Labunmi Lajide

Surveillance and source diagnostic investigation of hydrocarbon residues in sediments

The nature and seasonal distribution of hydrocarbons were studied in Ondo coastal region in Western Nigeria. The petroleum hydrocarbons were screened by gas chromatography with flame ionization detector (GC/FID) and gas chromatography-mass spectrometry (GC-MS). Complex series of compounds were identified. The overall molecular compositions obtained were characteristic of petrogenic origin with very little biogenic input. The concentrations of two important polycyclic aromatic hydrocarbons (PAHs); phenanthrene and anthracene exceeded the threshold level where adverse effects on biota would occasionally occur; a conclusion suggested to be clarified by site-specific studies on resident organisms. The study is useful for ecological risk assessment in the context of contaminant input, nature, pattern and trend.

Influence of diffuse and chronic metal pollution in water and sediments on edible seafoods within Ondo oil-polluted coastal region, Nigeria.

The bioconcentration levels of 3 non-essential elements (Pb, Cd and Ni) have been investigated in three different seafoods; Fish (Tilapia zilli), Crab (Callinectes sapidus) and periwinkle (Littorina littorea), to investigate the ecosystem health status in Ondo oil-polluted coastal region, Nigeria. The seafood samples were chosen based on their popularity as a food source and the potential of the species to contain high levels of metals based on past research results. Metal concentrations in the biota showed marked interspecific differences with C. sapidus recording the highest concentrations of all the metals. The bioconcentration factor (BCF) showed that C. sapidus and T. zilli have the greatest potential to concentrate Cd (BCF = 3–10) and Pb (BCF = 11–84) respectively. Lead uptake from both water and sediment (BCF ≈ BSAF: 0.003–0.018) were abysmally low in L. littorea as compared with other organisms. The high concentrations of Pb in fish species, effective bioaccumulation of Cd in species of crab and periwinkles, as well as very high BSAF of Ni found in species of crab indicated a strong influence from anthropogenic pollutant source on the biotic community. Oil pollution appears to be a major source of bioavailable metal contaminants for the selected biota. The study shows that C. sapidus and L. littorea can effectively compartmentalize potentially toxic metals such as Cd, Pb and Ni within their tissues. In terms of toxicity, C. sapidus had Cd concentrations greater than the 3,000 ng/g limit set by the Commission of the European Communities while Pb concentration exceeded their limits in both C. sapidus and T. zilli. All levels of Ni were below the U.S. Food and Drug Administration action levels for these metals in fish, crustaceans and shellfish. The study revealed anthropogenic enrichment of the metals studied which can possibly pose potential threats to the ecology of the area.

Cymbopogon citratus (DC) Stapf Volatile Oil from South - West, Nigeria

Abstract Chemical analysis of the volatile oil of Cymbopogon citratus and its antibacterial effects were investigated. Chemical analysis of the C. citratus oil was determined using Gas Chromatograph-Mass Spectrometry technique. Out of 47 peaks (representing 97.36 % of the total oil), 37 constituents were identified representing 90.86 % of the total oil constituents. The major constituents were geranial (40.9 %), neral (29.7 %), myrcene (11.3 %), linalool (1.7 %) and geranylacetate (1.6 %). The oil was examined against six bacteria; Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Klebsiella pneumonia, Serratia marcescens and Staphlycoccus aureus. It was found that C. citratus inhibited the growth of all tested microorganism.

Performance of bonded boards using lignin-based resins

Abstract Lignin was extracted from some underutilized plant materials using soda–anthraquinone and soda–anthraquinone–ethanol pulping chemicals. Soda–anthraquinone–ethanol gave higher lignin yield, ranging from 44.47% to 50.41% versus 39.40% to 47.92% of soda-anthraquinone. The isolated lignin was used as a partial substitution for phenol in preparation of lignin-phenol-formaldehyde. The free formaldehyde of the resins ranges from 0.25% to 0.67% versus 1.23% of phenol-formaldehyde (PF) resin used as control. The bonding effectiveness of the resin was evaluated when used as glue for board preparation. The density of the board ranges from 333.54 Kg/m3 to 363.84 Kg/m3. The result revealed that Musa sapientum-, Musa parasidiaca- and Tithonia diversifolia- soda–anthraquinone-derived resins, and soda-anthraquinone–ethanol-derived resin of M. parasidiaca and T. diversifolia had boards with better modulus of rupture (MOR) and modulus of elasticity (MOE) than the board obtained using PF resin.

Chemical Composition of the Seed Volatiles of Aframomum sceptrum (Oliv. & T. Hanb.) K. Schum. from Nigeria

Abstract The steam distilled volatile oil obtained from pulverized Aframomum sceptrum seeds was examined by gas chromatography-mass spectrometry (GC-MS). The major components were 1,8-cineole (81.9 %), α-terpineol (10.1 %) and β-pinene (4.8 %). The oil displayed no antibacterial activity against either Gram positive organisms such as Bacillus cereus, Staphylococcus aureus, or Gram negative organisms such as Escherichia coli, (MIC = 625 μg/mL).

Synthesis and Application of Carboxymethyl Cellulose from Gliricidia sepium and Cola gigantea

Carboxymethyl cellulose (CMC) was prepared from Gliricidia sepium and Cola gigantea cellulose with yields of 1.59 g/g and 1.76 g/g, respectively. The pH of the products were weakly acidic (6.47 and 6.54, respectively). The sodium chloride content was 0.22 for C. gigantea CMC and 0.27 for G. sepium CMC, while the degree of substitution was 0.46 and 0.51, respectively. The swelling capacity of G. sepium CMC was 802%, which was higher than the 519% of C gigantea CMC. Fourier transform infrared (FTIR) spectroscopy confirmed that the products were CMC, and a thermogravimetric analysis (TGA) confirmed that C. gigantea CMC was more stable than G. sepium CMC. Detergent fortified with G. sepium CMC had better performance than C. gigantea CMC in terms of cleaning action and emulsion index, and it competed favorably with a detergent fortified with commercial grade CMC.

Optimization and kinetic study of biogas production from rice husk through solid-state alkaline pretreatment method

Biogas production of raw and solid-state alkaline pretreated rice husk (RH) was investigated at mesophilic conditions. Three concentrations of sodium hydroxide was used to prepare the samples namely; 1, 3 and 5% at 100 and 120°C. The 3% pretreated RH at 100°C (3N100) produced the highest cumulative biogas of 4705 ml followed by 5% pretreated RH at 120°C sample with a cumulative volume of 4590 ml. The combined severity factor (CSF) showed that a moderate severity treatment was needed to improve biogas production for solid-state pretreated RH. First order kinetic model and the modified Gompertz model were used to evaluate biogas production while Chen and Hashimoto model was used to determine the critical hydraulic retention time (HRTcritical). The biodegradability constants (k0) ranged between 0.5163 to 1.1294 with 3N100 and 5N120 having the highest values of 0.8086 and 1.1294 d−1 respectively. Modified Gompertz model showed there was marginal percentage difference between experimental and predicted biogas production except for 1N100 with percentage difference of 11.57%. The HRTcritical for 3N100 was calculated to be 11.60 days. The optimum conditions for solid-state alkaline pretreatment of RH were 3% concentration of NaOH and reaction temperature of 100°C

Conversion of Siam weeds and rice straws to energy products and valuable chemicals via pyrolysis

Increasing global warming has necessitated reduction in combustion of waste and encouraged their conversion into useful materials. Rice straw and Siam weed were valorised via pyrolysis in a laboratory-scaled modified slow pyrolysis reactor and products collected and characterised. The major product obtained was bio-char for both wastes with 12.3% and 27.8% viscous bio-oil recovered from the pyrolytic condensates of rice straw and Siam weed respectively. The resulting bio-oil is less acidic compared to most known pyrolytic oils. Separation of condensates reduced acidity and retarded ageing of bio-oils. The most abundant compound found in Siam weed viscous bio-oil from GC-MS analysis was phenol (16.93%) while it was pentadecyl-2-propyl ester sulphurous acid (30.37%) in rice straw. Bio-chars from these residues showed a higher heating value of ∼21 MJ/kg and pH values of ∼9.00.

Volatile Components from the Stem Bark of Vitellaria paradoxa

Abstract The volatile oil from the stem bark of Vitellaria paradoxa (shea) has been obtained by hydrodistillation and analyzed by GC-MS. The oil is characterized by a high concentration of germacrene D (21.8 %), with smaller quantities of linalool (6.5 %), (E)-caryophyllene (6.3 %), (E)-phytol (4.9 %), and β-elemene (3.8 %). The V. paradoxa bark oil was screened for antibacterial activity but was inactive (MIC ≥ 625 μg/mL).