School of Physical Sciences

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Open Access
Adsorption and corrosion-inhibiting effect of dacryodis edulis extract on low-carbon-steel corrosion in acidic media
(Elsevier Inc, 2010-09-01) Oguzie, E. E.; Enenebeaku, C. K.; Akalezi, C. O.; Okoro, S. C.; Ayuk, A. A.; Ejike, E. N.
The inhibition of low-carbon-steel corrosion in 1 M HCl and 0.5 M H2SO4 by extracts of Dacryodis edulis (DE) was investigated using gravimetric and electrochemical techniques. DE extract was found to inhibit the uniform and localized corrosion of carbon steel in the acidic media, affecting both the cathodic and anodic partial reactions. The corrosion process was inhibited by adsorption of the extracted organic mat ter onto the steel surface in a concentration-dependent manner and involved both protonated and molec ular species. Molecular dynamics simulations were performed to illustrate the process of adsorption of some specific components of the extract
Open Access
Application of geographic information system (GIS) in composite land capability index mapping of a developing country (A case study of Enugu area, South -Eastern, Nigeria,
(U. P., 2011) Onunkwo, A. A.; Ibeneme, S. I.; Onyekuru, S. O.; Uzoije, A. P.
Enugu, the area under study is experiencing a high rate of population growth. Problems of housing, on employment, waste disposals and the general lowering of standard of living are always associated with over population. It has therefore become necessary to map out areas of residential, industrial and waste disposal land use for future utilization. Land capability index mapping using geographic information system(GIS) is one of the appropriate tools for solving these impending problems. Land capability index mapping of Enugu environs in composite form has been undertaken using Arc view 3.2 academic, excel statistical software and GIS Authcard software. A total of 12 land use determinants have been selected as the thematic data layers and the basic factors influencing the choice of waste, residential and industrial land use. These themes which are in map form are slope, water table, surface and subsurface water conditions, elevation, geology, soil, drainage and geo-structural stability(fault, erosion, landslide and flooding). These maps have been scanned, geo-referenced , digitized and polygonized using authcard drawing capacities to convert them to vector formats and later exported to arc view software environment for analysis. The thematic layers were weighted using the criteria obtained from fieldwork, laboratory and literature surveys. The thematic layers were further subjected to overlays using the arcview software overlay model builder. The operation yields layers showing areas of preferred waste disposal, residential and industrial landuse options in a map form. Three different maps of land use options(waste, industrial and residence) were produced. Areas of varying suitability were isolated, 3 each for waste, residence and industry, indicating suitable, low suitability and unsuitable areas respectively. The three land use maps were superimposed to obtain a single one appropriate for purposes of urban environmental planning.
Open Access
Corrosion inhibition and adsorption behavior of methionine on mild steel in sulfuric acid and synergistic effect of iodide ion
(Elsevier Inc., 2007) Oguzie, E. E.; Li, Y.; Wang, F. H.
The corrosion inhibition of mild steel in sulfuric acid by methionine (MTI) was investigated using electrochemical techniques. The effect of KI additives on corrosion inhibition efficiency was also studied. The results reveal that MTI inhibited the corrosion reaction by adsorption onto the metal/solution interface. Inhibition efficiency increased with MTI concentration and synergistically increased in the presence of KI, with an opti mum[KI]/[MTI] ratio of 5/5, due to stabilization of adsorbed MTI cations as revealed by AFM surface morphological images. Potentiodynamic polarization data suggest that the compound functioned via a mixed-inhibition mechanism. This observation was further corroborated by the fit of the experimental adsorption data to the Temkin and Langmuir isotherms. The inhibition mechanism has been discussed vis-à-vis the presence of both nitrogen and sulfur atoms in the MTI molecule
Open Access
Corrosion inhibition of aluminium in acidic and alkaline media by Sansevieria trifasciata extract
(Elsevier Ltd, 2007) Oguzie, E. E.
The inhibitive action of leaf extracts of Sansevieria trifasciata on aluminium corrosion in 2 M HCl and 2 M KOH solutions was studied using the gasometric technique. The results indicate that the extract functioned as a good inhibitor in both environments and inhibition efficiency increased with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the extract. A mechanism of physical adsorption is proposed for the inhibition behaviour. The adsorption characteristics of the inhibitor were approxi mated by Freundlich isotherm
Open Access
Corrosion inhibitive effect and adsorption behaviour of hibiscus sabdariffa extract on mild steel in acidic media
(UP, 2008) Oguzie, E. E.
The inhibiting action of the calyx extract of Hibiscus sabdariffa on mild steel corrosion in 2 M HCl and 1 M H2SO4 solutions was assessed using a gasometric technique. The results demonstrate that Hibiscus sabdariffa extract suppressed the corrosion reaction in both acid media and inhibition efficiency increased with extract concentration with slightly higher values obtained in 1 M H2SO4. Synergistic effects increased the efficiency of the extract in the presence of halide additives. Adsorption characteristics of the extract were approximated by the Langmuir isotherm. The inhibition mechanisms, estimated from the temperature dependence of inhibition efficiency as well from kinetic and activation parameters show that the extract functioned via mixed inhibition mechanism. It is suggested that molecular as well as protonated organic species in the extract contribute to the observed inhibiting action
Open Access
Effect of 2-amino-3-mercaptopropanoic acid (cysteine) on the corrosion behaviour of low carbon steel in sulphuric acid
(Elsevier Ltd., 2007) Oguzie, E. E.; Lia, Y.; Wang, F. H.
The effect of cysteine (cys) on the corrosion of low carbon steel (LCS) in sulphuric acid solution was investigated using electrochemical and scanning electron microscopy (SEM) techniques. Electrochemical impedance spectroscopy (EIS) results reveal that the presence of cys at low concentrations (0.1–0.5mmolL 1) promoted the LCS corrosion process, whereas an inhibiting effect was observed at higher concentrations (1.0–5.0 mmolL 1), which was enhanced on deaeration of the test solution. Polarization results revealed that cys actually inhibited the cathodic process at all concentration but exerted a stimulating effect on the anodic metal dissolution reaction. Despite the cathodic inhibiting effect, the polarization resistances at low cys concentrations were less than that in the blank acid. This suggests that the anodic reaction was the predominant influence determining the corrosion rates in the presence of cys. This has been discussed vis-` a-vis the catalytic effect of the Fe–cys complex, which turns the Fe surface more electrochemically active
Open Access
Engineering properties and uses of soil derive from maastritchian Ajali formation in a part of Se Nigeria
(European Centre for Research Training and Development UK (www.eajournals.org), 2014-12) Onunkwo, A. A.; Uzoije, A. P.; Onyekuru, S. O.
The study is necessitated by the recent move by Imo State government of Nigeria to raise Okigwe town to urban status. Ajali Formation being the prominent geological terrain in Okigwe area, most structures would be erected on the soil derived from it. The parameter measured include grain size, atterberg limits, and compaction, shear strength, permeability and porosity as well as bulk density. The result shows that the soil underlain by Ajali Formation within Okigwe area is sandy silt with low clay content and has plasticity index, bulk density, porosity and permeability values of 9.65%, 2.06%,kg/m3, 0.45 and 0.35cm/s respectively. The value for the optimum moisture content (OMC) maximum dry density(MDD) shear strength, angle of internal friction are 13.5%, 2.06kg/m3, 106.86KN/M2 and 28.4o. These values indicate that the soil derived from Maastrichtian Ajali Formation within Okigwe area of south eastern Nigeria is of high strength, porous and permeable and can be used as a recharge site for regional aquifer, but cannot be used as a waste disposal area or for road construction. The soil due to its low plasticity index with no swelling characteristics and high shear strength is a good site for building foundations, but cannot be used in dam construction. It is ideal for projects requiring good drainage and embankments. However, for the soil to be used in any engineering construction works, it has to be compacted to its maximum dry density value of 2.06kg/m3 within the range of optimum moisture content of 13.5% as to achieve maximum strength.
Open Access
Equilibrium, thermodynamic and kinetic studies on adsorption of zinc (II) from solutions using different low-cost adsorbents
(Open Science, 2015-11-05) Njoku, Pascal C.; Atu, A. Ayuk; Atulegwu, P. Uzoije; Justus I. Okolie
Many industrial wastewaters contain numerous toxic metals such as zinc, which must be removed before reuse of the water or discharge into the environment. In this present study, unripe plantain peel activated carbon (UPPAC), pineapple peel activated carbon (PPAC) and commercial activated carbon (CAC) were utilized as low cost adsorbents for the removal of Zn (II) from aqueous solutions. Batch adsorption methodology was used to evaluate the effect of solution pH, initial metal ion concentration, adsorbent dose, contact time and temperature on adsorption. Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrophotometer (FTIR) were used to characterize the adsorbents. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich and Temkin isotherm model. The kinetic data were analyzed using the pseudo-first order, pseudo-second order equations, Elovich equation and intraparticle rate equation. Maximum adsorption of Zn (II) on UPPAC, PPAC and CAC (82.45%, 89.95% and 93.45%) was observed at pH 6 and pH 7. The adsorbed amount of Zn (II) increased with increase in contact time and reached equilibrium within 180 minutes. The maximum adsorption was found to be 200 mg/L in the studied range (200 – 1000 mg/L). The adsorption capacity and percent removal of Zn (II) were found to increase with increase in temperature. The Freundlich isotherm models provided the best fit to the experimental data for Zn (II) as indicated by the regression coefficient values (R2> 0.97). The pseudo-second order equation gave the best fit to the experimental data for the metal ion (R2 > 0.99). Thermodynamic analysis showed a spontaneous adsorption process as negative values of ∆Go (-1.269 to -5.530) were obtained at all temperatures. The positive enthalpy change ∆Ho, 18.00, 20.46 and 23.45 kJ mol-1 for UPPAC, PPAC and CAC indicated an endothermic process. A highly disordered process was indicated by the positive entropy change ∆So .
Open Access
Equilibrium, thermodynamic and kinetic studies on adsorption of zinc (II) from solutions using different low-cost adsorbents
(U. P., 2015) Njoku, Pascal C.; Ayuk, Atu A.; Uzoije, Atulegwu, P.; Okolie, Justus I.
Many industrial wastewaters contain numerous toxic metals such as zinc, which must be removed before reuse of the water or discharge into the environment. In this present study, unripe plantain peel activated carbon (UPPAC), pineapple peel activated carbon (PPAC) and commercial activated carbon (CAC) were utilized as low cost adsorbents for the removal of Zn (II) from aqueous solutions. Batch adsorption methodology was used to evaluate the effect of solution pH, initial metal ion concentration, adsorbent dose, contact time and temperature on adsorption. Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrophotometer (FTIR) were used to characterize the adsorbents. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich and Temkin isotherm model. The kinetic data were analyzed using the pseudo-first order, pseudo-second order equations, Elovich equation and intraparticle rate equation. Maximum adsorption of Zn (II) on UPPAC, PPAC and CAC (82.45%, 89.95% and 93.45%) was observed at pH 6 and pH 7. The adsorbed amount of Zn (II) increased with increase in contact time and reached equilibrium within 180 minutes. The maximum adsorption was found to be 200 mg/L in the studied range (200 – 1000 mg/L). The adsorption capacity and percent removal of Zn (II) were found to increase with increase in temperature. The Freundlich isotherm models provided the best fit to the experimental data for Zn (II) as indicated by the regression coefficient values (R2 > 0.97). The pseudo-second order equation gave the best fit to the experimental data for the metal ion (R2 > 0.99). Thermodynamic analysis showed a spontaneous adsorption process as negative values of ∆Go (-1.269 to -5.530) were obtained at all temperatures. The positive enthalpy change ∆Ho, 18.00, 20.46 and 23.45 kJ mol-1 for UPPAC, PPAC and CAC indicated an endothermic process. A highly disordered process was indicated by the positive entropy change ∆So.
Open Access
Evaluation of the inhibitive effect of some plant extracts on the acid corrosion of mild steel
(Elsevier Ltd, 2008) Oguzie, Emeka E.
Corrosion inhibition of mild steel in 2M HCl and 1M H2SO4 by extracts of selected plants was investigated using a gasometric technique at temperatures of 30 and 60°C. The studied plants materials include leaf extracts Occimum viridis (OV), Telferia occidentalis (TO), Azadirachta indica (AI) and Hibiscus sabdariffa (HS) as well as extracts from the seeds of Garcinia kola (GK). The results indicate that all the extracts inhibited the corrosion process in both acid media by virtue of adsorption and inhibition efficiency improved with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Inhibition mechanisms were deduced from the temperature dependence of the inhibition efficiency as well as from assessment of kinetic and activation parameters that govern the processes. Comparative analysis of the inhibitor adsorption behaviour in 2M HCl and 1M H2SO4 as well as the effects of temperature and halide additives suggest that both protonated and molecular species could be responsible for the inhibiting action of the extracts
Open Access
Experimental and DFT evaluation of adsorption and inhibitive properties of Moringa oliefera extract on mild steel corrosion in acidic media
(Elsevier B. V. on behalf of King Saudi University, 2020-11) Akalezi, Christogonus Oudney; Maduabuchi, Arinze Chidiebere; Eneneneaku, Conrad Kenechukwu; Oguzie, Emeka Emmanuel
The corrosion response of mild steel in 0.5 M H2SO4 acid solution in the presence of Moringer oliefera (MO) leaf extract was investigated using gravimetric, electrochemical, and DFT techniques. Gravimetric results indicate that MO exhibits a high inhibition value up to 93.0% when the concentration was 1.5 g/L. Inhibition value in general increased with an increase in concentration of the extracts but decreased with prolonged exposure time and temperature. Analysis of polarization curves indicated that MO extract acted as mixed-type inhibitors. The adsorption process of MO on a mild steel surface in the acid solution fitted the Langmuir isotherm. GC/MS analysis of MO extract revealed the presence of more than 29 active constituents including 9,12-Octadecadienoic acid (Z, Z) methyl ester (28.55%); n-Hexadecanoic acid (11.24%); 9,12,15-Octadecatrienoic acid methyl ester (9.31%), Benzeneacetonitrile, 4-hydroxy-(6.32%),2-Furancarboxaldehyde,5-(hydroxymethyl)-(5.6%), Heptadecane (4.85%). Quantum chemical calculations were applied on some of the identified constituents to assess their adsorbability on the mild steel surface and the result revealed remarkable high interaction energies.
Open Access
Exploratory survey of geochemical aspects of underground water in Ehime Mbano Area Se Nigeria
(Global Journals Inc. (USA), 2011-04) Onunkwo, A.; Uzoije, A. P.
The exploratory survey of geochemical aspects of underground water resource in Ehime Mbano area of Imo State South-eastern Nigeria has been carried out. Since the creation of Ehime Mbano Local government area in 2001, there is the need for subsurface water quality assessment since the surface water has been polluted due to population explosion. The study was carried out by acquiring geologic and topographic maps of the area for easy identification of sample population areas, and to identify geological boundaries. Spring outcrops, land use elements, especially waste dump sites and agricultural projects were visited and examined. A total of 6 water samples, 2 from springs and 4 from boreholes were collected randomly and analyzed. Analysis was carried out using atomic absorption spectroscopy for major cations. Heavy metal analysis was undertaken using spectrophotometer, potassium was determined using flame photometer method, concentration of total iron (Fe2+) was determined calorimetrically using spekker absorption meter, while total dissolved solids (TDS) was determined using glass fiber filter. Turbimetric method was used to assess turbidity. Physical parameters like ph and dissolved oxygen were measured insitu in the field with appropriate standard meters. The result of geochemical survey shows that the water has high turbidity, high iron, slightly acidic, soft, portable and suitable for domestic, industrial and irrigation purposes. Above all the water has no bacteria presence, no heavy metals also no laxative effect. The average pollutional index of 2.50 indicates a slight pollution though Ezeoke Nsu area (NE) is highly polluted. Remediation to the problems of slight water pollution is proposed.
Open Access
Ground water quality assessment of newly created Local Governments in Nigeria – A case of Nkwerre, Local Government, Imo State
(U. P., 2013) Onunkwo, A. A.; Uzoije, A. P.; Onyekuru, S. O.; Agumanu, A. E.; Chinaemelu, E. S.
The creation of new Local governments in Nigeria brought about new socio-economic order such as over population, pressure on the available facilities and new land use elements with their generated wastes. There is the need to examine the present status of the underground water resource of these regions for effective development of the newly created local governments. For this reason it becomes necessary to carry out the ground water quality assessment of newly created local governments in Nigeria as a source of data base for development using Nkwerre Local Government Area of Imo State as a case study. The study was carried out by acquiring geologic and topographic maps of the area for easy identification of sample population areas and to identify geological boundaries, Spring out crops, landuse element especially waste dump sites. Agricultural and industrial projects were visited and examined. A total of 6 water samples from bore holes within six communities were collected and analyzed. Analysis was carried out using atomic absorption spectroscopy for major cations. Heavy metal analysis was undertaken using spectrophometer, potassium was determined using flame photometer method, concentration of total iron (Fe2+) was determined calorimetrically using spekker absorption meter while total dissolved solids (TDS) was determined using glass fiber filter. Turbidity. Physical parameters like ph and dissolved oxygen were measured insitu in the field with appropriate standard maters. The result of geochemical analysis shows that the water has high turbidity, high iron, slightly acidic, soft portable and suitable for industrial, agricultural and domestic purposes, but requires treatment to reduce iron and turbidity. The water type belongs to a no dominant cation and anion type and can be grouped as Mg2+-Ca2+ - So42+ - HCo3 water. North western segment in infested with ecoli bacteria. The general pollution index of 0.777 shows that the water in the area is ideal for various purposes, however, remediation of iron, turbidity and bacteria presence is proposed.
Open Access
Influence of halide ions on the inhibitive effect of Congo red dye on the corrosion of mild steel in sulphuric acid solution
(Elsevier B. V., 2004) Oguzie, E. E.
The inhibitive effect of congo red dye (CR) on mild steel corrosion in sulphuric acid solution was studied at different temperatures using gravimetric techniques. The influence of halide additives namely: KCl, KBr and KI on the inhibition efficiency of CR was also investigated. Inhibition efficiency increased with CR concentration but decreased with rise in temperature. Corrosion activation energies of 82.98 and 96.92kJmol−1 were observed in the absence and presence of CR, respectively. The observed corrosion data suggest that inhibition of mild steel corrosion is due to physical adsorption of the CR molecules on the metal surface, which follow Flory–Huggins isotherm. Inhibition antagonism and synergism were respectively observed at 30 and 60°C on addition of halide salts to inhibited systems containing CR. The inhibition efficiency of CR in the presence of halides increased with rise in temperature and corrosion activation energy in these systems decreased to 40.63kJmol−1. These observations indicate a chemical adsorption mechanism, thus suggesting that the halide ions reversed the mechanism of CR adsorption within the concentration range studied. The calculated values of heat of adsorption confirm physisorption and chemisorption mechanisms respectively for CR adsorption in the absence and presence of halides
Open Access
Inhibition of copper corrosion in chloride solution by caffeine isolated from black tea
(UP, 2014-05-02) Gudić, Senka; Oguzie, Emeka E.; Radonić, Ani; Vrsalović, Ladislav; Smoljko, Ivana; Kliškić, Maja
Caffeine (1,3,7-trimethylxanthine) was isolated from black tea and characterized using different physical methods (determination of melting point, thin layer chromatography, FTIR spectroscopy and UV spectrophotometry). The corrosion inhibition performance of the caffeine isolate on copper corrosion in neutral 0.5 mol L-1 NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The obtained results show that caffeine effectively inhibited the corrosion reaction in the chloride solution with inhibition efficiency up to » 92 %. Furthermore, caffeine was found to function essentially as a cathodic inhibitor by adsorption on the copper surface according to the Langmuir adsorption isotherm. The adsorption free energy of » –37 kJ mol-1 indicates strong adsorption of the caffeine on the metal surface. Quantum chemical computations and molecular dynamics simulations were adapted to understudy the adsorption of a single caffeine molecule as well as a polymeric cluster of caffeine molecules on a model Cu surface at a molecular level and show good agreement with the experimental findings
Open Access
Inhibition of mild steel corrosion in sulphuric acid using indigo dye and synergistic halide additive
(Elsevier Ltd, 2004) Oguzie, E. E.; Unaegbu, C.; Ogukwe, C. N.; Okolue, B. N; Onuchukwu, A. I.
Gravimetric method was used to study the inhibitory properties of indigo dye during corrosion of mild steel in aerated sulphuric acid solutions at 30–50°C. The effect of addition of halide salts KCl, KBr and KI was also investigated. The corrosion rates in all systems studied increased with rise in temperature. The inhibition efficiency of indigo dye increased with concentration and synergistically increased on addition of halide salts. Temperature studies revealed increased inhibition efficiency at higher temperatures, which is suggestive of chemisorption mechanism. The inhibitor adsorption characteristics were approximated by Frumkins isotherm and Flory–Huggins isotherm. Activation energy for Fe dissolution in sulphuric acid was observed to reduce from 54.6kJmol−1 in the uninhibited system to 34.9kJmol−1 in the inhibited system
Open Access
Inhibitory mechanism of mild steel corrosion in 2M sulphuric acid solution by methylene blue dye
(Elsevier Ltd, 2005) Oguzie, E. E.; Onuoha, G. N.; Onuchukwu, A. I.
Methylene blue dye (MB) was investigated as a corrosion inhibitor for mild steel in 2M sulphuric acid solution using gravimetric and thermometric techniques. The inhibition efficiency of MB increased with concentration and synergistically increased in the presence of the halide additives, namely KCl, KBr and KI. The trend of inhibition efficiency with temperature suggests that inhibitor molecules are physically adsorbed on the corroding metal surface at lower concentration (0.01–0.5mM), and chemically adsorbed at higher concentration (1.0–5.0 mM). These results were further corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from experimental data at the temperatures studied. MB was found to obey Langmuir and Frumkin adsorption isotherms in the concentration range investigated
Open Access
Lawsonia inermis as an active corrosion inhibitor for mild steel in hydrochloric acid
(MDPI, 2024-07-23) Okore, Glory; Ejiogu, Blessing; Pamela, Okeke; Amanze, Kenneth; Okore, Sunday; Oguzie, Emeka; Enyoh, Christain Ebere
Corrosion is a pervasive issue affecting metallic materials, with significant economic losses and safety risks in various industries. Mild steel, extensively used in construction and infrastructure, faces corrosion challenges, needing continuous research to effectively tackle them. Natural compounds, because of their eco-friendliness and corrosion inhibition potential, are attracting increasing interest for corrosion control. Lawsonia inermis (LI), or henna, a plant native to North Africa and South Asia, has bioactive compounds exhibiting corrosion inhibitive properties. This study comprehensively explores Lawsonia inermis’s effectiveness as a corrosion inhibitor for mild steel, filling a gap in the existing research. Various concentrations of Lawsonia inermis extract were tested in acidic solutions to evaluate corrosion inhibition. Experimental results indicate a significant reduction in the corrosion rate with increasing inhibitor concentration. Langmuir adsorption isothermal analyses reveal the adsorption mechanism as being an interplay between physisorption and weak chemisorption. Electrochemical measurements demonstrate Lawsonia inermis’s capability to alter both cathodic and anodic reactions, leading to improved corrosion resistance. Scanning electron microscopy reveals a more even surface morphology in the presence of the Lawsonia inermis, indicating corrosion inhibition. Gas chromatography–mass spectrometry (GC-MS) analyses identified organic compounds in Lawsonia inermis extract responsible for corrosion inhibition. Overall, Lawsonia inermis emerges as a promising corrosion inhibitor for mild steel, offering excellent inhibition efficiencies. This study sheds light on its adsorption behaviour and provides insights into its mechanism of action. These findings underscore Lawsonia inermis’s potential as a green corrosion inhibitor, paving the way for its practical application in industrial corrosion protection strategies
Open Access
Resistivity methods of aquifer mapping and pollution vulnerability assessment of a part of Imo River Basin of South-Eastern Nigeria (A case study of Mbaitoli Local Government Area of Imo State, Nigeria)
(IDOSI Publications, 2011) Onunkwo, A. A.; Uzoije, A. P.; Essien, A. G.
Aquifer mapping and pollution vulnerability assessment of a part of Imo River basin of South-eastern Nigeria has been carried out with the aim of addressing the underground water exploitation problems inherent in the area. The instruments used for the study include aerial photographs, satellite images, topographic and geologic map of the area. Geophysical investigations were carried out with the aid of terrameter 300 SAS employing vertical resistivity soundings. Eleven selected locations were sounded using Schulumberger array with maximum electrode separation of 900 meters. Result shows that the area has average lithology of eight (8) layers with underground water occurring between the fourth and fifth layers. The lithology is dominantly sand (about 90%) sandstone (about 2%) clay / shale (about 8%). Average depth to top of aquifer ranges from 100 to 228 meters. Depth to the base of aquifer ranges from 88m to 278m while the average aquifer thickness is 33.7m. Three aquifer systems exist in the area-confined, unconfined and semi-confined. Semi-confined aquifer is dominant, while unconfined aquifer is less common. The former offers natural protection against pollution of underground water by waste effluents while the later is prone to pollution. Average resistivity of the formations is relatively high indicating a formation likely to contain abundant conglomeritic and sandstone beds capable of promoting loss of circulation and difficulty in drilling bit penetration during underground water exploitation. Areas to the west are relatively shallow while the South (Egbeada) is very deep. There is an insignificant relationship between aquifer depth and elevation. This section of Imo River basin is promising for underground water development but requires caution since conglomeritic and sandstone traces can effect adversely underground water exploitation. Down the hole electric logging is necessary considering the aquifer depth. The problem of unprotected aquifer against environmental pollution should be noted and addressed.
Open Access
Studies on the inhibitive effect of Occimum viridis extract on the acid corrosion of mild steel
(Elsevier Ltd, 2006) Oguzie, Emeka E.
Corrosion inhibition of mild steel in 2M HCl and 1M H2SO4 by leaf extracts of Occimum viridis (OV) was studied using the gasometric technique at temperatures of 30 and 60°C. The results indicate that the extracts inhibit the corrosion process in both acid media and inhibition efficiency increased with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives namely KCl, KBr, KI. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the extract, probably implying that physical adsorption of cationic species may be responsible for the observed inhibition behaviour. Comparative analysis of the inhibitor adsorption behaviour in 2M HCl and 1M H2SO4 as well as the effect halide additives suggest that cationic species may not be the only constituents responsible for the inhibiting action of the extract