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Browsing by Author "Omorogie, Martins"

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Activated Carbon from Nauclea diderrichii Agricultural Waste–a Promising Adsorbent for Ibuprofen, Methylene Blue and CO2
(Elsevier, 2021-03-15) Omorogie, Martins
The adsorption potential of activated carbon derived from Nauclea diderrichii biomass (NDAC) was scrupulously harnessed as a low cost and ubiquitous adsorbent for the removal of greenhouse gas (CO2), and organic pollutants such as methylene blue (MB) and ibuprofen (IB) from water. NDAC was fully characterized by scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), universal attenuated total reflectance-infra red (UATR-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), solid state nuclear magnetic resonance (NMR) and nitrogen gas adsorption–desorption by Brunauer-Emmett-Teller (BET) technique. This study showed that NDAC comprises graphitic carbons that had some surface functional groups such as C C, C O, etc, which adsorbed these environmental contaminants. The adsorption equilibrium and kinetic data that the adsorption of these environmental contaminants formed multilayers (homogeneous surfaces) with the surface of NDAC. The adsorption mechanism of CO2, MB and IB onto NDAC occurred by via electrostatic attractions and π-π conjugal interactions. The adsorption capacity of NDAC for CO2 was ca. 3.2 cm3.g−1 at 298 K. The Langmuir maximum adsorption capacity, qmax of NDAC for MB and IB was obtained as 35.09 mg.g−1 and 70.92 mg.g−1 at 328 K respectively.
Adsorption and Desorption Kinetics of Toxic Organic and Inorganic Ions using an Indigenous Biomass: Terminalia ivorensis Seed Waste
(Springer, 2017-05-15) Omorogie, Martins
Environmental remediation has been a strategy employed by scientists to combat water pollution problems that have led to the scarcity of potable water. Hence, in this study, Terminalia ivorensis seed waste (TISW) was explored for the removal of Congo Red, Methylene Blue, Cadmium and Lead from aqueous solutions. Some experimental variables such as pH, biosorbent dose, initial solute ion concentration, agitation time and temperature were optimised. The surface microstructures of TISW were studied using proximate analysis, bulk density, specific surface area, pH of Point of Zero Charge, Fourier Transform Infra Red Spectroscopy, Thermogravimetric/Differential Thermal Analysis, Scanning Electron Microscopy and Energy Dispersive Analysis of X-ray. The maximum Langmuir monolayer saturation adsorption capacity, qmaxL, was obtained as 175.44 mg/g for the removal of Methylene Blue by TISW. Also, the qmaxL for CR, Cd(II) ion and Pb(II) ion were 85.47, 12.58 and 52.97 mg/g, respectively. Also, the pseudo-first-order constant, k1, and pseudo-second-order rate constant, k2, are 0.008–0.026/min and 0.012–0.417 mg/g min, respectively. Hence, TISW is recommended as a good adsorbent for the removal of both toxic industrial dyes and toxic metal ions from polluted water.
Adsorption Efficacy of Cedrela odorata Seed Waste for Dyes: Non linear Fractal Kinetics and non linear Equilibrium Studies
(Elsevier, 2016-08-15) Omorogie, Martins
Alteration of the structural and functional integrity of the aquatic ecosystems due to contamination from toxic industrial dyes warrants cost effective remedial strategies. Cedrela odorata Seed Chaff (COSC) was locally sourced, indigenous and ubiquitous. In support of this proposition, the efficacy of the COSC was assessed for the adsorption of some toxic industrial dyes, namely Methylene Blue (MB), Congo Red (CR), Methyl Violet (MV) and Methyl Orange (MO) from aqueous solutions. The microstructures of Cedrela odorata Seed Chaff (COSC) were carried out using pH of Point of Zero Charge (PZC), Specific Surface Area (SSA), Bulk Density (BD), Fourier Transform Infra Red Spectroscopy (FTIR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) which indicated that various organic moieties were present in COSC, which the toxic industrial dyes studied were adsorbed onto. Non linear equilibrium and non linear fractal models were used to fit experimental data. The experimental data best fit the Fritz-Schlunder four-parameter isotherm and the fractal-like pseudo-second order (three-parameter) kinetic equation. The Langmuir monolayer adsorption capacities, qmaxL of COSC for the uptake of MB, CR, MV and MO were 88.32–111.88 mg/g, 79.46–128.84 mg/g, 75.11–121.23 mg/g and 57.35–68.23 mg/g respectively as temperature increased from 298 to 318 K. The results support the use of Cedrela odorata Seed Chaff (COSC) as a cost effective material for removal of toxic industrial dye from an aquatic system. Large scale studies are required in the future to prove the efficacy of Cedrela odorata Seed Chaff (COSC) for toxic industrial dyes from varied environmental conditions.
Adsorptive Modelling of Toxic Cations and Ionic Dyes onto Cellulosic Extract
(Springer, 2016-12-01) Omorogie, Martins
This work reports the abstractive potential of Parkia biglobosa seed waste (PSW) and Parkia biglobosa cellulosic extract (PBCE) for the removal of Cr(VI), Pb(II), methylene blue (MB) and congo red (CR) from aqua system. Physicochemical analyses carried out for these biomaterials were proximate analysis, Fourier transform infra red (FTIR) Spectrophotometry and scanning electron microscopy (SEM). The FTIR data showed that –O–H, –C=C–, –C=O, –C:C– and –S–H functional groups were responsible for the sequestration of Cr(VI), Pb(II), MB and CR from aqua system. The equilibrium data fitted best to Langmuir isotherm model with the highest adsorption obtained for MB, being 1498.42 mg/g at 298 K and 403.23 mg/g at 298 K for PSW and PBCE respectively. Pseudo-second order model gave the best fits for the kinetic data among two other kinetic models used. The PSW and PBCE biomaterials demonstrated good potentials for the removal of toxic Cr(VI), Pb(II), MB and CR from aqua systems.
Biomass-based Hydrothermal Carbons for Catalysis and Environmental Cleanup: A Review
(Taylor and Francis, 2022-01-21) Omorogie, Martins
The growing demand for alternative green energy and environmental crises is a significant concern for the world population. Thus, researchers have devoted effort to finding cheap, eco-friendly, and robust functional materials. The bottleneck faced by scientists is the synthesis of a material with high surface area, highly functionalized, and cost-effective. To this end, biomass-based hydrothermal carbons are gaining increasing attention due to the presence of functional groups introduced during hydrothermal carbonization (HTC) and mild/tunable preparation conditions. This review Materials the synthesis, parameters that influence the carbonization process, and mechanisms involved during HTC. Other synthesis routes for enhancing the properties of HTC carbon materials are also discussed. The application of HTC carbon materials, including energy storage devices, catalysis, electrocatalysis, photocatalysis, and adsorption, are reported. Lastly, we present the challenges and possible strategies for improving the HTC process.
Biosorption of Heavy Metals from Aqueous Solutions by Parkia biglobosa Biomass: Equilibrium, Kinetics, and Thermodynamic Studies
(John Wiley, 2015-09-25) Omorogie, Martins
The adsorption capacities of Parkia biglobosa chaff biomass (PBC) and Parkia biglobosa pulp biomass (PBP) for Cr(III), Cd(II), Ni(II), and Pb(II) ions were studied. Experimental data suggested the highest monolayer sorption capacities of PBC and PBP, at equilibrium to be 170.07 mg/g at pH 7.0 and 324.68 mg/g at pH 6.0, for the uptake of Cr(III) ions, respectively. The minimum adsorption capacities obtained by PBC and PBP were 60.72 mg/g for Ni(II) and 16.70 mg/g for Cd(II) at pH value of 2.0, respectively. Pseudo second order kinetic model fits the all experimental data best, suggesting that the entire adsorption processes might have occurred by chemisorption mechanism. Thermodynamic data indicated that the adsorption of various metal ions by PBC and PBP was endothermic, with increase in disorderliness of the system. The Gibb’s free energy values for the uptake of Cr(III), Cd(II) and Ni(II) ions by PBC indicated the spontaneity of the processes. Moreover, the Gibb’s free energy values for the uptake of Pb(II) ion by PBC depicted the non spontaneity of the processes. Also, Gibb’s free energy values for the adsorption of various metal ions by PBP depicted the spontaneity of the processes.
Carbon-mediated Visible-light Clay-Fe2O3–graphene Oxide Catalytic Nanocomposites for the Removal of Steroid Estrogens from Water
(Elsevier, 2021-04-01) Omorogie, Martins
This study reports the development of efficient photosensitive nanocomposites made from clay, Fe2O3, and graphene oxide (GO). These nanocomposites were used for the removal of steroid estrogens (E1, E2, E3 and EE2) from water under visible-light. The use of these photocatalytic nanocomposites led to oxidation of the steroid estrogens at >80 % even under simultaneous presence of all estrogens in water. Mineralization was obtained for these estrogens within the range of 58–73 %. The presence of Fe-oxide in the nanocomposites increased the photocatalytic efficiency but addition of GO further improved the photocatalytic efficiency. This improved efficiency was further doubled when the nanocomposites were prepared with a carbon source (Carica papaya seeds). The presence of carbon in the nanocomposite matrix was confirmed using X-ray photoelectron spectroscopy and Elemental analysis. The main contributors to photocatalytic efficiency of these nanocomposites are superoxide radicals (•O2-) and holes (h+). Under competitive conditions, the photocatalysts are still active although the extent of estrogen oxidation is somewhat lower. Changes in the ionic strength did not significantly influence the efficiency of the photocatalyst. This signifies that adsorption only plays a minor role in estrogen removal from water. Toxicity tests show that the treated water is safe for human consumption and the most efficient nanocomposite can be recycled three times without any significant loss of performance. Overall, the nanocomposite show high potential for the effective removal of a cocktail of estrogens in raw wastewater, tap and rain water, attaining contamination levels that are within WHO safe limits.
Clays for Efficient Disinfection of Bacteria in Water
(Elsevier, 2018-01-15) Omorogie, Martins
Clay minerals are not only abundant in nature but can be easily engineered to make highly efficient materials for disinfection of water. A combination of their abundance and efficiency makes them a sustainable source of material for water disinfection. Several works have reported the use of clay minerals in modified form to make the removal of harmful pathogens from water sustainable and more efficient. This article reviews the various modified clay minerals that have been developed for the removal of these harmful pathogens from water. It also considers several operating factors that moderate the efficiencies of these materials during the pathogen removal process, techniques for measuring interaction between bacteria and clay-based adsorbents and future perspectives on their use in the treatment of potable water. It is believed that this will spur some interest in the quick development of very efficient and sustainable clay-based materials that will be useful for disinfection of water and wastewater in the near future.
Clean Technology and Response Surface Approach for the Photodegradation of Selected Antibiotics by Catalyst Supported on Pine Activated Carbon
(Springer, 2017-09-30) Omorogie, Martins
This study enthusiastically highlights for the first time, a new nano-photocatalyst (reconstruction of SnO2/MnO2/Al2O3/TiO2 on MCM-41 SiO2@KOH-modified pine bark activated carbon harnessed for the photodegradation of two pharmaceuticals, which are contaminants of emerging concern, namely tetracycline (TCL) and sulfamethoxazole (SMX), using the response surface methodology. The MCM-41 structure-directing agent and a new low-cost/locally synthesized activated carbon were used as support for semiconductor nano-photocatalyst, which in turn enhanced its surface area/pore structure and photoactivity through the decrease in electron–hole pair recombination. The optimal desirability histogram and ramp functions showed each optimal or desirable condition for each dependent variable (factor) and independent variable (response). In overall, after all targets have been achieved, the ramp function plots gave a desirability of 0.689 (68.9%) for the photodegradation of TCL and a desirability of 0.602 (60.2%) for the photodegradation of SMX. The response surface methodology (RSM) technique showed that experimental run 3 gave maximal condition for the photodegradation of TCL with 99.4% of photodegradation of TCL achieved in 30 min, with half-life (time taken for 50% of 20 mg/L of TCL to photodegrade) of 3.04 min and a quantity of 9.94 mg/g of TCL photodegraded. Likewise, experimental run 10 gave maximal condition for the photodegradation of SMX with 94.95% of photodegradation of SMX achieved in 60 min, with half-life (time taken for 50% of 20 mg/L of SMX to photodegrade) of 5.58 min and a quantity of 9.50 mg/g of SMX photodegraded. This lucidly shows that this nanophotocatalyst is more efficient for the photodegradation of low initial concentration of TCL and SMX, when compared to the high initial concentrations of these antibiotics studied.
Clean Technology Approach for the Competitive Binding of Toxic Metal ions onto MnO2 nano-bioextractant
(Springer, 2016-01-15) Omorogie, Martins
The competitive extraction of Cr(III) onto Nauclea diderrichii seed epicarp doped with MnO2 nanoparticles (MnO2 nano-bioextractant (MNB)) in a single and binary batch system was studied. For validity of experimental data, chi square test, root mean square error, sum of the square errors, hybrid fractional error function, Marquart’s percent standard deviation and standard absolute error were used. Among the kinetic models used, pseudo-second-order and Langmuir equations gave the best fits for the experimental data, with qe (mg/g) for the uptake of Cr(III) in single metal system onto MNB, then Cr(III) with Cd(II), Pb(II), Hg(II), KCl and CaCl2 in binary metal systems onto MNB were 2.611, then 1.989, 1.016, 2.208, 1.249 and 1.868 from kinetic standpoint, respectively. The initial sorption rates, h (mg/g/min), and half lives, t1/2 (min), for the uptake of Cr(III) in single metal system onto MNB, then Cr(III) with Cd(II), Pb(II), Hg(II), KCl and CaCl2 in binary metal system onto MNB were 3.497, then 2.311, 2.274, 0.242, 2.956, 45.568 and 0.747, then 5.769, 1.766, 12.144, 1.762, and 2.415, respectively. Physicochemical surface analyses such as pH of point of zero charge, Brunauer–Emmett–Teller single point and multipoint techniques for surface area analyses, scanning electron microscopy and transmission electron microscopy were done on MNB and MnO2 nanoparticles in order to understand their surface microstructures. Desorption study showed that MNB can be recycled and used for future study. Hence, MNB showed good potential to remediate Cr(III) from wastewaters and polluted water.
Clean Technology for Synchronous Sequestration of Charged Organic Micro-pollutant onto Microwave-assisted Hybrid Clay Materials
(Springer, 2020-03-01) Omorogie, Martins
The Sustainable Development Goal 6 (SDG #6) of the United Nations (UN) is hinged on the provision, availability, and sustainability of water for the global populace by 2030. In a bid to achieve this goal, the quest to seek for ubiquitous and low-cost adsorbents to treat effluents laden with industrial dyes, such as methylene blue (MB), is on the increase in recent years. Acute exposure of humans to (MB) dye causes cyanosis, necrosis, and jaundice and even leads to death. In this research, zinc-modified hybrid clay composite adsorbent (materials from kaolinite and biomass (crushed Carica papaya seeds and/or plantain peel)) was developed via microwave route. This adsorbent was characterized using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray (EDX), and high-resolution transmission electron microscopy (HR-TEM). These characterization techniques confirmed the success achieved in doping hybrid clay with Zn. These adsorbents were used to sequester cationic dye (MB) from aqueous solutions and textile effluent under various experimental conditions. The adsorption and desorption data obtained were analyzed using various kinetic models, which are two-step kinetics, pseudo-first order, pseudo-second order, fractal kinetics, first-order desorption, second-order desorption, and modified statistical rate theory (MSRT) desorption models. Results showed that the adsorption of the dye occurred via several chemical interactions, while the latter models (for desorption) indicated that desorption occurred in two different desorption sites on the adsorbent surfaces, which showed that the adsorption of MB dye onto the adsorbents was stable without the emergence of any secondary pollution. Adsorption of MB was achieved within 15 min for aqueous solutions and 900 min for textile effluent, which is an improvement on previous results from other studies. The three adsorption-desorption cycles for MB uptake by the adsorbents showed that it is pragmatically applicable to treat textile effluents. Hence, low-cost composite adsorbents have a potential for the effective remediation of MB dye from textile effluents as this study confirmed.
Disinfection of Water with New Chitosan-modified Hybrid Clay Composite Adsorbent
(Elsevier, 2017-08-15) Omorogie, Martins
Hybrid clay composites were prepared from Kaolinite clay and Carica papaya seeds via modification with chitosan, Alum, NaOH, and ZnCl2 in different ratios, using solvothermal and surface modification techniques. Several composite adsorbents were prepared, and the most efficient of them for the removal of gram negative enteric bacteria was the hybrid clay composite that was surface-modified with chitosan, Ch-nHYCA1:5 (Chitosan: nHYCA = 1:5). This composite adsorbent had a maximum adsorption removal value of 4.07 × 106 cfu/mL for V. cholerae after 120 min, 1.95 × 106 cfu/mL for E. coli after ∼180 min and 3.25 × 106 cfu/mL for S. typhi after 270 min. The Brouers-Sotolongo model was found to better predict the maximum adsorption capacity (qmax) of Ch-nHYCA1:5 composite adsorbent for the removal of E. coli with a qmax of 103.07 mg/g (7.93 × 107 cfu/mL) and V. cholerae with a qmax of 154.18 mg/g (1.19 × 108 cfu/mL) while the Sips model best described S. typhi adsorption by Ch-nHYCA1:5 composite with an estimated qmax of 83.65 mg/g (6.43 × 107 cfu/mL). These efficiencies do far exceed the alert/action levels of ca. 500 cfu/mL in drinking water for these bacteria. The simplicity of the composite preparation process and the availability of raw materials used for its preparation underscore the potential of this low-cost chitosanmodified composite adsorbent (Ch nHYCA1:5) for water treatment.
Efficient Chromium Abstraction from Aqueous Solution Using a Low-Cost Biosorbent: Nauclea diderrichii Seed Biomass Waste
(Elsevier, 2016-01-15) Omorogie, Martins
Toxic Cr(III) which poses environmental hazard to flora and fauna was efficiently abstracted by low-cost Nauclea diderrichii seed biomass (NDS) with good sequestral capacity for this metal was investigated in this study. The NDS surface analyses showed that it has a specific surface area of 5.36 m2/g and pHpzc of 4.90. Thermogravimetric analysis of NDS showed three consecutive weight losses from 50–200C (ca. 5%), 200–400C (ca. 35%), >400C (ca. 10%), corresponding to external water molecules, structural water molecules and heat induced condensation reactions respectively. Differential thermogram of NDS presented a large endothermic peak between 20–510C suggesting bond breakage and dissociation with the ultimate release of small molecules. The experimental data showed kinetically fast biosorption with increased initial Cr(III) concentrations, indicating the role of external mass transfer mechanism as the rate controlling mechanism in this adsorption process. The Langmuir biosorption capacity of NDS was 483.81 mg/g. The use of the corrected Akaike Information Criterion tool for ranking equilibrium models suggested that the Freundlich model best described the experimental data, which is an indication of the heterogeneous nature of the active sites on the surface of NDS.
Exploring the Binding Interactions of Structurally Diverse dichalcogenoimidodiphosphinate Ligands with α-amylase: Spectroscopic Approach Coupled with Molecular Docking
(Elsevier, 2020-12-01) Omorogie, Martins
Postprandial hyperglycemia has orchestrated untimely death among diabetic patients over the decades and regulation of α-amylase activity is now becoming a promising management option for type 2 diabetes. The present study investigated the binding interactions of three structurally diverse dichalcogenoimidodiphosphinate ligands with α-amylase to ascertain the affinity of the ligands for α-amylase using spectroscopic and molecular docking methods. The ligands were characterized using 1H and 31P NMR spectroscopy and CHN analysis. Diselenoimidodiphosphinate ligand (DY300), dithioimidodiphosphinate ligand (DY301), and thioselenoimidodiphosphinate ligand (DY302) quenched the intrinsic fluorescence intensity of α-amylase via a static quenching mechanism with bimolecular quenching constant (Kq) values in the order of x1011 M-1s-1, indicating formation of enzyme-ligand complexes. A binding stoichiometry of n≈1 was observed for α-amylase, with high binding constants (Ka). α-Amylase inhibition was as follow: Acarbose > DY301>DY300>DY302. Values of thermodynamic parameters obtained at temperatures investigated (298, 304 and 310 K) revealed spontaneous complex formation (ΔG<0) between the ligands and α-amylase; the main driving forces were hydrophobic interactions (with DY300, DY301, except DY302). UV–visible spectroscopy and Förster resonance energy transfer (FRET) affirmed change in enzyme conformation and binding occurrence. Molecular docking revealed ligands interaction with α-amylase via some key catalytic site amino acid residues (Asp197, Glu233 and Asp300). DY301 perhaps showed highest α-amylase inhibition (IC50, 268.11 ± 0.74 μM) due to its moderately high affinity and composition of two sulphide bonds unlike the others. This study might provide theoretical basis for development of novel α-amylase inhibitors from dichalcogenoimidodiphosphinate ligands for management of postprandial hyperglycemia.
Facile Synthesis of New Amino-functionalized Agrogenic Hybrid Composite Clay Adsorbents for Phosphate Capture and Recovery from Water
(Elsevier, 2017-10-15) Omorogie, Martins
New hybrid clay materials with good affinity for phosphate ions were developed from a combination of biomass-Carica papaya seeds (PS) and Musa paradisiaca (Plantain peels-PP), ZnCl2 and Kaolinite clay to produce iPS-HYCA and iPP-HYCA composite adsorbents respectively. Functionalization of these adsorbents with an organosilane produced NPS-HYCA and NPP-HYCA composite adsorbents. The pHpzc for the adsorbents were 7.83, 6.91, 7.66 and 6.55 for iPS-HYCA, NPS-HYCA, iPP-HYCA and NPP-HYCA respectively. Using the Brouer-Sotolongo isotherm model which best predict the adsorption capacity of composites for phosphate, iPP-HYCA, iPS-HYCA, NPP-HYCA, and NPS-HYCA composite adsorbents respectively. When compared with some commercial resins, the amino-functionalized adsorbents had better adsorption capacities. Furthermore, amino-functionalized adsorbents showed improved adsorption capacity and rate of phosphate uptake (as much as 40-fold), as well as retain 94% (for NPS-HYCA) and 84.1% (for NPP-HYCA) efficiency for phosphate adsorption after 5 adsorption-desorption cycles (96 h of adsorption time with 100 mg/L of phosphate ions) as against 37.5% (for iPS-HYCA) and 35% (for iPP-HYCA) under similar conditions. In 25 min desorption of phosphate ion attained equilibrium. These new amino-functionalized hybrid clay composite adsorbents, which were prepared by a simple means that is sustainable, have potentials for the efficient capture of phosphate ions from aqueous solution. They are quickly recovered from aqueous solution, non-biodegradable (unlike many biosorbent) with potentials to replace expensive adsorbents in the future. They have the further advantage of being useful in the recovery of phosphate for use in agriculture which could positively impact the global food security programme.
Fenton-modified Malacantha Alnifolia Tree Bark for Effective Surface Separation of Tetracycline
(Springer, 2021-09-16) Omorogie, Martins
This research work gave details on the application of Malacantha alnifolia tree bark as a low-cost adsorbent for the removal of tetracycline from aqueous solution. The tree bark was modified using different ratios of ferrous sulphate and hydrogen peroxide (Fenton’s reagent). Fenton modification of the adsorbent was more effective at high concentration of ferrous sulphate solution and at low concentration of hydrogen peroxide solution. Both the modified and unmodified adsorbents were characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), Boehm titration and pH of point of zero charge (pHpzc). The effects of various parameters such as pH, Fe2+/H2O2 concentration ratio, contact time, initial tetracycline concentration and adsorbent dose were studied. The experimental data were best described by Freundlich isotherm model and the adsorption kinetics followed the pseudo-second order kinetic model. The thermodynamic analysis of the adsorption processes indicated a non-spontaneous process for the unmodified adsorbent (UMA) and a spontaneous process for the modified adsorbent (MMA); change in enthalpy showed that the adsorption process for both adsorbents was exothermic and change in entropy indicated that the adsorption process was orderly. Desorption studies showed that the modified adsorbent can be regenerated more than the unmodified. Fenton-modification improved the adsorption capacity of Malacantha alnifolia tree bark.
Ferromagnetic FeSe2 from a Mixed Sulphur-selenium Complex of Iron [Fe {(SePPh2NPPh2S)2N}3] through Pyrolysis
(Elsevier, 2020-04-15) Omorogie, Martins
Iron (III) thioselenoimidodiphosphinate complex, Fe{(SePPh2NPPh2S)2N}3], was synthesized from the ligand [Ph2P(S)HNP(Se)Ph2], and the complex employed as the combined source of the targeted elements (Fe and Se) to generate orthorhombic FeSe2. This was achieved by thermolysis using a quartz glass tube, under reduced pressure at 500 °C during 1 h 30 min. The crystalline product was revealed by X-ray diffraction (XRD), while the morphology consisted of polygonal crystallites according to the scanning electron microscopy (SEM) studies. Superconducting quantum interference device (SQUID) measurements on the material confirmed its ferromagnetism as observed from the magnetization curve, indicated by the field-cooled and zero field-cooled conditions under a magnetic field of 100 Oe. This ferromagnetic material, FeSe2 finds useful application in producing electrical semiconductors.
Hybrid Materials from Agro-waste and Nanoparticles: Implications on the Kinetics of the Adsorption of Inorganic Pollutants
(Taylor and Francis, 2014-03-01) Omorogie, Martins
This study is a first-hand report of the immobilization of Nauclea diderrichii seed waste biomass (ND) (an agro-waste) with eco-friendly mesoporous silica (MS) and graphene oxide–MS (GO + MS) nanoparticles, producing two new hybrid materials namely: MND adsorbent for agro-waste modified with MS and GND adsorbent for agro-waste modified with GO + MS nanoparticles showed improved surface area, pore size and pore volume over those of the agro-waste. The abstractive potential of the new hybrid materials was explored for uptake of Cr(III) and Pb(II) ions. Analysis of experimental data from these new hybrid materials showed increased initial sorption rate of Cr(III) and Pb(II) ions uptake. The amounts of Cr(III) and Pb(II) ions adsorbed by MND and GND adsorbents were greater than those of ND. Modification of N. diderrichii seed waste significantly improved its rate of adsorption and diffusion coefficient for Cr(III) and Pb(II) more than its adsorption capacity. The rate of adsorption of the heavy metal ions was higher with GO + MS nanoparticles than for other adsorbents. Kinetic data were found to fit well the pseudo-second-order and the diffusion–chemisorption kinetic models suggesting that the adsorption of Cr(III) and Pb(II) onto these adsorbents is mainly through chemisorption mechanism. Analysis of kinetic data with the homogeneous particle diffusion kinetic model suggests that particle diffusion (diffusion of ions through the adsorbent) is the rate-limiting step for the adsorption process.
Investigation of the Binding Interaction of α-amylase with Chrysophyllum albidum Seed Extract and its Silver Nanoparticles: A Multi-spectroscopic Approach
(Elsevier, 2020-10-01) Omorogie, Martins
The interactions between α-amylase, one of the key enzymes linked with postprandial glucose regulation, and Chrysophyllum albidum seed methanolic extract(CSME) and its green-synthesized silver nanoparticles (CSAgNP) were investigated using multiple spectroscopy including Fourier Transform-Infrared (FT-IR), ultraviolet (UV)-visible absorption, fluorescence spectroscopy, and biochemical analysis. FT-IR spectroscopy revealed presence of some functional groups in the samples. CSME and CSAgNP inhibited α-amylase. The intrinsic fluorescence intensity of α-amylase was quenched by CSME and CSAgNP via static mechanisms, indicating formation of complex between the enzyme and inhibitors. α-Amylase-CSAgNP complex had higher binding constants. The binding processes were exothermic, entropy driven, spontaneous, and involved hydrogen bonds and van der Waals force. Synchronous fluorescence quenching indicated alteration in microenvironment of α-amylase catalytic site tyrosine residues.FT-IR spectroscopy revealed shifts in amide I peak position of α-amylase due to interaction with CSME/CSAgNP. Absorption spectroscopy also affirmed changes in enzyme conformation. This study may provide theoretical basis for designing novel α-amylase inhibitors.
Kinetics and Thermodynamics of Heavy Metal Ions Sequestration onto Novel Nauclea diderrichii Seed Biomass
(Elsevier, 2012-08-01) Omorogie, Martins
This study reports the sequestration of Cd(II) and Hg(II) using a new biosorbent, Nauclea diderrichii seed biomass. Experimental data obtained were fitted into kinetic and thermodynamic models. Experimental data fitted best into pseudo-second order kinetic model among others. Results obtained kinetically revealed that the biosorption of Cd(II) and Hg(II) using N.diderrichii seed biosorbent increased with increase in temperature. At the highest temperature, which was 333 K, the highest amount of metal biosorbed, qe, for Cd(II) and Hg(II) obtained were 6.30 and 6.15 mg/g respectively. The biosorption of Cd(II) was kinetically faster than that of Hg(II), the highest initial biosorption rates for Cd(II) and Hg(II) were 56.19 and 4.39 mg/g min respectively. Thermodynamic parameters obtained by Erying equation from this study revealed that the biosorption process was spontaneous, feasible, endothermic with a decrease in the degree of chaos in the biosorption system.

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