Metal deterioration over time is a process known as corrosion, an electrochemical process, which ... more Metal deterioration over time is a process known as corrosion, an electrochemical process, which can occur by surface chemical actions on metals by its environment. Metal corrosion have great economic, security, and environmental consequences, and its control is a major research area in corrosion science. Amongst the different corrosion protecting approaches, the use of corrosion inhibitors and protective coatings have attracted enormous research interest in this area of scholasticism. This has necessitated the computational and electrochemical investigations of aluminium corrosion inhibitive potentials of some compounds in 1M HCl. Metal free (5_H2), ClGa(III) (5_Ga) and Co(II) (5_Co) tetrakis(4-acetamidophenoxy)phthalocyanines as well as Co(II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (6) and Co(II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (7) were synthesized for the first time and studied for corrosion inhibition. The reported ClGa(III)...
Abstract N -(2-chloroethyl)morpholine-4-carboxamide (NCMC), N -(2-chloroethyl)tiomorpholine-4-car... more Abstract N -(2-chloroethyl)morpholine-4-carboxamide (NCMC), N -(2-chloroethyl)tiomorpholine-4-carboxamide (NCTC) and N , N -bis(2-chloroethyl)piperazine-1,4-dicarboxamide (NCPD) were studied as corrosion inhibitors for mild steel using atomic absorption spectroscopy (AAS) and gravimetry and thermometry. Results obtained from the three techniques are similar and reveal that the compounds inhibit mild steel corrosion. The inhibition efficiencies increased from 35.6% to 74.9% (NCMC), 44.5% to 82.4% (NCPD) and 52.6% to 90.1% (NCTC) at 30 °C when the inhibitor concentrations increased from 10 μM to 50 μM. The maximum inhibition efficiency values (at 50 μM) decreased to 46.6%, 58.1% and 61.2% for NCMC, NCPD and NCTC respectively, when the temperature was raised to 50 °C. The decrease in inhibition efficiency with increase in temperature suggested predominant physisorption mechanism in metal/inhibitor interactions. The formation of protective films of NCMC, NCPD and NCTC molecules on mild steel surface were confirmed by FTIR and XRD. The order of inhibitive strengths of the molecules is NCTC > NCPD > NCMC. Quantum chemical calculations revealed the prospective sites through which the molecules can interact with mild steel surface and some quantum chemically derived parameters were used to corroborate experimental.
Human African trypanosomiasis, also known as sleeping sickness, is caused by the single-celled ki... more Human African trypanosomiasis, also known as sleeping sickness, is caused by the single-celled kinetoplastid parasite Trypanosoma brucei transmitted to humans by infected tsetse flies. The disease threatens millions of people. Currently available treatment options are faced with some important challenges. In this work, a total of eighty-seven (87) morpholine derivatives were evaluated for drug-likeness based on Lipinski’s rule of five and their ability to inhibit the activities of trypanosomal triosephosphate isomerase was assessed by molecular docking and calculation of free energy of binding. Analysis of the results revealed that 97.7 % of the dataset complied with Lipinski’s criteria for a molecule to be orally bioavailable. Also, 50.0 % of the studied compounds had a good total polar surface area profile, a parameter which is of great importance for the treatment of stage two Trypanosoma infections. Docking studies showed that all the dataset demonstrated affinity for triosephosphate isomerase. Moreover, six morpholines scored higher than the co-crystallized inhibitor of triosephosphate isomerase (2-phosphoglycerate). These derivatives inhibited the activity of triosephosphate isomerase by making significant interactions with Glu 167, Val 214, 233, Asn 11, Lys 13, Ser 213, Leu 232, Ile 172, Gly 211, 212, 234, 235 and His 92 in the active site of the protein. Furthermore, besides the acceptable pharmacokinetic profiles of the six morpholines, they also showed inhibitory potencies toward four other validated antitrypanosomal drug targets. In view of the foregoing findings, we propose that the six morpholine derivatives be given worthwhile attention to develop them into novel trypanocides.
ABSTRACT Investigations were conducted to determine the geo-electrical properties, aquifer potent... more ABSTRACT Investigations were conducted to determine the geo-electrical properties, aquifer potential and quality of groundwater samples of the Ajali Sandstone Formation at Ninth mile area, Nigeria. Results reveal that the formation has 4 to 6 geo-electric layers, with the 5th recording hydraulic conductivity, transmissivity and transverse resistance values that suggested a general high yield to boreholes. The aquifer longitudinal conductance analysis indicates poor aquifer protective capacity, thus, high risk of contamination by effluents from the heavy industries within the area. Qualitative analysis shows major ionic concentrations, in the order: Na+>K+>Ca2+>Mg2+>Fe2+>HCO3->Cl->SO42-> NO3-, that satisfy all permissible limits for drinking purpose. All tested samples have heavy metals, except Pb2+, also fall within acceptable limits. High amount of Pb2+ originated most probably from improper disposal of ‘leaded’ petroleum products or leaching of lead from metal casing used in the well development. That the water samples satisfied almost all limits for drinking purpose despite the poor aquifer protective capacity and high industrialization may imply that the wastewater received fairly adequate treatments before discharge. Caution should; however, be applied in dealing with factors that give rise to lead contamination and in the water usage.
Characterization of red onion skin tannin (ROST) was done using FTIR and UV/visible spectrophotom... more Characterization of red onion skin tannin (ROST) was done using FTIR and UV/visible spectrophotometric techniques, revealing ROST to be made up of mixed (hydrolysable and condensed) tannins. ROST has been found to be an effective corrosion inhibitor of aluminium in hydrochloric acid solutions using gravimetric, thermometric, and UV/visible spectrophotometric techniques. Proposed kinetic model reveals complex reaction mechanism (parallel reactions) for aluminium corrosion inhibition by ROST. ROST adsorption on aluminium followed Langmuir isotherm in 0.1M and Fruendlich isotherm in 0.5M HCl and 2.0M HCl at 303 Kelvin. Physical adsorption (physisorption) of ROST on aluminium has been proposed.
Adsorption of anthocleista djalonensis leaf extract on aluminum in hydrochloric acid solution was... more Adsorption of anthocleista djalonensis leaf extract on aluminum in hydrochloric acid solution was studied at 30°C and 60°C using gravimetric technique. Increasing the concentration (v/v %) of anthocleista djalonensis leaf extract was observed to increase its corrosion inhibition efficiency. Temperature studies revealed an increase in inhibition efficiency with rise in temperature. Comparative analysis of kinetic and thermodynamic parameters revealed effective inhibition. This paper demonstrates the use of two statistical approaches – Analysis of variance (ANOVA) and Duncan multiple range test, in the determination of the performance of various linearised Langmuir equations.
ABSTRACT Anthocleista djalonensis leaf extract –a renewable, easily available and non-toxic agric... more ABSTRACT Anthocleista djalonensis leaf extract –a renewable, easily available and non-toxic agricultural byproduct of West African origin, has been demonstrated to have good corrosion inhibition property.The corrosion inhibition of aluminium in HCl using leaf extract of Anthocleista djalonensis is reported at 30˚C-60˚C using weight loss and thermometric techniques. Leaf extract of Anthocleista djalonensis acted as inhibitor for aluminium in HCl and the inhibition efficiency (%I) increased with concentration of leaf extract of Anthocleista djalonensis. The corrosion inhibition property was by adsorption of the phytochemicals – sitosterol, stigmasterol, sweroside or djalonenoside, 3-oxo- Δ -4, 5-sitosterone and ursolic acid, on the aluminium. Temperature studies revealed a decrease in inhibition efficiency with rise in temperature. The adsorption of the leaf extract of Anthocleista djalonensis on aluminum in HCl solution obeyed the Langmuir, Temkin, Freundlich and EL-Awady adsorption isotherms
Metal deterioration over time is a process known as corrosion, an electrochemical process, which ... more Metal deterioration over time is a process known as corrosion, an electrochemical process, which can occur by surface chemical actions on metals by its environment. Metal corrosion have great economic, security, and environmental consequences, and its control is a major research area in corrosion science. Amongst the different corrosion protecting approaches, the use of corrosion inhibitors and protective coatings have attracted enormous research interest in this area of scholasticism. This has necessitated the computational and electrochemical investigations of aluminium corrosion inhibitive potentials of some compounds in 1M HCl. Metal free (5_H2), ClGa(III) (5_Ga) and Co(II) (5_Co) tetrakis(4-acetamidophenoxy)phthalocyanines as well as Co(II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (6) and Co(II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (7) were synthesized for the first time and studied for corrosion inhibition. The reported ClGa(III)...
Abstract N -(2-chloroethyl)morpholine-4-carboxamide (NCMC), N -(2-chloroethyl)tiomorpholine-4-car... more Abstract N -(2-chloroethyl)morpholine-4-carboxamide (NCMC), N -(2-chloroethyl)tiomorpholine-4-carboxamide (NCTC) and N , N -bis(2-chloroethyl)piperazine-1,4-dicarboxamide (NCPD) were studied as corrosion inhibitors for mild steel using atomic absorption spectroscopy (AAS) and gravimetry and thermometry. Results obtained from the three techniques are similar and reveal that the compounds inhibit mild steel corrosion. The inhibition efficiencies increased from 35.6% to 74.9% (NCMC), 44.5% to 82.4% (NCPD) and 52.6% to 90.1% (NCTC) at 30 °C when the inhibitor concentrations increased from 10 μM to 50 μM. The maximum inhibition efficiency values (at 50 μM) decreased to 46.6%, 58.1% and 61.2% for NCMC, NCPD and NCTC respectively, when the temperature was raised to 50 °C. The decrease in inhibition efficiency with increase in temperature suggested predominant physisorption mechanism in metal/inhibitor interactions. The formation of protective films of NCMC, NCPD and NCTC molecules on mild steel surface were confirmed by FTIR and XRD. The order of inhibitive strengths of the molecules is NCTC > NCPD > NCMC. Quantum chemical calculations revealed the prospective sites through which the molecules can interact with mild steel surface and some quantum chemically derived parameters were used to corroborate experimental.
Human African trypanosomiasis, also known as sleeping sickness, is caused by the single-celled ki... more Human African trypanosomiasis, also known as sleeping sickness, is caused by the single-celled kinetoplastid parasite Trypanosoma brucei transmitted to humans by infected tsetse flies. The disease threatens millions of people. Currently available treatment options are faced with some important challenges. In this work, a total of eighty-seven (87) morpholine derivatives were evaluated for drug-likeness based on Lipinski’s rule of five and their ability to inhibit the activities of trypanosomal triosephosphate isomerase was assessed by molecular docking and calculation of free energy of binding. Analysis of the results revealed that 97.7 % of the dataset complied with Lipinski’s criteria for a molecule to be orally bioavailable. Also, 50.0 % of the studied compounds had a good total polar surface area profile, a parameter which is of great importance for the treatment of stage two Trypanosoma infections. Docking studies showed that all the dataset demonstrated affinity for triosephosphate isomerase. Moreover, six morpholines scored higher than the co-crystallized inhibitor of triosephosphate isomerase (2-phosphoglycerate). These derivatives inhibited the activity of triosephosphate isomerase by making significant interactions with Glu 167, Val 214, 233, Asn 11, Lys 13, Ser 213, Leu 232, Ile 172, Gly 211, 212, 234, 235 and His 92 in the active site of the protein. Furthermore, besides the acceptable pharmacokinetic profiles of the six morpholines, they also showed inhibitory potencies toward four other validated antitrypanosomal drug targets. In view of the foregoing findings, we propose that the six morpholine derivatives be given worthwhile attention to develop them into novel trypanocides.
ABSTRACT Investigations were conducted to determine the geo-electrical properties, aquifer potent... more ABSTRACT Investigations were conducted to determine the geo-electrical properties, aquifer potential and quality of groundwater samples of the Ajali Sandstone Formation at Ninth mile area, Nigeria. Results reveal that the formation has 4 to 6 geo-electric layers, with the 5th recording hydraulic conductivity, transmissivity and transverse resistance values that suggested a general high yield to boreholes. The aquifer longitudinal conductance analysis indicates poor aquifer protective capacity, thus, high risk of contamination by effluents from the heavy industries within the area. Qualitative analysis shows major ionic concentrations, in the order: Na+>K+>Ca2+>Mg2+>Fe2+>HCO3->Cl->SO42-> NO3-, that satisfy all permissible limits for drinking purpose. All tested samples have heavy metals, except Pb2+, also fall within acceptable limits. High amount of Pb2+ originated most probably from improper disposal of ‘leaded’ petroleum products or leaching of lead from metal casing used in the well development. That the water samples satisfied almost all limits for drinking purpose despite the poor aquifer protective capacity and high industrialization may imply that the wastewater received fairly adequate treatments before discharge. Caution should; however, be applied in dealing with factors that give rise to lead contamination and in the water usage.
Characterization of red onion skin tannin (ROST) was done using FTIR and UV/visible spectrophotom... more Characterization of red onion skin tannin (ROST) was done using FTIR and UV/visible spectrophotometric techniques, revealing ROST to be made up of mixed (hydrolysable and condensed) tannins. ROST has been found to be an effective corrosion inhibitor of aluminium in hydrochloric acid solutions using gravimetric, thermometric, and UV/visible spectrophotometric techniques. Proposed kinetic model reveals complex reaction mechanism (parallel reactions) for aluminium corrosion inhibition by ROST. ROST adsorption on aluminium followed Langmuir isotherm in 0.1M and Fruendlich isotherm in 0.5M HCl and 2.0M HCl at 303 Kelvin. Physical adsorption (physisorption) of ROST on aluminium has been proposed.
Adsorption of anthocleista djalonensis leaf extract on aluminum in hydrochloric acid solution was... more Adsorption of anthocleista djalonensis leaf extract on aluminum in hydrochloric acid solution was studied at 30°C and 60°C using gravimetric technique. Increasing the concentration (v/v %) of anthocleista djalonensis leaf extract was observed to increase its corrosion inhibition efficiency. Temperature studies revealed an increase in inhibition efficiency with rise in temperature. Comparative analysis of kinetic and thermodynamic parameters revealed effective inhibition. This paper demonstrates the use of two statistical approaches – Analysis of variance (ANOVA) and Duncan multiple range test, in the determination of the performance of various linearised Langmuir equations.
ABSTRACT Anthocleista djalonensis leaf extract –a renewable, easily available and non-toxic agric... more ABSTRACT Anthocleista djalonensis leaf extract –a renewable, easily available and non-toxic agricultural byproduct of West African origin, has been demonstrated to have good corrosion inhibition property.The corrosion inhibition of aluminium in HCl using leaf extract of Anthocleista djalonensis is reported at 30˚C-60˚C using weight loss and thermometric techniques. Leaf extract of Anthocleista djalonensis acted as inhibitor for aluminium in HCl and the inhibition efficiency (%I) increased with concentration of leaf extract of Anthocleista djalonensis. The corrosion inhibition property was by adsorption of the phytochemicals – sitosterol, stigmasterol, sweroside or djalonenoside, 3-oxo- Δ -4, 5-sitosterone and ursolic acid, on the aluminium. Temperature studies revealed a decrease in inhibition efficiency with rise in temperature. The adsorption of the leaf extract of Anthocleista djalonensis on aluminum in HCl solution obeyed the Langmuir, Temkin, Freundlich and EL-Awady adsorption isotherms
Uploads
Papers by Nnaemeka Nnaji