Chemical Characterization Research Articles

The assessment of organic contaminants at a paint manufacturing site: implications for health risks and source identification

The daily variation of organic contaminants, both gaseous and associated with suspended particulate matter, was investigated within the National Company of Paintings estate in Lakhdaria, Algeria, spanning the period 2014-2015. The research emphasizes the chemical characterization of suspended particulate matter, analyzing a range of organic compounds, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and highly polar organics (HPOC), such as phthalate esters and heterocyclic compounds. Vapours of PAHs and polychlorobiphenyls (PCBs) were also analyzed. Low molecular weight compounds were primarily associated with the gas phase (2-ring PAHs, approximately 95%; 3-ring PAHs, around 70%), while high molecular weight congeners were mainly associated with the particle phase (6-ring PAHs, 55%). The concentrations of PCBs (ranging from 0.6 to 42 ng m-3) were higher than those reported in other cities in Algeria and Europe. The source reconciliation of organic contaminants through principal component analysis (PCA) demonstrated that the primary sources were petroleum combustion, industrial manufacturing, tobacco smoking, and vehicular traffic. The significance of tobacco smoke was further confirmed by the analysis of PAHs diagnostic ratios. The variations in diagnostic ratio rates between gaseous and particulate PAHs were attributed to distinct contributions from sources such as industrial processes. Health risks for workers exposed to PAHs and PCBs in PM10 were quantitatively assessed in terms of Benzo[a]pyrene equivalent concentration (BaPeq) and incremental lifetime cancer risk (ILCR). ILCR presents novel findings, showcasing heightened risks among workers exposed to specific PAHs within production areas, whereas that related to PCBs suggested a high potential health risk for laboratory workers.

Integrated GIS-based and water quality index for evaluation of groundwater quality in the coastal slum settlements of Lagos, Nigeria

This study aimed to identify drinking water suitability through a statistical and water quality index (WQI) approach in coastal slum settlements in Lagos, Nigeria. A total of 250 borehole groundwater samples collected for drinking purposes during the wet (125) and dry (125) seasons were analysed for their physical and chemical properties from 2019 to 2020. The physical and chemical characterisation of the region was conducted based on the correlation matrix, scree plot, PCA, Q-mode HCA, and ROC curve to identify the types of weathering, the influence of rock on precipitation and evaporation, and types of reactions that affect groundwater composition. The analytical mean concentration results revealed that SO4, Cl, TH, NO3, TDS, and PO4 surpassed the USEPA and WHO permissible limits in both seasons. The WQI results demonstrate that 7.6% and 6.7% of water samples fall into the excellent category, while 12.4% and 11.5% are moderately tolerable. In contrast, for both seasons, >100% of the samples fell into the unsuitable drinking category across SA1-SA5, SB1-SB5, SC1-SC5, SD1−SD5, and SE1−SE5. Groundwater quality mainly deteriorates due to anthropogenic activities and climatic variability. The spatial variation map indicates that groundwater quality is primarily affected during the wet season and, to a lesser extent, in a few slums during the dry season. Seawater influx in coastline areas has been identified as the main factor threatening the quality and availability of groundwater resources. As a result, the groundwater quality is mostly poor to unsuitable, and this study confirms its unsuitability for drinking. Hence, this study serves as a guide for effective action in sustainable groundwater management.

Influence of Materials of Moulds and Geometry of Specimens on Mechanical Properties of Grouts Based on Ultrafine Hydraulic Binder.

Ultrafine hydraulic binder grout injection is a technique utilised for repairing masonry, either to connect sections, seal joints, or fill voids due to its great capacity for penetration and higher mechanical strength than lime grout. In this research, the mechanical properties of ultrafine hydraulic cement grout are analysed considering the influence of the mould material for preparing the specimens and their geometry characteristics in the context of the specifications set out in several international standards. The test campaign to ascertain compressive and flexural strength in different circumstances is supplemented with a physical and chemical characterisation of both binder and fresh and hardened grout. Significant differences in mechanical properties between specimens prepared with absorbent or non-absorbent-water material are found due to the influence of drying shrinkage and decanting binder during the curing process. Furthermore, the slenderness of specimens is presented as an important factor in determining the compressive strength of mixtures.

Oil from crambe seeds treated with different resistance inducers: Oil yield and chemical characterization

This study aimed to carry out the extraction and chemical characterization of oil from crambe treated with resistance inducers during its cultivation to promote greater efficiency in the defense system of plants. For this purpose, Agromos® and Ecolife® inducers were applied at rates of 0.5 and 1.0 L hectare−1 during crambe cultivation. Crambe seed oil was obtained in a Soxhlet extractor using n-hexane as a solvent and the oils were characterized in terms of fatty acid composition and minority compound contents (phytosterol and tocopherol). The oil obtained from seeds without the application of inducers (control) was also characterized. We determine the oxidative stability of oils with inducer application that presented higher minority compound contents. Crambe seeds that received the treatment with the Agromos® resistance inducer had higher oil content. However, in general, the fatty acid profile of the obtained oils was similar and showed a predominance of erucic and oleic acids (which represent ~82% of the composition). The application of the Agromos® inducer allowed obtaining seeds that provided oil with higher contents of phytosterols and tocopherols and higher oxidative stability.

Antibacterial and wound healing performance of a novel electrospun nanofibers based on polymethyl-methacrylate/gelatin impregnated with different content of propolis

Wound management and care mainly relies on the production of new and effective wound dressing materials. Chronic wounds require protection against pathogens and bacterial infection. Therefore, it is very important to design wound dressings with antibacterial and restorative capabilities. In this research, polymethyl-methacrylate (PMMA) and gelatin (Gel) nanofibers (NFs) were produced in different ratios by electrospinning method. Propolis (Pro) as a wound healing drug was added to the optimal PMMA70/Gel30 parent scaffold at different concentrations (10, 30 and 50 %w/v). Physical and chemical characterization, porosity, degradation, water vapor transmission rate (WVTR), swelling, mechanical properties and contact angle of the mats were analyzed. The NFs presented a homogeneous and defect-free morphology. The PMMA70/Gel30 mats showed the lowest average diameter (362.1 ± 132.3 nm) among the scaffolds. In addition, the highest wettability (∼70°) and WVTR (∼250 g/m2 × 24h) are related to PMMA70/Gel30. The addition of Pro extract (up to 50%) increased the mean diameter of NF (571.1 ± 171.8 nm). None of the scaffolds showed toxicity in the environment. The optimal PMMA/Gel/Pro50% NF showed more adhesion and higher cell viability than other samples. The antioxidant activity of PMMA/Gel/Pro50% is more about 10 times compared to PMMA70/Gel30. Pro extract showed significant antibacterial activity in the scaffolds, so that the release of Pro (∼70% in 24hrs) in the PMMA/Gel/Pro50% caused the inhibition of S. aureus (9 mm) and E. coli (11 mm) bacteria in Mueller's culture medium. All these findings confirm that the produced NF mats, especially those loaded with Pro, have a high potential to be used as an effective wound dressing.

Effects of Calcination Conditions on the Structural and Electrochemical Behaviors of High‐Nickel, Cobalt‐Free LiNi0.9Mn0.1O2 Cathode

AbstractEliminating cobalt from high‐nickel layered oxide cathodes lowers the cost of lithium‐ion batteries for electric vehicles. However, cobalt‐free cathodes with high Mn4+ and Ni2+ contents are prone to Li/Ni mixing after synthesis, potentially compromising battery energy density, rate capability, and cycling stability. Without cobalt facilitating cation ordering in the layered structure, the degree of Li/Ni mixing in cobalt‐free cathodes depends heavily on the calcination conditions. In this study, a systematic exploration of calcination temperatures and LiOH ratio for LiNi0.9Mn0.1O2 (NM‐90) provides detailed insights into the optimal synthesis conditions for high‐capacity cobalt‐free cathodes with extended cycle life. Surprisingly, high Li/Ni mixing does not necessarily lead to poor cycling stability whereas low Li/Ni mixing does not guarantee a long cycle life. More importantly, although excessive calcination temperature can further decrease Li/Ni mixing, it does not necessarily enhance capacity. Instead, the pernicious effects from the H2 → H3 phase transition are amplified due to a pronounced two‐phase reaction. An extensive suite of chemical and structural characterization methods uncovers a correlation between elevated calcination temperature, phase transformation, cation ordering, and capacity fading behavior: “overcooking” high‐nickel, cobalt‐free cathodes induce structural arrangement toward that of LiNiO2, with exacerbated lattice distortion and surface instability accelerating capacity fade.

LC-MS/MS metabolomics approach for chemical characterization of Beta vulgaris subspecies maritima extract through untargeted molecular networking, in correlation to its renoprotective activity in renal ischemia/reperfusion induced injury model in rats

This study evaluates the reno-protective effect of Beta vulgaris subspecies maritima lyophilized 70% ethanolic extract (BVLE) in renal ischemia/reperfusion (I/R) induced injury model in rats. Detailed investigation of the effects of its oral administration was checked. serum blood urea nitrogen (BUN), which was reduced to 0.7 ± 0.04 mmol/L at a dose of 200 mg/Kg of BVLE compared to 1.9 ± 0.08 mmol/L for the I/R group. And creatinine levels were reduced to 1.2 ± 0.06 nmol/L at a dose of 200 mg/Kg of BVLE compared to 4.7 ± 0.12 nmol/L for the I/R group. Oxidative stress biomarkers including MDA (reduced to 0.4 ± 0.03 compared to 1.7 ± 0.05 nmol/mg protein of I/R a dose of 200 mg/Kg) and GSH levels (increased to 1.3 ± 0.03 compared to 0.3 ± 0.02 nmol/mg protein of I/R a dose of 200 mg/Kg). Meanwhile, inflammatory mediators including TNF-α and IL-6 levels were lowered to 46.7 ± 0.60 and 32.1 ± 1.78 pg/mg protein, respectively. Oxidative stress genetic pathways including Nrf2/HO-1 signaling pathway via testing Nrf2 and its dependent HO-1 mRNA expression levels were studied as well. Metabolomic profiling of BVLE was achieved by UPLC-HR-ESIMS coupled with molecular networking. BVLE significantly improved renal inflammatory markers, oxidative stress biomarkers and renal functions test, in dose dependent manner. Thirty-nine compounds were tentatively identified in BVLE by UPLC-MS/MS. Mainly flavonoid glycosides, triterpenoidal saponins and fatty acids. Among identified saponins five unreported betavulgaroside derivatives were tentatively described for the first time.

Preparation and Mechanical Properties of Core-Shell PS&CeO2 Composite Abrasive Particles.

Core-shell composite abrasive particles are a topic of great interest in surface finishing. It is important to explore the preparation technology and performance parameters associated with them. In this paper, a core-shell composite abrasive particle made of polystyrene and cerium oxide (PS&CeO2, CSPC), which is rigid on the outside and flexible on the inside, is proposed. The microstructure, physical phase characteristics, and mechanical properties of the inner core and composite abrasive particles are investigated. PS microspheres and CSPC composite abrasive particles with different structural features were prepared through a series of experiments, morphological observations, and physical and chemical characterization experiments. Their microstructures and physical phase properties were investigated. The indentation load curves of the PS microspheres and CSPC composite abrasive samples were measured by using an atomic force microscope. The analysis focused on the effects of various dimensional and structural parameters on the modulus of elasticity of both PS microspheres and CSPC composite abrasive particles. The analysis shows that the experimentally prepared PS microspheres have good dispersion, a smooth surface, and a uniform particle size distribution. The prepared CSPC composite abrasive particles are regular spheres with rough, rice-like surfaces, low modulus of elasticity, and overall nonrigid and soft elastic properties. The results of this paper can provide a guide for the preparation technology, performance regulation, and application of polymer microspheres and core-shell composite abrasive particles in CMP.

UPLC-Q-TOF-MS Analysis of Chemical Constituents of the Kadsura coccinea Extract with Effect of Attenuating Lipid Accumulation in Vitro

Objective/Background: This study aims to explore the Kadsura coccinea extract (KCE)'s effect on lipid accumulation in vitro and its chemical components characterizations, aiming at developing a new alternative plant medicinal resource to fight against non-alcoholic fatty liver disease (NAFLD). Methods: After toxicological evaluation of KCE on HepG2 cells, Oil red O staining model and intracellular TGs quantification kit were used to examine the effects of KCE on lipid accumulation in vitro. The chemical components characterizations and potential active chemical constituents of the bioactive KCE were analyzed using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) technology. Results: Among the chosen non-toxic concentrations of KCE (5, 10, 20 μg/mL), KCE can reduce the number and volume of lipid droplets in the oleic acid induced HepG2 cells in a dose-dependent manner, and the results of TGs quantification were almost consistent with the results of the oil red O staining experiment. These data indicate the KCE has ameliorative effect on lipid accumulation in vitro. In addition, a total of 26 compounds from the KCE were tentatively identified, dibenzocyclooctadiene lignans (DCLs) including Kadsulignan L and Gomisin J could be the main supposed components. Conclusion: These findings support further investigation into Kadsura coccinea containing DCLs as a new alternative medicinal arsenal to battle against NAFLD.

Effect of conventional and novel techniques on extraction yield, chemical characterisation and biological activities of proteins from bitter gourd (Momordica charantia)

The study investigates the effect of conventional and novel extraction techniques on the protein extraction yield from bitter gourd seeds (Momordica charantia). Ultrasound assisted-extraction (UAE) treatment for 30 min at 4 °C using a 20 kHz ultrasound probe resulted in the highest extraction yield of crude proteins. After purification, 9.08 ± 0.23 g of protein with 82.69 ± 0.78% purity was obtained from 100 g of M. charantia seeds on a dry basis. Mass spectrometry identified proteins with reported antidiabetic activity. Antidiabetic assays showed significantly higher antidiabetic activity for the purified protein (81.10 ± 2.64%) compared to the crude protein (32.59 ± 2.76%). In vitro cytotoxicity analysis showed minimal cytotoxicity levels at concentrations <200 μg.mL−1. Overall, UAE was effective to obtain crude protein from M. charantia seeds and a subsequent purification step enhanced antidiabetic activity. However, further research is required to demonstrate in-vivo antidiabetic activity.

Non-negative matrix factorization-aided phase unmixing and trace element quantification of STEM-EDXS data

Energy-dispersive X-ray spectroscopy (EDXS) mapping with a scanning transmission electron microscope (STEM) is commonly used for chemical characterization of materials. However, STEM-EDXS quantification becomes challenging when the phases constituting the sample under investigation share common elements and overlap spatially. In this paper, we present a methodology to identify, segment, and unmix phases with a substantial spectral and spatial overlap in a semi-automated fashion through combining non-negative matrix factorization with a priori knowledge of the sample. We illustrate the methodology using a sample taken from an electron beam-sensitive mineral assemblage representing Earth's deep mantle. With it, we retrieve the true EDX spectra of the constituent phases and their corresponding phase abundance maps. It further enables us to achieve a reliable quantification for trace elements having concentration levels of ∼100 ppm. Our approach can be adapted to aid the analysis of many materials systems that produce STEM-EDXS datasets having phase overlap and/or limited signal-to-noise ratio (SNR) in spatially-integrated spectra.

Analyzing recycled waste-infused mortars: Preparation and Examination of thermal, mechanical, and chemical characteristics

In response to the urgent need for innovative and sustainable solutions in the construction industry, this study provides an in-depth investigation and experimental evaluation of the thermal, mechanical, and chemical properties associated with the incorporation of three different categories of waste into mortar. These categories include expanded polystyrene waste (EPSW), expanded perlite waste (EPW), human hair waste (HHW), textile fiber (TFW), and paraffin waste (PW). Various samples were prepared by adding different proportions of these waste materials as sand substitutes in cement mortar. To enable a thorough assessment of the material properties, a comprehensive series of tests were carried out, including measurements of thermal conductivity, flexural strength, compressive strength, chemical composition and crystalline structures. The results revealed that, for a replacement level of 50%, there was a decrease in thermal conductivity by 28%, 55%, 44% and 67% for EPSW, EPW, TFW, HHW and PW mortars, respectively, which resulted in a decrease in compressive strength by 75%, 71%, 50%, 79% and 81%, respectively. Furthermore, the chemical characterization showed that the chemical composition of the mortar remained consistent, even when a substantial proportion of waste materials was introduced. The study emphases the sustainable construction key role in reducing building life cycle emissions.

Valeriana jatamansi: Bioactive Compounds and their Medicinal Uses.

Valeriana jatamansi is a reputed perennial medicinal herb distributed throughout the world, where it is used in cytotoxicity, neuronal problems, insomnia, leishmania and acetylcho-linesterase inhibitor, antioxidant, antiviral and α-glucosidase inhibition activities. This review de-scribes the current state of chemical characterization of isolated metabolites, which are well ac-cepted for the treatment of various ailments in the indigenous system of medicine. This compre-hensive review covers previously published research articles and reviews up to 2023 with an em-phasis on the structural characterization of isolated bioactive compounds using different analyti-cal techniques. Furthermore, the present review also focuses on the detailed medicinal and phar-macological properties of isolated compounds from this threatened herb.

Isolation, identification and chemical characterization of compounds from phenolic extracts of peels of Kufri Chipsona-3 and Kufri Jyoti potatoes having synergistic antioxidant interactions in combination

The study focused on the isolation, identification and characterization of the bioactive compounds that are responsible for synergistic antioxidant interactions in combination from the peel extract of Kufri Chipsona-3 and Kufri Jyoti potato varieties by Thin-Layer Chromatography (TLC) bioautography mediated isolation technique which was followed by isobologram analysis as well as characterization using different spectrometric methods. The results revealed that among the isolated seven antioxidant components of potato peel extracts (three components with Rf : 0.33, 0.52 and 0.57 from the peel extract of Kufri Chipsona-3 and four components with Rf : 0.14, 0.22, 0.36, 0.61 from the peel extract of Kufri Jyoti, only one component from Kufri Chipsona-3 (Rf : 0.57) and one component from Kufri Jyoti (Rf : 0.61) potato varieties in combination exhibited synergistic antioxidant interactions in combination. Spectrometric analysis (UV/Vis, FT-IR and HR-LCMS/MS) revealed that the active component with Rf : 0.57 from Kufri Chipsona-3 is prodelphinidin trimer and the other component with Rf : 0.61 from Kufri Jyoti is 5-hydroxy-3’,4’,7-trimethoxyflavone. In a root growth inhibition test (LC50 &gt; 200 µg/ml), on Allium cepa, these two compounds showed no cytotoxicity. The results provide evidence that these two phenolic compounds, prodelphinidin trimer and 5-hydroxy-3’,4’,7-trimethoxyflavone in combination may serve as a stronger and efficacious novel natural antioxidant blend in pharmaceutical and food industries.

Tetraselmis chuii Edible Microalga as a New Source of Neuroprotective Compounds Obtained Using Fast Biosolvent Extraction.

Tetraselmis chuii is an EFSA-approved novel food and dietary supplement with increasing use in nutraceutical production worldwide. This study investigated the neuroprotective potential of bioactive compounds extracted from T. chuii using green biobased solvents (ethyl acetate, AcOEt, and cyclopentyl methyl ether, CPME) under pressurized liquid extraction (PLE) conditions and supercritical fluid extraction (SFE). Response surface optimization was used to study the effect of temperature and solvent composition on the neuroprotective properties of the PLE extracts, including anticholinergic activity, reactive oxygen/nitrogen species (ROS/RNS) scavenging capacity, and anti-inflammatory activity. Optimized extraction conditions of 40 °C and 34.9% AcOEt in CPME resulted in extracts with high anticholinergic and ROS/RNS scavenging capacity, while operation at 180 °C and 54.1% AcOEt in CPME yielded extracts with potent anti-inflammatory properties using only 20 min. Chemical characterization revealed the presence of carotenoids (neoxanthin, violaxanthin, zeaxanthin, α- and β-carotene) known for their anti-cholinesterase, antioxidant, and anti-inflammatory potential. The extracts also exhibited high levels of omega-3 polyunsaturated fatty acids (PUFAs) with a favorable ω-3/ω-6 ratio (>7), contributing to their neuroprotective and anti-inflammatory effects. Furthermore, the extracts were found to be safe to use, as cytotoxicity assays showed no observed toxicity in HK-2 and THP-1 cell lines at or below a concentration of 40 μg mL-1. These results highlight the neuroprotective potential of Tetraselmis chuii extracts, making them valuable in the field of nutraceutical production and emphasize the interest of studying new green solvents as alternatives to conventional toxic solvents.

Important Contribution to Aerosol Oxidative Potential from Residential Solid Fuel Burning in Central Ireland

Numerous studies have shown negative health effects related to exposure to ambient particulate matter (PM), likely due to induced oxidative stress. In this study, we have examined ambient PM samples from Birr, a small (~5000 inhabitants) town in central Ireland, for their water-soluble DTT-based oxidative potential (OP_DTT) with a resolution of 6 h, together with online chemical characterization measurements, to assess the OP of organic aerosols, in particular from residential solid fuel burning. The OP_DTT normalized by the volume of sampled air shows a high variability, ranging from &lt;0.1 to 3.8 nmol min−1 m−3, and a high correlation with PM mass. A lower variability was associated with the mass-normalized OP. Nevertheless, both tended to present higher values during night-time pollution episodes. Simple and multivariate linear regression approaches linked OP_DTT to residential solid fuel burning, and in particular to wood (~87%) and peat (~13%) combustion. The results of the present study show how residential solid fuel burning can have a severe impact on air quality, even in small towns, with potential negative health effects on the exposed population.

Influence of retention time and catalyst concentrations on catalytic pyrolysis yields of polyethylene and polystyrene

ABSTRACT The present work focuses on enhancing the liquid fraction yields having hydrocarbons in the diesel fuel range from pyrolysis of PS/PE (1:1 wt.%) under the influence of ZSM–5 catalysts in an autoclave reactor. The pyrolysis product yields and their compositions were investigated for varied catalyst concentrations (0%, 5%, 7.5%, and 10%), reaction temperatures (250–500°C), and retention times (20–60 min). The physical and chemical characterization of the feedstocks, catalysts, and thermally and catalytically derived oils were carried out along with elemental analysis of the liquid products. It was observed that 7.5% catalyst concentration exhibited the maximum liquid fraction yields (71.2 wt.%) at 350°C and a retention time of 30 min. Catalytic cracking with a retention time of 20–30 min produced maximum liquid yields with aromatic, aliphatic, and isomerized hydrocarbon contents of 42.9%, 30.15%, and 14.3%, respectively. Expedite weakening of the catalytic activity of the ZSM-5 catalyst was observed with process retention time higher than 30 min. The calorific values of catalytically derived oils were found to be in the range of 44.2–44.8 MJ/kg, and their carbon numbers were between C11 and C19. Thus, these characteristics make these oils a potential candidate to be used as an alternative to diesel fuel. Further, the higher proportions of aromatics and aliphatic compounds present in catalytically derived oils compared to that obtained from thermal pyrolysis affirmed its superiority as a potential diesel substitute.

Characterization and acid treatment of silica and organics in evaporator blowdown wastewater arising from SAGD operations

The evaporator blowdown (EBD) wastewater from high-pressure steam generation for the steam-assisted gravity drainage (SAGD) bitumen extraction process contains elevated concentrations of dissolved inorganic and organic compounds, of which silica and organics pose challenges in its treatment and disposal. This study investigated treatment options for EBD before its disposal. Following detailed physical and chemical characterization of the EBD, we examined its acid treatment with HCl and H2SO4 at pHs ranging from 12 to 2. The acid treatment performance was evaluated in terms of silica and organic removal efficiencies along with the filtration rate and filtrate recovery. Both acids gave similar silica and organic removal efficiencies; however, the filtration performance following the HCl-treatment was better than the H2SO4-treatment. In practice, the acids would likely perform comparably with regard to silica removal and the final process selection would more likely be influenced by other factors such as storage, material compatibility, cost, and downstream or subsurface compatibility. The HCl-treatment was investigated further with both the EBD and prepared silica solutions for the silica removal efficiency and filtration performance. The experiments conducted at ∼20 °C demonstrated higher silica removal efficiencies at pHs 10 and 8, whereas higher organic removal efficiencies were obtained at pHs 4 and 2. The experiments conducted at ∼80 °C showed enhanced silica removal at pH = 8 and higher organic removal at pH = 2. The precipitated solids were characterized using XRD and ATR-FTIR spectroscopy to identify the minerals and functional groups. The XRD patterns demonstrated that the solids generated were amorphous. The ATR-FTIR spectra revealed the predominance of siloxane, silanol, carboxylate and carbonyl compounds. These results confirmed a substantial removal of silica and organic constituents from the EBD through the acid treatment process.

Effect of HPO42− and brushite on gypsum reactivity and implications for utilization of phosphogypsum in plaster production

The implementation of a sustainable development strategy holds the potential to enhance productivity, profitability, and overall efficiency by leveraging by-products from other industries. In plaster manufacturing the substitution of natural gypsum with synthetic gypsum is worth exploring. Phosphogypsum (PG) represents a significant fraction of synthetic gypsum production, arising as a by-product of phosphoric acid manufacturing. However, the presence of impurities in PG, particularly phosphorus, poses challenges to its use as a plaster material. To identify the phases present in PG, quantify their occurrences and understand their effects on dehydration and hydration processes, our study aimed to examine simplified models. These models are specifically designed to provide insights into the underlying mechanisms governing the hydration reactivity of hemihydrate. Pure gypsum and brushite were synthesized, and mechanical mixing was carried out to explore how brushite affects the characteristics of gypsum. Additionally, a solid solution of Ca(SO4)1-x(HPO4)x·2H2O, where 0 < x < 1, was prepared to characterize and quantify the syncrystallized HPO42− as well as the effects of this impurity on typical gypsum use cases. The synthesized materials underwent physical and chemical characterization using SEM, XRD, IR spectroscopy, DSC, pH and conductivity measurements, and ion chromatography. The results demonstrated that the HPO42− ions can substitute for sulfate ions in gypsum to form solid solutions. The maximum quantity of HPO42− ions in the gypsum lattice is approximately 10%, leading to the crystallization of gypsum into sand rose shape rather than needle crystals. As the concentration of HPO42− ions increases, a new phase known as ardealite (Ca(SO4)1-x(HPO4)x·2H2O) with 0.42 < x < 0.54 emerges, followed by brushite (CaHPO4·2H2O). During the calcination of brushite at 160 °C, a mixture of brushite and monetite formed that exhibits different properties compared to its natural counterpart. In the presence of syncrystallized HPO42− ions, the transformation from anhydrite III to anhydrite II occurred at higher temperatures than for pure gypsum. The reactivity of calcined samples indicate that HPO42− ions from the dehydration products of brushite caused a delay in hydration, with the maximum delay observed at a calcination temperature of 160 °C. At this temperature, monetite begins to crystallize, and it is characterized by its inert nature, exhibiting no reactivity with water. This explains the observed decrease in setting times as the calcination temperature rises. Moreover, syncrystallized HPO42− ions induced a significant delay in the hydration process. Our research revealed that adjusting the calcination temperature can mitigate the retarding effect associated with this impurity, suggesting an industrial tendency to use the lowest possible temperature during the calcination process of PG containing syncrystallized phosphate impurity. In addition, we have observed that adjusting the pH of the mixing water to lower values can significantly accelerate setting times.

Microbial terroir: associations between soil microbiomes and the flavor chemistry of mustard (Brassica juncea).

Here, we characterized the independent role of soil microbiomes (bacterial and fungal communities) in determining the flavor chemistry of harvested mustard seed (Brassica juncea). Given the known impacts of soil microbial communities on various plant characteristics, we hypothesized that differences in rhizosphere microbiomes would result in differences in seed flavor chemistry (glucosinolate content). In a glasshouse study, we introduced distinct soil microbial communities to mustard plants growing in an otherwise consistent environment. At the end of the plant life cycle, we characterized the rhizosphere and root microbiomes and harvested produced mustard seeds for chemical characterization. Specifically, we measured the concentrations of glucosinolates, secondary metabolites known to create spicy and bitter flavors. We examined associations between rhizosphere microbial taxa or genes and seed flavor chemistry. We identified links between the rhizosphere microbial community composition and the concentration of the main glucosinolate, allyl, in seeds. We further identified specific rhizosphere taxa predictive of seed allyl concentration and identified bacterial functional genes, namely genes for sulfur metabolism, which could partly explain the observed associations. Together, this work offers insight into the potential influence of the belowground microbiome on the flavor of harvested crops.