N. Odewunmi | King Fahd University of Petroleum and Minerals (original) (raw)

Papers by N. Odewunmi

Research paper thumbnail of Watermelon waste products as green corrosion inhibitors for mild steel in HCl solution

Journal of Environmental Chemical Engineering, 2015

Three agro-waste products namely; watermelon rind extract (WMRE), watermelon seed extract (WMSE) ... more Three agro-waste products namely; watermelon rind extract (WMRE), watermelon seed extract (WMSE) and watermelon peel extract (WMPE) were investigated for their corrosion inhibition potentials for mild steel in HCl solution using electrochemical techniques at 25 C. All the extracts inhibited acid-induced corrosion of mild steel in the order WMSE > WMRE > WMPE. Corrosion inhibition effect was found to be dependent on extracts' concentrations. Inhibitive action of the extracts could be attributed to adsorption of the extracts' components on mild steel surface by physisorption mechanism according to Langmuir adsorption isotherm model and functions as mixed-typed inhibitors as revealed by potentiodynamic polarization studies.

Research paper thumbnail of Experimental and Theoretical Studies of Red Apple Fruit Extract as Green Corrosion Inhibitor for Mild Steel in HCl Solution

Journal of Dispersion Science and Technology, 2014

ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild st... more ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild steel in hydrochloric acid was investigated by gravimetric and electrochemical methods at 30–60°C. Inhibition efficiency increased with the increase in concentration and temperature. Polarization curves indicate that the extract functions as mixed-type inhibitor. The adsorption of the extract onto mild steel surface followed Langmuir adsorption isotherm model. Chemisorption mechanism is proposed based on the trend of inhibition efficiency with temperature. Quantum chemical calculations and molecular dynamics simulations have been used to provide insights into the mechanism of interaction of the major extract components with mild steel.

Research paper thumbnail of From Electrode Surface Fouling to Sensitive Electroanalytical Determination of Phenols

Electroanalysis, 2013

The present investigation of phenol and chlorophenols is conducted on the surface of glassy carbo... more The present investigation of phenol and chlorophenols is conducted on the surface of glassy carbon by cyclic and square wave stripping voltammetry, and by Fourier-transform infrared spectroscopy. The surface fouling is accompanied by the appearance of reversible peaks at lower potential range (+ 0.1 to + 0.4 V), that grew up with CV-cycling and attributed to the electro-redox reactions of formed polymer film via electropolymerization. The electroanalytical monitoring of formed polymer oxidation peaks improved both sensitivity and detection limit by 35 and 10 times, respectively. The FT-IR supported semiempirical prediction attributes the electropolymerization to the formation of ortho-para and/or ortho-meta CÀC coupled-system. Phenol, chlorophenol derivatives, pentachlorophenol sodium salt (pCP-Na salt), hydroquinone, disodium hydrogen phosphate (Na 2 HPO 4 ) and 0.05 microns gamma

Research paper thumbnail of Electroanalytical Determination of Antibacterial Ciprofloxacin in Pure Form and in Drug Formulations

Arabian Journal for Science and Engineering, 2014

A simple, rapid and sensitive electroanalytical method was developed to measure ciprofloxacin (CP... more A simple, rapid and sensitive electroanalytical method was developed to measure ciprofloxacin (CPF) concentration at an electrode surface made of a new composite material, electrochemically activated glassy carbon paste. Square-wave adsorptive stripping voltammetry comparisons of CPF measured at GCPE, glassy carbon and carbon paste electrode surfaces yielded the highest CPF signal at GCPE surfaces. When pH dependence was assessed, 0.1 M phosphate buffer solution, pH 5.0, showed the best anodic peak for CPF oxidation. When the conditions of the voltammetric method were optimized, a GCPE electrode surface 1.6 mm in diameter yielded a dynamic calibration curve (R 2 = 0.97) at CPF concentrations of 10-750 ppb. The limits of detection (3σ ) and quantification were 12.2 ppb (33 nM) and 10 ppb (27 nM) CPF, respectively. The new composite electrode yielded reproducible results, with a relative standard deviation of 6.96 % (intraday) and 6.47 % (interday) for five repeated measurements of 0.5 ppm CPF. Finally, when this method was used to determine the concentration of CPF (active ingredient) in Floxacin tablets dissolved in pure buffer and in buffer containing 10 % fresh urine, the recoveries of CPF were 100 and 105 %, respectively. This method thus allows the direct determination of CPF in urine samples, making it suitable for routine analysis in clinical laboratories.

Research paper thumbnail of Utilization of watermelon rind extract as a green corrosion inhibitor for mild steel in acidic media

Journal of Industrial and Engineering Chemistry, 2014

Electrochemical techniques were used to investigate the efficacy of watermelon rind extract (WMRE... more Electrochemical techniques were used to investigate the efficacy of watermelon rind extract (WMRE) as corrosion inhibitor for mild steel in HCl and H 2 SO 4 solutions. The inhibition efficiency increased as the concentration of the extract increases. Potentiodynamic polarization results indicate that WMRE act as a mixed-type inhibitor. The values of effective capacitance obtained by utilizing the impedance parameters in both acidic media are in the range of double layer capacitance. Corrosion inhibition effect of WMRE can be attributed to the adsorption of constituents of WMRE onto the mild steel surface which can be approximated by Temkin adsorption isotherm model.

Research paper thumbnail of Watermelon waste products as green corrosion inhibitors for mild steel in HCl solution

Journal of Environmental Chemical Engineering, 2015

Three agro-waste products namely; watermelon rind extract (WMRE), watermelon seed extract (WMSE) ... more Three agro-waste products namely; watermelon rind extract (WMRE), watermelon seed extract (WMSE) and watermelon peel extract (WMPE) were investigated for their corrosion inhibition potentials for mild steel in HCl solution using electrochemical techniques at 25 C. All the extracts inhibited acid-induced corrosion of mild steel in the order WMSE > WMRE > WMPE. Corrosion inhibition effect was found to be dependent on extracts' concentrations. Inhibitive action of the extracts could be attributed to adsorption of the extracts' components on mild steel surface by physisorption mechanism according to Langmuir adsorption isotherm model and functions as mixed-typed inhibitors as revealed by potentiodynamic polarization studies.

Research paper thumbnail of Experimental and Theoretical Studies of Red Apple Fruit Extract as Green Corrosion Inhibitor for Mild Steel in HCl Solution

Journal of Dispersion Science and Technology, 2014

ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild st... more ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild steel in hydrochloric acid was investigated by gravimetric and electrochemical methods at 30–60°C. Inhibition efficiency increased with the increase in concentration and temperature. Polarization curves indicate that the extract functions as mixed-type inhibitor. The adsorption of the extract onto mild steel surface followed Langmuir adsorption isotherm model. Chemisorption mechanism is proposed based on the trend of inhibition efficiency with temperature. Quantum chemical calculations and molecular dynamics simulations have been used to provide insights into the mechanism of interaction of the major extract components with mild steel.

Research paper thumbnail of From Electrode Surface Fouling to Sensitive Electroanalytical Determination of Phenols

Electroanalysis, 2013

The present investigation of phenol and chlorophenols is conducted on the surface of glassy carbo... more The present investigation of phenol and chlorophenols is conducted on the surface of glassy carbon by cyclic and square wave stripping voltammetry, and by Fourier-transform infrared spectroscopy. The surface fouling is accompanied by the appearance of reversible peaks at lower potential range (+ 0.1 to + 0.4 V), that grew up with CV-cycling and attributed to the electro-redox reactions of formed polymer film via electropolymerization. The electroanalytical monitoring of formed polymer oxidation peaks improved both sensitivity and detection limit by 35 and 10 times, respectively. The FT-IR supported semiempirical prediction attributes the electropolymerization to the formation of ortho-para and/or ortho-meta CÀC coupled-system. Phenol, chlorophenol derivatives, pentachlorophenol sodium salt (pCP-Na salt), hydroquinone, disodium hydrogen phosphate (Na 2 HPO 4 ) and 0.05 microns gamma

Research paper thumbnail of Electroanalytical Determination of Antibacterial Ciprofloxacin in Pure Form and in Drug Formulations

Arabian Journal for Science and Engineering, 2014

A simple, rapid and sensitive electroanalytical method was developed to measure ciprofloxacin (CP... more A simple, rapid and sensitive electroanalytical method was developed to measure ciprofloxacin (CPF) concentration at an electrode surface made of a new composite material, electrochemically activated glassy carbon paste. Square-wave adsorptive stripping voltammetry comparisons of CPF measured at GCPE, glassy carbon and carbon paste electrode surfaces yielded the highest CPF signal at GCPE surfaces. When pH dependence was assessed, 0.1 M phosphate buffer solution, pH 5.0, showed the best anodic peak for CPF oxidation. When the conditions of the voltammetric method were optimized, a GCPE electrode surface 1.6 mm in diameter yielded a dynamic calibration curve (R 2 = 0.97) at CPF concentrations of 10-750 ppb. The limits of detection (3σ ) and quantification were 12.2 ppb (33 nM) and 10 ppb (27 nM) CPF, respectively. The new composite electrode yielded reproducible results, with a relative standard deviation of 6.96 % (intraday) and 6.47 % (interday) for five repeated measurements of 0.5 ppm CPF. Finally, when this method was used to determine the concentration of CPF (active ingredient) in Floxacin tablets dissolved in pure buffer and in buffer containing 10 % fresh urine, the recoveries of CPF were 100 and 105 %, respectively. This method thus allows the direct determination of CPF in urine samples, making it suitable for routine analysis in clinical laboratories.

Research paper thumbnail of Utilization of watermelon rind extract as a green corrosion inhibitor for mild steel in acidic media

Journal of Industrial and Engineering Chemistry, 2014

Electrochemical techniques were used to investigate the efficacy of watermelon rind extract (WMRE... more Electrochemical techniques were used to investigate the efficacy of watermelon rind extract (WMRE) as corrosion inhibitor for mild steel in HCl and H 2 SO 4 solutions. The inhibition efficiency increased as the concentration of the extract increases. Potentiodynamic polarization results indicate that WMRE act as a mixed-type inhibitor. The values of effective capacitance obtained by utilizing the impedance parameters in both acidic media are in the range of double layer capacitance. Corrosion inhibition effect of WMRE can be attributed to the adsorption of constituents of WMRE onto the mild steel surface which can be approximated by Temkin adsorption isotherm model.