Asian Journal of Chemical Sciences

Management of Dioxins and Furans from Plastic Combustion: A Critical Narrative Review of Formation, Control and Residue Strategies Across Engineered and Uncontrolled Settings

2026-07-29T13:38:22+00:00

Polychlorinated dibenzo-p-dioxins and dibenzofurans, together with their brominated and mixed analogues, are unintentionally produced persistent organic pollutants of exceptional toxicity, and the combustion of plastics is a globally significant source. This review integrates the chemistry of dioxin formation from plastics with the full hierarchy of management options across both engineered incineration and uncontrolled open burning, a pairing that existing reviews have addressed only in part. Drawing on accessible peer-reviewed and institutional literature identified through scholarly indexes and appraised critically, the review examines formation mechanisms, feedstock and operating determinants, secondary abatement, residue management, and the governance framework. The evidence indicates that dioxins form predominantly by heterogeneous reactions in the post-combustion temperature window, that chlorine from poly(vinyl chloride) and bromine from flame retardants supply the halogen dioxins require, and that combustion quality and flue-gas cleaning, rather than feedstock halogen content, govern emissions wherever effective control exists. In engineered facilities the combination of good combustion, rapid quenching, sorbent injection and catalytic destruction has cut air emissions by two to three orders of magnitude, shifting the residual burden to dioxin-laden fly ash whose mature management routes immobilise rather than destroy the pollutant. Open burning, the fate of a large share of the world’s plastic waste, emits dioxins at factors thousands of times higher and delivers exposure to the most vulnerable populations, yet lies almost wholly outside the reach of the control technologies and standards that dominate the literature. Brominated and mixed halogenated dioxins remain under-recorded relative to their likely importance. The principal unresolved questions concern the quantification and prevention of open-burning emissions, the regulatory incorporation of brominated congeners, and the maturation of destruction-based residue treatment. The central conclusion is one of proportion: technical effort remains concentrated on the setting that already emits least.

Beyond Structural Design: Reaction Trajectories as a Discovery Variable for CHONPS Covalent Matter: Perspective

2026-09-29T13:22:18+00:00

Modern materials chemistry is highly effective at designing predefined structures, but target-driven strategies necessarily explore only structures that can be specified in advance. This Perspective proposes a complementary discovery framework in which reaction history is treated as a controlled search variable rather than solely as a route to an intended product. C, H, O, N, P and S define a deliberately bounded model space, termed CHONPS space, for examining whether persistent covalent materials can be reached through distinct time-ordered trajectories from the same experimentally defined initial state. The framework does not introduce a new physicochemical principle; it operationalises established path dependence by fixing the initial state X, varying the reaction trajectory Γ, and testing for reproducible divergence among persistent material outcomes. Minimal experimental sets compare operations A, B, AB, BA and A+B while controlling cumulative exposure and other relevant variables. Evidence is strongest when compositionally comparable outcomes differ reproducibly in connectivity or organisation and, where relevant, in function. Persistence is distinguished from stability, and candidate states require subsequent definition of their stability domains. In situ and operando characterisation, multimodal analysis, automation and self-driving laboratories provide practical tools for mapping such trajectories and retaining both positive and negative outcomes. CHONPS is therefore presented as a model space for asking which persistent states become experimentally accessible when the final material is not predetermined and reaction history itself is used as a discovery variable.

Seasonal Assessment of the Physicochemical Parameters of Groundwater in the Town of Houndé, Burkina Faso

2026-08-11T06:23:32+00:00

Groundwater is the principal source of drinking water for many residents of Houndé, Burkina Faso. This study examined the physicochemical and hydrochemical quality of groundwater in the Houndé region, Burkina Faso, where residents relied heavily on wells and boreholes for their drinking-water supply. Five (05) water sources, comprising two (02) boreholes and three (03) wells, were analysed during two sampling campaigns: one in the rainy season (August 2024) and the other in the dry season (March 2025). The measured parameters included temperature, pH, electrical conductivity, turbidity, total dissolved solids (TDS), hardness, major ions, and several trace metals. The presence of these parameters in water originating from geological formations is a characteristic of groundwater observed in most regions of Burkina Faso. Temperatures varied little, ranging from 26.1°C to 26.8°C throughout the year. Sample pH ranged from 5.4 to 7.8, with nearly 60% of the values within the WHO range of 6.5–8.5. The remaining 40% showed slightly acidic pH values, although this did not significantly affect water quality. Electrical conductivity was higher in the boreholes (292–397 µS/cm) than in the wells (21.3–67.9 µS/cm), while remaining below the WHO standard of 1,000 µS/cm. The conductivity values observed in the boreholes could be associated with human activities near these water sources and inadequate protective measures, which may have contributed to the infiltration of dissolved substances. Turbidity was generally low, except in wells 2 and 3, where values exceeded the WHO threshold of 5 NTU, possibly indicating an influence from human activities. Nitrate concentrations were low (3.54–18.3 mg/L). Metal concentrations were generally low, with a temporary exceedance of the WHO guideline value for total iron (0.3 mg/L). The ionic balance error remained below 10%, in accordance with WHO recommendations, thereby supporting the validity of the analyses. The Water Quality Index (WQI) ranged from 13.97 to 45.18, placing all samples in the excellent category for human consumption. The Piper and Schoeller–Berkaloff diagrams revealed predominantly calcium bicarbonate and calcium–magnesium hydrochemical facies, indicating that mineralisation was primarily influenced by water–rock interactions.

Prediction of the Molecular Lipophilicity of an Alkylphenol Family Using Quantum Chemistry and QSPR Methods

2026-08-20T11:04:11+00:00

This study examined the relationship between the water/octanol partition coefficient of eighteen alkylphenols and molecular descriptors derived from quantum-chemical calculations using a quantitative structure-property relationship (QSPR) approach. The experimental database was divided into a training set of fourteen compounds and a test set of four compounds. Three descriptors, the electronic energy (E_T), the energy of the Lowest Unoccupied Molecular Orbital (E_LUMO) and the energy gap (ΔE_gap) were used to develop a multiple linear regression model. The model showed a strong association between the experimental lipophilicity values and the selected descriptors, with R = 0.9850, R² = 0.9703, a standard deviation of 0.0853, and F = 108.9532. Internal validation using leave-one-out cross-validation and property randomisation, together with external validation using the test set and the Tropsha criteria, was applied to assess model stability and predictive performance. The applicability domain was evaluated using a Williams plot. Within the studied dataset and the defined applicability domain, the model showed close agreement between experimental and predicted water/octanol partition coefficients. The reported validation results indicate that the selected quantum-chemical descriptors can be used to model lipophilicity within this alkylphenol series. Predictions for additional alkylphenols should, however, remain restricted to compounds that fall within the model’s defined applicability domain.

Comparative Chemical Characterisation of Produced Water from Onshore and Offshore Oil Fields in the Niger Delta, Nigeria

2026-08-22T11:32:04+00:00

Background: Produced water is the largest waste stream generated during petroleum exploration and production and may contain chemical constituents that can cause adverse environmental impacts if inadequately managed.

Aim: This study comparatively characterised the chemical composition of produced water from selected onshore and offshore oil fields in the Niger Delta, Nigeria, and evaluated compliance with environmental discharge standards.

Materials and Methods: Twenty-four produced water samples were collected from eight oil fields, comprising four onshore and four offshore production facilities. Physicochemical parameters, major ions, heavy metals, total petroleum hydrocarbons (TPH), oil and grease, and polycyclic aromatic hydrocarbons (PAHs) were determined using standard analytical methods. Water Quality Index (WQI), Pollution Index (PI), Pearson correlation analysis, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) were employed to evaluate produced water quality, contamination patterns, and relationships among the measured parameters. Comparative statistical analyses were performed to determine differences between onshore and offshore produced water.

Results: The pH ranged from 6.66 to 7.34, while electrical conductivity and total dissolved solids ranged from 34,628 to 47,426 µS/cm and from 22,874 to 33,184 mg/L, respectively. Sodium (7,964–11,248 mg/L) and chloride (12,246–17,462 mg/L) were the dominant dissolved ions. Iron (3.86–8.42 mg/L) exhibited the highest heavy metal concentration, whereas cadmium ranged from 0.01 to 0.06 mg/L. Total petroleum hydrocarbons varied between 46.82 and 138.46 mg/L, oil and grease ranged from 18.64 to 62.84 mg/L, and total PAHs ranged from 16.50 to 58.62 mg/L, with consistently higher concentrations recorded in offshore produced water. Water Quality Index values ranged from 381.8 to 706.4, classifying all samples as unsuitable for direct environmental discharge. Strong positive correlations were observed between electrical conductivity and total dissolved solids (r = 0.996) and between oil and grease and TPH (r = 0.981). Principal Component Analysis explained 88.64% of the total variance, while Hierarchical Cluster Analysis grouped the oil fields into three distinct chemical clusters.

Conclusion: Offshore produced water exhibited significantly higher contaminant concentrations than onshore produced water, with several parameters exceeding regulatory discharge limits. These findings underscore the need for improved produced water treatment technologies, continuous environmental monitoring and stricter compliance with petroleum wastewater discharge regulations in the Niger Delta.

Gravimetric Evaluation of Calotropis procera Leaf Extract as a Green Corrosion Inhibitor for Mild Steel in Acidic and Alkaline Media

2026-08-26T07:41:13+00:00

Corrosion of mild steel remains a major industrial challenge, causing significant economic losses and equipment failure. Plant-derived corrosion inhibitors provide an environmentally friendly alternative to conventional synthetic chemicals. This study evaluated the corrosion inhibition performance of Calotropis procera (Sodom apple) leaf extract on mild steel in 0.5 and 1.0 M NaOH and 0.5 and 1.0 M H₂SO₄ using the gravimetric weight-loss method. Mild steel coupons were immersed in the corrosive media containing 0, 2, 4, 6, 8, and 10 g of the extract for 168, 336, 504, and 672 h. Weight loss, corrosion rate, inhibition efficiency (IE%), and surface coverage (θ) were determined to assess inhibitor performance. Results showed that the corrosion rate decreased progressively with increasing extract concentration, whereas inhibition efficiency and surface coverage increased, indicating concentration-dependent adsorption of phytochemical constituents onto the steel surface. The extract provided effective protection in both alkaline and acidic environments, with the highest inhibition efficiency of 94.3% and surface coverage of 0.943 achieved at 10 g after 672 h in 1.0 M H₂SO₄. Although corrosion was more severe in acidic than alkaline media, the extract markedly suppressed metal dissolution by forming a stable protective film on the mild steel surface. These findings demonstrate that Calotropis procera leaf extract is an efficient, eco-friendly, and cost-effective green corrosion inhibitor with strong potential for protecting mild steel in aggressive industrial environments and that it offers a sustainable alternative to conventional corrosion-control chemicals. The observed performance highlights its promise for environmentally sustainable corrosion management. Future industrial application is recommended.

A Stepwise Pedagogical Framework for Learning IUPAC Nomenclature of Aliphatic Organic Compounds

2026-08-27T12:13:27+00:00

This study presents a stepwise pedagogical framework designed to simplify the learning and application of IUPAC nomenclature for aliphatic organic compounds. Undergraduate learners often find nomenclature challenging because several interdependent rules must be considered simultaneously during the construction of a chemical name. The proposed framework organises the naming process into five sequential components—secondary prefix (2°-P), primary prefix (1°-P), word root, primary suffix (1°-S), and secondary suffix (2°-S)—to provide learners with a consistent and structured sequence for applying established nomenclature principles. Importantly, the proposed format is intended as an instructional framework and does not replace or modify IUPAC nomenclature rules. Its pedagogical usefulness was evaluated through a quasi-experimental study involving 64 undergraduate chemistry students. Students were divided into two groups: one was taught using a conventional instructional approach, while the other was taught using the proposed stepwise framework. Both groups completed identical pre-test and post-test assessments and nomenclature exercises. Students taught using the stepwise framework showed greater improvement in test performance and greater efficiency in completing naming exercises than those taught using the conventional approach. Feedback from students and faculty further indicated that the framework was easy to understand, recall, and apply, and helped reduce confusion during name construction. The findings suggest that the proposed stepwise framework may serve as a useful pedagogical tool for facilitating the teaching and learning of IUPAC nomenclature in undergraduate chemistry education.

Design and Formulation of Waste Plastic Materials with Asphalt for Road and Pavement Construction

2026-08-28T13:13:39+00:00

The rapid increase in plastic waste generation poses serious environmental, social, and economic challenges, particularly in developing countries such as Nigeria, where disposal infrastructure is inadequate. This study investigates the design and formulation of hot mix asphalt incorporating waste polyethylene terephthalate (PET) and high-density polyethylene (HDPE) for road and pavement construction. Using the dry mix method, PET and HDPE were processed to 2–4 mm and blended with 70/80 penetration grade bitumen and aggregates at 2%, 3%, 4%, 5%, and 6% by weight of the mix. Thirty Marshall specimens were prepared and evaluated for stability, flow, voids, voids filled with bitumen (VFB), and density in accordance with ASTM D1559. Results revealed that asphalt mixes containing PET and HDPE exhibited improved stiffness and resistance to rutting relative to the control. Optimal performance was observed at 2–4% plastic content. PET mixes showed higher Marshall Stability at 6% (4.70 kN) and higher VFB (81.42%) compared with HDPE. The incorporation of plastic waste offers significant environmental benefits by diverting waste from landfills and reducing binder demand, while also offering potential cost savings and extended pavement lifespan. The study concludes that integrating PET and HDPE into asphalt pavement is a viable, sustainable approach, but recommends standardisation, durability testing, and field-scale validation.

Mechanically Recycled and Upcycled Mixed Plastic Waste for Construction Units: FTIR Characterization and TCLP-Based Environmental Safety Assessment

2026-08-31T11:08:12+00:00

Post-consumer mixed plastic waste comprising PET, HDPE, and PP was mechanically recycled and upcycled into brick and interlocking construction units using a locally fabricated batch melter. Four specimen groups were produced, each with three replicates: recycled brick, upcycled brick, recycled interlock, and upcycled interlock. The recycled formulation contained 100 wt% mixed plastic waste, whereas the upcycled formulation contained 88 wt% mixed plastic waste, 10 wt% SiO₂, and 2 wt% carbon black masterbatch. Fourier transform infrared spectroscopy confirmed retention of the principal PET, HDPE, and PP functional groups after melt-processing. The diagnostic Si–O–Si triplet at 1097–1100, 1015–1025, and 795–810 cm⁻¹ was detected in all upcycled specimens and was absent from recycled-only specimens, confirming silica incorporation. One upcycled brick specimen showed an isolated, shifted carbonyl band at approximately 1689 cm⁻¹. Toxicity Characteristic Leaching Procedure testing showed cadmium below the detection limit in all specimens and no significant difference in chromium concentrations among groups. Lead concentrations were significantly higher in upcycled specimens than in recycled-only controls, although all measured concentrations remained below the applicable regulatory limit. The recycled interlocking group recorded the highest mean compressive strength at 4.268 ± 0.072 MPa. Overall, the results indicate that the fabricated mixed-plastic construction units were chemically distinguishable by formulation and environmentally compliant under the reported test conditions, while highlighting the need to verify additive-related contamination.

Influence of Elemental Composition of Geothermal Waters and Succulent Feedstocks on Cryo-mesophilic Biogas Production from Mt. Suswa, Kenya

2026-09-04T05:36:06+00:00

Background: Dependence on charcoal and firewood in the Mt. Suswa region creates environmental and health concerns and supports the need to evaluate locally available feedstocks for renewable biogas production. This study investigated the elemental composition of geothermal waters and three succulent feedstocks and examined their biogas production under cryo-mesophilic conditions.

Methods: Steam-vent water, water-pan samples, and Agave sisalana, Echinocactus grusonii, and Opuntia ficus-indica were analysed by Microwave Plasma Atomic Emission Spectroscopy. Biogas production was monitored for 132 h in 26 laboratory-scale batch digesters operated at 20–24.5°C with different feedstock-water combinations, with or without cow dung inoculum.

Results: Agave sisalana contained 3,765.53 ± 0.00 g/L potassium, 1.23 ± 0.00 g/L cobalt, and 1.08 ± 0.03 g/L nickel. Region II steam-vent water had 50,268.93 ± 29.19 ppm potassium, 1,317.85 ± 1.10 ppm nickel, 1,184.54 ± 5.76 ppm cobalt, and the lowest measured arsenic concentration among the steam-vent regions. The highest cumulative biogas yield was 62 mL in D6, containing A. sisalana, water-pan sample, and cow dung. Most O. ficus-indica treatments yielded 12–24 mL, although D10 reached 50 mL.

Conclusion: Biogas performance varied with feedstock, water source, and inoculation. A. sisalana-based treatments and cow dung inoculation showed the most favourable overall performance under the tested conditions.

Environmental Impacts Related to the Activities of the Medical Waste Incinerator at a Hospital in Abobo (Abidjan, Ivory Coast)

2026-09-09T10:41:09+00:00

The aim of this study was to assess the environmental impacts associated with the activities of an incinerator installed in a hospital in Abobo. The study involved weighing medical waste, measuring the quantities of gases released into the environment, and collecting and weighing the ash obtained after incineration. The collected ash represented 24% of the total mass of incinerated waste. Incineration reduced the mass of medical waste by 76%. The wastewater used to scrub the incinerator fumes was highly acidic (pH = 2.52) and therefore fell outside the discharge limits (5.5 ≤ pH ≤ 8.5) set by the Ivorian standard. In addition, the assessment of air-pollutant concentrations showed mean values of 223 ± 17 ppm, 4354 ± 123 ppm, 0.17 ± 0.04 ppm, and 0.24 ± 0.12 ppm for CO, CO₂, NO₂, and SO₂, respectively. These values exceeded the limits cited from the USEPA (2022) and WHO (2025) guidelines: 10 ppm for CO, 500 ppm for CO₂, and 0.04–0.06 ppm for NO₂ and SO₂. Similarly, the concentrations of Cr (112 ± 25 mg/kg), Cu (96 ± 17 mg/kg), Pb (53 ± 11 mg/kg), Ni (35 ± 09 mg/kg), and Zn (247 ± 29 mg/kg) in the ash were higher than the corresponding upper continental crust (UCC) background concentrations of 35, 14.3, 17, 18.6, and 52 mg/kg. However, the study was conducted using a single incinerator, which may limit the generalisability of the findings to settings with different sociopolitical and economic conditions. In addition, toxic gases were released into the environment without prior treatment. Therefore, medical waste and incineration residues should be disposed of appropriately to minimise environmental contamination and potential public-health risks.

Comparison of the Phenolic Composition of Piper nigrum L. and Piper cubeba L. Accessions Collected in the Ivorian Orchard

2026-09-09T12:54:48+00:00

Piper nigrum L. and Piper cubeba L. are aromatic pepper species recognised for their phytochemical diversity. This study compared the phenolic composition of six pepper accessions collected in Côte d’Ivoire, including two P. nigrum cultivars, Lompung (LG) and Muntok (MK), and four P. cubeba accessions, AC1, AC2, AB, and BH. Dried berry powders were extracted using 80% methanol, and the contents of total polyphenols, total flavonoids, anthocyanins, flavonoid aglycones, hydrolyzable tannins, and condensed tannins were determined using spectrophotometric methods. The results showed significant variation among species and accessions. Total polyphenol contents ranged from 35.656 to 89.082 µg GAE/g of extract, with the highest value recorded in MK. Total flavonoid contents ranged from 26.588 to 62.946 µg/g of extract, with the highest value observed in the AB accession. Flavonoid aglycones were most abundant in LG, with 0.411 mg/g of extract, while anthocyanin contents were highest in LG and BH. Hydrolyzable tannins and condensed tannins also varied among accessions, with comparatively high values observed in several P. cubeba accessions and in MK. These findings indicate that phenolic composition differs according to species and accession, suggesting that both P. nigrum and P. cubeba accessions may represent useful sources of phenolic compounds.

Hydrochemical Characterization and Organic Pollution Assessment of an Urban River Catchment under Anthropogenic Pressure: The Case of the Téguéré River (Korhogo, Côte d'Ivoire)

2026-09-16T12:34:21+00:00

Rapid and unplanned urbanisation in Sub-Saharan African cities exerts severe pressure on urban aquatic ecosystems due to the lack of adequate sanitation systems. This study evaluates the hydrochemical quality and organic pollution levels of surface water in the Téguéré River catchment (Korhogo, northern Côte d’Ivoire) to assess its suitability for human consumption and agricultural irrigation. Physical and biochemical parameters were analysed across ten sampling points from upstream to downstream. Hydrochemical facies were identified using Piper diagrams, while organic biodegradability and irrigation suitability were determined via COD/BOD₅ ratios and the Sodium Adsorption Ratio (SAR), respectively. The results show high turbidity (up to 322 NTU) and critical concentrations of NH₄⁺ (0.2–2.09 mg/L), total Fe (0.3–12.08 mg/L), and Mn²⁺ (0.19–8.05 mg/L), all exceeding WHO drinking water guidelines. COD (6.9–52 mg/L) and BOD₅ (3.2–24.4 mg/L) levels, paired with a constant COD/BOD ratio of 2.1, demonstrate a moderately biodegradable organic load of domestic origin. Three dominant hydrochemical facies were classified: Ca-Mg-HCO₃ (80%), Ca-Cl (10%), and Na-K-Cl (10%). Crucially, while unfit for drinking, the water remains suitable for irrigation, plotting within the low-to-medium salinity and low sodium hazard zones (C1S1 and C2S1 classes) with a SAR < 1. Water quality significantly deteriorates downstream due to untreated urban runoff and water treatment plant effluents. The immediate implementation of tailored filtration systems and continuous monitoring is urgently required to safeguard public health and local ecosystems.

In silico Design of Sulfenylated 5-Aminopyrazole Derivatives, Novel Butyrylcholinesterase Inhibitors for the Treatment of Alzheimer's Disease

2026-09-23T12:22:41+00:00

Alzheimer’s disease (AD) is a neurodegenerative disorder associated with cholinergic dysfunction, and butyrylcholinesterase (BuChE) becomes increasingly relevant as disease pathology progresses. This study aimed to design sulfenylated 5-aminopyrazole (APS) analogues as potential human BuChE inhibitors using an integrated computer-aided workflow. A structure-based quantitative structure–activity relationship (QSAR) model was developed using the human BuChE–tacrine crystal structure (PDB 4BDS) and 15 APS derivatives, comprising 12 compounds in the training set and three in the external validation set. Molecular docking, binding-energy and residue-level interaction analyses were combined with a 3D-QSAR pharmacophore model, virtual screening, and in silico ADME prediction. The selected QSAR model explained 98% of the variation in experimental inhibitory activity and showed strong validation performance. The pharmacophore model also demonstrated a close relationship between experimental and predicted activity, with R² = 0.93 and cross-validated R² = 0.92. Virtual screening of 49 newly designed APS analogues identified APSA22, APSA28, APSA35, and APSA39 among the most promising candidates on the basis of predicted inhibitory activity. QikProp analysis indicated favourable theoretical pharmacokinetic characteristics for these prioritised analogues. Overall, the integrated modelling strategy identified structurally plausible BuChE-binding candidates and provides a computational basis for selecting APS analogues for subsequent synthesis, biochemical testing, and experimental evaluation.

Structural Characterization of a Neutral Β-D-Glucan-Containing Fraction Isolated from the Basidiomycete Fungus Fomes fomentarius By NMR Spectroscopy

2026-09-30T12:23:40+00:00

Background: Fungal β-glucans are structurally diverse polysaccharides whose linkage patterns and branching characteristics influence their physicochemical properties. Fomes fomentarius contains chemically heterogeneous polysaccharide fractions; however, fraction-specific structural information on neutral polysaccharides isolated from naturally occurring fruiting bodies remains limited. Detailed NMR-based characterisation is therefore important for clarifying the glycosidic linkage and substitution patterns of purified β-glucan-containing fractions.

Aims: This study aimed to isolate a water-soluble melanin–glucan complex from the fruiting bodies of the basidiomycete fungus Fomes fomentarius collected in Uzbekistan, purify its polysaccharide components, and elucidate the structural features of the neutral polysaccharide fraction using nuclear magnetic resonance (NMR) spectroscopy.

Methodology: Dried and powdered fruiting bodies were defatted by Soxhlet extraction for 24 h and subsequently extracted with hot water at solid-to-liquid ratios of 1:20, 1:15, and 1:10. The combined aqueous extracts were concentrated and lyophilised to obtain the crude water-soluble melanin-glucan complex (BTW). The crude fraction was further purified by ion-exchange chromatography, yielding neutral (BTW-1) and anionic (BTW-2) polysaccharide fractions. The purified BTW-1 fraction was structurally investigated by ¹H NMR, ¹³C NMR, HSQC, and HMBC spectroscopy.

Results: Soxhlet pretreatment yielded 2.45% of extractable material, whereas subsequent hot-water extraction afforded 4.85% of the crude water-soluble fraction. BTW was obtained as a cream-coloured, water-soluble powder that exhibited opalescence at low concentrations and increased viscosity at higher concentrations. UV spectroscopy showed an absorption band around 230 nm, and the total carbohydrate content was 30.46%. Ion-exchange chromatography yielded 20.00% of the neutral BTW-1 fraction and 53.20% of the anionic BTW-2 fraction. The ¹³C NMR and HSQC spectra of BTW-1 revealed characteristic signals of carbohydrate residues, including anomeric correlations at δH/δC 4.373/103.058 and 5.250/99.855 ppm. The signal at δH/δC 3.604/84.342 ppm was consistent with a downfield-shifted C-3 environment indicative of O-3 substitution, whereas C-6 resonances at δC 68.269-69.587 ppm suggested possible O-6 substitution.

Conclusion: The chromatographic and NMR data indicate that the neutral BTW-1 fraction contains β-D-glucopyranosyl residues with structural features compatible with a β-(1→3)-linked glucan backbone and possible C-6 substitution or branching. The proposed linkage pattern is considered a provisional structural motif.

Apparent Recovery of Naturally Occurring Epoxy Fatty Acids from Alchornea cordifolia Seeds Across Solvents and Extraction Times: A Mass-balance Analysis of Batch Extractions

2026-10-01T10:34:41+00:00

Alchornea cordifolia seed oil is naturally enriched in a C20 epoxy fatty acid, but solvent comparisons may be misleading when extract composition is treated as equivalent to target-mass recovery. This study applied an explicit mass-balance approach to a batch-extraction screening dataset. Ground seeds (10 g) were extracted at 27–28 °C and 300 rpm with 60 mL of chloroform, n-hexane, methanol, 95% ethanol, or chloroform–methanol (1:1, v/v) for 15–150 min. Epoxy-fatty-acid content was inferred from a four-point GC-FID/oxirane calibration, and estimated apparent recovery was calculated from gravimetric extract yield and the inferred epoxy-fatty-acid mass fraction. Chloroform at 15 min produced the highest observed apparent recovery, 32.08 g per 100 g seed. In contrast, the highest estimated epoxy-fatty-acid concentration, 50.73%, occurred with n-hexane at 60 min but corresponded to an apparent recovery of only 14.63 g per 100 g seed. Thus, extract concentration and recovered target mass generated different descriptive rankings. Because each solvent–time condition comprised one observation, the crude gravimetric extracts were not independently confirmed as pure lipid, and the alcohol-derived estimates were based on values below the calibration interval, the findings support descriptive screening rather than exact recovery estimation, kinetic inference, or identification of a statistically confirmed optimum. Chloroform should therefore be regarded as an analytical benchmark rather than a production solvent. The mass-balance framework supports subsequent replicated optimisation using safer solvent systems.

Trimethylboroxine-free Mechanochemical Formation of Porous COF-1 from a Preconditioned Boronic-acid Precursor

2026-10-01T10:43:23+00:00

Boroxine-linked covalent organic frameworks are difficult to form mechanochemically because dehydrative condensation generates water that can hydrolyse newly formed B₃O₃ linkages. This study examines whether deliberate preconditioning of 1,4-benzenediboronic acid (BDBA) can enable trimethylboroxine-free formation of porous COF-1. BDBA was sequentially vacuum-dried, manually ground, continuously sonicated in anhydrous 1,4-dioxane, isolated, thermally dried, and then subjected to liquid-assisted planetary ball milling with a 1:1 1,4-dioxane/mesitylene mixture. The preconditioned precursor showed changes in the O–H envelope and low-frequency boron–oxygen region relative to pristine BDBA; these changes were interpreted qualitatively because pristine BDBA also contains spectral structure near ~704 cm⁻¹. Milling at 1100 rpm for 40 min with 70 µL of liquid produced a material with FTIR, PXRD, ¹³C CP/MAS NMR, and ¹¹B MAS NMR signatures consistent with COF-1. A matched direct-milling control prepared from pristine BDBA remained spectroscopically less converted after identical work-up, indicating that precursor history affects the extent of conversion under the conditions examined. Nitrogen adsorption at 77 K gave an apparent BET surface area of 711 m² g⁻¹. Across four mechanochemical runs, the isolated product mass recovery was 60.0 ± 0.7%. These findings establish a trimethylboroxine-free route to porous COF-1 under the investigated conditions while supporting further quantitative investigation of precursor-conditioning effects.

Mineralogical and Physicochemical Characterization of Three Natural Bentonite Samples from the Tahoua Sites (Niger)

2026-10-01T11:55:23+00:00

This study evaluated the physicochemical, mineralogical, structural and textural characteristics of three natural bentonite samples collected from Adoua (BN-G₁), Mougia (Madaoua) (BN-G₂) and Bouza (BN-G₃) in the Tahoua region of Niger, with the aim of assessing their potential relevance to catalytic applications. The samples were characterized through preliminary physicochemical analyses, X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and nitrogen adsorption using the Brunauer–Emmett–Teller method. Mineralogical analysis showed that the samples contained quartz, montmorillonite, kaolinite and calcite, with quartz particularly prominent in the Mougia and Bouza samples. X-ray fluorescence indicated that BN-G₁ contained 61.27% SiO₂ and 20.12% Al₂O₃, whereas BN-G₂ contained 85.45% SiO₂ and 7.93% Al₂O₃ and BN-G₃ contained 85.84% SiO₂ and 6.76% Al₂O₃. BN-G₁ had a specific surface area of 87.2959 m²/g, substantially higher than those of the other samples, together with the highest swelling index and cation-exchange capacity. Scanning electron microscopy of BN-G₁ showed a layered smectite morphology consistent with montmorillonite, while its SiO₂/Al₂O₃ ratio was 3.045. Overall, the comparative characterization distinguished Adoua bentonite from the Mougia and Bouza samples and identified BN-G₁ as the material with the most favourable measured properties for subsequent evaluation in the proposed catalytic application. These findings provide a comparative basis for selecting local bentonite for further catalytic testing.