Chemical Science International Journal

Characterization of the Bir-Hâmiya Hydrothermal Spring, Ouaddaï Region, Chad

Thu, 29 Oct 2026 00:00:00 +0000

Bir-Hâmiya thermal spring, located in Ouaddaï Province, eastern Chad, is a hydromineral resource that local communities have used for therapeutic purposes for generations, although it remains poorly documented in the scientific literature. This study characterizes its physicochemical properties and assesses their relevance for thermalism. Four sampling campaigns were conducted between January 2025 and May 2026. The parameters analysed were temperature, pH, electrical conductivity, total dissolved solids, total hardness, major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃⁻, Cl⁻, SO₄²⁻), and NO₃⁻, NO₂⁻, F⁻, Mn²⁺, Fe²⁺, and NH₄⁺. Data were interpreted using descriptive statistics, Piper, Stiff, Schoeller, and Gibbs diagrams, ionic ratios, and a correlation matrix. The results indicate a hot (48.6 °C), moderately mineralized thermal water with near-neutral pH and a calcium–magnesium–bicarbonate (Ca–Mg–HCO₃) facies. Hydrochemical evolution is controlled by water–rock interaction and weathering of minerals of the Ouaddaï crystalline basement. Mean fluoride (2.15 mg/L) and manganese (0.23 mg/L) concentrations exceed WHO guideline values. These characteristics give the spring potential for thermalism and crenotherapy: the high temperature and the Ca–Mg–HCO₃ facies may contribute to its therapeutic value, notably in rheumatological and dermatological conditions.

Production of a Composite Organomineral Fertilizer Based on Plant Residue and Phosphorite Raw Material

Fri, 30 Oct 2026 00:00:00 +0000

Background: Mineralized mass (MM), a low-grade by-product of phosphorite beneficiation, contains phosphorus with low laboratory solubility.

Aims: To characterise the physicochemical composition of a composite organomineral fertiliser obtained by processing mineralized mass (MM), a by-product of phosphorite ore beneficiation, with plant residue (PR) oxidised by hydrogen peroxide in the presence of sulfuric acid, and to determine the optimal component ratios.

Study Design: Laboratory experimental study; six MM:PR mass ratios were tested at four H₂O₂:H₂SO₄ molar ratios (24 experimental points, each in triplicate).

Place and Duration of Study: Institute of General and Inorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, Uzbekistan, 2025–2026.

Methodology: PR was oxidised with 10% H₂O₂ in the presence of H₂SO₄ (H₂O₂:H₂SO₄ molar ratios 1:0.1, 1:0.2, 1:0.4 and 1:0.5) and mixed with MM at MM:PR mass ratios from 100:40 to 100:200. The product was neutralised with ammonia water, dried and granulated. The composition was determined by gravimetric and titrimetric analysis (n = 3; SD ≤ 0.5%). Trilon B-soluble P₂O₅ (% of total P₂O₅) was used as an operational laboratory index of phosphorus solubility.

Results: MM contained 14.43% P₂O₅, of which only 9.11% was Trilon B-soluble. As the PR share increased, the organic matter content of the product rose from 26.08 to 55.97%, the humic acid content from 3.94 to 17.62% and Trilon B-soluble P₂O₅ from 38.78 to 86.65% of total P₂O₅, while total P₂O₅ fell owing to dilution. A higher H₂SO₄ share increased this index at every MM:PR ratio. At the recommended ratio (MM:PR = 100:150; H₂O₂:H₂SO₄ = 1:0.5) the product contained 4.22% total P₂O₅ (72.51% Trilon B-soluble), 49.94% organic matter and 13.18% humic acids.

Conclusion: Oxidised plant residue combined with sulfuric acid increased the Trilon B-soluble fraction of phosphorus in substandard mineralized mass; however, in the present design the effect of the organic component cannot be separated from that of the acid. To our knowledge, this is the first systematic data set of this kind for mineralized mass. The recommended ratio is a screening-level choice; control experiments, contaminant analysis (F, Cd, Pb, As) and pot and field trials are required before any agronomic claim.

Physicochemical and Technological Principles of Potassium Hydroxide Production by Causticization of Potassium Carbonate with Lime Milk

Sat, 31 Oct 2026 00:00:00 +0000

The physicochemical and technological principles underlying the production of potassium hydroxide through the causticisation of potassium carbonate with lime milk were studied. The influence of the K₂CO₃ solution concentration, the concentration of lime milk, and the Ca(OH)₂ dosage on the composition of the liquid and solid phases, the KOH yield, and the settling, filtration and washing characteristics of the precipitate was examined. Conversion was carried out at temperatures up to 95 °C for 90 min. The results showed that the yield of potassium into the target product under the studied conditions was 76.74–85.19%. X-ray phase analysis of the washed precipitates showed a predominance of CaCO₃ (91.04–94.50%) with a residual Ca(OH)₂ content of 5.50–8.96%. The rheological characteristics of the suspensions were examined in the range of 20–80 °C at a KOH content in the liquid phase of 5–30% and an S:L ratio of 1:2 to 1:4. The density of the suspensions varied from 1.136 to 1.534 g/cm³, and the viscosity from 2.42 to 9.68 cP. Three-stage washing was found to be suitable for the near-complete washing of the precipitate; after the third stage, KOH was no longer detected in the precipitate, and the K₂CO₃ content decreased to 0.07–0.26%. Subsequent evaporation of the filtrate can increase the KOH concentration to 73.81%. The results obtained provide a basis for the design of a resource-saving process flow sheet for the production of liquid and concentrated potassium hydroxide with the return of wash water to the process.

Investigation of the Essential oil Composition of Elaeagnus angustifolia L. Flowers

Mon, 09 Nov 2026 00:00:00 +0000

Elaeagnus angustifolia L. is an aromatic plant whose floral volatile composition may vary with geographical origin, developmental stage and environmental conditions. This study investigated the essential oil obtained from flowers collected in the Republic of Karakalpakstan, Uzbekistan, in May 2025. The flower material was subjected to hydrodistillation using a Clevenger-type apparatus, and the resulting essential oil was analysed by gas chromatography–mass spectrometry. The essential-oil yield was approximately 0.05–0.10% relative to the initial plant material. Three selected chromatographic signals were evaluated by mass-spectral library comparison. Peaks at retention times of 5.186, 8.848 and 12.399 min were tentatively assigned to ethyl (Z)-cinnamate, 2-pentadecanone, 6,10,14-trimethyl-, and E-11-hexadecenoic acid ethyl ester, respectively. The corresponding software-reported probability values were 51.990, 45.280 and 8.890. These assignments represent aromatic cinnamate ester, aliphatic ketone and unsaturated fatty acid ester classes. Because identification was based principally on mass-spectral library comparison and authentic reference standards were not analysed, the reported compounds should be regarded as tentative. The findings provide a preliminary chemical fingerprint of the volatile fraction of E. angustifolia flowers collected under the investigated regional conditions. Further confirmation using defined retention-index comparisons, authentic standards and quantitative chromatographic analysis is required for definitive characterisation of individual constituents and their relative abundance.