Scanning Electron Microscopy With Energy Dispersive Spectroscopy Research Articles

Slipper Limpet (Crepidula fornicata) Shells Support In Vitro Osteogenesis of Human Adipose-Derived Stem Cells.

This study aimed to investigate a cost-effective alternative to man-made calcium phosphate ceramics for treating bone defects. The slipper limpet is an invasive species in European coastal waters, and its shells composed of calcium carbonate could potentially be a cost-effective source of bone graft substitutes. This research analyzed the mantle of the slipper limpet (Crepidula fornicata) shells to enhance in vitro bone formation. Discs machined from the mantle of C. fornicata were analyzed using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray crystallography (XRD), Fourier-transform infrared spectroscopy (FT-IR) and profilometry. Calcium release and bioactivity were also studied. Cell attachment, proliferation, and osteoblastic differentiation (RT-qPCR and alkaline phosphatase activity) were measured in human adipose-derived stem cells grown on the mantle surface. The mantle material was mainly composed of aragonite and showed a sustained Ca2+ release at physiological pH. In addition, apatite formation was observed in simulated body fluid after three weeks, and the materials supported osteoblastic differentiation. Overall, our findings suggest the mantle of C. fornicata shows potential as a material for fabricating bone graft substitutes and structural biomaterials for bone regeneration.

THE STRUCTURAL, MORPHOLOGICAL AND ELEMENTAL CHARACTERIZATION OF A SICA SCABBARD DISCOVERED AT BURIDAVA

In 2019, on one of the most important dacian archaeological sites (Ocnița, Vâlcea County, Romania), in a tomb dug into the rock, along with various weapons, ceramics, bones, etc. there was also discovered a fragmentary sica scabbard. As a consequence of the lack of information on solely such iron-made objects, the urgent need to obtain as much information as possible regarding this type of military equipment was mandatory. Thus we applied different characterization methods aimed at obtaining results regarding the inner structure assembly of the scabbard, the chemical composition and the elemental distribution of the material the scabbard was made of, in order to better understand the technique used by the dacian blacksmiths. With the help of optical macroscopy, energy dispersive - X-ray fluorescence spectrometry (EDXRF), X-ray CT scanning, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) we tried to reconstruct how the scabbard was made, and how it survived until present times.

Preparation and Characterization of Geopolymers Based on Metakaolin with the Addition of Organic Phase PVA

Geopolymers have excellent physical and mechanical properties, so they can be used as a substitute for ordinary polymers. Geopolymers are ceramic materials, which exhibit the property of brittleness, which can be a limitation in some structural applications. To overcome this shortcoming, a new group of materials (organic geopolymers) was developed. The aim of this work is the synthesis of organic (hybrid) geopolymers. A geopolymer based on metakaolin was synthesized as a reference sample, while polyvinyl alcohol was added as an organic phase for synthesizing a hybrid geopolymer. It was concluded that the systems follow the rule of behavior in liquid systems. The chemical composition of the samples was determined by X-ray fluorescence analysis (XRF). Structural and phase characterization of hybrid and reference materials were analyzed using X-ray diffraction (XRD)and Fourier-transform infrared spectroscopy (FTIR), which revealed new phases in the PVA-added samples. The results show that the content of added PVA in the reaction mixture affects the phase composition of the synthesized materials. To examine the possibility of adsorption of the samples, Ultraviolet-visible spectroscopy (UV/VIS) was used. The morphology was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM/EDS), where efflorescence was observed and identified. After characterizing the geopolymer with the addition of PVA, we obtained a material that was far more porous than the basic sample, and we can conclude that we have synthesized a material that shows good mechanical properties.

Optimization of the Two‐ and Three‐Dimensional Characterization of Rare Earth‐Traced Deoxidation Products

Tracing by means of the light rare earths (REs), particularly La and Ce, is a state‐of‐the‐art method used to track deoxidation products during the steelmaking process. Traced heterogeneous multiphase inclusions are analyzed using scanning electron microscopy with energy‐dispersive spectroscopy (SEM/EDS) to perform a 2D characterization. The sequential chemical extraction technique is implemented for a 3D investigation to determine traced particles’ actual sizes and shapes. The automated SEM/EDS measurement must be optimized since RE oxides appear brighter in the backscattered electron images due to their high atomic numbers. Therefore, two grayscales are implemented for the detection of RE‐containing multiphase inclusions. Within this technique, individual RE‐traced heterogeneous nonmetallic inclusions (NMIs) are counted as separate particles. Thus, the measured NMIs must be recombined, which is achieved using a self‐developed MATLAB tool. The extracted particles are also analyzed by automated and manual SEM/EDS measurements to determine the 3D morphologies and sizes of traced NMIs.

Mineralogical and Geochemical Constraints on the Occurrence Forms of REEs in Carboniferous Karst Bauxite, Central Guizhou Province, Southwest China: A Case Study of Lindai Bauxite

Karst bauxite is a major source of aluminum and contains high concentrations of trace elements such as Li, Ga, Sc, and rare earth elements (REEs). It is regarded as a potential non-conventional REE source due to the increasing demand for REEs. This study provides new mineralogical and geochemical evidence of a Lindai bauxite deposit in central Guizhou Province, aiming to analyze the genesis of REE minerals and reveal the forms of REEs occurring in these deposits. The results indicate that a large number of detrital and authigenic rare-earth phosphate minerals, including monazite and xenotime, were identified. In terms of their genesis, the authigenic monazite was mainly precipitated under alkaline and reducing conditions, whereas the authigenic xenotime was formed in acidic and reducing conditions. The mineralogical evidence detected by scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) and a TESCAN Integrated Mineral Analyzer (TIMA) suggests that the REEs in the Lindai bauxite exhibit multiple forms, including rare-earth phosphate minerals (monazite and xenotime) and REE scavenging by hematite and anatase phases. Among them, the anatase controls some LREE (such as La, Ce, and Pr) distributions in addition to monazite, whereas the hematite also controls relatively large amounts of Sm, Eu, and HREE (such as Gd, Tb, Dy, Ho, Er, Tm, and Lu) distributions. According to the calculation of the percentage of REE-bearing mineral phases obtained by a TIMA analysis, REE scavenging by hematite accounted for 93.28% of all forms of REEs, REE scavenging by anatase accounted for 5.88%, monazite accounted for 0.67%, and xenotime accounted for 0.17%. This study provides new evidence of the forms of REEs occurring in Carboniferous karst bauxite in central Guizhou Province.

Late Roman copper smelting in Polis Chrysochous, Cyprus

Two Late Roman slag heaps located near Polis Chrysochous, western Cyprus, were studied to reconstruct the technological processes of copper production. This is the second richest mining region on the island. The Pelathousa slag heap (4th – 6th century CE) is located at the foothills of the Troodos Mountains, about 5 km inland from the coast, while the Argaka slag heap (3rd – 8th century CE) is situated by the coast. An assemblage of 112 slag pieces collected from the two slag heaps was macroscopically examined. Subsequently 49 of the samples were chemically analysed using Hand Held portable X-ray Fluorescence (HHpXRF). A smaller subset of the analysed samples were selected for optical microscopy and Scanning Electron Microscopy with Energy-Dispersive Spectrometry (SEM-EDS). The chemical and microscopic analysis showed that the samples from both slag heaps have a similar composition, including a wide variability in manganese content, which ranges from less than 1 wt% to almost 40 wt%. Manganese has most likely been added as a flux procured from the umber deposits of the Pera Pedi formation which is readily accessible from the nearby mines. The prevalence of sulfide inclusions across all samples indicates that the slag assemblage derives exclusively from copper-matte smelting. The results are then discussed to understand the difference in manganese content, and the organization of copper production within the landscape.

Ternary Polyaniline@Bi2O3-BiOCl Nanocomposites as Innovative Highly Active Photocatalysts for the Removal of the Dye under Solar Light Irradiation.

Ternary PANI@Bi2O3-BiOCl nanocomposites were successfully synthesized during the oxidative polymerization of aniline monomer in the presence of Bi2O3. PANI@Bi2O3-BiOCl nanocomposites were characterized by several analytical techniques, including X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), N2 physisorption, UV-Vis Diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). The effective PANI-semiconductor interaction promotes the fast separation and transfer of photogenerated electrons and holes, enhancing the photocatalytic efficiency of the materials towards methylene blue (MB) degradation under solar light irradiation. The best results were obtained by 0.5%PANI@Bi2O3-BiOCl, leading to 80% MB degradation in 2 h, four times higher than pristine Bi2O3-BiOCl. Moreover, 0.5%PANI@Bi2O3-BiOCl maintained stable photocatalytic performances for four cycles without significant activity loss. Various scavengers (isopropyl alcohol, formic acid, and benzoquinone) were used to identify the active species by trapping holes and radicals generated during the photocatalytic degradation process. Finally, a probable photocatalytic mechanism of PANI@Bi2O3-BiOCl photocatalyst was suggested.

Evaluation of the aminosilane and colloidal silica treated red iron oxide pigment effects in styrene acrylic and polyurethane dispersion

PurposeThis study aims to perform the surface treatment of synthetic α-Fe2O3 red iron oxide pigment with hydrolysate 3-aminopropyl silane (A) and colloidal silica (CS) and investigate the effects of surface-treated pigment on the styrene acrylic (SA) emulsion and polyurethane (PU) dispersion.Design/methodology/approachFor this purpose, firstly red iron oxide particles were modified with A and CS separately in an aqueous medium. After isolation of the modified iron oxide were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Moreover, the degree of the dispersion stability of the modified pigment in coatings with SA emulsion and PU dispersion was investigated by using an oscillation rheometer. Loss (G''), storage (G') modulus, loss factor [tan(δ)] and yield stress (τ0) values were determined by performing amplitude and frequency sweep tests.FindingsThe τ0 in SA coatings decreases with the amount of used A and increases with the amount of used CS. The τ0 decreases as the amount of used A and CS in PU coatings increases. The use of CS on red iron oxide pigments causes storage modulus to increase in SA coatings at low angular frequencies, while it causes a decrease in PU coatings.Originality/valueTo the best of the authors’ knowledge, for the first time, the suspended state of the iron oxide hybrid pigment formed with CS in the coating was investigated rheologically in this study.

Zn Modification of Pd/TiO2/Ti Catalyst for CO Oxidation.

The main goal of this study was to modify the activity of Pd/TiO2/Ti catalyst in the reaction of CO oxidation by the addition of Zn. Plasma electrolytic oxidation (PEO) of Ti wire was conducted to produce a uniform porous layer of TiO2. A mixture of Pd and Zn was then introduced by means of adsorption. After reduction treatment, the activity of the samples was examined by oxidation of 5% CO in a temperature range from 80-350 °C. Model catalysts with sufficient amounts of the metals for physico-chemical investigation were prepared to further investigate the reaction between Pd and Zn during CO oxidation. The structures and compositions of the samples were investigated using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), inductively coupled plasma mass spectrometry (ICP-MS), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). Modification of Pd/TiO2/Ti catalyst by Zn with a Pd:Zn atomic ratio of 2:1 decreased the temperature of complete CO oxidation from 220 °C for Pd/TiO2/Ti to 180 °C for Pd-Zn/TiO2/Ti. The temperature of 50% CO conversion on Pd-Zn(2:1)/TiO2/Ti was around 55 °C lower than in the reaction on monometallic Pd catalyst. The addition of Zn to the Pd catalyst lowered the binding energy of CO on the surface and improved the dissociative adsorption of oxygen, facilitating the oxidation of CO. FTIR showed that the bridging form of adsorbed CO is preferred on bimetallic systems. Analysis of the surface compositions of the samples (SEM-EDS, TOF-SIMS) showed higher amounts of oxygen on the bimetallic systems.

Separation and recovery of indium from solution in a sulfite-sulfuric acid system

In this investigation, to separate and recover indium (In), the adsorption and desorption characteristics of indium in the sulfite-sulfuric acid system using IRA-900 resin and the adsorption mechanism were explored. When sodium sulfite and sulfuric acid concentrations were 0.5 mol/L, IRA-900 resin exhibited the best adsorption selectivity to indium, with an adsorption capacity of 95.56 mg/g(318 K), while the adsorption capacities of Al, Sr, Fe, Zn and Cu were weak. In(Ⅲ) adsorption by resin conforms to the second-order kinetic model, and the Langmuir model is more suitable for adsorption. In desorption experiments, 2 mol/L hydrochloric acid was selected as the desorption agent, with a desorption rate of 82.39 %. FT-IR (Fourier-transform infrared spectroscopy), SEM-EDS (Scanning electron microscopy with energy dispersive spectroscopy), XPS (X-ray photoelectron spectroscopy) and elemental analysis results indicated that the adsorption mechanism of indium could be attributed to the formation of an anionic complex between In3+ and HSO3-/HSO4-, which could be exchanged with Cl- on the resin to adsorb the metal ions. In addition, the column experiment could efficiently separate indium from simulated indium-containing solution. In(Ⅲ) recovery yield was about 99.6%, indicating its effective separation and recovery from ITO (Indium tin oxide) film.

Corrosion resistance of magnesium phosphate cement under long-term immersion in different solutions

Magnesium phosphate cement (MPC) is widely utilised in engineering. However, it may be subject to corrosion in the Western Chinese saline soil environment. This study analysed the factors of magnesium phosphorus ratio, borax content, water binder ratio and fly ash content. Mix proportions of MPC were devised through orthogonal testing. The corrosion performance of MPC specimens in water, 5% Na2SO4 solution, 5% NaCl solution and saline soil solution were analysed in terms of mass loss and the strength anti-corrosion coefficient. The corrosion mechanisms of MPC in different solutions were analysed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric and differential scanning calorimetry (TG-DSC) and Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). There were no obvious changes in MPC appearance or morphology after soaking in different solutions for 180 days. The mass loss was < 5% and the strength loss was < 25%, indicating that MPC has good resistance to saline soil and other saline solutions. The strength anti-corrosion coefficients of MPC soaked in various solutions for 180 days were > 0.75, and the influences on strength can be ranked as follows: 5% Na2SO4 solution > saline soil solution > water > 5% NaCl solution. On the basis of TG-DSC, FTIR and XRD analyses, when MPC was soaked in different solutions for 180 d, the contents of the hydration product MgKPO4·6H2O (MKP) were ranked as water > 5% NaCl solution > saline soil solution > 5% Na2SO4 solution. SEM-EDS analysis shows that MKP was corroded to varying degrees after the MPC was soaked in different solutions, with the 5% Na2SO4 solution causing the greatest corrosion.

Green Synthesis of Silver Nanoparticles Using Salvia verticillata and Filipendula ulmaria Extracts: Optimization of Synthesis, Biological Activities, and Catalytic Properties.

The study's objective was to obtain silver nanoparticles (SVAgNP and FUAgNP) using aqueous extracts of Salvia verticillata and Filipendula ulmaria. The optimal conditions for nanoparticle synthesis were determined and obtained; nanoparticles were then characterized using UV-Vis, Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Dynamic Light Scattering (DLS), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS). SVAgNP and FUAgNP possessed a crystalline structure with 48.42% and 60.41% silver weight, respectively. The highest percentage of nanoparticles in the solution had a diameter between 40 and 70 nm. In DPPH˙ and ABTS˙+ methods, FUAgNP (IC50 15.82 and 59.85 µg/mL, respectively) demonstrated a higher antioxidant capacity than SVAgNP (IC50 73.47 and 79.49 µg/mL, respectively). Obtained nanoparticles also showed pronounced antibacterial activity (MIC ˂ 39.1 µg/mL for most of the tested bacteria), as well as high biocompatibility with the human fibroblast cell line MRC-5 and significant cytotoxicity on some cancer cell lines, especially on the human colon cancer HCT-116 cells (IC50 31.50 and 66.51 µg/mL for SVAgNP and FUAgNP, respectively). The nanoparticles demonstrated high catalytic effectiveness in degrading Congo red dye with NaBH4. The results showed a rapid and low-cost methodology for the synthesis of AgNPs using S. verticillata and F. ulmaria with promising biological potential.

Volcanic Pozzolan from the Phlegraean Fields in the Structural Mortars of the Roman Temple of Nora (Sardinia)

In this paper, we discuss the presence of volcanic pozzolans in the structural mortars of the Roman Temple of Nora in Sardinia (3rd c. AD), represented by pyroclastic rocks (pumices and tuffs) employed as coarse and fine aggregates. The provenance of these materials from the Phlegraean Fields was highlighted through a multi-analytical approach, involving Polarized Light Microscopy on thin sections (PLM), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Quantitative Phase Analysis by X-ray Powder Diffraction (QPA-XRPD), and X-ray Fluorescence (XRF) investigations. These volcanic pozzolans, outcropping in the Bay of Naples between Pozzuoli and the Vesuvius, are traditionally associated with the pulvis puteolana, the famous pozzolanic ash prescribed by Vitruvius and Pliny in order to confer strength and waterproofing capabilities to ancient concretes. This is the first evidence of the trade of this volcanic material from the Neapolitan area to Sardinia, starting at least by the Middle Imperial Age. The use of the pulvis puteolana in the Roman Temple of Nora seems primarily targeted to strengthen above-ground masonries, while waterproofing capabilities were not strictly pursued. This opens new questions about the construction reasons for which the demand and commercialization for this product was intended.

Historical and Physicochemical Analysis of the Clinker Bricks in the Smart Memorial Gymnasium of the Tiancizhuang Campus at Soochow University, China

Clinker bricks were popular as a facade material in the United States between the 1890s and the 1930s. However, this material was unknown to Chinese builders and was seldom found in Chinese modern architecture from 1840 to 1949. The Smart Memorial Gymnasium built in the years 1934–1937 in the Tiancizhuang Campus of Soochow University (Suzhou, China) is one of the rare examples of a building featuring clinker bricks in modern China. Notably, those clinker bricks were not imported but locally manufactured. Despite the heritage significance of the Smart Memorial Gymnasium as part of a major historical and cultural site protected at the national level in China, the history and characteristics of those historical bricks have remained virtually unexplored. This study first provides a historical analysis of those bricks, giving insights into the general knowledge of this construction material around that time based on British and American historical sources from the 19th and 20th centuries, with a focus on historical treaties and documents. This analysis sheds light on the raw materials mixtures of clinker bricks, their manufacturing processes, and their architectural applications at the time. Moreover, this study presents a physicochemical analysis of the clinker bricks employed at Soochow University, focusing on the correlation between historical studies and physicochemical characteristics, as well as the materials’ characteristics that respond to the natural environment. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and total immersion tests were employed to investigate the physicochemical properties of the bricks at various locations of the Smart Memorial Gymnasium facades. Our findings deepen the knowledge and understanding of clinker bricks transferred from the West to China in the early 20th century. Additionally, our results reveal the chemical composition and physical characteristics of different types of clinker bricks used in the Smart Memorial Gymnasium, outlining practical implications and future research directions. Overall, this study lays a foundation for the heritage recognition and conservation of Chinese clinker bricks.

Comparative Characterization of the TiN and TiAlN Coatings Deposited on a New WC-Co Tool Using a CAE-PVD Technique

The main objective of this work was to assess and compare the structure and mechanical properties of the TiN and TiAlN coatings deposited on a new WC-Co tool using the cathodic arc evaporation vacuum deposition (CAE-PVD) technique. The cutting tool was sintered at high temperature and high pressure using a powder tungsten carbide matrix ligated with cobalt (WC-Co). Powdered grain growth inhibitors (TiC, TaC, and NbC) were admixed into the matrix to enhance its strength and to facilitate the adhesion of the Ti base coatings. Detailed scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS) and X-ray diffraction (XRD) analyses were performed, aiming to substantiate the effectiveness of the inhibitor additions. XRD data were thoroughly exploited to estimate the phase contents, average crystallite sizes (D), coating thicknesses (t), texture coefficients (Thkl), and residual stress levels (σ). Atomic force microscopy (AFM) was used to calculate the average roughness (Ra) and the root mean square (Rq). The microhardness (µHV) was measured using the Vickers method. The TiAlN characteristics (D = 55 nm, t = 3.6 μm, T200 = 1.55, µHV = 3187; σ = −2.8 GPa, Ra = 209 nm, Rq = 268 nm) compared to TiN ones (D = 66 nm, t = 4.3 μm, T111 = 1.52, µHV = 2174; σ = +2.2 GPa, Ra = 246 nm, Rq = 309 nm) substantiate the better adequacy of the TiAlN coating for the WC-Co substrate. The structural features and data on the TiN and TiAlN coatings, the tool type, the different stress kinds exerted into these coatings, and the way of discrimination of the coating adequacy are the novelties addressed in the paper.

Phase transition, microstructure and solidification of Ce–La–Fe and Ce–Nd–Fe alloys: Experimental investigation and thermodynamic calculation

In this work, phase transition temperatures of La–Fe and Ce–Fe alloys were determined using differential thermal analysis (DTA), while phase transition temperatures, microstructure, and phase compositions of La–Ce–Fe and Ce-Nd-Fe alloys were studied using DTA and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Based on the available experimental data reported in the literature and the experimental results determined in this work, the La–Fe and Ce–Fe systems were re-assessed thermodynamically using the CALPHAD (CALcuation of PHAse Diagrams) method, and then the Ce–La–Fe and Ce-Nd-Fe systems were calculated by combining the re-assessed La–Fe and Ce–Fe systems with the previously assessed Nd–Fe, Ce–La, and Ce–Nd systems. The calculated phase diagrams and thermodynamic properties of the La–Fe and Ce–Fe systems are consistent with the experimental data. The calculated isothermal sections and vertical sections in the Ce–La–Fe and Ce-Nd-Fe systems are in good agreement with the experimental results. The solidification behaviors of Ce–La–Fe and Ce-Nd-Fe as-cast alloys were analyzed through the experimental examination and thermodynamic calculation with Scheil-Gulliver non-equilibrium model. The simulated results agree well with the experimental results. It indicates that the reasonable thermodynamic parameters of the Ce–La–Fe and Ce-Nd-Fe systems were obtained finally, which would be fundamental to developing a thermodynamic database of the multi-component Nd-RE-Fe-B alloy systems and then to designing novel Nd-Fe-B permanent magnets with light rare-earth metals La and Ce.

Production of nanostructured crystalline composite using residual ashes from flocculated sludge burning process in a poultry slaughterhouse wastewater treatment system

Nanostructured crystalline composite (activated carbon) was synthesized from residual ashes of the burning process of the sludge generated in the flotation step of a poultry slaughterhouse and was used for Allura red dye adsorption. The ashes were chemically activated using two types of reagents, H2O2 and H3PO4, and the structure, morphology, and surface of the adsorbents were characterized by different techniques such as scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), N2 adsorption/desorption isotherms with Brunauer-Emmett-Teller (BET) method and Barret-Joyner-Hallenda (BJH) method, Fourier transform infrared spectroscopy (MID/FTIR), X-ray diffraction (XRD), and the point of zero charge (PZC). The adsorbent synthesized with H3PO4 at 400 ºC displayed the best performance in removing dye molecules in 10 mg.L-1 solution, with a removal rate of approximately 100% when using a concentration of 2 g.L-1 in particle size of 0.42 mm. Besides that, the adsorbent synthesized with H3PO4 had a particle diameter of approximately 15 Å, a size corresponding to the nanometer range, presented a crystallinity structure with well-defined phases such as quartz and the major elements in the composition were carbon and silicon. The surface area of the ashes enlarged from 14.71 to 448.1 m2.g-1 when H3PO4 was used as an activator, producing a high-quality adsorbent, with an excellent cost-benefit, being it possible to be produced for a price of 9.35 USD.kg-1, a price lower than the commercial activated carbon, making it a promising candidate for application in an industrial environment.

Trace Metal Enrichment in the Colloidal Fraction in Soils Developing on Abandoned Mine Spoils

The release of colloid-bound trace metals from abandoned coal mine spoils can potentially be a significant source of contamination during weathering. We examined the size-dependent enrichment of trace metals in mine spoil samples using centrifugation and acid extraction to compare metal loading in the bulk and colloid fractions. A combination of X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and focused ion beam (FIB) sectioning of selected colloids for transmission electron microscopy (TEM) analyses was used to determine the morphology and elemental and mineral composition at the micro- and nanoscales. In contrast to bulk soils, primary Fe-sulfides (up to 11%) and secondary Fe(III)-bearing phases (up to 5%) were a significant portion of the colloid mineralogy. Secondary Fe-(hydro)oxides and (hydroxy)sulfates were enriched with Mn, Ni, Cu, and Zn, and these metals showed stronger correlations with Fe in the colloid fraction (R2 of 0.58, 0.77, 0.94, and 0.81, respectively) than in the bulk fraction (R2 of 0.40, 0.09, 0.84, and 0.62, respectively), indicating that Fe-bearing colloids are likely major trace-metal-bearing phases. The results from this study will help to design better remediation projects for abandoned mine spoils to better account for a potentially underappreciated mode of contaminant transport.

Toeslope ferricretes in the tropical rainforest of southern Cameroon: Internal properties, mechanisms and conditions of genesis

The formation of toeslope ferricretes under humid tropical rainforest is common. However, no specific work has been devoted to the toeslope ferricretes to determine the mechanism of formation and the exact time. The study pointed out the internal properties (petrology, mineralogy and geochemistry) of southern Cameroon toeslope ferricretes, their spatial distribution in relation to the landscape morphology, and the mechanisms and conditions of their genesis. Fieldwork included the study of the soil properties and patterns, as well as of their geometric relationships. Laboratory analysis included X-ray powder diffraction (XRD), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), X-ray fluorescence spectrometry (XRF) and inductively coupled plasma (ICP-AES). The main results revealed that, at the bottom of the studied toeslope soil profiles, iron oxides (Al-goethite and hematite) accumulate in situ, starting from domains in which the parental granodiorite rock structure is still preserved. This relative accumulation is relayed towards the top of the profiles by an absolute accumulation of Fe from the upslope ferricrete dismantling. New ferruginous accumulation patterns occur in varying degrees of rubification and show various degree of hardness from soft soil patterns to carapace, as precursor of two types of toeslope ferricrete genesis: spotted massive carapace (with a continuous framework) on the moderate slope and variegated vesicular carapace (ferruginous network with vacuoles) on the gentle slope. Ferricretes on the moderate slope are thick, with limited lateral extension and light induration, while those on gentle slope are thinner, but more hardened and more extended on the slope. Such processes are clearly linked to the present-day humid climate with flattening of landscapes and rising of groundwater table.

Recovery and analysis of valuable materials from a discarded crystalline silicon solar module

Mechanical, thermal, and chemical treatments were employed on a discarded small-sized silicon solar module to recover valuable materials from it. Materials like glass, junction box, polymer back sheet, and aluminium frame were recovered without damage. Ethylene-vinyl acetate layer (EVA) was obtained through the treatment of the panel with toluene solution. Optimised solution of 2 M HCl was used for Pb and Sn stripping from connecting wires to recover Cu Strips. Pb was extracted as PbCl2 from the solution through precipitation in an ice bath. Sn was recovered as SnO2 and SnCl2 through electrolysis of the residual solution. Al from the back contact was recovered as Al(OH)3 through sequential treatment with KOH and H2SO4. The effect of the molar concentration of KOH solution on Al etching was also investigated, and it was found that the 2 M solution was optimal. An innovative and cost-effective approach was adopted for the recovery of silver. Ag extraction involved, the treatment of solar cell pieces with HNO3 acid followed by reduction of AgNO3 with the copper strips. As recovered Cu strips were reused for Ag recovery, it can be considered a cost-reducing step for the reported recycling process. At last, ARC coating was removed by employing an H3PO4 solution to get silicon wafer pieces. X-Ray Diffraction and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) were used for phase identification and purity of the recovered materials. An overall recovery rate of 92.4% is achieved. Environmental impact and revenue generation through the process is also discussed.