DSpace Repository :: Browsing by Author "Nkiko, Mojisola O."

Browsing by Author "Nkiko, Mojisola O."

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Adaptive neuro-fuzzy inference system (ANFIS) approach for the irreversibility analysis of a domestic refrigerator system using LPG/TiO2 nanolubricant
(Energy Reports, 2020-05-28) Gill, Jatinder; Singh, Jagdev; Ohunakin, Olayinka S.; Adelekan, Damola S.; Atiba, Opemipo E.; Nkiko, Mojisola O.; Atayero, Aderemi A.
This work presents an adaptive neuro-fuzzy inference system (ANFIS) artificial intelligence methodology of predicting the 2nd law efficiency and total irreversibility of a refrigeration system running on LPG/TiO2–nano-refrigerants. For this purpose, substractive clustering and grid partition approaches were utilized to train the ANFIS models required in estimating the 2nd law efficiency and total irreversibility using some experimental data. Furthermore, predictions of ANFIS models with subtractive clustering approach was found to be more accurate than ANFIS models predictions with grid partition approach. The predictions of ANFIS models with subtractive clustering approach were also compared with experimental results that were not included in the model training and predictions of already existing ANN models of authors previous publication. The comparison of variance, root mean square error (RMSE), mean absolute percentage error (MAPE) were 0.996–0.999, 0.0296–0.1726 W and 0.108–0.176 % marginal variability values. These results indicate that the ANFIS model with subtractive clustering approach having cluster radii 0.7 and 0.5 can predict the 2nd law efficiency and total irreversibility respectively, with higher accuracy than authors’ previous publication ANN models.
Adoption Kinetics and Thermodynamics of Malachite Green Onto Chitosan / Sodium Citrate Beads
(Ife Journal of Science, 2013) Bamgbose, Janet; Bamigbade, A.A.; Nkiko, Mojisola O.
Corrosion Inhibitive Effect of Ocimum Gratissimum Extract on Zinc-Aluminium Alloy in Hydrochloric Acid
(Sociedade Portuguesa de Electroquímica, 2011-11) Nkiko, Mojisola O.; Bamgbose, Janet T.
The inhibitive effect of Ocimum gratissimum by seed extract on the corrosion of zinc-aluminium (ZA) alloy in 2 M hydrochloric acid (HCl) solution has been studied using gravimetric methods. Inhibition increases with concentration of extract but decreases with temperature. This observation implies that Ocimum gratissimum seed extract is an effective and non toxic inhibitor of the corrosion of zinc-aluminium alloy. Adsorption of the extract on the surface obeyed the Freundlich adsorption isotherm. The calculated rate constant (k) shows a first order kinetics in the absence and presence of the inhibitor. The kinetic parameter B, measured for the reaction has a high negative value which implies that Ocimum gratissimum becomes more effective as the temperature increases. Synergistic effect of halide additives shows an increase in the efficiency of the extract. However synergism parameter shows that synergism of halide additives decreases with increased concentration of inhibitor.
Effect of Electrodeposition Mechanism and α-Si3N4/ZrBr2 Doped Composite Particle on the Physicochemical and Structural Properties of Processed NiPZn Coatings on Mild Steel for Advance Application
(Key Engineering Materials (Volume 900), 2021-09) Fayomi, Ojo Sunday Issac; Ayodeji, Sode Adedamola; Anyanwu, Benedict Uche; Nkiko, Mojisola O.; Dauda, Khadijah Tolulope
Ni-P-Zn nanocomposite coatings were plated on mild steel surface from sulphamate rich bath containing (α-Si3N4 and α-ZrBr2) nanoparticle produced via electrodeposition process. The compositions of the particulate were varied from 0 to 10 wt% with time variation between 10 to 25 min after ascertaining other optimum parameters. The crystal evolution and morphological quantification were examined using scanning electron microscope supported with energy dispersive spectroscopy. The corrosion degradation in an acidic and alkaline environment was considered and compared to establish the suitability and extents of the corrosion vulnerability of deposited coatings. The surface flake crystal identified on the microstructural properties show the presence of compositional constituent and disperse particle of α-Si3N4 and α-ZrBr2. Finally, corrosion properties show a resilient crystal surface stability in the presence of chloride and sulphate ion with a remarkable surface film still retained at the bulk interface. This study has confirmed that α-Si3N4 and α-ZrBr2 composite coating can be used for structural development and corrosion improvement in the presence of active ions. Keywords: Nanomaterials, Structure, Corrosion, Prevention, Coatings
Effect of Inositol Hexaphosphate on the Azide Binding Reactivity of Mouse Methaemoglobin
(International Journal of Science and Technological Research, 2007) Nkiko, Mojisola O.; Demehin, A. A.; Ogunmola, G. B.
Methernoglobin (metl—lb) reactswith neutral and negative ligands because of the availability of a net positivecharge to form complexes. This reaction involves the replacement of the water molecules at the sixth Coordinated position
Effect of temperature on the formation and decomposition of butan-2-3-dione in wort brewed with sorghum and barley during fermentation
(Hrvatsko društvo kemijskih inženjera i tehnologa, 2006-12-18) Nkiko, Mojisola O.; Taiwo, E. A.; Uruebor, A.; Ogunyemi, A.
The rate of breakdown of fermentable sugar and the formation/decomposition of butan-2,3-dione (diacetyl) in wort made with unmalted sorghum, malted sorghum, malted barley and sorghum/barley malt adjunct during fermentation was studied as a function of temperature. The rate of fermentation of sugar, formation and decomposition of butan-2,3-dione increases with increasing temperature and is dependent on the nature of the substrate. The decomposition of butan-2,3-dione is faster in wort made with malted sorghum and barley when compared to wort made with unmalted sorghum or sorghum/barley malt adjunct.
Effect of Temperature on the Formation and Decomposition of Butan-2-3-dione in Wort Brewed with Sorghum and Barley During Fermentation
(Chem. Biochem. Eng. Q., 2006) Nkiko, Mojisola O.; Taiwo, E. A.; Uruebor, A.; Ogunyemi, A.
The rate of breakdown of fermentable sugar and the formation/decomposition of butan-2,3-dione (diacetyl) in wort made with unmalted sorghum, malted sorghum, malted barley and sorghum/barley malt adjunct during fermentation was studied as a function of temperature. The rate of fermentation of sugar, formation and decomposition of butan-2,3-dione increases with increasing temperature and is dependent on the nature of the substrate. The decomposition of butan-2,3-dione is faster in wort made with malted sorghum and barley when compared to wort made with unmalted sorghum or sorghum/ barley malt adjunct
Effect of ZrB2 Functionalized Nanoparticles Growth on Microstructural and Corrosion Resistance on Mild Steel through Electrodeposition Route
(Key Engineering Materials, 2021) Fayomi, Ojo Sunday Issac; Nkiko, Mojisola O.; Dauda, Khadijah Tolulope; Oluwasegun, Kunle Michael
In other to have a better performance of Ni-P-Zn multifunctional applications, crystallite-like Ni-P-Zn-ZrB2 composite was actively fabricated by electrodeposition principle. The corrosion, structural evolution and surface active phenomena were investigated by various techniques. The influence of ZrB2 particulate on the morphology and corrosion properties was examined. The outcomes show an inclusive flower-like doped ZrB2 phase constituent and is uniformly distributed Ni-P-Zn-ZrB2 improved strengthening effect. The corrosion progression of the developed metal alloy was compared with other coating matrix from 10-25 minutes interval. The integration of ZrB2 on Ni-P-Zn phase especially for 25 min deposits significantly enhances corrosion resistance due to good grain refinement. Keywords: Ni-based composite, electrodeposition, time difference, coating, corrosion
Evaluation of the Industrial Potential of Pentachletra Mycrophylla Seed
(lntegrated Journal of Science and Engineering, 2000) Taiwo, E. A.; Nkiko, Mojisola O.; Adekoya, T. S.
Experimental and Quantum Chemical Studies of the Inhibition of Copper with Sodium Dodecyl Sulphate (SDS) in Acidic Medium
(Scientific Research Publishing, 2018) Nkiko, Mojisola O.; Oluwabi, Abayomi; Ahmed, Sikiru A.; Bamgbose, Janet T.
This work investigates the inhibitive properties of sodium dodecyl sulphate (SDS) on the corrosion of copper (Cu) in nitric acid using gasometric methods. The inhibition efficiency increases with time and concentration of SDS. The corrosion rate of copper decreases as concentration of SDS increases. Adsorption of the SDS on the surface obeyed the Langmuir adsorption isotherm. The high negative values of the kinetic parameter B suggest that the inhibitor’s effectiveness increases with temperature. The equilibrium constant and the free energy of adsorption of SDS to copper are negative and large. This observation implies that the adsorption mechanism maybe chemisorption. The quantum chemical calculation of copper dodecyl sulphate shows that the energy change in the HOMO-LUMO energy of the moiety is positive and small. This observation implies that the SDS is an efficient inhibitor. The high dipole moment obtained implies that corrosion inhibition of Cu is enhanced by adsorption of SDS and this observation correlates with the observed experimental inhibition efficiency
Experimental Investigation and Time Effect on the Anticorrosion and Microstructural Properties of Zinc Flake Nickel−Phosphorus Coating Electrodeposited on Mild Steel
(ACS Publications, 2021-04-21) Fayomi, Ojo Sunday Isaac; Ayodeji, Sode Adedamola; Agboola, Oluranti; Oluwasegun, Kunle Michael; Nkiko, Mojisola O.
In this work, the potential of ZnSO4·7H2O in NiP sulphate electrolyte deposited on mild steel under constant optimum pH of 5, current density of 1 A/cm2, stirring rate of 200 rpm, and varying time parameter between 10, 15, 20, and 25 min were studied using the electrodeposition method. The microstructure properties and corrosion resistance characteristics were analyzed using a scanning electron microscope enhanced with an energy-dispersive spectroscope and potentiodynamic polarization apparatus, respectively. The codeposited was subjected to different media test rig of 0.5 M H2SO4 and 3.5% NaCl to examine the susceptibility effect. The results pointed out that there is a stable mass weight gain as the time increases, which facilitates the formation of dispersed crystal build-up and homogeneous NiPZn content within the interface. A remarkable corrosion property was also noticed with deposits of highest time effect, which is invariably a factor of solid bonding seen at the surface lattice.
Experimental studies and influence of process factor on zinc-nickel based coating on mild steel
(Taylor & Francis: Advances in Materials and Processing Technologies, 2021-03) Fayomi, O.S.I.; Sode, A.A.; Anyanwu, B.U.; Ayoola, A.A.; Nkiko, Mojisola O.; Oluwasegun, K.M.; Alkhuele, D.O.; Ighravwe, D.E .
Sulphate-rich electrolytic bath containing ZnSO4.7H2O in NiP solution was used to develop coating with Ni-P-Zn matrix under optimised process parameter. The major considerations are to examine the factor variance and the effect of varying time parameter between 10, 15, 20 and 25 min on the developed coating. Wear loss evolution was examined using reciprocating sliding wear tester with a force of 10 N and 20 N. The microhardness behaviour was examined using durascan microhardness tester with diamond indenter. The change in the structural build-up and the corrosion performance trend was observed using a scanning electron microscope enhanced with energy dispersive spectroscopy and potentiodynamic polarisation route. From the result we observe that time-dependant factors impact maximally on the crystal growth which rightly influences the coating hardness performance. For wear performance, the counter with external forces couldn’t penetrate wholly into the lattice of the developed coating due to the resilient formation of stable flakes. The microstructure formation shows stable dispersed crystal build-up and homogeneous growth. An excellent corrosion resistance characteristic was noticed with Ni-P-Zn-25 min matrix.
INTERACTIONS OF CROSS-LINKED AND UNCROSS-LINKED CHITOSAN HYDROGELS WITH SURFACTANTS FOR BIOMEDICAL APPLICATIONS
(Ife Journal of Science, 2014) Bamgbose, J. T.; Nkiko, Mojisola O.; Bamigbade, A. A.; Dare, E. O.
The swelling equilibrium of Chitosan and sodium tripolyphosphate (NaTPP) cross-linked chitosan hydrogels in o aqueous solutions of surfactants differing in structure and hydrophobicity at 25 C is reported. Anionic surfactant sodium dodecylsulfate (SDS), the cationic surfactant hexadecyltrimethylammonium bromide (HTAB) and neutral surfactants Triton X-100 were employed. The surfactants induced abrupt change in the gel volume. The equilibrium swelling ratio first decreased sharply as the concentration of the surfactant increased and remained almost constant up to the critical micelles concentration (CMC) of the surfactants and then increased again as the concentration increased above the CMC of the surfactants used. The equilibrium volume change of hydrogel was significantly increased from HTAB > Triton X-100 > SDS> the mixed SDS/Triton X- 100 system. A decrease in equilibrium swelling ratio of the gel in SDS/TX-100 mixtures was observed with an increase in the mole ratio of SDS. The results also revealed that cross-linking with 3% or 5% w/v NaTPP exhibited lower equilibrium swelling values. This swelling study showed that cross-linking density, surfactant type, and their respective concentrations were important parameters that could affect equilibrium swelling of chitosan gel. Structural elucidation of the nanocomposites was monitored using Infra-red Spectroscopy (IR), and X-Ray Diffractography (XRD)
Interactions of cross-linked and uncross-linked chitosan hydrogels with surfactants for biomedical applications
(Faculty of Science, Obafemi Awolowo University, 2014) Bamgbose, J. T.; Nkiko, Mojisola O.; Bamigbade, A. A.; Dare, E. O.
The swelling equilibrium of Chitosan and sodium tripolyphosphate (NaTPP) cross-linked chitosan hydrogels in aqueous solutions of surfactants differing in structure and hydrophobicity at 250C is reported. Anionic surfactant sodium dodecylsulfate (SDS), the cationic surfactant hexadecyltrimethylammonium bromide (HTAB) and neutral surfactants Triton X-100 were employed. The surfactants induced abrupt change in the gel volume. The equilibrium swelling ratio first decreased sharply as the concentration of the surfactant increased and remained almost constant up to the critical micelles concentration (CMC) of the surfactants and then increased again as the concentration increased above the CMC of the surfactants used. The equilibrium volume change of hydrogel was significantly increased from HTAB > Triton X-100 > SDS> the mixed SDS/Triton X- 100 system. A decrease in equilibrium swelling ratio of the gel in SDS/TX-100 mixtures was observed with an increase in the mole ratio of SDS. The results also revealed that cross-linking with 3% or 5% w/v NaTPP exhibited lower equilibrium swelling values. This swelling study showed that cross-linking density, surfactant type, and their respective concentrations were important parameters that could affect equilibrium swelling of chitosan gel. Structural elucidation of the nanocomposites was monitored using Infra-red Spectroscopy (IR), and X-Ray Diffractography (XRD).
Interrogating the Teaching and Learning of Chemistry in Nigerian Private Universities: Matters Arising
(Journal of Education and Learning, 2021-05-14) Nkiko, Mojisola O.
The indispensability and vast career possibilities associated with Chemistry notwithstanding, there is a palpable growing decline enrollment in Chemistry in Nigerian universities, particularly the private universities. The paper interrogated the teaching and learning of Chemistry in Nigerian private universities with a view to re-awakening the students’ interest for effective mastery of the subject. It relied on secondary sources and critical analysis and found out that major inhibiting factors include: Students’ faulty foundation in Chemistry, syndrome of area of concentration, absence of competitiveness in the admission process, poor attitude of students and lecturers as well as the ambience for effective scholarship. The paper concluded that the current downturn in the students enrolment in Chemistry and the seemingly poor interest in the subject portend sufficient threat to the future of Chemistry, chemical-related industries and the replacement of ageing Chemistry lecturers in Nigeria. It recommended the following strategies to mitigate the vicious cycle: targeted tutorial system, adoption of digital modes of teaching and learning, problem-based learning, capacity building initiatives for Chemistry lecturers, quality assurance mechanism, overhauling science education at the primary and secondary school levels, need-based assessment and provision of quality materials as well as adequate funding.
Isothermal, kinetics and thermodynamics studies of the biosorption of Pb (II) ion from aqueous solution using the scale of croaker fish (Genyonemus lineatus)
(IWA Publishing, 2013-09-01) Nkiko, Mojisola O.; Adeogun, Abideen I.; Babarinde, N. A.; Sharaibi, Oluwabunmi J.
Biosorbent prepared from the scale of croaker fish (Genyonemus lineatus) has been used for the removal of Pb(II) ion from aqueous solution in a batch system. The effects of some important parameters such as pH, initial metal concentration, temperature and biosorbent dosage on biosorption capacity were investigated. Equilibrium time for the biosorption process is 20 and 30 min at lower and higher concentrations, respectively. The process at 28 °C is in agreement with a pseudo-second-order kinetics model. The equilibrium data obeyed the Langmuir adsorption isotherm with a maximum monolayer adsorption capacity of 14.58 mg g−1. The study showed that the sorption process depends on biomass dosage, temperature, pH and initial metal ion concentration. The calculated thermodynamics parameters (ΔGo, ΔHo and ΔSo) indicated that the biosorption of the metal ion onto fish scale is feasible, spontaneous and exothermic in nature.
Ocimum Gratissimum Extract As potentials Eco-Friendly Inhibitor for Aluminum Alloy in Hydrochloric Acid
(Chemical Society of Nigeria, 2010) Nkiko, Mojisola O.
Performance of a domestic refrigerator in varying ambient temperatures, concentrations of TiO2 nanolubricants and R600a refrigerant charges
(Heliyon, 2021-01) Adelekan, D.S.; Ohunakin, O.S.; Oladeinde, M.H.; Jatinder, Gill; Atiba, O.E.; Nkiko, Mojisola O.; Atayero, A.A.
This study investigates the effect of varying test conditions including ambient temperature (19, 22, and 25 C), mass charges of R600a refrigerant (40, 50, 60, and 70 g), and concentrations of TiO2 nanolubricant (0, 0.2 and 0.4 g/L) on the performance of a slightly modified 100g R134a domestic refrigeration system. The investigated parameters include evaporator air temperature, energy consumption, coefficient of performance, and second law efficiency of the system. The results showed that the performance of the refrigeration system at 0.2 and 0.4 g/L concentrations of TiO2 nanolubricant, improved at optimum ambient temperature and R600a mass charge conditions. At optimum conditions, the evaporator air temperature and energy consumption reduced within the range 5.26 to 26.32 %, and 0.13 to 14.09 % respectively, while the coefficient of performance and second law efficiency increased within the range 0.05 to 16.32 %, and 2.8 to 16 %, respectively. However, at other conditions (nonoptimum), the energy consumption and evaporator air temperature were higher and within the range 0.28 to 8.26 %, and 5 to 40 % respectively, while the coefficient of performance and second law efficiency reduced within the range 2.99 to 10.94 %, and 0.55 to 13.43 % respectively. In conclusion, we observed variations in the performance of the refrigerator with varying test conditions.
Protection of Zinc Alloy in H3PO4 using Extract of Lantana Camara
(Life Science Journal, 2014) Nkiko, Mojisola O.; Oguntoyinbo, Esther. S.; Bamgbose, Janet.T.; Bamigbade, Akeem .A.
The inhibitive effect of lantana camara leaf extract on the corrosion of Zinc alloy in phosphoric acid solution has been studied using gravimetric methods. Inhibition increases with time and concentration of extract and temperature. This observation implies that lantana camara leaf extract is an effective and non-toxic inhibitor of the corrosion of zinc alloy. Adsorption of the extract on the surface obeyed the Langmuir adsorption isotherm. The kinetic parameter B, measured for the reaction has a high negative value which implies that lantana camara becomes more effective as the temperature increases. The free energy calculated for adsorption is small and negative in magnitude which suggests that the mechanism of adsorption is physical. The Brinell hardness test which is a measure of the tensile strength shows that lantana camara provides protection for Zn alloy in acid solutions.
Review of metal protection techniques and application of drugs as corrosion inhibitors on metals
(IOP Conference Series: Materials Science and Engineering, 2021-04) Nduma, R.C .; Fayomi, O.S.I.; Nkiko, Mojisola O.; Inegbenebor, A.O.; Udoye, N.E.; Onyisi, O.; Sanni, O.; Fayomi, J.
The inability of metals to resist degradation as a result of corrosion remains a unique global problem that depend on different metals for daily operations. Therefore, knowing the appropriate method to use is a key to ameliorate corrosion effect on metals. Green inhibitors serve as a modern, cheaper and environmentally favorable method to retard the effects of corrosion. Drugs are corrosion inhibitors which can reduce the action of corrosion without being hazardous to the environment as they are synthesized from natural products. The review studies the metal protection techniques and the use of drug as corrosion inhibitors. The importance of copper as a useful metal as good corrosion resistance due to inherent properties alongside its malleability was also discussed.

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