RÉSUMÉ
Surfactant flooding has suffered a huge setback owing to its cost and the ecotoxic nature of synthetic surfactants. The potential of natural surfactants for enhanced oil recovery has attracted a great deal of research interest in recent times. In this research, orange mesocarp extract (OME) was studied as a potential green surface-active agent in recovering heavy oil. The extract obtained from the orange (Citrus sinensis) mesocarp using alkaline water as solvent was characterized by Fourier transform infrared spectrophotometry . Phase behavior was studied to ascertain its stability at 100 °C and compatibility with divalent ions. Microemulsion system, interfacial tension, optimal salinity, and critical micelle concentration were analyzed to evaluate the surfactant. Oil displacement analysis using an oil-wet sandstone medium under reservoir conditions was performed. Surfactant adsorption mechanism on the core was investigated at atmospheric conditions (28 °C) using the Langmuir, Freundlich, Temkin, and linear isotherm models, while the kinetics pattern was modeled with the pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models. Results showed fluid compatibility and bicontinuous microemulsion at varied temperatures. Surfactant flooding produced an additional oil recovery of 44 and 29.1%, which confirms the capability of this natural surfactant in recovering heavy oil. Langmuir isotherm gave the highest correlation coefficient (R2) value of 0.982, indicating that the adsorption of the surfactant (OME) on the core occurred at specific homogeneous sites, which when occupied by a higher surfactant concentration will disallow further adsorption on these sites. From the R2 values, almost all of the kinetic models corroborated good adsorption capacity of the core and an affinity for the surfactant at low concentration. This indicates that low concentration of the surfactant may not favor the enhanced oil recovery operation due to adsorption in the reservoirs, hence the need to flood at a higher surfactant concentration.
RÉSUMÉ
5-hydroxymethylfurfural (5-HMF) yield during bioethanol production from starch was determined using spectrophotometry and chromatography. Increasing acid concentration and time favored 5-HMF production with HCl while yield decreased after 45-minute hydrolysis time for HNO3 and H2SO4 hydrolyzed samples. Impacts of glucose (substrate) concentration and produced 5-HMF on bioethanol yield were studied with different sulphuric acid concentrations and different α-amylase and amyloglucosidase activities. A central composite rotational design was utilized to determine the conditions of hydrolysis for optimum glucose production. The results showed that maximum glucose yield occurred at 0.5 M acid concentration and 45-minute hydrolysis time, while maximum yield was achieved at 120 and 280 units of α-amylase and amyloglucosidase activities respectively. It was shown that 5-HMF did not exhibit much inhibition on ethanol yield at low acid concentrations but became pronounced at higher acid concentrations, while high glucose concentrations had a pronounced negative effect on ethanol yield and fermentation efficiency.
RÉSUMÉ
Industrialization and urbanization have caused a hike in all forms of emissions, many of which have detrimental effects on plants, animals, the environment, and worse still, humans. In a quest for novel products (household, and medical), manufacturing industries work tirelessly worldwide using metals to meet man's needs. However, such metals especially those confined to this research (Hg, Cd, and Pb) are inherently hazardous to not just the environment but human life and existence. Thirty (30) male Wistar rats divided into six groups of five rats each was used for the study. Stock solutions of the heavy metals were prepared and the required dose calculated according to individual weight and administered as such to group 2-5, plantain stem juice (PSJ) was administered to groups 3 to 5 in increasing dose after receiving the HMM (heavy metal mixture) while group six received medium-dose of PSJ used in the study only. Bodyweight of the rats was monitored once in three weeks while the feed and fluid intake were monitored thrice a week. At the end of the ninth week, the animals were weighed and sacrificed. Organs of interest (brain, heart, lungs, and thymus) were harvested and analyzed. Analysis done include Histopathology, hematological, biochemical, and organs/blood metal concentration. The results obtained showed a decline in the weight of animals that received metal mixture only when compared to normal control and PSJ treated groups. This could be traceable to the decline in feed intake of the metal-induced groups. However, no significant effect was observed in the histology of the Thymus and cerebellum even though the presence of a vacuole in the cerebral cortex indicated an anomaly. The histology of the heart and the lungs showed some level of distortion which was ameliorated dose-dependently with the administration of PSJ. Interestingly, after a decrease in the antioxidant level upon administration of metal mixture, a booster effect was observed with an increasing dose of PSJ. In conclusion, the recent findings have demonstrated that treatment with PSJ in HMM induced intoxication has a significant role in protecting the animals from all possible organ toxicity by modulating hemato-biochemical parameters and oxidative stress level.
RÉSUMÉ
Heavy metal mixture can induce multiple organ damage through oxidative stress and inflammatory processes. Dietary intervention using natural antidotes in resource poor countries where classical metal chelators are either not affordable or available can be explored as an alternative means of management of public health effects of chronic heavy metal exposure. The search for natural antidote against the deleterious effects of heavy metals gives the thrust for this study. Thus, the study investigated the effect of aqueous leaf extract of Costus afer on liver, kidney, brain and testis induced by low dose heavy metal mixture (LDHMM) of PbCl2, CdCl2 and HgCl2 of concentrations of 20 mg/kg, 1.61 mg/kg and 0.40 mg/kg, respectively. Five groups of seven rats each (weight-matched) were used. First and second groups received deionized water and heavy metal mixture and served as normal and toxic controls, respectively. Groups 3, 4 and 5 received through oral gavage 750, 1500, 2250 mg/kg of the Costus afer extract respectively, with the metal mixture concurrently. All treatments were four times a week for 90 days (4/week/90 days). Hepatorenal, hormonal, oxidative stress markers, cytokines (interleukin-6 and interleukin-10), and heavy metals (Pb, Cd and Hg) concentrations were assayed. The one-way analysis of variance, agglomerative hierarchical clustering, parallel coordinates plot, principal component analysis and Bray Curtis dissimilarity were used to statistically analyze the data. LDHMM caused significant changes in these organs and however, the plant extract provided a protective effect against these pathological changes. The statistical analysis revealed that the kidney was the most affected organ, followed by the liver, then brain and testis, respectively. Costus afer may be an important nutraceutical in multi-organ deleterious effects of LDHMM following its regulation of oxidative stress markers, inflammatory cytokines and biometal chelation.
RÉSUMÉ
Crude oil pollution has consistently deteriorated all environmental compartments through the cycle of activities of the oil and gas industries. However, there is a growing need to identify microbes with catabolic potentials to degrade these pollutants. This research was conducted to identify bacteria with functional degradative genes. A crude oil-polluted soil sample was obtained from an aged spill site at Imo River, Ebubu, Komkom community, Nigeria. Bacteria isolates were obtained and screened for hydrocarbon degradation potential by turbidometry assay. Plasmid and chromosomal DNA of the potential degraders were further screened for the presence of selected catabolic genes (C230, Alma, Alkb, nahAC, and PAHRHD(GP)) and identified by molecular typing. Sixteen (16) out of the fifty (50) isolates obtained showed biodegradation activity in a liquid broth medium at varying levels. Bacillus cereus showed highest potential for this assay with an optical density of 2.450 @ 600 nm wavelength. Diverse catabolic genes resident in plasmids and chromosomes of the isolates and, in some cases, both plasmid and chromosomes of the same organism were observed. The C230 gene was resident in >50% of the microbial population tested, while other genes occurred in lower proportions with the least observed in nahAC and PAHRHD. These organisms can serve as potential bioremediation agents.
RÉSUMÉ
The study evaluated the protective effect of Costus afer on low-dose heavy metal mixture (LDHMM)-mediated effects in the testis of albino rats. The weight-matched animals were divided into six groups: normal control, metal mixture of (PbCl2 + CdCl2 + HgCl2 ), combination of metal mixture + Costus afer at 750 mg/kg, combination of metal mixture + Costus afer at 1,500 mg/kg, combination of metal mixture + Costus afer at 2,250 mg/kg and combination of metal mixture + (ZnCl2 ). LDHMM reduced (p < .05) the antioxidant biomarkers (superoxide dismutase, SOD; catalase, CAT; and glutathione, GSH) and increased (p < .05) the lipid peroxidation marker (malondialdehyde, MDA) and lead, cadmium and mercury concentrations in the testis. Treatment with LDHMM increased (p < .05) abnormal sperm morphology and plasma prolactin (PRL) level and decreased epididymal sperm count, viability, follicle-stimulating hormone (FSH), luteinising hormone (LH) and testosterone. LDHMM exposure caused deleterious changes in the testis. Treatment of rats with Costus afer (750, 1,500 and 2,250 mg/kg) dose-dependently reduced (p < .05) the LDHMM-mediated toxicity. Treatment with Costus afer also reversed the testicular weight and LDHMM decrease in antioxidant biomarkers. Costus afer may be a defensive modulator of LDHMM-mediated testicular lesions.