Chemical Science International Journal

Estimation of Lead Content in Aqueous Solution Using pH-metric Method

Abhijit Mallick — 2026-08-06

Lead estimation is widely used in environmental monitoring, industrial quality control, and public health protection. Conventional techniques for estimating lead concentrations, such as atomic absorption spectroscopy (AAS), inductively coupled plasma–optical emission spectroscopy (ICP–OES), inductively coupled plasma–mass spectrometry (ICP–MS), UV–visible spectrophotometry, and electrochemical methods, provide accuracy and sensitivity; however, these methods are relatively expensive. Furthermore, sample preparation for these methods requires the maintenance of high purity. Complexometric titration is another method for estimating lead content. However, its results may be less reliable because of parallax errors. The present work proposes a novel pH-metric technique for estimating lead content in a given lead sample solution. The method is based on the pH-metric titration of a lead nitrate solution using disodium hydrogen phosphate as the titrant. During titration, various chemical reactions occurring between plumbous ions (Pb²⁺) and hydrogen phosphate ions (HPO₄²⁻) are believed to be responsible for the continuous change in pH. The resulting pH curve shows four distinct regions. Initially, the pH decreases and then remains stable up to a certain volume of added titrant. This region is referred to as the stabilisation volume. The stabilisation volume is a characteristic parameter representing the volume of titrant over which the pH remains nearly constant. Experimental observations reveal that the stabilisation volume depends on the concentration of the titrant used. As the titrant concentration increases, the stabilisation volume decreases. Based on the observed pH profile during the titration process, possible chemical reaction mechanisms are proposed. A unique feature of this method is that the nature of the pH curve predicts the possible chemical reactions occurring during the titration process. This novel pH-metric approach does not require an external indicator and is believed to offer a promising alternative for lead estimation.

Blending of Polyethylene Pyrolysis Oil and Natural Rubber Latex as Binder for Water Resistant Emulsion Paint

Sunday A. Osemeahon — 2026-08-08

Water-based paint, also called emulsion paint, is a type of paint that uses water as its solvent during production. The binder, typically made of acrylic or polyvinyl acetate, acts as a film-forming agent by holding the pigments and other additives together. In this study, emulsion paint was formulated using waste polyethylene pyrolysis oil (PEPO) and natural rubber latex (NRL) as binders. Polyethylene pyrolysis oil was blended with natural rubber latex at different ratios, beginning with 10% PEPO in a 90% NRL solution at 30 °C. The blended binders were mixed using a glass rod for 30 minutes. This process was repeated for PEPO concentrations of 20%, 30%, 40%, 50%, and 60% (i.e. 10%–60%), and the resulting blends were analysed and compared with other binders. Each blend ratio was used in the paint formulations and coded as PA, PB, PC, PD, PE, and PF. The paints were characterised and compared with the standard. Most of these paints were within the standard range. Paint E (PE) performed best because it passed all tests within the standard range, with a viscosity of 1400 mPa·s, density of 1.39 g, pH of 7.6, dry-to-touch time of 23 minutes, and dry-to-hard time of 80 minutes; opacity, adhesion, resistance to blistering, flexibility, tackiness, water resistance, and stability were also satisfactory. This indicates its suitability for both exterior and interior applications. The effects of concentration on viscosity, density, turbidity, refractive index, pH, elongation at break, moisture uptake, melting point, and water solubility were studied for the PEPO/NRL binder to assess its suitability. FTIR, XRD, SEM, TGA, and DTA were employed to characterise the binder. The investigation revealed properties associated with conventional emulsion paint in the formulated PEPO/NRL binder-derived emulsion paint, including drying time, moisture uptake, and water solubility.

Proximate and Mineral Safety Index of Hunteria umbellata Seeds

Oluwagbenle H. N — 2026-08-13

Hunteria umbellata is widely used in African traditional medicine for the management of diabetes mellitus, gastrointestinal disorders, obesity, inflammatory conditions, and other ailments. This study evaluated the nutritional quality of Hunteria umbellata to establish its suitability as a potential food source. Dried seeds of Hunteria umbellata were processed into flour and subjected to proximate and mineral analyses using standard analytical methods. Proximate parameters, including moisture, ash, crude protein, crude fat, crude fibre, and carbohydrate contents, were determined. Mineral analysis focused on essential macro- and microelements; mineral ratios and the mineral safety index were also determined. The proximate composition revealed that Hunteria umbellata seeds contained low moisture (8.10 ± 0.03%) and appreciable levels of crude fat (24.03 ± 0.05%), carbohydrate (33.34 ± 0.03%), crude protein (17.42 ± 0.03%), crude fibre (9.06 ± 0.05%), and ash (8.05 ± 0.03%), indicating considerable nutritional value and good storage stability. Mineral analysis showed the presence of essential elements, with potassium being the most abundant (610.72 mg/100 g), followed by phosphorus (218.52 mg/100 g) and calcium (181 mg/100 g), while selenium was the least abundant (0.03 mg/100 g). The low Na/K ratio and high K/Na ratio suggest potential benefits for maintaining cardiovascular health and electrolyte balance, particularly in relation to the control of high blood pressure. Hunteria umbellata seeds also possess substantial nutritional potential and contain bioavailable minerals that are essential for human nutrition.

Effect of Sapropel Dispersion on the Colloidal-Chemical Properties and Structure of Urea-Sapropel Heterogeneous Dispersion Systems

Shamshod Fatilloyev — 2026-08-17

Aims: The aim of this study was to determine the effects of sapropel dispersion on the colloidal-chemical, rheological, and structural properties of a heterogeneous urea-sapropel dispersion system and to substantiate their role in controlled nitrogen release.

Study Design: An experimental laboratory study was conducted to evaluate the colloidal-chemical, rheological, and structural properties of a heterogeneous urea-sapropel dispersion system.

Place and Duration of Study: The study was conducted at Bukhara State Technical University and Navoi State University of Mining and Technologies from 20 January to 1 June 2026.

Methodology: Urea-sapropel granules containing sapropel of different particle sizes were prepared. Dried sapropel was separated into six fractions within the 0.063-1.000 mm range and incorporated into urea at mass ratios of 100:1-100:10. The granules were produced using a melt-granulation method. The dissolution time of the granules in water, crystallisation temperature, and density and viscosity of the melts were determined. Samples prepared using the 0.25 mm sapropel fraction were further characterised by scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS) and Brunauer-Emmett-Teller/Barrett-Joyner-Halenda (BET-BJH) analyses to evaluate their morphological, elemental, and surface-adsorption properties.

Results: Increasing the sapropel content and decreasing the particle size increased the dissolution time of the granules and decreased their crystallisation temperature. At a 100:10 mass ratio, the dissolution time was 214.62 s for the 0.063 mm fraction and 193.28 s for the 0.75-1.00 mm fraction. The corresponding crystallisation temperatures were 110.88 and 121.57 °C, respectively. For the 0.25 mm sapropel fraction at a 100:5 mass ratio, the melt viscosity was 2.491 mPa·s at 130 °C, and the temperature range of 138-142 °C was identified as suitable for granulation. The 100:5 sample exhibited a specific surface area of 1.10 m²/g, a total pore volume of 0.0021 cm³/g, and an average pore diameter of 12.5 nm.

Conclusion: Control of sapropel particle size and content enabled regulation of the dissolution, crystallisation, and rheological properties of urea-sapropel granules. The 0.25 mm sapropel fraction, a 100:5 urea-to-sapropel mass ratio, and a temperature range of 138-142 °C were identified as suitable conditions for the granulation process. These findings support the feasibility of using local sapropel to produce organo-mineral nitrogen fertilisers with controlled dissolution characteristics.

Examination of a Novel Hydrazone Derivative as a Corrosion Inhibitor of Mild Steel Exposed to Oil Field Water

Aniedi E. Nyong — 2026-08-18

A novel hydrazone derivative, [(1E,8E)-9-(3-bromo-4-methoxyphenyl)-1,8-bis(2-(2,4-dinitrophenyl) hydrazone)-3,3,6,6-tetramethyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine], with the molecular formula C₃₆H₃₆BrN₉O₉, was evaluated as a corrosion inhibitor for mild steel in oil-field water collected from the Niger Delta region of Nigeria. The oil-field water was characterised for pH, conductivity, total dissolved solids, dissolved oxygen, and chloride and sulphate ion contents. The medium was slightly acidic (pH 6.8) and had a conductivity of 54,000 μS/cm, indicating a highly conductive corrosive environment. Corrosion rate and inhibition efficiency were determined by weight-loss measurements as functions of inhibitor concentration, exposure time, and temperature. The maximum inhibition efficiency during the 30-day exposure test was 35.11% at 10 ppm. Inhibition efficiency decreased as the temperature increased above room temperature, whereas the corrosion rate increased. Adsorption data were evaluated using the Langmuir isotherm. The reported enthalpy and entropy of adsorption were −47.82 kJ mol⁻¹ and −170.09 J mol⁻¹ K⁻¹, respectively. The reported standard Gibbs free energies of adsorption at 303, 313, 323, and 333 K were −99.65, −101.05, −102.78, and −104.46 kJ mol⁻¹, respectively. These findings demonstrate concentration-dependent inhibition and reduced inhibitor performance at elevated temperatures. The thermodynamic and adsorption results were interpreted as evidence of spontaneous adsorption; however, further electrochemical and surface-characterisation studies are required to confirm the inhibition mechanism.

Eco-friendly Synthesis of Silver Nanoparticles Using Anacardium occidentale Juice and their Deposition on Cellulose Derived from Agricultural Residues

Kakou Charles Kinimo — 2026-08-18

This study investigated an eco-friendly route for producing silver nanoparticles (AgNPs) and immobilising them on cellulose recovered from coconut coir, an agricultural residue. Cellulose was extracted from Cocos nucifera coir through alkali treatment, acid treatment and bleaching. Juice obtained from Anacardium occidentale cashew apples was used as the bioreducing medium for AgNP synthesis from a 5 mM silver nitrate solution under microwave irradiation. The AgNPs, pristine coir fibre cellulose (CFC) and AgNP-coated cellulose nanocomposite (AgNPs@CFC) were characterised using ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. AgNP formation was indicated by a visible colour change and a characteristic absorption maximum at 432 nm. The infrared spectra supported the effective removal of lignin and partial removal of hemicellulose during cellulose extraction and showed changes associated with AgNP deposition. X-ray diffraction confirmed the retention of the cellulose I crystalline phase after nanoparticle deposition and identified a characteristic silver reflection at 46.44°. The crystallinity indices of CFC and AgNPs@CFC were 63% and 64%, respectively. Scanning electron micrographs showed a fibrous cellulose morphology and well-dispersed AgNPs on the cellulose surface. The findings demonstrate a practical green synthesis approach that combines cashew apple juice and coconut coir cellulose for agricultural-waste valorisation. Application-specific testing is required before the nanocomposite can be validated for pollutant removal, antimicrobial use or packaging.

Factors Controlling Groundwater Mineralization in Korhogo, Côte d’Ivoire: A Statistical Approach

Kpan Oulai Jean-Gautier — 2026-08-18

Groundwater is a major drinking-water source in northern Côte d’Ivoire, and understanding the processes governing its dissolved mineral content is important for groundwater protection. This study investigated the mechanisms controlling groundwater mineralisation in the Korhogo department using hydrochemical and statistical approaches. Forty-seven groundwater samples were examined through descriptive statistics, hydrochemical facies classification using a Piper diagram, and standardised principal component analysis. Field and laboratory measurements covered the physicochemical variables used to characterise the sampled groundwater. The groundwater was generally acidic and weakly mineralised, with a mean pH of 6.19 and mean electrical conductivity of 123.77 µS/cm. Four hydrochemical facies were identified: calcium–magnesium bicarbonate (56.76%), calcium–magnesium chloride–sulphate (29.73%), sodium–potassium bicarbonate (8.10%), and sodium chloride (5.41%). The first four principal components explained 75.27% of the total variance. The multivariate results indicate that groundwater chemistry is mainly associated with residence time and water–rock interactions, particularly silicate mineral hydrolysis, together with soil leaching and weathering processes. Secondary statistical associations indicate localised anthropogenic influence, especially where nitrogen species and potassium are involved. Overall, the results suggest that natural geogenic processes dominate groundwater mineralisation in Korhogo, while anthropogenic inputs contribute to spatial variability in selected locations. These findings support continued groundwater-quality monitoring in areas affected by agricultural and domestic activities.

GC-MS Phytochemical Analysis of Smokeless Tobacco (SNUFF) Used in Port Harcourt

Kuhuodu, Tryphaena Ojei — 2026-08-19

Smokeless tobacco (snuff) is consumed in different forms and may contain chemically diverse constituents that vary with source, processing and additives. This preliminary study characterised the phytochemical profile of an aqueous extract of a commercially available snuff sample obtained from Mile 3 Market, Port Harcourt, Rivers State, Nigeria. Forty grams of ground snuff was extracted with 400 mL of distilled water for 48 h, filtered and concentrated in a water bath at 60°C. The extract was further processed and analysed by gas chromatography–mass spectrometry (GC–MS), and tentative compound identification was based on comparison of acquired mass spectra with the National Institute of Standards and Technology spectral library. The analysis detected 20 major chromatographic peaks between retention times of 3.149 and 16.804 min. Reported constituents included nicotine- and anabasine-related pyridine derivatives, long-chain hydrocarbons and alcohols, fluorinated esters, organosilicon derivatives, phenolic compounds and a low-abundance arsenous acid ester. The highest reported relative abundance was for hexacosyl trifluoroacetate (17.17%), followed by 1-heptacosanol/pentadecafluorooctanoic acid ester (13.30%), 17-pentatriacontene (13.29%) and a nicotine-related pyridine derivative (10.86%). Alkaloid and hydrocarbon fractions were prominent in the analysed extract. Because the study examined a single sample and compound assignments were based on spectral library matching, the findings should be regarded as preliminary and as representative of the analysed extract under the applied conditions rather than of all snuff products used in Port Harcourt.

Heavy Metal Speciation in Sediments of the Chari and Logone Rivers Near the City of N’Djamena, Chad

Mbailaou N. Goussou — 2026-08-21

Sediments are a major sink and potential secondary source of potentially toxic metals in freshwater ecosystems, and their environmental risk depends not only on total metal concentrations but also on chemical speciation and mobility. During this study, the pH ranged from 5.99±0,01^a to 7.33±0,01^c in the first sampling series in June, whilst it ranged from 6.92±0,01^a to 6.94±0,01^c in the second. Electrical conductivity ranged broadly from 11.16±0,01^a to 191.10±0,01^c over the two study seasons, with a maximum recorded in the second series in December. Residual moisture ranged from 0.50±0,01 to 5.50±0,01^. This study investigated the speciation of Pb²⁺, Cr⁶⁺, Cd²⁺, Mn³⁺, Cu, and Fe²⁺ in sediments collected from the Chari and Logone Rivers near N'Djamena, Chad, at three sites (Logone, Chari, and their confluence) during two contrasting hydrological periods — June 2024 (flood) and December 2024 (recession). Sediment samples were characterised for pH, electrical conductivity, and moisture content, and metal fractionation was assessed using the modified BCR (Bureau Communautaire de Référence) (Community Office Reference) sequential extraction procedure, which partitions metals into exchangeable/acid-soluble, reducible, oxidisable, and residual fractions. Potential mobility and bioavailability were further evaluated using the Risk Assessment Code (RAC). Results showed that Pb was mainly associated with the reducible fraction across all sites, with a substantial labile fraction (up to ~60% in the Logone sediments), indicating high potential mobility. Cr and Cu distributions varied by site, being predominantly reducible or oxidisable in the Logone River but shifting towards oxidisable and residual fractions in the Chari River and at the confluence. Mn was overwhelmingly bound to the reducible fraction (>85% at all sites), reflecting a strong association with Fe–Mn oxyhydroxides, whereas Cd was almost exclusively associated with the oxidisable fraction, pointing to a strong affinity for organic matter and sulfides likely linked to anthropogenic inputs. RAC values confirmed that Pb, Cr, and Cu presented the highest potential ecological risk due to their significant labile fractions. These findings demonstrate that anthropogenic activities substantially influence heavy-metal partitioning in the Chari–Logone system and underscore the need for continuous monitoring and pollution-source management to safeguard this ecologically and socio-economically important watershed.

Synthesis and Preliminary Spectroscopic-Thermal Characterization of a Novel Thiourethane-Group Oligomeric Modifier (TGF-8) Based on Thiourea and Glycerol

Doston M. Murodov — 2026-08-22

Aims: The study aims to synthesise a novel thiourethane-group oligomeric modifier (TGF-8) from thiourea, glycerol and formaldehyde using locally available raw materials, and to determine its molecular structure, molecular mass and thermal behaviour, thereby establishing the scientific basis for its subsequent use as an adhesion- and hydrophobicity-enhancing modifier for sodium liquid-glass adhesives.

Study Design: A two-stage laboratory synthesis (formation of an intermediate dithiourethane, followed by its alkaline polycondensation with formaldehyde), purification by selective liquid–liquid extraction, and structural characterisation by cryoscopic molecular-mass determination, infrared (IR) spectroscopy, gas chromatography–mass spectrometry (GC–MS), and simultaneous differential thermal–thermogravimetric analysis (DTA/TGA). For comparison, an ethylene-glycol-based analogue (TEF-7) was synthesised under identical conditions.

Place and Duration of Study: Department of Chemical Technology, Bukhara State Technical University, Republic of Uzbekistan; the synthesis and the spectroscopic and thermal-analytical work were carried out over the period 2024–2026.

Methodology: Thiourea and glycerol were reacted in a 2:1 molar ratio at 100–110 °C, with ammonia evolution monitored, to give an intermediate dithiourethane. This intermediate was then polycondensed with formalin in an alkaline medium (NaOH) at 120–140 °C to form the target oligomer; the optimal temperature range was established from a series of trials at 110, 120 and 140 °C, with the reaction monitored through the relative viscosity of the reaction mass. The product was separated from unreacted thiourea, formaldehyde and low-molecular-weight fractions by exploiting its selective solubility in dimethyl sulfoxide (DMSO). Molecular mass was determined cryoscopically (GOST 20287-2023 / ISO 3016:2019, triplicate measurements); molecular structure was probed by IR spectroscopy (Shimadzu IRAffinity-1S, 4000–400 cm⁻¹) and GC–MS, while thermal behaviour was examined by DTA/TGA on a LINSEIS synchronous thermal analyser fitted with a K-type thermocouple. The isolated (purified) product yield was not gravimetrically quantified in the present preliminary study and is reported as a target for the companion and follow-up work.

Results: The optimal synthesis temperature was found to be 120–140 °C; below this range methylolation and polycondensation remained incomplete, while above it uncontrolled branching and reduced product solubility were observed. The average molecular mass of the bulk TGF-8 oligomer, determined cryoscopically (colligative, ensemble-averaged measurement), was 2880–3110 g mol⁻¹. IR spectra confirmed hydroxyl (3301.68 and 3184.12 cm⁻¹), amine (1607.11 cm⁻¹), thiourethane [N–C(=S)–O, 1519.66 cm⁻¹] and thiocarbonyl (C=S, 1263.04 cm⁻¹) bands, while the absence of a carbonyl (C=O) absorption is consistent with a thiourethane — rather than urethane — linkage. GC–MS, which is only applicable to volatile, low-molecular-weight species, showed a dominant ion at m/z = 254; this value is far below the cryoscopic average and is interpreted as arising from a low-molecular-weight monomeric/precursor-related species (or an injection-port thermal-decomposition product) rather than from the intact bulk oligomer, and should not be read as the molecular mass of TGF-8 itself. Simultaneous DTA/TGA showed that TGF-8 was thermally stable up to ≈613 °C, above which an exothermic pyrolytic decomposition occurred, the overall mass loss reaching 37.5%; the glycerol-based TGF-8 exhibited a smaller mass loss and higher thermal stability than the ethylene-glycol-based TEF-7 (mass loss 40.5%, decomposition onset ≈556 °C), a difference attributable to the additional hydroxyl group of glycerol.

Conclusion: A new thiourethane-group oligomeric modifier (TGF-8) was successfully synthesised from inexpensive, locally available raw materials and consistently characterised by complementary spectroscopic and thermal methods; full structural elucidation (e.g., by NMR and X-ray diffraction) was not undertaken and remains a target for future work. The oligomer's confirmed thiourethane functionality, cryoscopically determined bulk molecular mass and thermal stability up to industrially relevant temperatures establish it as a promising modifier for silicate-based (liquid-glass) adhesive systems, whose adhesion- and hydrophobicity-enhancing performance is examined in a companion study.