Michael A Okposo | DELTA STATE UNIVERSITY, ABRAKA, DELTA STATE, NIGERIA (original) (raw)

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Papers by Michael A Okposo

Biosurfactants are amphiphilic compounds produced by microorganisms as secondary metabolite. Its ... more Biosurfactants are amphiphilic compounds produced by microorganisms as secondary metabolite. Its unique properties such as low toxicity, higher biodegradability, mild process conditions, higher foaming capacity, temperature, pH and salinity stability and synthesis under user-friendly conditions makes them possible to replace synthetic surfactants which are mainly used in food, cosmetics and pharmaceutical industries and in environmental applications. In this study, biosurfactant production by P. aeruginosa was investigated as well as the influence of fermentation factors (stay time, pH and salinity), the result showed that increased in pH to alkaline medium favoured the biosurfactant yield, as the stay time increased to 4days the yield increased, the optimum salinity was found to be 1.5w/v. Optimization of the process was carried out using response surface methodology adopting Box-behnkien design. The selected factors were stay time, pH and salinity and the optimum time for biosurfa...

This work presents the kinetic experiments carried out for the removal C57 as a basic dye from wa... more This work presents the kinetic experiments carried out for the removal C57 as a basic dye from waste water using avocado pear seed waste biomass. The impacts of major variables governing the efficiency of the process such as temperature, interaction time, concentration, adsorbent dosage, and pH were checked. However the parameter impact result reflected that the quantity of the basic dye taken away increased from 0.194-0.212mg/g as the pear seed dosage was increased from 2000-6000 mg. In the same line the quantity of dye taken up increased from 0.198-0.202mg/g as increase interaction time changed from 20-40mins, thereafter the dye adsorbed decreased at a interaction time of 60-100 mins. Also, the dye adsorption capacity increased from 0.195-1.194mg/g with an increase in concentration of dye from 10mg/l-50mg/l. the Langmuir and Freundlich models were applied to depict the adsorption efficiency. The squares of correlation coefficient (R 2) for both isotherms were 0.102 and 0.019 respectively. The basic dye abatement mechanism was analyzed using the linearized pseudo-first order and pseudosecond order kinetics having a correlation coefficient (R 2) of 0.336 and 0.999 respectively and the rate constant K1 and K2 were also determined. The experimental data was perfectly described by pseudo second-order adsorption kinetics.

— Biosurfactants are amphiphilic compounds produced by microorganisms as secondary metabolite. It... more — Biosurfactants are amphiphilic compounds produced by microorganisms as secondary metabolite. Its unique properties such as low toxicity, higher biodegradability, mild process conditions, higher foaming capacity, temperature, pH and salinity stability and synthesis under user-friendly conditions makes them possible to replace synthetic surfactants which are mainly used in food, cosmetics and pharmaceutical industries and in environmental applications. In this study, biosurfactant production by P. aeruginosa was investigated as well as the influence of fermentation factors (stay time, pH and salinity), the result showed that increased in pH to alkaline medium favoured the biosurfactant yield, as the stay time increased to 4days the yield increased, the optimum salinity was found to be 1.5w/v. Optimization of the process was carried out using response surface methodology adopting Box-behnkien design. The selected factors were stay time, pH and salinity and the optimum time for biosurfactant production is 6 days, optimum pH of 8 and a salinity level of 1.0% (w/v), also a second order polynomial model was generated which was found significant across all model criteria.

The phytochemical constituents and antioxidant activity of Mucuna pruriens root was determined vi... more The phytochemical constituents and antioxidant activity of Mucuna pruriens root was determined via in vitro model. The extraction from the plant roots was using different solvents (distilled water, petroleum ether, ethylacetate, methanol and ethanol) in soxhlet extractor apparatus. The qualitative phytochemical analysis of Mucuna pruriens root extracts showed the presence of alkaloids, flavonoids, Steroids, phenolic compounds and tannis in all solvent root extracts except in petroleum ether while terpenoids was absent only in water extract. Quinones were present in petroleum ether, ethylacetate and ethanolic extracts and saponin was found only in ethanolic extract. The total phenolic and total flavonoid content of the methanolic, ethanolic and water extracts were estimated spectrophotometrically using tannic acid and quercetine respectively as standard. The total phenolic content obtained from methanolic, ethanolic and water extracts were 27.40±0.17, 30.66±2.68 and 45.95±2.68µg/g respectively of tannic acid equivalent while that for flavonoid content were 96.31±0.06, 60.79±0.79 and 58.26±1.23µg/g respectively of quercetin equivalent from methanolic, ethanolic and water extracts respectively. Furthermore, invitro antioxidant activity of both the methanolic and ethylacetate extracts of Mucuna pruriens root were carried out using ascorbic acid as standard. The methanolic extract showed antioxidant activity in scavenging a DPPH radical with a maximum percentage inhibition of 66.78% at 250 µg/ml that of ethylacetate extract was 66.27% whereas for the ascorbic acid, it was 71.35% at 250µg/ml. The IC 50 was calculated graphically and the result obtained are 154 µg/ml, 165 µg/ml and 122 µg/ml respectively. The invitro models indicate that Mucuna pruriens root extract is a better source of natural antioxidant. This justifies its application in traditional and herbal medicine in the treatment of various diseases and correction of sexual anomaly such as erectile dysfunction caused by reactive oxygen species (ROS).

– This work presents the kinetic experiments carried out for the removal C57 as a basic dye from ... more – This work presents the kinetic experiments carried out for the removal C57 as a basic dye from waste water using avocado pear seed waste biomass. The impacts of major variables governing the efficiency of the process such as temperature, interaction time, concentration, adsorbent dosage, and pH were checked. However the parameter impact result reflected that the quantity of the basic dye taken away increased from 0.194 – 0.212mg/g as the pear seed dosage was increased from 2000-6000 mg. In the same line the quantity of dye taken up increased from 0.198-0.202mg/g as increase interaction time changed from 20-40mins, thereafter the dye adsorbed decreased at a interaction time of 60 – 100 mins. Also, the dye adsorption capacity increased from 0.195-1.194mg/g with an increase in concentration of dye from 10mg/l – 50mg/l. the Langmuir and Freundlich models were applied to depict the adsorption efficiency. The squares of correlation coefficient (R 2) for both isotherms were 0.102 and 0.019 respectively. The basic dye abatement mechanism was analyzed using the linearized pseudo-first order and pseudo – second order kinetics having a correlation coefficient (R 2) of 0.336 and 0.999 respectively and the rate constant K1 and K2 were also determined. The experimental data was perfectly described by pseudo second-order adsorption kinetics.

Malachite dye is among the millions of dyes used in every aspect of our daily life. The adsorptio... more Malachite dye is among the millions of dyes used in every aspect of our daily life. The adsorption kinetic of the pollutant (dye) from adsobate using palm kernel shell (Elaeis Guineasis) as the biomass was studied. From the several experimental parameters measured, the optimum adsorption occurred at 20 minutes giving 92.3%. Adsorption also decreased from 92.49% to 87.9% with increase in absorbent dosage giving the optimum dosage of 2g. Also increase in temperature decreased the adsorption from 95.6% to 92.7% having it optimum temperature to be 30 o C. Increase in dye ion concentration from 10-50mg/L also increased adsorption from 79.3% to 93.0%. There was a decrease in the percentage of dye removed for all the parameters investigated except for dye ion concentration. The value of S F for Langmuir model is 0.232 and R 2 value is 0.6326 while for Freundlich model, the value of 1/n is 2.8092 and R 2 value is 0.9135 which indicate that Langmuir and Freundlich model are both good isotherm models because they have a S F value of < 1 and 1/n value > 1. Pseudo second order model best fit the experimental data than pseudo first order having R 2 values of 1 and 0.5613 respectively. This shows that palm kernel shell can be used as an effective biomass for removing waste water from dye.

Malachite dye is among the millions of dyes used in every aspect of our daily life. The adsorptio... more Malachite dye is among the millions of dyes used in every aspect of our daily life. The adsorption kinetic the pollutant (dye) from adsobate using palm kernel shell (Elaeis Guineasis) as the biomass was studied. From the several experimental parameters measured, the optimum adsorption occurred at 20 minutes giving 92.3%. Adsorption also decreased from 92.49% to 87.9% with increase in absorbent dosage giving the optimum dosage of 2g. Also increase in temperature decreased the adsorption from 95.6% to 92.7% having it optimum temperature to be 30 o C. Increase in dye ion concentration from 10-50mg/L also increased adsorption from 79.3% to 93.0%. There was a decrease in the percentage of dye removed for all the parameters investigated except for dye ion concentration. The value of S F for Langmuir model is 0.232 and R 2 value is 0.6326 while for Freundlich model, the value of 1/n is 2.8092 and R 2 value is 0.9135 which indicate that Langmuir and Freundlich model are both good isotherm models because they have a S F value of < 1 and 1/n value > 1. Pseudo second order model best fit the experimental data than pseudo first order having R 2 values of 1 and 0.5613. This shows that palm kernel shell can be used as an effective biomass for removing waste water from dye.

This work presents the kinetic model for the sorption of methyl violet dye by African nutmeg (mon... more This work presents the kinetic model for the sorption of methyl violet dye by African nutmeg (monodora myristica) shells. The effects of various experimental parameters such as pH, contact time, adsorbent dosage, temperature and dye ion concentration were evaluated. From the analysis, the amount of dye adsorbed increased from 1.41mg/L to 1.97mg/L with increase in contact time ranging from 20 to 100 minutes. Adsorption also increased from 1.30mg/L to 1.70mg/L with increase in adsorbent dosage from 2 to 6g. It was also observed that increase in concentration from 10 to 50mg/L lead to increase in amount of dye adsorbed. Also, increase in pH from 2 to 10 lead to increase in amount of dye adsorbed from 0.74mg/L to 2.35mg/L. While in the effect of temperature, the amount of dye adsorbed decreased from 2.53mg/L to 2.18mg/L with increase in temperature from 30 0 C to 70 0 C. There was an increase in the percentage of dye removed in the effects of temperature and concentration, while contact time, pH and adsorbent dosage, reverse was the case. The R 2 values for the Langmuir and Freundlich isotherms were 0.600 and 0.920 respectively, indicating that the Freundlich isotherm has a better relationship and is more suitable for describing the process. The pseudo-first and pseudo-second order kinetics were used to analyze the data and it was found that they had R 2 values of 0.766 and 1 respectively. By implication, the pseudo-second order model fit into it because of its R 2 value. The Pseudo-second order agrees with the sorption process.

Drafts by Michael A Okposo

Malachite dye is among the millions of dyes used in every aspect of our daily life. The adsorptio... more Malachite dye is among the millions of dyes used in every aspect of our daily life. The adsorption kinetic the pollutant (dye) from adsobate using palm kernel shell (Elaeis Guineasis) as the biomass was studied. From the several experimental parameters measured, the optimum adsorption occurred at 20 minutes giving 92.3%. Adsorption also decreased from 92.49% to 87.9% with increase in absorbent dosage giving the optimum dosage of 2g. Also increase in temperature decreased the adsorption from 95.6% to 92.7% having it optimum temperature to be 30 o C. Increase in dye ion concentration from 10-50mg/L also increased adsorption from 79.3% to 93.0%. There was a decrease in the percentage of dye removed for all the parameters investigated except for dye ion concentration. The value of S F for Langmuir model is 0.232 and R 2 value is 0.6326 while for Freundlich model, the value of 1/n is 2.8092 and R 2 value is 0.9135 which indicate that Langmuir and Freundlich model are both good isotherm models because they have a S F value of < 1 and 1/n value > 1. Pseudo second order model best fit the experimental data than pseudo first order having R 2 values of 1 and 0.5613. This shows that palm kernel shell can be used as an effective biomass for removing waste water from dye.