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

Le Thi Thuy Duong, Tran Ngoc Bao Luan, Tran Thi Van Trinh — Wed, 29 Jul 2026 00:00:00 +0000

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.

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

Corneille Bakouan, Césard Millogo, Regie Dimanche Ouédraogo, Issan Ki — Tue, 11 Aug 2026 00:00:00 +0000

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

Fatogoma Diarrassouba, Kafoumba Bamba, Nahossé Ziao — Thu, 20 Aug 2026 00:00:00 +0000

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

Sat, 22 Aug 2026 00:00:00 +0000

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

Wed, 26 Aug 2026 00:00:00 +0000

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

Yasobanta Das — Thu, 27 Aug 2026 00:00:00 +0000

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

Fri, 28 Aug 2026 00:00:00 +0000

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

Mon, 31 Aug 2026 00:00:00 +0000

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

Evans Ochieng Odhiambo, Alloys Osano, Meshack Sitati — Fri, 04 Sep 2026 00:00:00 +0000

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)

Wed, 09 Sep 2026 00:00:00 +0000

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

Wed, 09 Sep 2026 00:00:00 +0000

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.