Scanning Electron Microscopy With Energy Dispersive X-ray Spectroscopy Research Articles

Efficient incorporation of highly migratory thallium into struvite structure: Unraveling the stabilization mechanisms from a mineralogical perspective

The remediation of high-concentration thallium (Tl+) contaminated wastewater is a critical environmental concern. Current research emphasizes the effectiveness of adsorption and oxidation methods for Tl+ treatment, yet challenges persist in enhancing their performance. This study explores the feasibility of emergency Tl+ wastewater treatment and elucidates the mechanisms of Tl+ incorporation into mineral structures, with a focus on the struvite mineral as a framework for Tl+ integration via NH4+ ion exchange. To assess the efficacy and mechanisms of Tl+ immobilization, we utilized comprehensive analytical techniques, including X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS), Thermogravimetric Analysis (TG), and Density Functional Theory (DFT) calculations. The findings reveal that struvite adsorbs Tl+ onto its surface, followed by an ion exchange process between monovalent cations (NH4+/K+) within the structure and Tl+. Ultimately, Tl+ is incorporated in the form of a (NH4,Tl)MgPO4 solid solution within the structure, achieving a remarkable maximum incorporation capacity of 320.56 mg/g, which significantly surpasses the capacity of typical adsorbents. The findings demonstrate significant Tl+ incorporation, validating the approach for emergency wastewater treatment and suggesting the potential of mineralogy in environmental remediation. This research contributes to advancing heavy metal wastewater treatment strategies, offering a foundation for further investigation.

Facile fabrication of Ag decorated MnFeO3 catalyst: Comparative analysis of visible light driven antibiotic reduction and antibacterial performance

Photocatalysis is an effective method with the potential to eliminate pharmaceutical compounds from water sources. Manganese ferrite (MnFeO3), a type of multiferroic perovskite catalyst, has attracted significant attention due to its small band gap, however its application was limited due to its high recombination rate and low quantum efficiency. It was therefore aimed to improve the properties of MnFeO3 by doping silver (Ag)-particles. In this study, Ag–MnFeO3 photocatalysts with different Ag content (1–3 mmol%) were synthesized by performing a facile hydrothermal method. The as-prepared samples were characterized using x-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), ultraviolet–visible spectroscopy (DRS), photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS) and Brunauer-Emmett-Teller (BET) method, showing successful addition of Ag-particles with the MnFeO3 structure. Then, the as-synthesized materials were investigated as: (i) photocatalysts for degradation tetracycline (TC) antibiotic and (ii) antibacterial agents for bacteria. The Ag–MnFeO3 catalyst demonstrated superior catalytic performance (95.7%), which was 1.6 times higher than that of pristine MnFeO3 (59.7%). The positive effect was ascribed to oxygen vacancies, enhanced light absorption ability, and lower recombination rate. The Ag–MnFeO3 catalyst also showed satisfactory removal performances in real water matrices. Furthermore, radical trapping tests depicted that the superoxide radicals played a dominant role in the photodegradation system. In addition, Box–Behnken design (BBD) was performed to determine the optimum conditions, which were determined as catalyst dosage of 0.45 g/L, initial TC concentration of 5.10 mg/L, and initial solution pH value of 3.69. In terms of antibacterial tests, the incorporation of Ag into the MnFeO3 structure greatly increased the antimicrobial resistance against bacteria. Our findings disclose that the incorporation of Ag into the MnFeO3 structure can be regarded as a feasible and promising approach to improve both photocatalytic degradation and antibacterial performances.

Dissimilar welding between Cu–6Al–2Ni alloy and stainless steel 316L using continuous ytterbium YAG laser

The Cu–6Al–2Ni alloy has much higher ultimate tensile strength compared to pure copper and may potentially replace it in the dissimilar joints between titanium alloys and stainless steels. Laser welding of aluminum bronze to stainless steel has not been reported in the scientific literature, which motivated the present weldability study of Cu–6Al–2Ni/316L dissimilar joint with a continuous ytterbium Yb:YAG laser. Different laser spot offsets from the joint line were selected in order to produce the joints with various dilutions of welded materials. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) probe and X-ray diffraction (XRD) analyses of the melted zones were performed, along with microhardness measurements and tensile testing. The phase evolution in the obtained microstructures was evaluated using Thermo-Calc software. For the dilutions ranging from 23 to 63 at.% Cu, the melted zones showed globular microstructures with primary and secondary phase separation due to the miscibility gap existing in the Cu–Fe system. Lower Cu contents resulted in cellular γ-Fe structures with rare globular Cu-rich inclusions. The XRD analysis indicated the presence of ∼10% of ternary AlFe2Ni phase, however, it did not harm the mechanical properties of the welds. According to Thermo-Calc, this phase is formed from γ-Fe during the cooling process. Microhardness measurements did not indicate the embrittlement of the melted zones, which can be explained by the submicronic dispersion of AlFe2Ni. The welds exhibited a ductile fracture in Cu–6Al–2Ni at ultimate tensile strength of 350–420 MPa in a wide range of laser offsets, which is much higher than previously reported results for pure copper/316L joints.

Characterization and thermal behavior of some types of kaolin of different origin from Northern Vietnam

Kaolin (mainly composed of kaolinite, whose chemical formula is Al2Si2O5(OH)4), serves as a versatile raw material widely used in various industries including production of ceramics, paper, paints, cosmetics, pneumatics, building materials, and hazardous waste storage. In the northern part of Vietnam, due to favorable geological conditions, there are diverse deposits of high quality kaolin of different origin and scale. Decades of research indicate the diversity of kaolin sources in the region, with special attention paid to hydrothermally altered and exchange types of kaolin, the formation of which is associated with complex processes of weathering, hydrothermal alteration and reprecipitation. The aim of this study was to characterize three different types of kaolin derived from different sources in Northern Vietnam (from weathered pegmatites, weathered felsic effusives, and hydrothermal-metasomatic altered rocks). The main focus was to analyze the thermal behavior of these samples during calcination in the temperature range from 300 °C to 1,100 °C. The comprehensive characterization was performed by X-ray diffraction (XRD), FT-IR spectroscopy (FT-IR), thermal analysis (thermogravimetry / differential thermogravimetry (TG / DTG)) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that kaolinite with particle size less than 2 μm was identified in all samples. Minor amounts of muscovite and montmorillonite are present in some samples, and pyrophyllite is present in a sample from the hydrothermally altered rocks. Kaolinite morphology in all the samples showed typical forms including hexagonal and pseudohexagonal. The main chemical constituents of the samples are SiO2 and Al2O3; in addition to these, K2O + Na2O, TiO2 and iron are present in smaller quantities. Thermal analysis allowed to reveal the formation of metakaolinite phase at temperatures around 494 °C and 507 °C in the two studied samples from weathered rocks, while the pyrophyllite-bearing sample undergoes this transition at a higher temperature of 653.8 °C. The onset of metakaolinization was observed at about 500 °C for the weathered rock samples and about 700 °C for the pyrophyllite-bearing sample. In addition, mullitization leading to the formation of mullite was evident at 1,100 °C. The study findings allow concluding that the studied kaolins can be used in traditional ceramics production.

Synthesis of kaliophilite by alkaline fusion and ultrasonic treatment method from kaolin raw material

Mexico has important kaolin deposits, which must be assessed to obtain products with a high commercial value, such as kaliophilite as raw material for biodiesel production. Two kaolins, A and B, with approximate SiO2:Al2O3 ratios of 1 and 1.2, respectively, were used as raw materials to produce kaliophilite. Both kaolins were obtained from the municipality of Agua Blanca in the State of Hidalgo, Mexico. Kaolins are a source of Al and Si for the synthesis of kaliophilite through an alkali fusion process at 700 °C followed by ultrasonic treatment at 28 kHz to different times and for Kaolin-KOH ratios of 1:1 and 1:1.2 (mass: mass). The kaolins as received and the alkaline mixtures heat and ultrasonically treated were analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The most suitable kaolin for synthesizing kaliophilite was kaolin A with the Si/Al mass ratio of approximately 1, which exhibited a higher crystallinity index range from 54 to 79.6%. Higher KOH concentrations promote the amorphous material formation decreasing the kaliophilite amount. The crystallinity index was increased when the time of ultrasonic treatment was increased.

Isolation and Characterization of Indigenous Ureolytic Bacteria from Mindanao, Philippines: Prospects for Microbially Induced Carbonate Precipitation (MICP)

Microbially induced carbonate precipitation (MICP), a widespread phenomenon in nature, is gaining attention as a low-carbon alternative to ordinary Portland cement (OPC) in geotechnical engineering and the construction industry for sustainable development. In the Philippines, however, very few works have been conducted to isolate and identify indigenous, urease-producing (ureolytic) bacteria suitable for MICP. In this study, we isolated seven, ureolytic and potentially useful bacteria for MICP from marine sediments in Iligan City. DNA barcoding using 16s rDNA identified six of them as Pseudomonas stutzeri, Pseudomonas pseudoalcaligenes, Bacillus paralicheniformis, Bacillus altitudinis, Bacillus aryabhattai, and Stutzerimonas stutzeri but the seventh was not identified since it was a bacterial consortium. Bio-cementation assay experiments showed negligible precipitation in the control (without bacteria) at pH 7, 8, and 9. However, precipitates were formed in all seven bacterial isolates, especially between pH 7 and 8 (0.7–4 g). Among the six identified bacterial species, more extensive precipitation (2.3–4 g) and higher final pH were observed in S. stutzeri, and B. aryabhattai, which indicate better urease production and decomposition, higher CO2 generation, and more favorable CaCO3 formation. Characterization of the precipitates by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and attenuated total reflectance Fourier transform spectroscopy (ATR-FTIR) confirmed the formation of three carbonate minerals: calcite, aragonite, and vaterite. Based on these results, all six identified indigenous, ureolytic bacterial species from Iligan City are suitable for MICP provided that the pH is controlled between 7 and 8. To the best of our knowledge, this is the first report of the urease-producing ability and potential for MICP of P. stutzeri, P. pseudoalcaligenes, S. stutzeri, and B. aryabhattai.

Multilayer Silk Sericin-Based Coating for Controlled Release of Water and Nutrients in Soil: Development, Characterization, and Performance Evaluation in Agricultural Production Model

The use of fertilizers coated with insoluble organic compounds is a promising approach for enhancing fertilizer efficiency and crop yield. Silk sericin (SS) is a protein with a high potential for the development of materials oriented toward fertilizer coating and soil amendment because of its biodegradability and the fact that it represents an important source of nitrogen for plants. Thus, this study proposes the design and evaluation of a novel SS-based multilayer coating for fertilizer granules. A pan-coating process was applied to form two distinct layers on the granules: an inner layer made of silk sericin/polyvinyl alcohol, SS/PVA (50/50 w/w), which has low solubility and porosity, and an outer hydrogel layer of SS/PVA with carboxymethyl cellulose CMC (SS/CMC/PVA 45/25/30 w/w/w). Scanning electron microscopy (SEM) was employed for the morphological characterization of the coated fertilizer (CF), examining both the cross-section and surface, while SEM with energy-dispersive X-ray spectroscopy (SEM/EDS) was used to analyze the chemical composition of the surface. The ability of the coating to reduce the nutrient-release rate was studied using water- and soil-release tests. Furthermore, its performance was evaluated in in vivo assays using jalapeño bell pepper (Capsicum annum) plants. The results revealed that the structure and composition of the multilayer coating significantly influenced its ability to delay nutrient release in both water and soil. Moreover, the inclusion of SS in the coating potentially contributed to the increased nitrogen content in the soil, thereby improving plant growth rates.

Identification of black and white antique photographs via non-destructive microscopic and spectroscopic techniques coupled with chemometric approaches

In this study, we investigated three types of black and white antique photographs, namely salt print, albumen photograph, and silver gelatin photograph, utilizing multiple techniques. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy and spectroscopic imaging, confocal light and laser microscopy, X-ray Fluorescence (XRF), and Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS) were employed to characterize these antique photographs, providing structural and chemical information. Chemometric methods including Principal Component Analysis (PCA) and k-means clustering were utilized to analyze the ATR-FTIR spectroscopic imaging data obtained from the surface and cross-sectional samples of the photographs, respectively. Successful differentiation of the three antique photographs and chemical characterization of different layers within each photograph were achieved. These results demonstrate a promising approach for the non-destructive and efficient identification of various photographs with distinct manufacturing processes.

A Sustainable Banana Peel Activated Carbon for Removing Pharmaceutical Pollutants from Different Waters: Production, Characterization, and Application.

Due to the growing concerns about pharmaceutical contamination and its devastating impact on the economy and the health of humans and the environment, developing efficient approaches for removing such contaminants has become essential. Adsorption is a cost-effective technique for removing pollutants. Thus, in this work, banana peels as agro-industrial waste were utilized for synthesizing activated carbon for removing pharmaceuticals, namely amoxicillin and carbamazepine from different water matrices. The chemically activated carbon by phosphoric acid (H3PO4) was carbonized at temperatures 350 °C, 450 °C and 550 °C. The material was characterized by several techniques such as scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), Boehm titration, point of zero charge (pHPZC), BET surface area (SBET), the proximate and ultimate analyses, X-ray powder diffraction (XRD), and thermos-gravimetric analysis (TGA). The SEM of banana peel activated carbon (BPAC) depicted a semi-regular and heterogeneous morphology, characterized by an abundance of pores with diverse forms and sizes. Boehm titration revealed an increase in the amounts of acidic groups by 0.711 mmol/g due to activation by H3PO4. FTIR recorded different peaks suggesting significant modifications in the spectroscopic characteristics of the BPAC surface due to the successful activation and adsorption of the pollutant molecules. The pHpzc of BPAC was calculated to be 5.005. The SBET surface area dramatically increased to 911.59 m2/g after the activation. The optimum conditions were 25 °C, a materials dosage of 1.2 g/L, a saturation time of 120 min, a pollutants mixture of 25 mg/L, and a pH of 5. Langmuir exhibits a slightly better fit than Freundlich with a low value of the residual sum of squares (SSE) and the data were better fitted to the pseudo-second-order kinetic. Furthermore, the efficacy of BPAC in eliminating pharmaceuticals from Milli Q water, lake water, and wastewater was successfully investigated over the seven cycles. The results of the present work highlighted a potential usage of agro-industrial waste in eliminating organic micropollutants while exhibiting sustainable management of this waste.

Archaeometric Investigations on Archaeological Findings from Palazzo Corsini Alla Lungara (Rome)

This study reports the analytical investigations on clayey and ceramic finds, characterised by high variability in terms of prime materials, with the aim to determine the role of this important ceramic production situated close to the city walls, fortuitously found during service excavations developed in the garden of Palazzo Corsini in Rome. The complexity of the finds led to the choices of appropriate methodologies and techniques suitable for defining the diagnostic elements of each find. Optical microscopy (OM) combined with micro-Raman (µ-Raman) spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), and differential thermal analysis (DTA) were used to analyse the nature and microstructure of the ceramic and burned clay that were found. In such a complicated setting, the objective of conducting chemical analyses is to provide clues to describe the various kinds of ceramics produced, the production and processing methods, and, as a result, the typology of the workshop.

Upgrading recovered carbon black (rCB) from industrial-scale end-of-life tires (ELTs) pyrolysis to activated carbons: Material characterization and CO2 capture abilities

The current study presents for the first time how recovered carbon black (rCB) obtained directly from the industrial-scale end-of-life tires (ELTs) pyrolysis sector is applied as a precursor for activated carbons (ACs) with application in CO2 capture. The rCB shows better physical characteristics, including density and carbon structure, as well as chemical properties, such as a consistent composition and low impurity concentration, in comparison to the pyrolytic char. Potassium hydroxide and air in combination with heat treatment (500–900 °C) were applied as agents for the conventional chemical and physical activation of the material. The ACs were tested for their potential to capture CO2. Ultimate and proximate analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), Raman spectroscopy, thermogravimetric analysis (TGA), and N2/CO2 gas adsorption/desorption isotherms were used as material characterization methods. Analysis revealed that KOH-activated carbon at 900 °C (AC-900K) exhibited the highest surface area and a pore volume that increased 6 and 3 times compared to pristine rCB. Moreover, the AC-900K possessed a well-developed dual porosity, corresponding to the 22% and 78% of micropore and mesopore volume, respectively. At 0 °C and 25 °C, AC-900K also showed a CO2 adsorption capacity equal to 30.90 cm3/g and 20.53 cm3/g at 1 bar, along with stable cyclic regeneration after 10 cycles. The high dependence of CO2 uptake on the micropore volume at width below 0.7–0.8 nm was identified. The selectivity towards CO2 in relation to N2 reached high values of 350.91 (CO2/N2 binary mixture) and 59.70 (15% CO2/85% N2).

Synergistic effects of microencapsulated bacterial spores and superabsorbent polymer on self-healing performance in mortar

This study explores the feasibility of utilizing a superabsorbent polymer (SAP) to improve the self-healing performance of microbial-induced calcium carbonate precipitation (MICP) in cement-based materials. The amount of microencapsulated bacterial spores was varied from 0.25–1 % by cement weight. The SAP content was set to either 0 or 4 % by cement weight. As additives, the impact of SAP and MICP bacteria on mortar properties, including flowability and compressive strength, was assessed. The self-healing performance was evaluated based on crack-healing percentage and water permeability recovery. Microstructural analyses, including thermogravimetry/differential thermal analysis (TG/DTA), X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), were performed to investigate the microstructural and chemical changes during the healing process. The findings revealed that specimens exclusively mixed with 4 % SAP exhibited a slightly lower crack-closure efficiency compared to those mixed exclusively with 1 % MICP bacteria. However, the SAP-containing specimens exhibited a higher degree of permeability recovery. Meanwhile, in the binary additive system with 0.5 % MICP bacteria and 4 % SAP, the specimens exhibited the highest crack-closure percentage of 91 % and a final water discharge rate of 15 mL/min after 45 days of healing. In contrast, specimens mixed exclusively with 1 % MICP bacteria showed a crack-closure percentage of 76 % and a final water discharge rate of 59 mL/min. These results suggest that incorporating SAP into the MICP system enables a reduction in MICP bacterial content without compromising self-healing performance.

Thermal, Morphological, and mineralogical characterization of ancient potsherds: Insights from activation energy and degradation profiles

The six representative potsherds sourced from the excavated Buddhist site of Udayagiri, Odisha, in eastern India, were studied using analytical characterization techniques of X-ray diffractometry (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), thermogravimetry (TG-DTG), and a porosity study. The analysis has unveiled the clay composition, firing temperatures, and environment along with internal morphology of these potsherds after firing process. The thermal behavior of the pottery samples was meticulously examined and degradation profiles depicted through TG-DTG curve. The activation energy of potsherds was calculated using the Horowitz and Metzger equation, shedding light on the various stages of degradation. Notably, the calculated activation energies for the first stage of degradation ranged from 5.78 to 16.64 kJ/Mole, while for the 2nd/3rd stage degradation, the range was between 2.59 KJ/Mole to 8.38 KJ/Mole, underlining the intricate firing processes involved. This research has successfully estimated firing temperatures across different environmental conditions, spanning from 450 to 900 °C. The pottery fragments were categorized into two distinct varieties following a comprehensive analysis of firing temperature, inclusions, morphological characteristics, firing conditions, and degradation profiles. The multifaceted approach employed in this study has contributed significantly to our understanding of these potsherds' composition and their firing profile.

Preparation of magnetic surface molecularly imprinting polymers based on glycidyl methacrylate as selective sorbents for aniline removal from aqueous medium

In this paper, two molecularly imprinted polymers (MIPs) based on glycidyl methacrylate were synthesized by radical suspension polymerization and surface imprinting method in the presence of silica-coated magnetic nanoparticles. Ethylenediamine (eda) and triethylentetramine (teta) were used for surface imprinting. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and mercury porosimetry. The sorption and desorption behaviors of two MIPs as an aniline sorbent from aqueous solutions were evaluated. Sorption studies were carried out in the pH range of 2.0 - 10.0, and maximum sorption capacities were attained at pH 6.0. Also, the effect of different desorption agents were examined and acetonitrile was chosen as the best desorbing eluent for aniline. The obtained MIPs were regenerated in four sorption/desorption cycles, and the results show that these two MIPs could be reusable as sorbents for removing aniline from polluted wastewater.

Improved strength of alkali activated materials based on construction and demolition waste with addition of rice husk ash

A promising solution to the environmental problem of managing a huge amount of construction and demolition waste (CDW) is its use as precursor in the production of new alkaline-activated cements. Specifically, the main objective of this investigation is to increase the strength of alkaline activated cements synthesized from unseparated CDW of low reactivity due to a high presence of crystalline phases in their composition. The effect of two factors is analyzed: the partial substitution of CDW by rice husk ash (RHA) (20–40 wt%) as well as the modulus of the alkaline activator used (Ms=SiO2/Na2O of 0.5, 1.0 and 2.0). Physical, mechanical and thermal testing, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) are used to characterize alkali-activated cements. Results show that the incorporation of increasing amounts of RHA and the increase in the modulus of the activator produce changes in the general structure of the gel, obtaining a greater amount of N-A-S-H geopolymeric gel with respect to the main reaction product, the C-A-S-H gel obtained in the control cements containing CDW as the only precursor. The new reaction products and the change in the microstructure make it possible to achieve a compressive strength of 59.6 MPa at 28 curing days in the materials with 40 wt% RHA and Ms= 2.0 compared to 18.5 MPa for the material developed exclusively from CDW. Therefore, this study validates the use of CDW together with RHA as precursors in the production of alkaline activated materials with improved technological properties. These green cements would help to reduce the presence of CDW and RHA in landfills and would generate new environmentally sustainable materials.

Characterization and treatment effects on Mutaka kaolin for additive in coatings: Mineral composition, thermal and structural modifications

Previous studies in Uganda have primarily explored kaolin's applications in composites, pottery, bricks, and insulation, neglecting its potential for coatings and paints, which is crucial for industrialization and saving foreign exchange. This study investigates the transformation of kaolin through various treatments and analyzes their impacts on its physical and chemical properties for potential use in coating applications. Thermal analysis, X-ray Fluorescence Spectroscopy (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM) techniques were employed to assess these alterations. The results show that thermal treatment of kaolin at 45.9 °C had minimal impact on mass loss, while the crystallinity of kaolinite was found to be lost around 600 °C, resulting in structural changes. XRF result demonstrates variations in SiO2 and Al2O3 composition, with low TiO2 content desirable for paint and coating applications. XRD results showed well-defined diffractions associated with kaolinite in all treated and untreated kaolin samples. The presence of K-feldspar and quartz are also identified. However, the thermal treatment at 800 °C transforms kaolinite into metakaolin, essential for enhancing coating properties. SEM-EDS results indicate increased porosity and reduced impurities in the thermal-treated sample, which might enhance the whiteness and suitability of pigment and binder dispersion in coatings. TEM images confirmed the hexagonal nature of kaolinite platelets and demonstrated the amorphous nature of kaolin nanoparticles with ammonium molybdate treatment, which led to the delamination and exfoliation of kaolinite layers, improving dispersibility. Kaolin thermally treated exhibited good crystallinity, solid growth, cubic morphology, and uniform size distribution. These findings suggest that tailored treatments can optimize kaolin's properties, making it a promising additive for high-performance coatings.

Cleaner Leather Tanning and Post-Tanning Processes Using Oxidized Alginate as Biodegradable Tanning Agent and Nano-Hydroxyapatite as Potential Flame Retardant.

In this study, sodium alginate (SA) was oxidized with potassium periodate to produce an alginate-based tanning agent. Using OSA as a biodegradable tanning agent and a nano-hydroxyapatite (nano-HAp) low concentration suspension to give flame retardancy to leather, eco-design concepts were applied to establish a chrome-, aldehyde-, and phenol-free tanning process. Micro-DSC, 1H unilateral nuclear magnetic resonance (NMR), attenuated total reflection mode Fourier transform infrared spectroscopy (FTIR-ATR), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the complex matrix collagen-OSA-nano-HAp. Micro-differential scanning calorimetry (micro-DSC) was used to assess OSA's ability to interact with collagen and stabilize the collagen-OSA matrix, while 1H unilateral (NMR) was used to investigate the aqueous environment and its limitations around collagen molecules caused by their association with OSA and nano-HAp. Industrial standard tests were used to assess the mechanical properties and fire resistance of the new leather prototype. The findings reported here indicate that both OSA and nano-HAp are suitable alternatives for cleaner tanning technologies and more sustainable leather.

Microbially induced precipitation of silica by anaerobic methane-oxidizing consortia and implications for microbial fossil preservation.

Authigenic carbonate minerals can preserve biosignatures of microbial anaerobic oxidation of methane (AOM) in the rock record. It is not currently known whether the microorganisms that mediate sulfate-coupled AOM-often occurring as multicelled consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB)-are preserved as microfossils. Electron microscopy of ANME-SRB consortia in methane seep sediments has shown that these microorganisms can be associated with silicate minerals such as clays [Chen et al., Sci. Rep. 4, 1-9 (2014)], but the biogenicity of these phases, their geochemical composition, and their potential preservation in the rock record is poorly constrained. Long-term laboratory AOM enrichment cultures in sediment-free artificial seawater [Yu et al., Appl. Environ. Microbiol. 88, e02109-21 (2022)] resulted in precipitation of amorphous silicate particles (~200 nm) within clusters of exopolymer-rich AOM consortia from media undersaturated with respect to silica, suggestive of a microbially mediated process. The use of techniques like correlative fluorescence in situ hybridization (FISH), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and nanoscale secondary ion mass spectrometry (nanoSIMS) on AOM consortia from methane seep authigenic carbonates and sediments further revealed that they are enveloped in a silica-rich phase similar to the mineral phase on ANME-SRB consortia in enrichment cultures. Like in cyanobacteria [Moore et al., Geology 48, 862-866 (2020)], the Si-rich phases on ANME-SRB consortia identified here may enhance their preservation as microfossils. The morphology of these silica-rich precipitates, consistent with amorphous-type clay-like spheroids formed within organic assemblages, provides an additional mineralogical signature that may assist in the search for structural remnants of microbial consortia in rocks which formed in methane-rich environments from Earth and other planetary bodies.

Patulin removal and biopreservation of apple by three lactic acid bacteria strains isolated from foods

ABSTRACTPenicillium expansum contamination and patulin production can occur at various stages of the food chain, leading to detrimental effects on the quality and shelf life of food. Consequently, it is imperative to develop safe and efficient methods to control fungal growth and prevent mycotoxin contamination. The use of lactic acid bacteria (LAB) for food biopreservation has become one of the most promising alternatives. In this study, we investigated the antifungal activity of three LAB strains, namely Lactiplantibacillus plantarum 4F, Lactiplantibacillus plantarum 4JC, and Lacticaseibacillus paracasei 3MI3 against Penicillium expansum, and we further evaluated their biopreservative potential using apple as a food model against the blue mould. Moreover, their ability to remove patulin (10 µg/mL) from MRS broth and apple juice was also examined. The mechanism involved in this decontamination was investigated using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and fourier transform infrared spectroscopy (FTIR). It was found that in vitro antifungal activity of the three strains was validated in vivo. All strains were able to reduce patulin from MRS medium, notably L. plantarum4F exhibited the highest rate of reduction (88.18%). This particular strain eliminated patulin from juice, with a reduction of 87.26%. The C = O, C–H, and N–H were the main functional groups engaged in patulin adsorption indicated by FTIR and SEM-EDS. Furthermore, in terms of morphological changes, SEM analysis revealed that bacterial cell wall became irregular. This research provides evidence of control of blue Penicilium growth on apple and patulin removal using antifungal LAB strains.

A comprehensive study of diverse techniques for enhanced physicochemical and structural properties of bio-calcium from hybrid catfish bone

This research examined the impact of various comparative preparation methods on enhanced physicochemical, and structural properties of bio-calcium (BC) from hybrid catfish bone. Raw hybrid catfish bones (RB) were used to make bio-calcium in four steps. High-pressure water jet processing produced washed bone (WB), soaking the bone in an alkaline solution to remove proteins (PR), immersing it in ethanol to remove lipids (LR), then bleaching, and grinding it to make bio-calcium powder. The BC had greater lightness values (L*) (p < 0.05), and contained significant calcium, and phosphorus. The SDS-PAGE showed three significant protein bands with molecular weights of 250, 133, and 116 kDa. The crystalline structure of hydroxyapatite in BC was confirmed using X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The percentage of crystallinity of BC had a notable rise, increasing from the RB to BC of 36.25%–45.32%. The BC powder exhibited a consistent distribution of particle sizes, ranging from 2 to 10 μm. Additionally, the analysis of elemental profiles, and mappings using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) revealed that BC exhibits a significant concentration of calcium, and phosphorus. BC showed superior %bioavailability of calcium (18.94%) in an in vitro simulated gastrointestinal system (GIMs) compared to RB (10.58%), and calcium carbonate (11.19%). Hence, the BC production process proved to be a viable method for acquiring premium-grade BC, which holds potential for further development as a calcium dietary supplement.