DEPARTMENT OF CHEMISTRY

This study assessed the levels of selected heavy metals and polycyclic aromatic hydrocarbons (PAHs) in suya meat sold in Ugbowo, Benin City, to evaluate its safety for consumers. Ugbowo is a busy area with dense traffic and open-air vending that exposes food to contamination from vehicle emissions, dust, and smoke. Two composite suya samples were analyzed—one obtained from roadside vendors along major express routes and the other from residential areas including 19th Street, BDPA, and Edo Street in Ekosodin. The samples were oven-dried, homogenized, digested with nitric acid and hydrogen peroxide, and analyzed for heavy metals using Atomic Absorption Spectrophotometry (AAS). Polycyclic aromatic hydrocarbons (PAHs) were extracted and determined using Gas Chromatography–Mass Spectrometry (GC–MS). The AAS results showed the presence of lead (Pb), cadmium (Cd), copper (Cu), and nickel (Ni), while chromium (Cr) was below detection in both samples. Concentrations (mg/kg) for express road samples and residential sample were Pb (4.348, 5.002), Cr (<0.001, <0.001), Cu (1.635, 0.654), Cd (4.381, 3.988), and Ni (9.578, 5.230), all exceeding WHO/FAO permissible limits, indicating contamination likely from road dust, metal grills, or fuel combustion. GC–MS analysis revealed that all sixteen priority PAHs were below the detection limit (0.000 mg/kg) in both samples, suggesting minimal formation during grilling. Overall, the results indicate that while PAH contamination was negligible, heavy metal levels were significantly high, posing potential health risks to frequent consumers. The study recommends regular monitoring of street-vended foods and improved hygiene and roasting practices among suya vendors in Benin City.

Atrazine is a widely used triazine herbicide employed for the control of broadleaf weeds in maize cultivation. However, its persistence, toxicity, and mobility in aquatic environments have made it a serious environmental and public health concern. Conventional water treatment methods such as coagulation and chlorination are often ineffective for atrazine removal due to its high stability and low reactivity. In this study, a zinc–aluminum layered double hydroxide (Zn–Al LDH) with a metal composition ratio of 3:1 was synthesized by the co-precipitation method and subsequently modified with disodium ethylenediaminetetraacetate (EDTA) to enhance its surface and structural properties for the adsorption of atrazine from aqueous solution. Adsorption experiments were carried out using a constant atrazine concentration of 100 mg/L and a fixed contact time of 120 minutes, while varying the adsorbent dosage between 0.1 g and 1.0 g. Results showed that the modification of Zn–Al–Cl LDH with disodium EDTA led to an increase in surface area and thermal stability, as evidenced by broadened XRD peaks, new carboxylate and amine bands in FTIR spectra, and improved decomposition temperature in TGA analysis. The modified LDH exhibited higher atrazine uptake compared to the unmodified sample, demonstrating the beneficial effect of EDTA in enhancing surface reactivity and active site availability. This study demonstrates that EDTA-modified Zn–Al LDH is an efficient, low-cost, and thermally stable material for the removal of atrazine from contaminated water. The findings
highlight the potential of modified LDHs as promising adsorbents for environmental remediation and sustainable water treatment applications.

Chemical industries increasingly rely on catalytic processes, and more than 90% of large scale chemical transformations depend on catalysts. Some of the commonly used homogeneous catalysts in Fridel Crafts alkylation reaction are; BF3, H2SO4, HF, AlCl3. Though, readily available at low cost, they have several limitations and these include toxicity, difficulty in separation and recovery and disposal problems. These limitations have intensified the demand for sustainable, efficient, and environmentally benign heterogeneous catalysts. This study focuses on the development of metal-doped coconut-shell biochars as robust heterogeneous catalysts for the Friedel Crafts benzylation of toluene. Biochars derived from the coconut shell produced at different pyrolysis temperatures (350, 400, 450, 500, 600 and 700 °C) were characterized in terms of their physicochemical and textural properties, surface oxygen functional groups and surface morphology using standard methods. The coconut shell biochar (CSB) sample with the optimal textural properties (CSB450) was then co-pyrolysed with Fe³⁺, Zn²⁺, and Fe³⁺/Zn²⁺ ions to produce metal doped biochars (Fe³⁺ - doped, Zn²⁺- doped, and Fe³⁺/Zn²⁺-doped biochar). Central Composite Design (CCD) of the Response Surface Methodology (RSM) was employed to optimize the process variables (metal loading, pyrolysis temperature and pyrolysis time) for the co-pyrolysis reaction. Similarly, RSM was used to optimized the process variables (mole ratio of toluene: benzyl chloride (T:BC), reaction temperature and reaction time) on benzyl chloride conversion to benzylated toluenes with the metal doped biochars. RSM-derived optimal conditions resulted in enhanced specific surface areas of 2098.04 m2 .g-1 for the Fe³⁺-doped biochar, 1721.40 m2 .g-1 for the Zn²⁺-doped biochar, and 2124.5 m2 .g-1 for the Fe³⁺/Zn²⁺-doped biochar. Compared with the pristine biochar (CSB450), the metal doped biochars (MBCs) showed improved physicochemical properties and textural properties. In addition, surface elemental analysis confirmed the successful incorporation of the Fe (10.09%), Zn (5.17%) and Fe/Zn (9.44/6.51%) on the MBCs. The results of the conversion process showed that the reaction temperature, mole ratio, and reaction time significantly affected benzyl chloride conversion with the metal doped biochar. Three novel models were developed for benzyl chloride conversion process. From the models, we predicted optimized process conditions; optimum benzyl chloride conversion of 93% was found for Fe3+/Zn2+ - doped biochar, with values of 87 and 81% for the Fe3+ - and Zn2+ - doped biochar respectively. This research established metal doped coconut shell biochar as an effective, low-cost, and environmentally friendly heterogeneous catalysts for organic transformations, presenting a viable alternative to conventional corrosive and non-recyclable catalysts in industrial alkylation processes.

Chemical industries increasingly rely on catalytic processes, and more than 90% of large scale chemical transformations depend on catalysts. Some of the commonly used homogeneous catalysts in Fridel Crafts alkylation reaction are; BF3, H2SO4, HF, AlCl3. Though, readily available at low cost, they have several limitations and these include toxicity, difficulty in separation and recovery and disposal problems. These limitations have intensified the demand for sustainable, efficient, and environmentally benign heterogeneous catalysts. This study focuses on the development of metal-doped coconut-shell biochars as robust heterogeneous catalysts for the Friedel Crafts benzylation of toluene. Biochars derived from the coconut shell produced at different pyrolysis temperatures (350, 400, 450, 500, 600 and 700 °C) were characterized in terms of their physicochemical and textural properties, surface oxygen functional groups and surface morphology using standard methods. The coconut shell biochar (CSB) sample with the optimal textural properties (CSB450) was then co-pyrolysed with Fe³⁺, Zn²⁺, and Fe³⁺/Zn²⁺ ions to produce metal doped biochars (Fe³⁺ - doped, Zn²⁺- doped, and Fe³⁺/Zn²⁺-doped biochar). Central Composite Design (CCD) of the Response Surface Methodology (RSM) was employed to optimize the process variables (metal loading, pyrolysis temperature and pyrolysis time) for the co-pyrolysis reaction. Similarly, RSM was used to optimized the process variables (mole ratio of toluene: benzyl chloride (T:BC), reaction temperature and reaction time) on benzyl chloride conversion to benzylated toluenes with the metal doped biochars. RSM-derived optimal conditions resulted in enhanced specific surface areas of 2098.04 m2 .g-1 for the Fe³⁺-doped biochar, 1721.40 m2 .g-1 for the Zn²⁺-doped biochar, and 2124.5 m2 .g-1 for the Fe³⁺/Zn²⁺-doped biochar. Compared with the pristine biochar (CSB450), the metal doped biochars (MBCs) showed improved physicochemical properties and textural properties. In addition, surface elemental analysis confirmed the successful incorporation of the Fe (10.09%), Zn (5.17%) and Fe/Zn (9.44/6.51%) on the MBCs. The results of the conversion process showed that the reaction temperature, mole ratio, and reaction time significantly affected benzyl chloride conversion with the metal doped biochar. Three novel models were developed for benzyl chloride conversion process. From the models, we predicted optimized process conditions; optimum benzyl chloride conversion of 93% was found for Fe3+/Zn2+ - doped biochar, with values of 87 and 81% for the Fe3+ - and Zn2+ - doped biochar respectively. This research established metal doped coconut shell biochar as an effective, low-cost, and environmentally friendly heterogeneous catalysts for organic transformations, presenting a viable alternative to conventional corrosive and non-recyclable catalysts in industrial alkylation processes.

The increasing environmental impact of petroleum-based plastics has intensified the global search for renewable, biodegradable alternatives. Agricultural wastes, particularly cassava and potato peels, offer promising sources of starch for sustainable bio plastic production. This study focused on the comparative development and evaluation of bio plastic films produced from cassava peel starch (CPS) and potato peel starch (PPS), using identical formulation and processing conditions. The aim was to assess how starch source influences the physicochemical, mechanical, structural, and biodegradation characteristics of the resulting films. Starch was extracted from the peels through sedimentation and drying processes, and the yield was determined gravimetrically. Bio plastic films were prepared using a standard casting method. The films were characterized for tensile strength, elongation at break, thickness, water absorption, solubility, and biodegradability. Structural and morphological properties were examined through visual observation and scanning electron microscopy (SEM). The results revealed that cassava peel produced a higher starch yield (18.6%) compared to potato peel (14.9%), confirming its superior extraction efficiency. CPS films exhibited greater tensile strength (4.85 MPa) and Young’s modulus (62 MPa), indicating stronger and more rigid films, while PPS films displayed higher elongation at break (32%), signifying greater flexibility. SEM analysis showed smoother and more homogeneous surfaces in CPS films, whereas PPS films exhibited minor surface irregularities. Both films demonstrated good biodegradability under soil burial, with PPS degrading slightly faster due to its higher hydrophilicity. Overall, the findings establish cassava and potato peel starches as viable raw materials for biodegradable film production, promoting waste valorization and environmental sustainability. The higher yield and superior mechanical integrity of cassava peel starch films suggest greater industrial potential, particularly for eco-friendly packaging applications.

Groundwater pollution from improper waste disposal is a growing environmental and publichealth concern in rapidly urbanizing regions such as Benin City, Nigeria. The widespread use of unlined, open dumpsites without leachate control has intensified the infiltration of decomposed organic and inorganic wastes into the subsurface, resulting in gradual deterioration of groundwater quality. This study investigates the influence of leachate from two major dumpsites on groundwater in the Saint Saviour area of Ikpoba-Okha LGA, where a dense population relies heavily on groundwater for domestic use. Groundwater samples were collected at radial distances of 100 m, 200 m, and 300 m from Dumpsite 1 and Dumpsite 2. Leachate samples were obtained directly from seepage zones within the waste cells. All samples were analyzed following APHA standard procedures. In situ measurements included temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), and salinity. Nutrient parameters—nitrate, phosphate, and sulphate— were determined using UV-Vis spectrophotometry. Heavy metals (Pb, Cd, Cr, Ni, Zn, Fe, Cu, Mn, Ca, Mg, Na, K) were analyzed through acid digestion (leachate) and Atomic Absorption Spectrophotometry (AAS). Results were compared with WHO (2017; 2021) and SON (2015) drinking-water standards. Findings indicate a clear spatial gradient of contamination: pollutant concentrations were highest within the dumpsites and decreased with distance. Leachate exhibited extremely high EC (up to 6,888 µS/cm), elevated TDS (>3,300 mg/L), high salinity, and pH values ranging from slightly acidic to neutral (4.70–7.46). These patterns reflect the breakdown of organic refuse, plastics, detergents, metals, and other waste materials. The acidity promotes metal solubility, increasing the mobility of toxic elements. Nutrient concentrations were elevated near the dumpsites, with nitrate (0.481–0.585 mg/L), phosphate (0.429–1.584 mg/L), and sulphate (0.070–1.538 mg/L), indicating early nutrient enrichment from sewage, food waste, and detergents. Though below WHO limits, these values suggest a potential progression toward eutrophication and long-term ecological stress. Heavy metals provided the most significant evidence of contamination. Lead (Pb) reached 0.70 mg/L—over sixty times the WHO guideline of 0.01 mg/L. Cadmium (0.01 mg/L), chromium (0.10 mg/L), and nickel (0.06 mg/L) exceeded or approached recommended limits. Their sources include batteries, electronics, metal scraps, plastics, and paints commonly found in municipal waste. These metals are persistent, nonbiodegradable, and pose severe health risks such as neurological damage (Pb), renal dysfunction (Cd), carcinogenicity (Cr⁶⁺), and respiratory disorders (Ni). Iron levels (up to 2.50 mg/L) exceeded aesthetic limits, affecting taste and appearance of water. Overall, results show that the shallow aquifers of Saint Saviour, characterized by the permeable sandy soils of the Benin Formation, are highly vulnerable to leachate migration. The findings align with previous studies highlighting groundwater deterioration around unregulated dumpsites in developing urban centers. This study underscores the urgent need for improved waste-management policies, groundwater monitoring, and the prevention of prolonged human exposure to contaminated water sources.

This study evaluated the physicochemical and microbiological quality of borehole water from five student-dominated areas in Ekosodin Village, Benin City, to assess compliance with World Health Organization (WHO) and Nigerian Industrial Standard (NIS)
guidelines. Standard analytical methods were employed to determine key physicochemical parameters, major ions, heavy metals, and microbial indicators Most physicochemical parameters, including turbidity (0.98 - 4.38 NTU), TDS (10.32 - 92.27 mg/L), Conductivity (16.13 - 144.10 µS/cm), hardness (0.15 - 2.90 mg/L), sulphates (3.0 - 4.61 mg/L), nitrates (2.87- 8.94 mg/L), and nitrites(0.01- 0.02 mg/L), were within permissible limits of 5NTU, 500mg/L, 1000µS/cm, 500mg/L, 250mg/L, <50mg/L and 3mg/l respectively. However, pH values at Edo Street (5.77) were below the recommended range of 6.5-8.5, and water temperatures exceeded the 25 °C guideline in most locations. Concentrations of cadmium (up to 0.03 mg/L) and lead (up to 0.03 mg/L) exceeded permissible limits (0.003 mg/L and 0.01 mg/L, respectively), suggesting potential toxicological risks. Microbiological assessment indicated elevated heterotrophic bacterial counts (3.00– 76 CFU/mL) and fecal contamination, making the water unsuitable for direct consumption. The findings from this study underscore the need for regular water quality monitoring, appropriate treatment measures, and improved borehole management to safeguard student health in Ekosodin Village.

The study investigated the proximate composition, phytochemical constituents, mineral nutrient content, and antimicrobial activity of the aqueous leaf decoction of Mucuna pruriens, a plant of notable ethnomedicinal importance in Nigeria. Analyses were
conducted using standard procedures. Proximate evaluation revealed 7.17% ash, 18.43% carbohydrates, 9.67% crude fat, 18.52% crude fibre, 37.88% crude protein, and 8.33% moisture, confirming the leaf as a protein- and fibre-rich nutritional resource.
Phytochemical screening showed the presence of flavonoids, alkaloids, phenolic compounds, eugenols, and reducing sugars, while saponins, tannins, steroids, terpenoids, and glycosides were not detected. Mineral analysis indicated appreciable levels of sodium (1343.67 mg/kg), potassium (1018 mg/kg), calcium (238.33 mg/kg), magnesium (377 mg/kg), copper (23.33 mg/kg), iron (336.67 mg/kg), zinc (29.67 mg/kg), manganese (106.67 mg/kg), and nickel (11.33 mg/kg). Antimicrobial assays demonstrated
concentration-dependent inhibition of Escherichia coli (15.0 mm), Staphylococcus aureus (14.1 mm), Pseudomonas aeruginosa (23.0 mm), and Klebsiella pneumoniae (22.0 mm) at 100 mg/mL. The minimum inhibitory concentration (MIC) was 25 mg/mL for all isolates, while the minimum bactericidal concentration (MBC) was 25 mg/mL for S. aureus, P. aeruginosa, and K. pneumoniae, but 75 mg/mL for E. coli. These findings validate the traditional medicinal use of M. pruriens leaves and demonstrate that decoction, a safe and culturally relevant extraction method, yields a nutritionally valuable, mineral-rich, and bactericidal extract with potential therapeutic applications

This study examined the mineral composition and phytochemical profile of Tetrapleura tetraptera fruit pods. The fruit pod was purchased from Uselu market, dried and extracted by maceration method using aqueous, methanol and hexane solvents. The elemental composition was analyzed with a portion of the powdered sample using g X-ray fluorescence spectroscopy (XRF) while phytochemical screening of the three extracts was done via standard methods. Mineral analysis revealed potassium (28.317%) as the most abundant element, followed by calcium (12.962%), magnesium (7.656%), and aluminum (6.413%). Moderate amounts of
Sulphur (1.652%) and chlorine (2.412%) were also detected, while iron was present at a relatively low concentration (1.502%). The dominance of potassium and calcium highlights the fruit’s nutritional potential for maintaining electrolyte balance, bone development, and muscle function. Magnesium and aluminum further contribute to enzymatic activities and possible medicinal value, though the low iron content indicates limited benefit for hemoglobin synthesis and oxygen transport. Phytochemical screening showed that alkaloids, eugenol, and reducing sugars were present across all extracts. Glycosides, flavonoids, tannins, phenolics, and terpenoids were prominent in methanol and aqueous extracts, while hexane extracts yielded fewer polar compounds. Steroids were absent in all extracts. These results confirm that solvent polarity strongly influences phytochemical extraction, with polar solvents yielding a broader spectrum of bioactive constituents

Ocimum gratissimum is a widely recognized medicinal plant known for its diverse therapeutic properties, including antimicrobial, antioxidant, anti-inflammatory, and antidiabetic effects. Its rich content of bioactive compounds has made it a staple in traditional medicine for managing infections, digestive disorders, and general wellness. This study investigates the nutritional composition, amino acid profile, antioxidant potential, enzyme inhibitory activity, and phytochemical constituents of O. gratissimum stem extract, providing scientific insight into its medicinal relevance. The qualitative Proximate analysis showed high carbohydrate (53.69%), crude fiber (12.50%), and crude protein (12.26%) content with notable levels of moisture (7.40%), ash (6.27%) and crude fat content (4.92%). Amino acid profiling revealed abundant essential and non-essential amino acids, notably Isoleucine (29.42 mg/ml) and Alanine (22.55 mg/ml). In vitro Total Antioxidant Capacity assay demonstrated significant antioxidant activity, with ascorbic acid values increasing from 0.31 to 0.52 mg/ml as the concentration rose from 0.1 to 0.3 mg/ml, while the In vitro Nitric Oxide Scavenging Assay showed a progressive increase in the %NO Scavenging from 42.48% to 55.03% for concentrations of 0.1 to 0.3 mg/ml, confirming significant radical scavenging ability. The extract also showed strong alpha amylase (60.43%) and alpha glucosidase (76.91%) inhibition. GCMS identified 35 bioactive compounds, with Erucic acid (with a peak area of 4.59%), D-carvone (5.78%), Oleic Acid (8.90%), Cyclopropane (17.01%) and 9 borabicyclo compounds (28.30%), having the most prominent peak areas. These results suggest the extracts potential in nutritional and therapeutic applications.