Energy Dispersive X-ray Spectroscopy Analysis Research Articles

Selective recovery of rare earth elements by smelting of magnets

Rare earth elements (REEs) play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars. Permanent magnets account for a quarter of total global REEs production and have high recycling value. In this study, smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe2O3. This separates REEs into a slag phase from an iron-rich metallic phase. B2O3 was also added to the system as a flux to lower the slag melting temperature. This minimizes REEs loss to the metallic phase and allows a more efficient phase separation. The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB (NdCeFeB) magnets. At 1350 °C and for 1 h, the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe2O3 and 40 wt% of B2O3. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX) analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron. After the selective removal of iron into the metallic phase, REEs are recovered from the slag phase through an acid leaching process allowing >99% of REEs recovery. Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique. The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.

The processing behaviour of the sphalerites from the Big Syncline deposit, South Africa

Abstract Big Syncline is one of the few unexploited deposits of the Aggeneys-Gamsberg Ore District of the Northern Cape Province of South Africa and comprises Zn > Pb > Cu mineralisation. Future exploitation of this deposit requires a good understanding of the mineralisation textures and mineralogy for beneficiation purposes. Two of the most commonly occurring mineralisation types at Big Syncline, the mineralised pelitic schist (PEL) and garnet-magnetite-associated mineralisation (GM), are investigated with regards to sphalerite petrography and mineralogy and their potential impact on Zn flotation recovery and grade. Detailed optical petrographic analyses revealed three colour variations in the sphalerite: the opaque (i.e., black) and ruby-red varieties prevalent in the PEL; and the honey-yellow variety more common in the GM. Scanning electron microscopy with energy dispersive X-ray spectroscopy (EDS) analyses indicated increasing Fe content from the honey-yellow to ruby-red to opaque sphalerite varieties. The latter two varieties were also observed to have elevated Mn contents. Laboratory-scale differential flotation tests were applied on the two mineralisation types to determine their processing behaviour. Despite poor selectivity, the GM produced a bulk Zn concentrate of superior quality to the PEL. However, the latter showed better selectivity with the bulk of the Zn reporting to the Zn concentrate. The reduced overall quality of the PEL concentrate is attributed to the increased dilution. This is due to the high abundance of gangue sulphides in the flotation feeds as well as higher Fe and Mn contents in sphalerite. The higher Mn content in the PEL sphalerites also leads to higher Mn recovery and grade in the Zn concentrates. Although the GM overall has higher Mn contents, it is hosted in silicates leading to substantial Mn rejection to the tailings.

Influence of Gypsum on the Residual Properties of Fly Ash-Slag-Based Alkali-Activated Concrete

High-temperature exposures of concrete lead to serious damage in concrete structures, resulting in the significant decay of mechanical properties and spalling of concrete. Alkali-activated concretes (AAC) of blended aluminosilicate precursors and activators have been proven to have higher thermal endurance than conventional portland cement concrete. Incorporation of gypsum (GY) in alkali-activated systems has proven to positively impact the mechanical properties when adopted in controlled amounts. GY releases SO42- to the binder system, which helps in the formation of ettringites, along with Ca2+, which leads to the formation of hydrates. This causes a reduction in porosity and improves strength gain. Incorporation of GY into the fly ash-slag-based alkali-activated system further improves thermal endurance by retaining considerable residual strengths even after 800°C exposure. In the present study, the influence of GY on the residual mechanical properties of fly ash-slag-based AAC is investigated to explore the thermal endurance of the ternary mix at elevated temperatures. The mechanical properties of fly ash (FA), Ground Granulated Blast Furnace Slag (GGBS), and gypsum (GY) ternary blended AAC subjected to elevated temperatures are studied in comparison with conventional portland cement concrete (control mix). AAC design mixes with varying proportions of GY as a replacement to FA-GGBS precursor are tested for mechanical properties to obtain the optimum mix. The residual mechanical properties of the FA-GGBS-GY optimum ternary AAC mix are obtained after exposure to elevated temperatures up to 800°C. The morphology and microstructural characteristics of AAC are studied by Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analyses to investigate the influence of gypsum on the thermal endurance of concrete when exposed to elevated temperatures. Improved thermal endurance is observed for AAC when FA-GGBS precursors are replaced with 5% of GY as compared to the thermal endurance of conventional portland cement concrete (PCC) of the same compressive strength. Doi: 10.28991/CEJ-2024-010-03-017 Full Text: PDF

Electrospun Cu-Co ferrite nanofibers: synthesis, structure, optical and magnetic properties, and anti-cancer activity.

In this study, we investigated Cu-Co ferrite nanofibers (NFs) that were synthesized for the first time employing the electrospinning technique. The structure, phase purity and crystallite size of all the prepared NFs were revealed by powder X-ray diffraction (PXRD) analysis. The NFs crystallized in the Fd3̄m (no. 227) space group and the cation distribution arrangement over distinct sites in their structure was analyzed. Scanning electron microscopy (SEM) together with energy-dispersive X-ray (EDX) spectroscopy analysis showed the microstructure of the NFs and verified their expected chemical compositions. High-resolution transmission electron microscopy (TEM) images confirmed the fibrous nature and the construction of the NFs. The band gap energies derived from the UV-vis reflectance spectra showed a blue shift with an increase in the amount of Cu in the sample from 1.42 eV to 1.86 eV. Magnetization (M) as a function of magnetic field (H) measurements performed at ambient and low temperatures showed the ferrimagnetic behavior of all the NFs. The magnetic parameters including coercivity (Hc), saturation magnetization (Ms), remanent magnetization (Mr), and squareness ratio were determined from the recorded magnetization curves. At 300 K, Ms was reduced from 78.8 to 42.4 emu g-1, Mr reduced from 22.8 to 7.6 emu g-1 and the Bohr magneton reduced from 3.3 to 1.8μB with an increase in the content of Cu in the samples. The same trend was observed at 10 K, where Ms was reduced from 93.7 to 50.9 emu g-1, Mr reduced from 60.9 to 35.9 emu g-1 and the Bohr magneton reduced from 3.94 to 2.16μB. Alternatively, Hc has the highest values for x = 0 (850 Oe at 300 K and 5220 Oe at 10 K) and x = 0.6 (800 Oe at 300 K and 5400 Oe at 10 K). The anti-cancer activity of the NFs was evaluated using the MTT cell viability assay, showing a reduction in the viability of both HCT-116 and HeLa cancer cells compared to non-cancerous HEK-293 cells after treatment with the NFs. Apoptotic activity was examined by DAPI staining, where treatment with the NFs induced chromatin condensation and nuclear disintegration in HCT-116 cells.

Magnesium silicate chimneys at the Strytan hydrothermal field, Iceland, as analogues for prebiotic chemistry at alkaline submarine hydrothermal vents on the early Earth

The Strytan Hydrothermal Field (SHF) in basaltic terrain in Iceland is one of the extant alkaline submarine hydrothermal vent systems favoured as analogues for where life on Earth may have begun. To test this hypothesis we analyse the composition, structure, and mineralogy of samples from hydrothermal chimneys generated at the SHF. We find that the chimney precipitates are composed of Mg-silicates including clays of the saponite-stevensite group (high Mg and Si, low Fe and Al), Ca-carbonates and Ca-sulfates. The chimneys comprise permeable structures with pores sizes down to 1 µm or less. Their complex interiors as observed with SEM (Scanning Electron Microscopy) and X-ray CT (computed tomography scanning), exhibit high internal surface areas. EDX (energy-dispersive X-ray spectroscopy) analysis reveals an increase in the Mg/Si ratio toward the chimney exteriors. Chemical garden analogue experiments produce similar Mg–silicate chimneys with porous internal structures, indicating that injection-precipitation experiments can be high-fidelity analogues for natural hydrothermal chimneys at the SHF. We conclude that SHF chimneys could have facilitated prebiotic reactions comparable to those proposed for clays and silica gels at putative Hadean to Eoarchean alkaline vents. Analysis of the fluid dynamics shows that these chimneys are intermediate in growth rate compared to faster black smokers though slower than those at Lost City. The SHF is proposed as a prebiotic alkaline vent analogue for basaltic terrains on the early Earth.

Environmental friendly approach on biosorption of Ag nanoparticles using Aspergillus terreus BIOS PTK 6 biomass: Optimization, kinetics and characterization studies

The present study focused on the biosorption of Aspergillus terreus dead biomass for the removal of silver nanoparticles (AgNPs) from aqueous solution. For the better removal of AgNPs, pH, temperature, incubation time, initial biomass concentration and agitation speed were optimized and AgNPs treated as well as control biosorbents were characterized using Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray spectroscopy (EDX) analyses. In our study, the optimum conditions of pH, temperature, incubation time, initial biomass concentration and agitation speed for the maximum removal of AgNPs was found to be 4, 30 °C, 200 min, 1 mg/mL and 125 rpm, respectively. Interestingly, in our study, Langmuir isotherm model was best correlated with the highest regression coefficient (R2) of 0.992 and the maximum biosorption was found to be 740.63 μg/mL. FTIR results showed that carboxyl, carbonyl and secondary amine groups were involved in the biosorption of AgNPs. FESEM images of AgNPs treated biosorbent depicted rough surface and the presence of AgNPs on the surface of biosorbent was clearly observed. EDX spectrum showed Ag peak, which confirmed the successful uptake of AgNPs by A. terreus dead biomass. Thus, our study shows that A. terreus could be used as a cost-effective eco-friendly biosorbent for AgNPs removal from aqueous solution. Therefore, exploiting the same fungus for both synthesis and removal of AgNPs could be a novel approach in the context of mycoremediation practices.

Ultrasound Pretreatment for Enhancing Fine and Ultrafine Flake Graphite Flotation Beneficiation.

With the severe depletion of coarse flake graphite (a critical raw material) resources, developing and utilizing fine and ultrafine graphite resources have recently attracted attention. Froth flotation is a widely used technique for the initial enrichment of graphite; however, the flotation selectivity decreases significantly along with particle size reduction. Ultrasound pretreatment would be a promising method to improve the flotation of fine particles. As an innovative approach to understand better the flotation response of different flake graphite sizes, this study conducted a comparative analysis based on flotation concentrate yield and ash as well as ash removal rate between the flake graphite with various particle sizes after ultrasound pretreatment. Particle size, X-ray powder diffraction, and scanning electron microscopy and energy dispersive X-ray spectroscopy analyses were used to investigate the effect of ultrasound treatment on mineralogical properties of the flake graphite with varied particle sizes. Process outcomes indicated that the flotation performance of fine flake graphite (mean chord length: 62.63 μm) was significantly enhanced after ultrasound pretreatment. However, flotation of the ultrafine flake graphite (mean chord length: 24.97 μm) after ultrasound treatment was limited due to the difficulty of generating sufficient fragmentation and dissociation by microjets and shock waves formed by the cavitation effect. Compared with conventional flotation, the concentrate yield of ultrasound flotation increased from 88.95 to 94.98%, ash content decreased from 5.72 to 4.87%, and ash removal rate enhanced from 36.94 to 42.61%. Particle size and mineral property analyses confirmed that further crushing and dissociation of the larger flake graphite after ultrasound pretreatment would be the main factors contributing to improved flotation performance. Additionally, the formation of air flocs in the coarse flake graphite during the ultrasound pretreatment process facilitated the flotation recovery of the crushed graphite particles.

DFT and electrochemical determination of Hg2+ and Pb2+ in water using polyaniline–quinoxaline composite modified GCE electrode

In this study, we designed and synthesized a new class of donor–acceptor conjugated polymers containing the polyaniline-quinoxaline [Acenaptho [1, 2 -b] quinoxalin-9-amine] (PAni-QUA) composite, and we subsequently utilized it as an electrochemical sensor to detect Hg2+ and Pb2+ ions with good selectivity and sensitivity. Energy dispersive X-ray analysis spectroscopy (EDAX), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and UV–Vis spectroscopy (UV–Vis) were employed to analyze the structural and morphological characteristics of the resulting composite. The electrochemical characteristics of the electrode modifiers were analyzed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Several sensitivity-influencing factors, including chemical and electrochemical parameters like pH and the impact of the supporting electrolyte medium, were also identified to improve the efficiency of the developed sensor. In the presence of different hazardous metal ion species, the interference ability of the proposed sensor was also examined. They were also used to conduct individual and simultaneous sensing studies of various metal ions in different supportive electrolyte media utilizing the differential pulse voltammetry technique (DPV). The PAni-QUA composite modified GCE sensor shows remarkable selectivity and sensitivity towards Hg2+ and Pb2+ ions over the other heavy metal ions in 1 to 20 µM ranges, respectively. The detection limits (3σ/m) were 1.28 nM and 5.91 nM for Hg2+ and Pb2+ ions. Density Functional Theory (DFT) was used in the present study to accomplish the adsorption mechanism of the suggested sensors. The DFT calculation demonstrated that the PAni-QUA composite was formed with a lower band gap energy than QUA and DD PAni. These results showed that the suggested sensor (PAni-QUA) had the lowest detection limit in the acetate buffer medium compared to the specified electrolyte media. Based on these findings, it is possible to use this technology to identify harmful metal ions (Hg2+ and Pb2+) with high sensitivity in real water samples.

Facile synthesis of MgO/ZnO nanocomposite for efficient removal of alizarin red S dye from aqueous media

The prevalence of dyes in aquatic environments raises severe concerns on a global scale. Alizarin red s dye can result in dangerous impacts on the health of humans that involve digestive system problems, skin and eye irritation, somnolence, breathing disorders, and blood clotting. So, in this work, MgO/ZnO nanocomposite with a low crystal size and high surface area was facilely produced by the Pechini sol–gel method using tartaric acid as a complexing agent and propylene glycol as a crosslinker for the first time. The scanning electron microscope (SEM) exhibited that the MgO/ZnO nanocomposite consists of semi-spherical particles with an average diameter of about 73.82 nm. Moreover, the energy-dispersive X-ray spectroscopy (EDS) analysis clearly demonstrated that the synthesized MgO/ZnO nanocomposite consists of Mg, Zn, and O with weight percentages equal to 24.83, 58.92, and 16.25 %, respectively. The average crystal size (D) of the MgO/ZnO nanocomposite is 67.37 nm. Also, the Brunauer, Emmett and Teller (BET) surface area of the MgO/ZnO nanocomposite is 141.51 m2/g. Moreover, in an acidic medium, the high surface area of the synthesized nanocomposite renders the surface of the MgO/ZnO nanocomposite highly positively charged, enabling it to effectively attract and remove anionic alizarin red s dye through electrostatic interaction. The maximum adsorption capacity (Q) of the MgO/ZnO nanocomposite towards alizarin red s dye is 378.79 mg/g. Besides, pH equals 2, contact time equals 90 min, and temperature equals 298 K are considered the ideal conditions for achieving the maximum elimination percentage (% E = 90.74) by mixing 0.05 g of the MgO/ZnO nanocomposite with 100 mL of a 200 mg/L alizarin red s dye solution. Moreover, the elimination of alizarin red s dye on the MgO/ZnO nanocomposite is spontaneous, exothermic, chemical, and more accurately described by the pseudo-second-order model and Langmuir isotherm. Furthermore, the MgO/ZnO nanocomposite can be used many times to get rid of the alizarin red s dye without affecting its efficiency.

Effect of silver diamine fluoride on the longevity of the bonding properties to caries-affected dentine

ObjectivesThis study aimed to evaluate the adhesive properties in dentine after the application of silver diamine fluoride (SDF) on carious dentine lesions immediately and after 2 years of water storage. Methods96 human molars used were subjected to artificial dentine caries production, and then randomly divided into 12 experimental groups according to 1. application of an SDF solution (carious dentine lesion without SDF treatment [control], with 12 % silver diamine fluoride [SDF 12 %] or 38 % silver diamine fluoride [SDF 38 %]); 2. Universal adhesives (Clearfil Universal Bond Quick [CUQ] and Single Bond Universal [SBU]); 3. adhesive strategy (etch-and-rinse [ER] and self-etch [SE]). After restoration, the specimens were sectioned and submitted to the microtensile bond strength test (μTBS) and energy-dispersive X-ray spectrometry analysis (SEM/EDX). All tests were performed immediately and after 2 years of water storage. Data from the μTBS were analyzed using four-way ANOVA and Tukey's test (α = 0.05). ResultsOnly the interaction of factors 'SDF' vs 'time' was significant (p = 0.03). After 2 years of storage, the groups where SDF was applied showed higher μTBS values compared to the control group. No significant decrease in μTBS values was observed for SBU when comparing immediate and 2-year results, but a significant reduction in μTBS values was observed after 2 years for CUQ. ConclusionIndependent of the adhesive strategy, the use of SDF may be a promising alternative to maintain the bonding of universal adhesives to carious dentinal lesions. Clinical significanceThis study may clarify and support clinicians regarding the longevity of resin-based restoration in caries-affected dentine treated with silver diamine fluoride.

Contributions of Chinese hamster ovary cell derived extracellular vesicles and other cellular materials to hollow fiber filter fouling during perfusion manufacturing of monoclonal antibodies.

Hollow fiber filter fouling is a common issue plaguing perfusion production process for biologics therapeutics, but the nature of filter foulant has been elusive. Here we studied cell culture materials especially Chinese hamster ovary (CHO) cell-derived extracellular vesicles in perfusion process to determine their role in filter fouling. We found that the decrease of CHO-derived small extracellular vesicles (sEVs) with 50-200 nm in diameter in perfusion permeates always preceded the increase in transmembrane pressure (TMP) and subsequent decrease in product sieving, suggesting that sEVs might have been retained inside filters and contributed to filter fouling. Using scanning electron microscopy and helium ion microscopy, we found sEV-like structures in pores and on foulant patches of hollow fiber tangential flow filtration filter (HF-TFF) membranes. We also observed that the Day 28 TMP of perfusion culture correlated positively with the percentage of foulant patch areas. In addition, energy dispersive X-ray spectroscopy-based elemental mapping microscopy and spectroscopy analysis suggests that foulant patches had enriched cellular materials but not antifoam. Fluorescent staining results further indicate that these cellular materials could be DNA, proteins, and even adherent CHO cells. Lastly, in a small-scale HF-TFF model, addition of CHO-specific sEVs in CHO culture simulated filter fouling behaviors in a concentration-dependent manner. Based on these results, we proposed a mechanism of HF-TFF fouling, in which filter pore constriction by CHO sEVs is followed by cake formation of cellular materials on filter membrane.

Calcium absorption by Alaska pollock surimi protein hydrolysate promotes osteoblast differentiation.

The calcium-binding capacity and osteoblast proliferation and differentiation were studied in Alaska pollock surimi hydrolysate (APSH) using a system that mimics the gastrointestinal digestive system. Evaluation of the calcium absorption-promoting ability of APSH revealed that the best calcium-binding ability was achieved after hydrolysis with a combination of pepsin, α-chymotrypsin, and trypsin, and separation into <3kDa (APSH-I), 3-5kDa (APSH-II), 5-10kDa (APSH-III), and <10kDa (APSH-IV) fractions. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis confirmed that the hydrolysate and calcium ions formed a complex. Comparison of the calcium absorption capacity using Caco-2 cells showed that calcium absorption was promoted by these hydrolysates. Measurement of the osteoblast activation revealed higher alkaline phosphatase activity, collagen synthesis, and mineralization effect for the low-molecular-weight hydrolysate (LMH) than for the other hydrolysates. In addition, LMH promoted the expression of osteocalcin, osteopontin, and bone morphogenetic protein-2 and -4, which are hormones related to bone formation. Expression of the Runx2 transcription factor, which regulates the expression of these hormones, also increased. These results suggest that Alaska pollock surimi protein hydrolysates prepared using a system that mimics gastrointestinal hydrolysis may result in better osteoblast proliferation and bone health than those prepared using other proteases.

Visible light photocatalytic dye degradation, antimicrobial activities of green synthesized Ag/TiO2 nanoparticles

The co-precipitation approach was used in this study to synthesize Ag/TiO2 nanoparticles (NPs) using an extract of the flowers from C. pulcherrima. As a reducing agent and a stabilizer during the synthesis process, the flower extract performed a dual function. The surface plasmon resonance in the diffuse reflectance spectroscopy spectrum provided assurance that the Ag+, and Ti4+ ions were significantly reduced. The bandgap study of the Ag/TiO2 NPs revealed that they are suitable for optical and catalytic applications. The NPs were analyzed using X-ray diffraction (XRD) to assess their size and crystal structure. Through scanning and transmission electron microscopy (SEM and TEM), the shape and size changes of the Ag/TiO2 NPs were studied. Energy-dispersive X-ray spectroscopy (EDX) analysis was employed to investigate the elements' chemical composition in the produced NPs. A Fourier transform infrared spectroscopy (FTIR) study was carried out to identify functional groups that might be present in the plant extract and might be involved in the chemical reduction, stabilization, and bonding processes. The photocatalytic disintegration of the hazardous organic dye pollutant methylene blue was studied for 40 min while being exposed to visible light. The flower extract was used to create Ag/TiO2 NPs efficiency degradation rate of 94 %. Additionally, then NPs antimicrobial capacity was assessed, and it was discovered that they were most effective against the infections P. aeruginosa and E. coli.

Pozzolanic Metakaolin Reactions: Stoichiometric and Kinetic Modeling

In the pursue of environmentally-friendly binders for the construction industry, metakaolin (MK) has emerged as promising material, with its hardening performance primarily driven by pozzolanic reactions. However, in systems containing MK and calcium hydroxide (CH), transformation reactions from metastable to stable phases, particularly in excessive CH conditions, can adversely affect material properties. To anticipate these processes, this study introduces a stoichiometry-based reaction modeling approach for pozzolanic MK reactions, encompassing both short-term kinetics and long-term transformation processes. The primary pozzolanic reactions of MK are briefly outlined, highlighting two sequential, partially overlapping reactions forming C4AH13 and C2ASH8. Short-term reaction kinetics are modeled using isothermal calorimetry measurements and deconvoluting the two reaction peaks. The model is in good agreement with experimental quantitative X–ray diffraction (qXRD), thermogravimetric analysis (TGA) and helium pycnometer (density, i.e. solid volume) results. Model limitations are discussed based on qualitative scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX) analysis. Leveraging the proposed model, the temperature dependency of pozzolanic MK reactions is analyzed, revealing an activation energy for the primary reaction of 84 kJ/mol. The model is intended to lay a foundation for designing innovative binder systems based on metakaolin, while paving the way for sustainable construction in the future.

Optimization and characterization of sustainable geopolymer mortars based on palygorskite clay, water glass, and sodium hydroxide

Abstract The synthesis of ambient-cured sustainable geopolymer mortars (GMs) was studied throughout this work. To reduce carbon dioxide emissions, new materials must be used in the production of sustainable concrete and mortars. Many types of binders are used in the synthesis of GM and concrete (GPC), especially clay minerals. These clay minerals are considered sources of alumina and silica in GM and concrete. The geopolymerization process relies on the alkaline solution activating the alumino-silicate to produce geopolymer gel products. The palygorskite (PA) clay mineral, sodium hydroxide (NaOH), and sodium silicates (Na2SiO3) were chosen as a binder (solid material) and alkaline activator solution to synthesize GM at ambient temperature. PA was thermally treated at 550, 650, 700, and 750°C, respectively, to convert into high-reactive PA (HRP) HRP550, HRP650, HRP700, and HRP750, respectively. The characteristics of PA clay, HRP powders, and HRP-based GM were evaluated using compressive strength (CS) testing, X-ray fluorescence analysis, carbon footprint analysis, X-ray diffraction (XRD) diffractograms, Fourier transform infrared spectroscopy (FTIR) spectroscopy, scanning electron microscopy (SEM) images, and energy-dispersive X-ray spectroscopy (EDS) analysis. The maximum CS of 25.1 MPa was acquired for geopolymer synthesis utilizing HRP700-based GM cured at 30°C for 28 days. FTIR spectroscopy demonstrated that HRP-based GM showed the presence of Si–O, Al–O, and O–C–O bonds stretching vibrations in the alumino-silicate network. The results showed that the CO2 emissions had a reduction in the HRP-based GM compared with the reference mix of ordinary Portland cement mortar (OPM). The percentage of reductions was 14.1, 13.7, 13.1, and 12.4 for HRP550, HRP650, HRP700, and HRP750, respectively, compared with the OPM mixture. SEM images/EDS analysis and XRD diffractograms confirmed the presence of sodium alumino-silicate hydrates, magnesium silicate hydrate, and calcium silicate hydrate gels with high quantities particularly in the HRP700-based GM than that in HRP550, HRP650, and HRP750, respectively. The results indicate the suitability of HRP calcined at 700°C (HRP700) in the synthesis of the GM.

Obtaining of transdermal patches by means of natural active principles

In the present paper the contributions are directed to obtaining transdermal therapeutic patches provided with a functional cotton textile support (acting as a reservoir) which would result in the controlled release of certain natural active principles (propolis and menthol), with .pharmaceutical action on people and children in order to support the treating and preventing of some irritations, wounds, injuries, scratches as well as certain allergic skin conditions in a natural, efficient and comfortable manner which would avoid the classic administration . In order to prove and characterize the inclusion of the active principles (propolis and menthol) into the cavity of the reactive cyclodextrin product grafted on the surface of the biofunctional textile support the following analytical methods were applied: scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TG-DTG).

Synthesize of heterostructure TiO2 by simultaneous doping of double silver and phosphate to degradation of methylene blue under visible light

Photocatalysts show great potential as compounds for restoring contaminated water and wastewater resources. The study aims to synthesize a composite with high photocatalytic potential under visible light to photodegrade the organic pollutants. Ag/Ag3PO4@ TiO2 were synthesized by doping Ag and Ag3PO4 on TiO2. The composite was characterized using X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy, Field emission scanning electron microscopy, and Energy-dispersive X-ray spectroscopy analyses, and its photodegradation ability was investigated by methylene blue. Utilization of pure TiO2 yielded a removal efficiency that was merely half of the efficiency achieved when using modified particles, owing to the reduction of TiO2 s band gap from 3.2 to 1.94 eV. In addition to its enhanced photocatalytic performance under visible light, the synthesized Ag/Ag3PO4@TiO2 photocatalyst demonstrated remarkable efficiency in removing dyes such as methylene blue from aqueous solutions. The removal efficiency at pH less than 7 in 50 ppm methylene blue solution using 3 g/l photocatalyst over 45 min visible light irradiation was approximately 90 percent. Under sunlight, photocatalytic reactions exhibited an efficiency of over 95 percent within 45 min. It can be concluded that the simultaneous introduction of metallic (Ag) and nonmetallic (PO43−) dopants significantly increases the efficiency of electron–hole recombination suppression in the photocatalyst and also decreases the band gap.

Effect of additive type and amount on structural and mechanical properties of ZrO2/B4C/Al2O3/SiC added Al 1050 based composite structures produced by vacuum infiltration—Comparative study

With this experimental study, ZrO2/B4C/Al2O3/SiC ceramics in different weight ratios were added to 99.5% pure aluminum and composites were produced by vacuum infiltration, which is very rare in the literature. It is aimed to investigate how different ceramics will affect the technical properties of an aluminum composite. First, scanning electron microscope images were taken to examine their microstructures, and energy-dispersive x-ray spectroscopy analyses were performed. In addition, x-ray diffraction analyses of phase structures were performed. Then, the densities of the composite structures were measured. In the last stage of the experiments, hardness measurement, bending strength, and abrasive wear amount tests were carried out to determine the mechanical properties of the composite structures. According to the data obtained, a relatively homogeneous structure was obtained up to 10% of the ceramic particles in the structure. It was observed that thermal damage did not occur in the composite structures and no significant phase changes occurred. The highest infiltration distance was obtained from B4C-reinforced samples, and the lowest infiltration distances were obtained from ZrO2-reinforced samples. Ceramic reinforcement elements have reduced the density values of composite structures. With the increase in the ratio of ceramic reinforcement particles, the hardness values of the composites increased and the flexural strength values decreased. In the abrasive wear tests, the least wear loss was obtained from SiC-reinforced samples and the highest wear loss was obtained from ZrO2-reinforced samples. When the composites were evaluated according to their microstructure and mechanical strength, the best results were obtained with SiC and then Al2O3, B4C, and ZrO2 reinforcements, respectively. It has been concluded that SiC, Al2O3, B4C, and ZrO2 reinforcement elements in Al 1050-based composites produced by vacuum infiltration have a positive effect on most of the mechanical properties and a negative effect on some of them.

Mineralogical Analysis of Lithomargic Clay Deposits along the Coastal Belt of Uttara Kannada Region in South India

The Lithomargic clay, generally known as Shedi soil found below the lateritic soil along the coastal belt of Karnataka. This lithomargic clay is rich in silt content and dispersive in nature. The dispersion or de-flocculation behaviour of clays is influenced by factors including mineral composition, soil chemistry, the presence of dissolved salts in the pore water, and the characteristics of the erosive water. This type of soil is liable to erosion and landslides. At present, coastal belt of Uttara Kannada district is witnessing a lot of developments in terms of Industry, infrastructures, and other activities. Lithomargic clay represents a challenging soil variety that necessitates comprehensive examination to render it compatible for supporting various engineering structures such as buildings, pavements, railways, and dam. The X-ray diffraction and Energy Dispersive X-Ray Spectroscopy (EDS) analysis were conducted to identify the presence of minerals and compounds for the various soil samples collected along the coastal belt of Uttara Kannada District. The minerals observed in most of the locations are quartz, feldspar like orthoclase, microcline, albite, mica group consisting of muscovite and biotite, those that are not altered chemically since the time of formation and deposition. The presence of secondary minerals like kaolinite, illite, montmorillonite, vermiculite, gibbsite, and calcite are witnessed by the X-ray diffraction analysis.

Monodispersed biodegradable microparticles with wrinkled surface coated with silver nanoparticles for catalytic degradation of organic toxins

AbstractMicrofluidic fabrication of monodisperse microgels for biomedical, nanotechnological, environmental, and catalytic applications has become the subject of growing interest. In this work, monodisperse polyethylene glycol diacrylate [P(EGDA)] microgel particles were fabricated using a CNC-milled microfluidic device with a Lego-inspired interlocking mechanism. Silver nanoparticles (AgNPs) were synthesised and stabilised in situ on the wrinkled surface of the microgel particles using AgNO3 as a metal precursor and NaBH4 as a reductant. The loading of AgNPs (7.5 wt%) on microgel beads was confirmed by energy-dispersive X-ray spectroscopy, X-ray diffraction, and thermogravimetric analysis. Surface wrinkles were found to be a useful morphological feature acting as reservoirs for the accumulation of AgNPs. Ag–P(EGDA) hybrid polymer particles were shown to be an efficient catalyst for the reduction of 4-nitrophenol (4NP) into 4-aminophenol (4AP) by sodium borohydride at room temperature. After 40 min, 0.08 M 4NP was completely converted into 4AP using 2.1 mg/mL of Ag–P(EGDA) catalytic particles, and the reaction followed a pseudo-first-order kinetics. The apparent rate constant increased from 0.0142 to 0.117 min−1 when the loading of catalytic particles increased from 1.7 to 2.50 mg/mL indicating that the reduction is occurring on the catalyst surface according to the Langmuir–Hinshelwood model. Ag–P(EGDA) hybrid microgel was a potent and recyclable catalyst for room-temperature degradation of methylene blue (MeB) by NaBH4. At the Ag–P(EGDA) loading of 2.0 mg/mL, 25 µM of MeB was completely degraded in 6 min. Composite Ag–P(EGDA) microgel beads can be used as an eco-friendly and easily recoverable catalyst for the transformation of other organic pollutants into useful chemicals. Graphical abstract