has been studied that both two-dimensional (2D) MoS2 and V2O5, which are classified as transition metal dichalcogenides and transition metal oxides, are good photocatalyst materials. For this purpose, the hydrothermal method was practiced to synthesize V2O5(1−x)MoS2(x) (X = 1–5% w/w) nanocomposites with different 1–5% w/w weight percent of MoS2 as a prominent photocatalyst under laser irradiation for 2, 4, 6, 8, and 10 min to tune photocatalytic degradation of industrial wastage water. The surface of the 2D molybdenum nanolayered matrix was efficaciously decorated with V2O5 nanoparticles. The crystal phase and layered structures of the V2O5(1−x)MoS2(x) (X = 1–5% w/w) nanocomposites samples were verified by X-ray diffraction and scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy respectively. In the range of the UV visible spectrum, the increment in light absorption from 3.6 to 14.5 Ω−1 cm−1 with an increase of active surface from 108 to 169 μ m 2 {{\rm{\mu }}{\rm{m}}}^{2} with increased MoS2 doping percentage. Furthermore, dielectric findings like the complex dielectric function, tangent loss, electrical conductivity, quality factors, and impedance of V2O5(1−x)MoS2(x) (X = 1–5% w/w) nanocomposites are studied. According to photoluminescence studies, the intensity of peaks decreases when laser irradiation time and doping percentages of MoS2 are increased. As a result, a small peak indicates a decrement rate of electron–hole pair recombination, which increases the capacity for separation. Thermo-gravimetric analysis and differential thermal analysis results revealed that weight loss decreased from 0.69 to 0.35 mg and thermal stability increased with increased doping concentrations. Methylene blue was degraded in 150 min, proving that the prepared MoS2-doped V2O5 material was a stable and economically low-cost nanocomposite for photocatalytic activity.

Physicochemical properties of 2-amino-5-methylpyridinium 3-carboxy-4-hydroxybenzenesulfonate single crystal: An efficient material for optoelectronic applications

A novel third-order organic nonlinear optical (NLO) material with promising excellent properties in the crucial NLO application. For the first time high NLO active 2-amino-5-methylpyridinium 5-sulfosalicylic acid (2A5MP3C4H) has been rationally designed and single crystals have been grown by the slow evaporation solution growth technique (SEST). X-ray diffraction analysis revealed that 2A5MP3C4H belongs to the category of triclinic system and has a Centro symmetric space group of P1. Remarkably, the grown crystal exhibits competitive and even superior physical properties including high thermal stability and wider transparency than the standard NLO single crystal. The morphology of the as-grown 2A5MP3C4H crystal was equivalent to the theoretically produced morphology. Fourier transform infrared spectroscopy (FTIR) was used to investigate the molecular vibrations of 2A5MP3C4H. The optical characteristics of 2A5MP3C4H recorded optical transmittance spectrum reveals that the 2A5MP3C4H crystal possesses good optical transparency in the range between ultraviolet (UV) and near-infrared (NIR) regions. Intriguingly, the short cut-off edge of the grown crystal is found to be about 345 nm which is more favourable for developing modern photonic and optoelectronic devices application. The Laser Damage Threshold (LDT), were investigated to understand its effectiveness to be utilized in the area of optoelectronics and photonics. The thermal and mechanical stability of 2A5MP3C4H was tested using Thermo gravimetric Differential Thermal Analysis (TG-DTA) and Vickers hardness test. The third-order nonlinear optical properties of 2A5MP3C4H single crystals were analyzed, which involves studying the absorption coefficient and refractive index behaviour using a continuous wave laser. Additionally, the grown crystal exhibits outstanding third-order NLO response and wide LDT, which are crucial characteristics for developing practical NLO devices. There are various 2-amino-5-methylpyridine (2A5MP) derivative single crystals available in the literature. However 2A5MP3C4H crystal has not been reported earlier. So, we have carried out our researcher on this new novel crystal. Our findings consequently open a novel path for the logical design of enormous, thermally stable and NLO-active organic complexes for true NLO applications.

Croton macrostachyus leaf-mediated biosynthesis of copper oxide nanoparticles for enhanced catalytic reduction of organic dyes

Introduction. Owing to the increasing use of organic dyes, the biosynthesis of metal oxide nanocatalysts is urgently needed as an economical and environmentally friendly solution to reduce their waste release. Method. In this study, we synthesized copper oxide nanoparticles (CuO NPs) by the sol–gel method using Croton macrostachyus leaf extracts as capping and reducing agents. The biosynthesized CuO catalysts were characterized using x-ray diffraction analysis (XRD), thermogravimetric differential thermal analysis (TGA-DTA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). Result. The result showed that the synthesized CuO NPs had a crystallite size of about 9 nm and had good crystalline texture. Furthermore, the catalyst showed the best catalytic reduction performance in 1 min for methylene blue (MB) and 3 min for methyl orange (MO). Furthermore, the CuO catalyst synthesized using Croton macrostachyus leaf extract resulted in apparent rate constant (Kapp) values for MB and MO of 0.06793 s−1 and 0.01877 s−1, respectively. Discussion. The recyclability of the CuO catalyst was investigated, and it was shown that the catalysts are suitable for reuse in dye reduction. Therefore, the catalytic activity of this study suggests that the CuO nanocatalysts prepared in this work are a potential candidate for controlling organic pollutants or trace amounts of naturally occurring active organic chemicals in all environmental dye wastes.

Acidic pathway in formation of SiO2–AlO2–PO2 geopolymeric ceramic: Investigation of structural evolution and electrical behaviour

The investigation into the acidic pathway in geopolymer formation has been overlooked compared to the alkaline pathway. This study seeks to fill the gap by exploring the development mechanism and electrical properties of this type of geopolymer. The microstructural properties of geopolymer ceramics were assessed through the deconvolution of attenuated total reflectance-Fourier-transform infrared spectra (ATR-FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), simultaneous thermogravimetric analysis and differential thermal analysis (TGA/DTA). Furthermore, the electrical properties of the prepared ceramics were monitored using solid-state impedance spectroscopy (ss-IS). Maintaining an Al to P molar ratio of 1:1, various post-treatment temperatures (60 °C, 105 °C, 300 °C, 1200 °C) were employed to observe their effects on the (micro)structural properties of the samples under investigation. This ratio ensures the formation of an amorphous structure of SiO2·Al2O3·P2O5·nH2O. Additionally, the emergence of new crystalline aluminium and phosphate phases was observed.

Quantification of organic and inorganic hydrogen in mudstones: a novel approach using the difference between organic-rich and organic-free mudstones during pyrolysis process

Whether mudstone is rich in or free of organic matter has a great influence on the occurrence of water. Comparing different types of water in organic-rich and organic-free mudstones is helpful for further understanding the role of water in hydrocarbon generation. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) combined with mass spectrometry (MS) afford the opportunity to identify the mass change, reactions and products of the sample in a real-time monitored heating process. This study compared the pyrolysis characteristics of an organic-rich mudstone (CN1) and an organic-free mudstone (CW1) by using the TGA/DTA-MS method to estimate the content of different types of H2O and CO2 in organic-rich mudstones. The results show that the mass changes in CN1 and CW1 can be divided into the three thermogravimetric (TG) stages of 0°C–200°C, 200°C–650°C, and 650°C–900°C, while the peak temperatures of H2O and CO2 obtained through MS are different for CN1 and CW1. The differences in mineral components and organic matter between CN1 and CW1 suggest that the MS peaks of H2O and CO2 in CW1 are mainly influenced by clay and carbonate minerals, and that those of CN1 are also influenced by organic matter. In addition, quantification equations for CO2 and H2O contents from both the organic and inorganic origin of the organic-rich mudstone can be established by using the MS peak area of CO2 and H2O, mass loss in TGA and the mineral composition of the organic-free mudstone. This work provides useful insights for further understanding the hydrocarbon generation mechanism, as well as quantifying different types of water in organic-rich mudstones.

Effect of calcination temperature on structural, optical, and morphological properties of RAlO3 (R = La, Sm) perovskite oxides

RAlO3 (R = La, Sm) have attracted the research community due to their interesting optoelectronic properties and viable applications. The solution combustion method allows for a faster process and lower calcination temperature than the traditional solid-state method and is an economical alternative to wet chemical synthesis for producing RAlO3. This work explores the thermal, structural, morphological, optical, and electrical properties of RAlO3 (R = La, Sm) synthesised by the solution combustion method using urea as fuel. Thermogravimetric analysis—differential thermal analysis (TGA-DTA) showed the crystallization temperatures of lanthanum aluminate (LaAlO3) and samarium aluminate (SmAlO3) at 864 and 887 °C, respectively. The x-ray diffraction (XRD) and Rietveld analysis revealed the structure of LaAlO3 as rhombohedral (R-3c) and SmAlO3 as orthorhombic (Pbnm). The LaAlO3 and SmAlO3 samples calcinated at 800 °C showed crystallite size (D) of 19.26 nm and 19.06 nm, respectively. The field emission scanning electron microscopy (FE-SEM) images show a highly porous and large sheet-like morphology with voids and cracks. High resolution transmission electron microscopy (HR-TEM) images and the selective area electron diffraction (SAED) pattern show crystalline nature and the indexed planes agreed with the XRD results. The LaAlO3 and SmAlO3 samples had specific surface areas of 16.374 and 12.953 m2 g−1, respectively. The TGA-DTA results were affirmed by Fourier transform infrared spectroscopy (FT-IR) results which showed only the presence of metal-oxide bonds for materials annealed at and above 800 °C. These results were further validated by the electron dispersive x-ray spectroscopy (EDX) and the x-ray photoelectron spectroscopy (XPS) showing no additional peaks. The band gap of 5.08 and 4.82 eV were calculated from ultraviolet-visible spectroscopy (UV–vis) for LaAlO3 and SmAlO3, respectively. The results imply that the solution combustion technique using urea as fuel is a viable route for synthesising RAlO3.