Thermogravimetric And Differential Thermal Analysis Research Articles

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.

Fabrication of Efficient and Non-Enzymatic Electrochemical Sensors for the Detection of Sucrose.

Molecularly imprinted polymers have been used for the creation of an electrochemical sensor for the detection of sucrose, which are modified by using functionalized graphene (fG). Using AIBN as the free radical initiator and sucrose as the template, imprinted polymers are synthesized. The monomer, 4,4'-diisocyanatodiphenylmethane (DPDI), has both proton donor groups (N-H or O-H) and lone-pair donor groups (C=O). By creating H-bonds with electron donor groups (C=O), the proton donor group in this polymer may interact with the sugar molecule serving as its template. The sensor signals have improved as a result of the interaction between the monomer and the template. Thermogravimetric and differential thermal analysis (TGA/DTA) curves, scanning electron microscopy (SEM), and FT-IR spectroscopy have been employed to characterize the fabricated receptors. The fabricated sensor has exhibited a limit of detection of 16 ppb for the target analyte that is highly sensitive, linear, reversible, regenerative, and selective. Moreover, the sensor's stability, reproducibility, and reusability have been evaluated for six months, following the device's manufacturing, and the results revealed similar responses with the percentage error of less than 1%. Most importantly, this sensor has demonstrated a quick response time, which is very sensitive, stable, and selective.

Development of an Aerated Sulfoaluminate Cement–Based Material for Coal Mine Filling

Coal mine filling requires a safe, lightweight, and high-strength filling material, but current commonly used aeration agents, such as hydrogen peroxide, which produces the combustible gas O2, and aluminum powder, which produces the explosive gas H2, are not suitable for coal mine filling. In this paper, a new inorganic composite aeration agent, namely sodium bicarbonate and potassium aluminum sulfate, which produces inert gas CO2, was developed. The effects of this composite aeration agent admixture (at contents of 0%, 2%, 4%, 6%, and 8%) on the properties such as fluidity, setting time, compressive strength, and water resistance of sulfoaluminate cement paste with high water-to-cement ratios were investigated systematically. The evolution of the microstructure and pore structure of this foamed material was determined using X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), and scanning electron microscopy (SEM). The results showed that when the amount of aeration agent was 8%, the 7-day compressive strength of the prepared sulfoaluminate cement–based foamed material with a dry density of 600 kg/m3 was 1.2 MPa. Compared with the control group, the setting time was shortened by 87%, dry density was reduced by 42.1%, 7-day compressive strength was increased by 47.5%, and water resistance was increased by 45.4%. The composite admixture not only formed uniform bubbles within the sulfoaluminate cement paste but also produced in situ calcium carbonate, which promoted the hydration of sulfoaluminate cement and made the microstructure of the hardened paste denser. The results provide new materials for coal mine foam filling, which can be applied to corner gas control and foam filling in mining areas and coal mine fire prevention.

Celtis tournefortii LAM. Yaprak Özütüyle Gümüş Nanopartiküllerin Hızlı Biyosentezi; Antimikrobiyal ve Antikanser Aktivitelerinin İncelenmesi

The usage of metallic nanoparticles are very common. Environmentally friendly approaches in obtaining nanoparticles attract a lot of attention because of their advantages. In this study, an easy and economical biosynthesis of silver nanoparticles (AgNPs) was made with the extract of Celtis tournefortii LAM. leaf. For the characterization of synthesized nanoparticles, Spectrophotometer (UV-vis), Transmission Electron Microscope (TEM), Field Emission Scan Electron Microscopy (FE-SEM), Atomic Power Microscopy (AFM), Electron Disperse X-ray (EDX) Fourier Transformation Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Thermogravimetric and Differential Thermal Analysis (TGA-DTA), Zeta Sizer and Zeta Potential Analysis data were used. As a result of the data analysis, it was determined that the AgNPs had a spherical appearance, an average size distribution of 4.8 nm, had a maximum absorbance at a wavelength of 482.13 nm, a crystal nanosize of 10.95 nm, and a surface charge of -21.6 mV. Inhibition activities of AgNPs on the growth of pathogenic strains were determined by the microdilution method. The results showed that the nanoparticles were effective even at low concentrations. The Minimum Inhibitory Concentration (MIC) value of the tested materials on the growth of the strains was found between 0.03-1.00 µg mL-1. Anticancer activity of AgNPs was investigated on CaCo-2, U118, Skov3 cancer cell lines and healthy cell line HDF by the MTT method.

Influence of annealing on structural, morphology, magnetic and optical properties of PLD deposited CuFe2O4 thin films

• Successfully produced of CuFe 2 O 4 nanoparticles and prepared thin films which is grown on a glass substrate by pulsed laser deposition (PLD) technique. • The detailed structural properties of films are studied using experimental (XRD, FE-SEM, VSM, and Optical properties). • The magnetization and remanence of prepared samples have decreased with increased annealing substrate temperatures. • As per report the thin films have direct band gap energy; it reduces with increasing annealing temperature, which is due to improve the crystallinity. In this work, copper-ferrite (CuFe 2 O 4 ) nano-crystallite was synthesized by the gel method and deposited on a microscope glass substrate using a pulse laser deposition (PLD) technique at room temperature. The obtained deposited thin films were annealed at four different temperatures (200 °C, 300 °C, 400 °C, and 500 °C) for 4 hours in an air atmosphere. The structural, morphological, thermal, magnetic, and optical properties of the thin film samples were characterized using an X-ray diffractometer (XRD), Field emission scan electron microscopy (FE-SEM), thermogravimetric and differential thermal analysis (TG-DTA), Vibrating sample magnetometer (VSM) and Ultraviolet-Visible spectrophotometer (UV-Vis). X-ray diffraction patterns of the unannealed and annealed films show the presence of the anti-ferromagnetic (α-Fe 2 O 4 ) phase along with the single-cubic spinel structure phase. The grain sizes were found to have low crystalline copper ferrite with a mixture magnetic and hematite crystalline phases. With the decrease of the grain size and increasing of annealing substrate temperatures, the ratio of hematite to magnetite phases increased, and reached to an impure magnetite phase for the 6.35 nm grain. The morphological images obtained by transmission electron microscopy technique showed that the particle size of copper ferrite nanoparticles gradually became smaller from 10 nm to 5 nm. Surface morphology of all fabricated samples investigated by field emission scan electron microscopy technique exhibiting different sizes, almost spherical grains and agglomerates, which may be depending upon preparation method and substrate temperature. The correlation between structure and thermal stability of prepared materials was studied by (TG-DTA). With increasing of annealing substrate temperature from room temperature to 500 °C, the saturation magnetization (M s ) value decreased from 8.79 emu/g to 2.12 emu/g while the coercivity (H c ) value increased from 52.22 Oe to 91.26 Oe. The lowest widening of optical band gap in the copper ferrite film was 1.57 eV. The magnetic and the optical parameters suggested that these films are potential candidates for gas sensor applications.

Synthesis, structure, thermal, magnetic, dielectric properties of Ce3+ doped M-type SrFe12O19 and electrochemical determination of L-cysteine

• Nanostructured Sr (1-x) Ce x Fe 12 O 19 nanoferrites were prepared by auto combustion method with dual fuel (Urea and glycine). • The dielectric properties of all the samples have been measured using LCR meter at room temperature and electrochemical studies was using by cyclic voltammetry at RT. • The XRD patterns and IR spectra confirmed the formation of hexagonal structure. • The dielectric parameters decreases while AC conductivity increases with frequency. At a particular frequency, the dielectric constant, dielectric loss real part and imaginary part of impedance increases, attain maximum, then begins to decrease with increase in composition. • The SrHF’s/GCE electrode showed impressive results including increased sensitivity, limit of detection, higher concentration range, stability, and reproducibility properties. Cerium substituted SrFe 12 O 19 with the nano composition of Sr (1-x) Ce x Fe 12 O 19 ( x = 0.00, 0.01, 0.05 and 0.09) have been prepared using auto-combustion technique with dual fuel. The PXRD images confirmed a single-phase hexagonal crystalline structure similar to a magnetoplumbhite for all samples. Fourier transform infra-red spectroscopy (FT-IR), field emission-scanning electron spectroscopy (FE-SEM), elemental mapping (EDS) were used to examine for the structure and morphology of the samples. The temperature dependent hexagonal phase formation and percentage weight loss was studied by thermogravimetric and differential thermal analysis (TG-DTA). Vibrating sample magnetometer (VSM) analysis confirmed that M-SrHF’s are hard magnetic in nature and super paramagnetic, these are measured at room temperature. It was found that, with the increase of the dopant Ce 3+ in strontium ferrites, the values of saturation magnetization (M S ), remanence magnetization (Mr), coercivity (H C ) and magnetic parameters of strontium ferrites decrease. The electrochemical behavior of the SrHF’s electrode and the electro-oxidation of L-cysteine was investigated using of cyclic voltammetry (CV). The best voltammetric response has been observed for a SrHF’s electrode in buffer solution at pH of 7.0 with an acquisition and scan rate of 50 mV s − 1 . The dielectric properties are measured in LCR meter and described based on the Maxwell–Wagner’s two layer model. The electron hopping between Sr 2+ and Sr 3+ , as well as Fe 3+ and Fe 2+ ions on B-sites, drives the conduction mechanism in these ferrites, these nano hexaferrites which shows its suitability in various technological applications.

Preparation and characterization studies of chitosan encapsulated ZnO nanoparticles modified with folic acid and their antibacterial activity against selected bacterial species

This article deals with the preparation of Chitosan (CS) coated Zinc Oxide (ZnO) nanoparticles modified with Folic Acid (FA) via the simple solvothermal method. The physicochemical properties were evaluated through characterization studies such as X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDAX), UV-Visible spectroscopy (UV-Vis), and Thermogravimetric and differential thermal analysis (TG/DTA). The crystalline size of the nanoparticles examined was 21.45 nm and 16.57 nm. The samples were subjected to antibacterial test (Gram-positive S. aureus, B. subtilis, and Gram-negative E. coli, P. aerugenosa) by the modified Kirby- Bauer well diffusion method and minimum inhibitory concentration (MIC) by using the broth dilution method in 96-well microtiter plate. This method was used to test the susceptibility of microorganisms. At high concentrations, CS-ZnO nanoparticles were found to have the highest zone of inhibition against S. aureus (20 mm) and B. subtilis (20 mm) and the lowest against E. coli (18 mm) and P. aeruginosa (10 mm). The MIC results were determined to be in the order CS-ZnO ˂ FA-CS-ZnO. The zeta potential of nanoparticles was estimated to be −19.1 ± 6.60 mV (CS-ZnO) and −29.3 ± 5.56 mV (FA-CS-ZnO), respectively.

Ceramic membrane support based on kaolin and solid waste from hydrodistillation of Rosmarinus officinalis L

Investigations of organic pore-performing agents are becoming of great interest for the improvement of mineral membranes microstructures and also their mechanical and separation performances. The solid residue of Rosmarinus officinalis L. is a kind of green and abundant by-product generated by the hydrodistillation of essential oils (EOs). In this study, the exhausted solid residue of rosemary (ESRRO) was tested as a pore-generating agent for the development of low-cost kaolin-based ceramic membranes. The kaolin and the exhausted solid residue of R. officinalis powders were characterized by thermogravimetric and differential thermal analysis (TG-DTA), X-ray fluorescence spectrometry (XRF), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The effects of ESRRO and sintering temperature on membranes performances (porosity, water absorption, density, and compressive strength) were evaluated. Prepared ceramic membranes were analyzed by Scanning Electron Microscopy (SEM). The chemical composition of ESRRO revealed the dominance of organic matter (85.21%), for which the degradation temperatures ranged between 115 °C and 600 °C. Regarding kaolin, the characterization analysis showed the dihydroxylation of kaolin into metakaolinite in the range of temperature between 435 and 765 °C. When sintering temperatures rises to 1100 °C, all the amorphous phase of metakaolinite reacted, while the diffraction peaks of the crystal phase of mullite appeared. The results of membrane characteristics revealed that the addition of 10% ESRRO to kaolin-based membranes sintering at 1100 °C improved the membrane porosity which almost doubled. The density and compressive strength decreased, while the water absorption increased with the increase of ESRRO content (2.5%–10%). The SEM analysis indicated the homogenous surface structure of the ceramic supports.

Effect of Coal Dust Content on the Low-temperature Oxidation of Silo Coal.

Coal’s low-temperature oxidation (LTO) poses a significant threat to the safety of storing coal in silos. This study investigates the impact of coal dust content on the LTO characteristics of silo coal samples. The results indicate that the larger the coal dust content the higher the oxygen (O2) consumption rate and carbon monoxide (CO) generation rate and the stronger the LTO capacity. To clear the mechanism of the impact, the thermal physical characteristics were studied and thermogravimetric and differential thermal analysis (TG-DTA) experiments were performed on various coal samples. The results show that, first, with the increase of coal dust content, the thermal conductivity of the silo coal samples initially increased and then decreased, whereas the thermal diffusion and heat capacity decreased and increased linearly, respectively. This indicates that the heat storage capacity of the silo coal sample is enhanced with the increase of the coal dust content. Second, the maximum oxygen absorption rate and differential thermal reduction value of the coal samples increased linearly with the decrease in their particle size; this result verifies that decreasing the particle size of silo coal can advance its LTO process. The study findings indicate that the risk of LTO and spontaneous combustion of silo coal can be effectively reduced by controlling the coal dust content (fine coal particles).

Morphological, magnetic and electrochemical studies of Mn1-xSrxFe2O4 by co-precipitation approach

The influence of Sr2+ on the structure, topography, magnetic, and electrochemical behavior of MnFe2O4 prepared by co-precipitation approach. The unique products were characterized by Thermogravimetric and Differential Thermal Analysis (TG-DTA), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscope with Energy Dispersive X-Ray Analysis (EDX), X-ray Photoelectron Microscopy (XPS), Brunauer-Emmett-Teller (BET) and Vibrating Sample Magnetometer (VSM). XRD pattern declares the cubic structure with a mean crystallite size decrease from 49.54 nm to 34.6 nm. Metal oxide bands were identified for all samples using Fourier Transform Infrared Spectroscopy. The BET analysis exhibit a specific surface area of 22.89 m2/g. Magnetic investigations revealed a steady drop in saturation magnetization, remanence, and an increase in the coercive field with increasing Sr2+ content. The electrochemical behavior of pure (MF) and doped manganese ferrite (MSF9) electrodes was investigated using KOH electrolytes by Voltammetry, Charge–Discharge Spectroscopy, and Electrochemical Impedance Spectroscopy. A three-electrode setup with a high specific capacity of 381F/g at 1A/g was attained. Sr2+ (9%) doped MnFe2O4 electrode have excellent surface mobility and high conductivity than pure MnFe2O4 electrode. The synthesized electrodes deliver (MSF9) a higher energy density of 68Whkg−1 at a power density of 5400 Wkg−1 at 5A/g. Such excellent capacitive performances were due to fast charge transport and self-assembled robust microstructural stability.

Development of a Tailored Sol-Gel Immobilized Biocatalyst for Sustainable Synthesis of the Food Aroma Ester n-Amyl Caproate in Continuous Solventless System.

This study reports the synthesis of a hybrid sol-gel material, based on organically modified silanes (ORMOSILs) with epoxy functional groups, and its application in the stabilization of lipase type B from Candida antarctica (CalB) through sol-gel entrapment. The key immobilization parameters in the sol-gel entrapment of lipase using epoxysilanes were optimized by the design of numerous experiments, demonstrating that glycidoxypropyl-trimethoxysilane can allow the formation of a matrix with excellent properties in view of the biocatalytic esterifications catalyzed by this lipase, at an enzyme loading of 25 g/mol of silane. The characterization of the immobilized biocatalyst and the correlation of its catalytic efficiency with the morphological and physicochemical properties of the sol-gel matrix was accomplished through scanning electron microscopy (SEM), fluorescence microscopy (FM), as well as thermogravimetric and differential thermal analysis (TGA/DTA). The operational and thermal stability of lipase were increased as a result of immobilization, with the entrapped lipase retaining 99% activity after 10 successive reaction cycles in the batch solventless synthesis of n-amyl caproate. A possible correlation of optimal productivity and yield was attempted for this immobilized lipase via the continuous flow synthesis of n-amyl caproate in a solventless system. The robustness and excellent biocatalytic efficiency of the optimized biocatalyst provide a promising solution for the synthesis of food-grade flavor esters, even at larger scales.