Adeniyi S. Ogunlaja

Design, fabrication and evaluation of intelligent sulfone-selective polybenzimidazole nanofibers.

Molecularly imprinted polybenzimidazole nanofibers fabricated for the adsorption of oxidized organosulfur compounds are presented. The imprinted polymers exhibited better selectivity for their target model sulfone-containing compounds with adsorption capacities of 28.5±0.4mg g(-1), 29.8±2.2mg g(-1) and 20.1±1.4mg g(-1) observed for benzothiophene sulfone (BTO2), dibenzothiophene sulfone (DBTO2) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO2) respectively. Molecular modeling based upon the density functional theory (DFT) indicated that hydrogen bond interactions may take place between sulfone oxygen groups with NH groups of the PBI. Further DFT also confirmed the feasibility of π-π interactions between the benzimidazole rings and the aromatic sulfone compounds. The adsorption mode followed the Freundlich (multi-layered) adsorption isotherm which indicated possible sulfone-sulfone interactions. A home-made pressurized hot water extraction (PHWE) system was employed for the extraction/desorption of sulfone compounds within imprinted nanofibers at 1mL min(-1), 150°C and 30 bar. PHWE used a green solvent (water) and achieved better extraction yields compared to the Soxhlet extraction process. The application of molecularly imprinted polybenzimidazole (PBI) nanofibers displayed excellent sulfur removal, with sulfur in fuel after adsorption falling below the determined limit of detection (LOD), which is 2.4mg L(-1)S, and with a sulfur adsorption capacity of 5.3±0.4mg g(-1) observed for application in the fuel matrix.

Imidazole-functionalized polymer microspheres and fibers – useful materials for immobilization of oxovanadium(IV) catalysts

Both polymer microspheres and microfibers containing the imidazole functionality have been prepared and used to immobilize oxovanadium(IV). The average diameters and BET surface areas of the microspheres were 322 μm and 155 m2 g−1 while the fibers were 1.85 μm and 52 m2 g−1, respectively. XPS and microanalysis confirmed the incorporation of imidazole and vanadium in the polymeric materials. The catalytic activity of both materials was evaluated using the hydrogen peroxide facilitated oxidation of thioanisole. The microspheres were applied in a typical laboratory batch reactor set-up and quantitative conversions (>99%) were obtained in under 240 min with turn-over frequencies ranging from 21.89 to 265.53 h−1, depending on the quantity of catalyst and temperature. The microspherical catalysts also proved to be recyclable with no drop in activity being observed after three successive reactions. The vanadium functionalized fibers were applied in a pseudo continuous flow set-up. Factors influencing the overall conversion and product selectivity, including flow rate and catalyst quantity, were investigated. At flow rates of 1–4 mL h−1 near quantitative conversion was maintained over an extended period. Keeping the mass of catalyst constant (0.025 g) and varying the flow rate from 1–6 mL h−1 resulted in a shift in the formation of the oxidation product methyl phenyl sulfone from 60.1 to 18.6%.

The Ratios of Vanadium-to-nickel and Phenanthrene-to-dibenzothiophene as Means of Identifying Petroleum Source and Classification of Nigeria Crude Oils

Nigeria light, medium, and heavy crude oils were categorized based on the ratio of vanadium-to-nickel (V/Ni) and the ratio of phenanthrene-to-dibenzothiophene (PHEN/DBT) derivatives. V/Ni ratio of 0.47, 1.36, and 2.77 were observed for light, medium, and heavy crude oils, respectively, while the PHEN/DBT ratio was observed to be 8.35, 4.33, and 1.09 for the light, medium, and heavy crude oils, respectively. From the results obtained, light crude oil was suggested to originate from marine organic matter while the heavy oil originates from the terrestrial organic matter.

Selective removal of isoquinoline and quinoline from simulated fuel using 1,1′-binaphthyl-2,2′-diol (BINOL): crystal structure and evaluation of the adduct electronic properties

1,1′-Binaphthyl-2,2′-diol/quinoline (BINOL/QUN) and 1,1′-binaphthyl-2,2′-diol/isoquinoline (BINOL/ISOQUN) adducts were successfully synthesized. X-ray single crystals of BINOL/QUN and BINOL/ISOQUN were grown and analysed. The crystal packing of the molecules in both adducts confirmed that they are held in aggregates by strong hydrogen bonds (O2–H2⋯O3), (O3–H3⋯N1), (O2–H2⋯O1), (O1–H1⋯N1), (O2–H2⋯O1) and weak hydrogen C–H⋯π bonds. The patterns of the hydrogen bonding network as well as the conformation of BINOL contribute to the formation of the shape of the voids that entrap quinoline and isoquinoline. Molecular modelling which was employed to investigate the electronic properties of BINOL/QUN and BINOL/ISOQUN shows that the HOMO positions of the adducts are localized around the 1,1′-binaphthyl-2,2′-diol (BINOL), while the LUMO is positioned on isoquinoline and quinoline. Thermodynamic parameters obtained from isothermal titration calorimetry (ITC) revealed a stronger isoquinoline/BINOL interaction compared to quinoline/BINOL. 6-Vinyl-1,1′-binaphthyl-2,2′-diol was co-polymerized with styrene to form [DBN-co-STY]. Electrospun [DBN-co-STY] exhibited selectivity for quinoline and isoquinoline in a model simulated fuel presenting an adsorption capacity of 2.2 and 2.4 mg g−1 respectively. The adsorption study showed a higher adsorption capacity for isoquinoline compared to quinoline. This may be attributed to the more favourable electronic properties (HOMO–LUMO properties) of isoquinoline. This concept demonstrates the possibility of extracting/separating isoquinoline and quinoline from fuel.

Nanofiber-supported metal-based catalysts

Catalysis utilizing heterogeneous catalysts remains favoured in the chemical industry due to their ease of separation and recyclability compared to homogeneous catalysts. Electrospun nanofibers as catalyst support materials can enhance catalyst performance due to increased surface area-to-volume ratio. Recently, metal oxides and metallic nanoparticles immobilized onto electrospun nanofibers have displayed enhanced catalytic activities towards various reactions. Metal ion complexes supported on electrospun nanofibers, via coordination to the desired functional groups of polymer chains, have also been applied as heterogeneous catalysts in some organic syntheses. The nanofiber-based catalytic materials exhibited good catalytic activities for various reactions, as well as good recyclability and reusability. Concerns over the mechanical and chemical stability of electrospun nanofibers as well as the metal ion leaching sometimes occurring when employed under extreme conditions are also emphasized. This review covers progress in the fabrication and catalytic applications of various metal-based catalysts immobilized onto nanofibers. It will also highlight the challenges associated with the use of electrospun nanofibers in catalysis.

Separation of rhodium(III) and iridium(IV) chlorido complexes using polymer microspheres functionalized with quaternary diammonium groups

ABSTRACT Merrifield resin functionalized with different quaternary diammonium groups derived from ethylenediamine (EDA), tetramethylenediamine (TMDA), hexamethylenediamine (HMDA), 1,8-diaminooctane (OMDA), 1,10-diaminodecane (DMDA) and 1,12-diaminododecane (DDMDA) were investigated for the separation of [RhCl5(H2O)]2− and [IrCl6]2−. Selective loading of [IrCl6]2− in 6 M HCl medium onto the column was achieved in the presence of [RhCl5(H2O)]2− by the synthesized sorbents. The iridium loading capacities were 3.80, 6.49, 13.07, 19.29, 27.09 and 4.36 mg/g for EDA, TMDA, HMDA, OMDA, DMDA and DDMDA-functionalized microspheres, respectively. The materials showed great potential for application in separating rhodium and iridium from aqueous HCl solutions.

The Development of Palladium(II)-Specific Amine-Functionalized Silica-Based Microparticles: Adsorption and Column Separation Studies

The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources.

Kinetic analysis and modeling of stability of bitumen-in-water emulsion stabilized by polyvinyl alcohol (PVA)

ABSTRACT Description of emulsion stability is an essential aspect of process design and development for separation and production operations. In this investigation, bitumen-in-water emulsions were formed with bitumen contents (CB) of 50% and 70% w/w stabilized in the aqueous solution containing Polyvinyl alcohol and dissolved salt ranging from 0.5% to 3.5% w/w. Water separation under gravity was monitored in real time at isothermal condition. Data collected were used in evaluating kinetic parameters and developing model to predict the stability of emulsions with time. The model was found to adequately predict the emulsion stability under the conditions of the investigation.

Synthesis, crystal structure and desulfurization properties of zig-zag 1D coordination polymer of copper(II) containing 4-methoxybenzoic acid ligand

ABSTRACT Combustion of fuels containing organosulfur compounds has resulted in the emission of sulfur oxides (SOx) into the atmosphere, therefore, causing serious environmental and health hazards. Herein, slightly distorted octahedral zig-zag 1D coordination polymer of copper(II) [Cu(4-mba)2(H2O)3] was synthesized by reacting copper sulfate pentahydrate with a carboxylate-containing ligand (H-4mba = 4-methoxybenzoic acid) and employed for sulfur compound uptake. The ligand coordinates to the copper(II) atom via two pairs of deprotonated ligating atoms (carboxylate oxygens) and two water molecules. Structural characterization also reveals that interplay of O–H···O, N–H···O, C-H···O and C–H···π interactions between lattice and coordinated water and ligands significantly contribute to the crystal packing leading to the formation and strengthening of three-dimensional supramolecular assembly. The complex, [Cu(4-mba)2(H2O)3], show potential for desulfurization of fuel with an observed adsorption capacity of 9.6 mg/g at 32°C for 6 h. DFT calculations further revealed a transfer of electron sulfur-containing compounds and the complex, [Cu(4-mba)2(H2O)3], thus leading to a stronger pi–pi interaction. GRAPHICAL ABSTRACT

Polymer nanofibers for desulfurization of fuels

X-beam imaging of mice utilizing a colloid arrangement of Au nanoparticles that were covered with silica and hence surface-adjusted with carboxymethylcellulose (CMC) (Au/SiO2/CMC) was acted in this work. The silica-covering for Au nanoparticles and the amination for silica-covered particles were at the same time acted within the sight of the Au nanoparticles with a size of 17.9 nm, which were set up by decreasing Au particles (III) with sodium citrate in water at 80°C and by surface-changing the Au nanoparticles with (3-aminopropyl)- trimethoxysilane, by a sol-gel measure utilizing tetraethylorthosilicate, (3-aminopropyl)- triethoxysilane, water and sodium hydroxide (Au/SiO2-NH2). The surface alteration of Au/SiO2-NH2 particles with CMC was performed by essentially adding CMC with carboxyl gatherings that respond with an amino gathering to the Au/SiO2-NH2 molecule colloid arrangement. The as-arranged the Au/SiO2/CMC molecule colloid arrangement was concentrated by centrifugation for estimations utilizing figured tomography (CT). Figure 1 shows a photo of the concentrated molecule colloid arrangement and a conveyance electron microscopy picture of the Au/SiO2/CMC particles in the concentrated colloid arrangement. Most particles contained a solitary center of the Au nanoparticles. Their molecule size was 67.4±5.4 nm. A CT estimation of the Au/SiO2/CMC molecule colloid arrangement with an Au convergence of 0.043 M was as high as 344±12 Hounsfield units (HU). This worth compared to 8.0×103 HU/M as for the Au fixation, which was bigger than that of Iopamiron 300, a business X-beam contrast specialist. Mouse tissues were imaged following infusion of the Au/SiO2/CMC molecule colloid arrangement.