International Research Journal of Pure and Applied Chemistry

A New Zinc(II) Thiocyanate Complex of a Pyridine-4-carbohydrazide Schiff Base: Crystal Structure and Redox Properties of a Related Copper(II) Complex

2026-08-03T10:16:33+00:00

A new zinc(II) complex, ZnCl(SCN)(H₂L)₂, derived from the Schiff base ligand N′-[(E)-(2-hydroxy)methylidene]pyridine-4-carbohydrazide (H₂L), was synthesised and structurally characterised by single-crystal X-ray diffraction. The complex crystallises in the orthorhombic space group Ama2, with unit-cell parameters a = 26.0306(2) Å, b = 16.0094(1) Å, and c = 6.840(1) Å. The asymmetric unit comprises two neutral H₂L ligands coordinated to the Zn²⁺ ion through their pyridine nitrogen atoms, one thiocyanate anion (SCN⁻) coordinated through nitrogen, one chloride anion, and one lattice water molecule. The zinc centre adopts a distorted tetrahedral geometry, with Zn–N bond lengths of 1.979(4) and 2.052(3) Å, a Zn–Cl bond length of 2.1919(12) Å, and bond angles that depart markedly from the ideal tetrahedral value (103–125°). To complement the structural study, the redox behaviour of the related copper(II) complex [Cu(H₂L)Cl·H₂O]Cl (L-4) was investigated by cyclic voltammetry in acetonitrile containing 0.1 M TEATFB, using a Pt disk working electrode (r = 2 mm), a stainless-steel wire counter electrode, and an Ag/AgCl reference electrode. Over the potential range −1.0 to +1.0 V versus SCE and at scan rates of 10–50 mV s⁻¹, the voltammograms displayed a single quasi-reversible redox couple, characterised by a sharp cathodic peak at −0.75 V and a broader anodic peak at −0.45 V versus SCE. The observation of a single redox wave indicates a uniform Cu(II) coordination environment, consistent with the structural and spectroscopic data obtained for the complex.

Extraction and Characterization of Chitosan from Crab and Periwinkle Shells

2026-08-12T12:52:48+00:00

Chitosan is a biopolymer obtained by deacetylating chitin and is commonly produced from crustacean shell waste. This study compared the extraction and characterisation of chitosan from crab (Callinectes amnicola) and periwinkle (Tympanotonus fuscatus) shells under identical chemical conditions. The shell powders were subjected to demineralisation with 1.25 M HCl, deproteinisation with 2.5% NaOH, and deacetylation with 25% NaOH. The products were assessed for percentage yield, degree of deacetylation (DDA) by potentiometric titration, solubility, and functional groups by Fourier-transform infrared spectroscopy. Crab shells produced a chitosan yield of 18.4% and a DDA of 80.3%. The corresponding FTIR spectrum showed characteristic amine and polysaccharide bands and no residual carbonate peaks, indicating effective demineralisation and deacetylation. In contrast, periwinkle shells produced a lower yield of 10.9%, while the resulting product had a DDA of <10% and poor solubility. Its FTIR spectrum showed strong carbonate bands and an absence of characteristic amine bands, indicating incomplete demineralisation and deacetylation. The periwinkle-derived product was therefore predominantly chitin rather than chitosan under the applied conditions. These findings show that identical processing conditions do not yield equivalent products from crustacean and molluscan shell matrices. Source-specific optimisation, particularly more intensive demineralisation and deacetylation for periwinkle shells, is required to improve conversion to chitosan.

Physicochemical Characteristics and Selected Metal Concentrations in Sachet, Bottled, and Freshly Blended Fruit Juices at the Kenya-Uganda Border

2026-08-18T09:24:33+00:00

Fruits form an important part of the human diet as they are rich in fibre and vitamins such as A, B, C, D and K. They can be consumed fresh or whole, in liquid forms such as juices and smoothies/blends, as well as in cooked or baked form. The objective of this study is to assess the physicochemical parameters of locally produced and bottled fruit juices at the Kenya – Uganda border. Three broad categories (five samples in each category) of juice samples were analysed for pH, TDS, electrical conductivity and heavy metals. The physical parameters were measured using a Hanna Instruments combo portable meter, while heavy metals were measured using an inductively coupled plasma mass spectrometer (ICP-MS 7900, Agilent Technologies, USA). For heavy metals, cadmium and copper were below the WHO recommended limits. For iron, all samples recorded concentrations below the WHO limit with the exception of one sachet sample whose concentration was above the WHO limit. Chromium and nickel concentrations were above the WHO recommended levels. The high levels of chromium and nickel point to the use of heavy-metal-contaminated water during the manufacturing process; contamination of juice by equipment during manufacture; heavy-metal-contaminated soil leading to bioaccumulation of heavy metals in fruit tissues as well as the use of metal-based pesticides and herbicides in agriculture. However, this study was designed to measure the levels of heavy metals in fruit juice samples and did not include direct source tracing analysis of the potential contamination sources. The explained sources are therefore treated as possible contamination pathways rather than confirmed causes of the observed heavy metal concentration. The study recommends the use of acid-resistant machinery to avoid corrosion and leaching of heavy metals into juice products during manufacture; treatment of water to remove heavy metals before its use in the juice manufacturing process; and thorough washing of fruits to remove pesticides before blending. All the juice brands demonstrated strong correlations between a few metal pairs. In sachet brands, iron showed a strong correlation with cadmium (r = 0.83) while copper showed a strong correlation with chromium (r = 0.90). All the other metal pairs showed very low and negative correlations. In bottled brands, there was no strong correlation between the metal pairs. Copper and iron registered a moderate correlation (r = 0.66); cadmium and chromium registered the same moderate correlation (r = 0.50) and the same was observed for nickel and copper (r = 0.55). In blended brands, only copper and nickel demonstrated a strong correlation (r = 0.80) whereas all the other metals demonstrated weak and negative correlations. The strong correlation between metal pairs indicates that an increased concentration of one metal leads to a higher concentration of another paired metal, but does not indicate a similar contamination pathway or causal relationship between metal pairs. Some metals demonstrated negative correlations. These included: Chromium and iron (r = – 0.84), cadmium and nickel (r = – 0.69), cadmium and copper (r = – 0.80), copper and iron as well as cadmium and chromium (r = – 0.64 in both cases). This indicates that the higher concentration of one metal tends to cause a lower concentration of the corresponding metal. However, this does not mean that one metal causes the other metal to decrease in concentration. Although strong negative correlations were observed for some metal pairs, the correlations were not statistically significant at p = 0.05.

Deep Purification of Wet-process Phosphoric Acid Using Acetone as a Green Organic Solvent

2026-08-18T09:31:01+00:00

Wet-process phosphoric acid contains a range of mineral impurities that negatively impact acid quality and restrict its use in producing high-purity phosphate products. This study investigates an integrated purification process that combines defluorination using microcrystalline silica, desulfation with strontium carbonate, and acetone-assisted purification. After preliminary treatment, the phosphoric acid was standardised to 35 wt.% P₂O₅ and subjected to acetone treatment under varying acid-to-acetone weight ratios and contact times. The optimal conditions were identified as an acid-to-acetone mass ratio of 1:3 at 25 °C for 30 minutes, which achieved an effective balance between impurity removal and phosphorus retention. Under these parameters, the precipitation efficiencies for CaO, MgO, Fe₂O₃, Al₂O₃, SO₃, and F were 75.99%, 95.37%, 99.40%, 99.50%, 99.66%, and 98.97%, respectively, while P₂O₅ precipitation was limited to 18.02%. Following separation and vacuum acetone removal, the purified acid contained 35.06 wt.% P₂O₅, with CaO and MgO concentrations reduced to 0.13 and 0.03 wt.%, respectively, and Fe₂O₃, Al₂O₃, SO₃, and F below detection limits. The purified acid exhibited a consistent decrease in density and dynamic viscosity as temperature increased from 20 to 90 °C, indicating improved flowability for handling and transport. Material balance analysis indicated an acetone recovery rate of 98.96% and a solvent loss of 1.04%, with 78.27% of the initial P₂O₅ retained in the final product. These results indicate that the acetone-assisted purification route shows considerable promise for laboratory-scale production of high-quality phosphoric acid suitable for further phosphate fertiliser processing. Keywords: wet-process phosphoric acid, acetone, deep purification, defluorination, desulfation, rheological properties, phosphate products.

Evaluation of 2,5,7-Triphenyl-1,2,4-triazolo[1,5-a] pyrimidine as an Efficient Corrosion Inhibitor for Stainless Steel in 1.0 M Hydrochloric Acid

2026-08-19T09:59:46+00:00

Corrosion inhibition of 316 L stainless steel in 1.0 M hydrochloric acid by 2,5,7-triphenyl-1,2,4-triazolo[1,5-a]pyrimidine (TPTP) was evaluated using weight-loss measurements, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarisation (PDP). The effect of inhibitor concentration was examined over the reported test range, and adsorption behaviour and thermodynamic parameters were assessed to elucidate the inhibition process. Weight-loss measurements showed a progressive decrease in corrosion rate as TPTP concentration increased, with inhibition efficiency reaching 94.0% at 500 ppm and 303 K. Surface coverage increased with concentration, consistent with progressively greater adsorption of TPTP molecules on the stainless-steel surface. The tabulated EIS results showed that charge-transfer resistance increased from 32 to 535 Ω cm², while double-layer capacitance decreased from 162 to 33 μF cm⁻² between the uninhibited solution and 500 ppm TPTP. The tabulated PDP results showed a reduction in corrosion current density from 126.4 to 7.6 μA cm⁻², accompanied by a 19 mV shift in corrosion potential, supporting mixed-type inhibition. The adsorption data were described by the Langmuir adsorption isotherm, while the reported Gibbs free-energy values indicated spontaneous adsorption with contributions from physical and chemical interactions. Overall, the reported gravimetric and electrochemical data indicate that TPTP reduces stainless-steel corrosion through adsorption and formation of a protective interfacial layer under the investigated conditions.

Production and Physicochemical Characterization of Polyethylene Pyrolysis Oil from Sachet Water LDPE Waste

2026-08-20T05:02:19+00:00

This study investigated the production and characterisation of polyethylene pyrolysis oil obtained from waste low-density polyethylene materials, specifically sachet-water packaging bags. The polyethylene waste was collected, sorted, washed, rinsed, and dried. A 15 kg portion of PE was subjected to thermal pyrolysis at 400 °C for 3 hours in the absence of oxygen and was then distilled for a further 3 hours in a batch reactor. The condensed liquid product comprised 3.0 kg of polyethylene pyrolysis oil and was evaluated for selected physicochemical and instrumental properties. The residue obtained was 9.5 kg. The measured physicochemical properties included viscosity, density, refractive index, turbidity, pH, adhesion, drying time, and water solubility. The oil had a viscosity of 17.7 mPa·s, a density of 0.99 g/mL, a refractive index of 1.400, a turbidity of 50 NTU, and a pH of 6.7, and it was insoluble in water. Fourier-transform infrared spectroscopy indicated the presence of hydrocarbon-related and oxygen-containing functional groups in the pyrolysis oil. X-ray diffraction analysis suggested low crystallinity and predominantly amorphous characteristics. Scanning electron microscopy showed a relatively smooth and homogeneous surface in the prepared sample, while thermogravimetric and differential thermal analyses indicated thermal degradation behaviour, with mass-loss events observed during heating. The findings show that waste polyethylene can be converted into a liquid pyrolysis product with measurable physicochemical and structural characteristics. Further studies are required to determine its detailed chemical composition, safety, distillation behaviour, and suitability for specific industrial applications.

Design, Synthesis and Antibacterial Evaluation of 3-oxo-2-[2-(1-phenylethylidene)hydrazinyl]-3,4-dihydroquinoxaline-6-sulfonyl Azide Derivatives

2026-08-25T09:12:31+00:00

This study was designed to synthesized some 3-oxo-2-(2-(1-phenylethylidene)hydrazinyl)-3,4-dihydroquinoxaline-6-sulfonyl azide derivatives and study their antibacterial potentials on some bacterial strains. 3-oxo-2-(2-(1-phenylethylidene)hydrazinyl)-3,4-dihydroquinoxaline-6-sulfonyl azide derivatives were synthesized from the reaction of 2-hydrazinyl-3-oxo-3,4-dihydroquinoxaline-6-sulfonyl azide with different acetophenones in a typical condensation reaction. FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic analysis were used to characterized the newly synthesized 3-oxo-2-(2-(1-phenylethylidene)hydrazinyl)-3,4-dihydroquinoxaline-6-sulfonyl azide derivatives. The compounds were investigated for their potential antibacterial properties. The results showed that all the compounds including the standard antibiotics activity increase with time and concentration showing that the agents' activity is time of exposure and concentration-dependent. Also, the killing rate pattern of B. steatrothermophilus by the agents differs from that of B. subtilis showing that the activity of the agent is also bacterial type dependent.

Design, Synthesis and Antibacterial Potency of 3-(2-(Benzylidenehydrazinyl)-1-Phenylquinoxalin-2(1H)-one Derivatives

2026-09-02T13:09:23+00:00

Context: Studies on the synthesis of quinoxalines remain of considerable interest because of their chemical and biological properties.

Objective: This study was designed to synthesize 3-(2-(benzylidene)Hydrazinyl)-1-Phenylquinoxalin-2(1H)-One derivatives and to study their antibacterial properties against selected bacterial strains.

Materials and Methods: Some 3-(2-(benzylidene)Hydrazinyl)-1-Phenylquinoxalin-2(1H)-One derivatives were synthesized via condensation reactions between 3-hydrazinyl-1-phenylquinoxalin-2(1H)-one and various substituted benzaldehydes. The compounds were evaluated for their antibacterial properties.

Results: All the compounds evaluated demonstrated broad-spectrum activity against ten clinically isolated bacterial strains. The minimum inhibitory concentration (MIC) values ranged from 0.0781 to 0.625 mg/mL, while the minimum bactericidal concentration (MBC) values ranged from 0.125 to 0.625 mg/mL. These findings indicate antibacterial activity across the tested isolates.

Discussion and Conclusion: The study found that the synthesized 3-(2-(benzylidene)Hydrazinyl)-1-Phenylquinoxalin-2(1H)-One derivatives demonstrated antibacterial activity against both Gram-positive and Gram-negative bacterial strains. The findings support further evaluation of these compounds as potential lead structures for antibacterial development, particularly in the context of the continuing need for new agents against resistant pathogens.

Investigation of the Efficiency of Peanut Shells as a Biosorbent for the Removal of Ni (II) Ions from the Galvanic Wastewater in Accordance with Circular Economy Principles

2026-09-02T13:22:38+00:00

Water pollution by heavy metal ions poses a significant environmental problem due to their toxicity, persistence, and potential for accumulation in living organisms. Nickel requires particular attention, as it can occur at elevated concentrations in galvanic industry wastewater. Therefore, the aim of this study was to investigate the efficiency of peanut shells as a natural and readily available biosorbent for the removal of Ni(II) ions from galvanic wastewater within the context of circular economy principles. As an agricultural residue, peanut shells represent a potentially economically and environmentally acceptable alternative to conventional adsorbents.

The experimental study examined the influence of key process parameters on adsorption efficiency, primarily wastewater pH, initial Ni(II) concentration, and biosorbent mass. Based on the obtained results, optimal process conditions were determined and adsorption efficiency was evaluated. The adsorption equilibrium was analysed using the Freundlich and Langmuir isotherm models.

The results demonstrated that peanut shells can serve as low-cost biosorbents for the efficient removal of Ni(II) ions from galvanic wastewater. For both samples, the highest removal efficiency was achieved at pH 6 and an initial Ni(II) concentration of 1000 mg L^-1. The Freundlich adsorption isotherm model showed good agreement with the experimental data, with R²>0.9 for Sample 1 and R²>0.8 for Sample 2. The comparable adsorption performance of the two samples indicates that peanut-shell residue previously used can be further valorised as a biosorbent for Ni(II) removal. The multiple use of the same biomass residue contributes to waste reduction and improved resource utilisation, supporting the potential application of peanut shells within a circular economy approach.

Design of New Alkylphenols with Theoretical Values of their Water/ Octanol Partition Coefficients

2026-09-04T12:54:03+00:00

In our previous work, we established a predictive QSPR (Quantitative Structure-Property Relationship) model for the water/octanol partition coefficient, based on electronic energy (E_T), LUMO (Lowest Unoccupied Molecular Orbital) energy, and the energy gap (ΔE_gap). This model has been shown to be suitable for predicting properties of new alkylphenols falling within its applicability domain, with a 5% risk level. The present study, which builds upon that earlier work, aims to expand the database for this family of compounds by designing new alkylphenols that fit within the established model's applicability domain and by predicting their water/octanol partition coefficients. In this context, we designed a series of forty-two (42) new alkylphenols. All these molecules were optimized at the B3LYP/6-311G(d,p) level of theory, and vibrational frequencies were calculated at the same level. Water/octanol partition coefficients calculated for these molecules using the model indicate that they are all lipophilic. The formation reaction for these new compounds proceeds spontaneously, accompanied by heat release and a decrease in disorder.

Fruit Waste Extract-Modified Zeolite as a Sustainable Sorbent for Cu (II) Removal from Aqueous Solutions

2026-09-07T12:19:11+00:00

Natural zeolites may exhibit certain limitations in the adsorption of metal ions from aqueous solutions due to their heterogeneous mineral composition, variable content of exchangeable extra-framework cations, and the presence of impurities. In this study, natural clinoptilolite zeolite was modified using an ethanolic extract derived from lemon peel waste to evaluate the effect of this sustainable modification approach on Cu(II) adsorption from synthetic aqueous solutions. Batch adsorption experiments were conducted using 50 mL of Cu(II) solution at 300 rpm for 60 min. A one-factor-at-a-time (OFAT) approach was applied to investigate the effects of initial solution pH (2–6), initial Cu(II) concentration (10–100 mg/L), and adsorbent dosage (500-2500 mg) for both unmodified natural zeolite (UN-zeolite) and fruit-waste-extract-modified zeolite (FWEM-zeolite). All experiments were performed in triplicate. At pH 6, complete Cu(II) removal (100%) was achieved using UN-zeolite, whereas FWEM-zeolite reached a removal efficiency of 84.37%. At initial Cu(II) concentrations of 10 and 50 mg/L, complete removal was achieved using UN-zeolite, whereas FWEM-zeolite achieved removal efficiencies of 87.97% and 80.91%, respectively. Increasing the UN-zeolite dosage resulted in complete Cu(II) removal at 2000-2500 mg, while FWEM-zeolite reached its maximum removal efficiency of 91.9% at a dosage of 1000. Overall, modification with lemon peel waste extract did not improve Cu(II) removal compared with the unmodified natural zeolite under the investigated conditions. Nevertheless, FWEM-zeolite maintained high Cu(II) removal efficiency, particularly at elevated initial concentrations, demonstrating the potential of fruit-waste-derived extracts as sustainable modifying agents for natural mineral adsorbents

Molecular Design and DFT/TD-DFT Investigation of N3 Derived Ruthenium(II) Azopyridine Complexes for Dye-sensitized Solar Cells

2026-09-11T08:03:41+00:00

Renewable energy technologies are increasingly important for meeting rising global energy needs while reducing reliance on polluting fossil fuels. Among them, Dye-Sensitised Solar Cells (DSSCs) are attractive third-generation photovoltaic devices because they are inexpensive to produce, relatively simple to fabricate, and can perform well under low-light conditions. Their efficiency, however, depends largely on the sensitising dye used to capture sunlight and transfer electrons.

This study explores ways to improve the well-known ruthenium-based N3 dye. Drawing on the structures of N3 and the α- and β-isomers of RuCl₂(azpy)₂, eight new ruthenium(II) complexes, labelled D1–D8, were designed by modifying bipyridine, azopyridine, NCS, and chloride ligands. Their structural, electronic, optical, and photovoltaic properties were evaluated using DFT and TD-DFT calculations at the B3LYP/LANL2DZ level.

The analysis examined molecular geometry, frontier orbitals, energy gaps, reactivity indicators, absorption spectra, and parameters related to electron injection into TiO₂. Among the eight proposed dyes, D1 and D7 showed the most promising results. Both absorb strongly in the visible region, provide favourable conditions for electron injection into TiO₂, and display electronic characteristics that could support efficient charge separation. Importantly, these improvements were achieved without substantially altering the coordination environment around the ruthenium centre.

Overall, the findings suggest that ruthenium complexes containing azopyridine ligands could be effective sensitisers for DSSCs. They also offer useful theoretical guidance for designing improved ruthenium-based dyes. Experimental synthesis and photovoltaic testing will be needed to confirm these predictions.

Integrated Elemental and Mineralogical Characterization of Petroleum System Sediments in the Central Niger Delta Basin

2026-09-11T11:19:07+00:00

This study presents an integrated elemental and mineralogical characterisation of petroleum-system sediments from Wells 13 and 14 in the Abua-Odual area of the central Niger Delta Basin, southern Nigeria, with an emphasis on sediment composition, provenance, reservoir quality, and basin evolution. Drill-cutting samples (6 samples from Well 13 and 8 samples from Well 14) collected from depths of 8,000–15,000 ft were investigated using inductively coupled plasma–optical emission spectrometry (ICP–OES) for major-element composition and X-ray diffraction (XRD) for mineralogical characterisation. The elemental results demonstrate considerable vertical variability in both wells. Well 13 is characterised by relatively elevated Fe and Ca concentrations, with Ca reaching 34,000 mg/kg at 11,000 ft, whereas Well 14 exhibits pronounced elemental variability and exceptional Na enrichment, reaching 57,000 mg/kg at 12,000 ft. Pearson correlation analysis reveals a strong positive relationship between Al and K in Well 13 (r = 0.93), suggesting their association with aluminosilicate mineral phases. Well 14 displays stronger positive relationships among Al, Mg, Ca, and K, indicating greater integration among the principal mineral-forming elements. Mineralogical analysis confirms quartz as the dominant phase in both wells, with abundances ranging from 50–88 wt% in Well 13 and 24–81 wt% in Well 14. Kaolinite, albite, orthoclase, and illite constitute subordinate mineral phases, with Well 14 exhibiting greater mineralogical variability. In Well 13, quartz shows a strong negative correlation with albite (r = −0.92), while a similar inverse quartz–albite relationship occurs in Well 14, indicating systematic changes between quartz-rich and feldspar-rich intervals. The integrated elemental and mineralogical characteristics indicate predominantly siliciclastic sedimentation accompanied by variations in sediment supply, mineralogical maturity, and post-depositional modification. Well 13 represents a comparatively quartz-rich and mineralogically mature succession, whereas Well 14 exhibits greater geochemical and mineralogical heterogeneity. The findings demonstrate the usefulness of integrated elemental and mineralogical datasets for understanding sediment provenance, reservoir heterogeneity, and petroleum-system evolution in the central Niger Delta Basin.

Mechanochemical Green Synthesis, Characterization and Antibacterial Evaluation of the N-Hydroxy-4-Phenylpyridine-2-Carboxamide Ligand and Its Mononuclear Mn (II), Co (II), Ni (II) and Cu (II) Complexes

2026-09-14T12:00:00+00:00

A solvent-minimised mechanochemical approach was developed for the synthesis of N-hydroxy-4-phenylpyridine-2-carboxamide (HL) and its Mn(II), Co(II), Ni(II) and Cu(II) complexes. The ligand was designed as a multifunctional tridentate N, O′, O donor through the pyridyl nitrogen and the two oxygen atoms of the hydroxamate group. The ligand and its metal complexes were characterized by elemental analysis, FT-IR, UV–Visible spectroscopy, magnetic susceptibility and electron paramagnetic resonance spectroscopy. Spectroscopic changes included shifts in the hydroxamate carbonyl and N–O stretching bands and changes in pyridyl nitrogen vibrations upon coordination. The proposed [ML₂] formulation provides an N₂O₄ donor environment around the metal centre. This is consistent with approximately octahedral geometries for Mn(II), Co(II) and Ni(II), and a Jahn–Teller-distorted octahedral geometry for Cu(II) complexes. The mechanochemical route reduced solvent consumption and reaction time compared with conventional solution synthesis. The antibacterial activities of HPPCA and its Mn(II), Co(II), Ni(II) and Cu(II) complexes were evaluated against representative Gram-positive and Gram-negative bacterial strains. The observed activity order was as follows: [CuL2] ˃ [NiL2] ˃ [CoL2] ˃ [MnL2] ˃ HPPCA (free ligand). The study provides a systematic platform for investigating the relationships among metal-ion identity, coordination environment, spectroscopic properties, and antibacterial activity in hydroxamate-based transition-metal (II) complexes.

Comparative Study of the Essential Oils from the Leaves, Trunk Bark and Roots of Erythrophleum ivorense A. Chev. (Fabaceae), Collected in Agboville (Côte d’Ivoire)

2026-09-16T11:45:43+00:00

Erythrophleum ivorense A. Chev. (Fabaceae) is a medicinal tree widely used in traditional African medicine, with different plant parts employed for various therapeutic purposes. Although previous phytochemical investigations have mainly focused on its non-volatile constituents, the volatile fraction remains poorly characterised. In particular, comparative information on the essential-oil composition of the leaves, trunk bark, and roots is limited, despite the potential for organ-specific chemical variation.

The aim of this study was to determine and compare the chemical composition of essential oils extracted from the leaves, bark and roots of Erythrophleum ivorense A. Chev. (Fabaceae), and to discuss the pharmacological potential of their major constituents. Samples were collected in September 2025, during the rainy season, from three mature trees in the Agboville Protected Forest (Agnéby-Tiassa region, south-east Côte d’Ivoire). The essential oils were obtained by hydrodistillation using a Clevenger-type apparatus (European Directorate for the Quality of Medicines & HealthCare, 2019, General Chapter 2.8.12), and then analysed by GC/MS and GC/FID (Agilent 7890B GC system) to identify the constituents on the basis of retention indices and comparison of mass spectra. Hydrodistillation yielded 0.084 per cent (leaves), 0.036% (trunk bark) and 0.062% (root bark). GC/MS and GC/FID analyses identified 54 compounds in the leaves, 47 in the trunk bark and 51 in the root bark. Hydrocarbon sesquiterpenes dominated all three oils, with β-caryophyllene as the major compound (18.34% in the leaves, 24.67% in the trunk bark, 20.18% in the root bark). Oxygenated monoterpenes accounted for 20.56% of the leaf oil, 15.26% of the trunk-bark oil and 24.52% of the root-bark oil; the corresponding 1,8-cineole contents were 12.47%, 5.83% and 8.34%, respectively. To the best of our knowledge, this is the first report on the composition of the essential oils from the leaves, bark and roots of E. ivorense. The range of compounds detected may help to explain the plant’s pharmacological potential and may guide further phytochemical research.

Variability of Coal Quality in Tuzla Canton, Bosnia and Herzegovina: Implications for Energy Efficiency and Energy Transition

2026-09-18T09:24:25+00:00

Coal remains an important component of the electricity system of Bosnia and Herzegovina, while the country is simultaneously undergoing a gradual energy transition toward lower-carbon technologies. This study evaluates the quality of coal from major mining areas in Tuzla Canton using laboratory results for composite samples from Kreka, Đurđevik and Banovići. The principal indicators were total moisture, ash, combustible matter and lower heating value (LHV). Eight mining areas were compared using five analytical samples per area, giving 40 observations for the primary statistical analysis. An additional 15 observations from five Banovići separation products were evaluated separately. Marked differences were identified among mining areas. Mean LHV ranged from 7,836 kJ/kg at PK Dubrave to 19,794 kJ/kg at Jama Omazići. Lignite from the Kreka area had substantially higher mean total moisture than the analysed brown coals, while several brown-coal areas were constrained by high ash content. Across the 40 primary observations, LHV showed a moderate negative correlation with total moisture (r = -0.43) and with ash (r = -0.37). A multiple linear model using moisture and ash explained approximately 98.4% of the observed LHV variation, although the small number of samples and the compositional nature of the variables require cautious interpretation. The findings demonstrate that coal reserves alone are insufficient for evaluating the future role of coal: fuel quality, preparation efficiency, plant efficiency, emissions intensity, economic performance and regulatory conditions must be considered together. The results support a transition strategy that combines improved coal characterisation and combustion efficiency in the medium term with accelerated deployment of renewable generation, storage, grid modernisation and just-transition measures.