DISTRIBUTION AND BIOAVAILABILITY OF METALS IN GASOLINE CONTAMINATED SITES IN LAGOS, NIGERIA

Distribution of metals in soil of two gasoline contaminated sites in Lagos were studied. Total Concentrations of twenty-five elements were investigated in composite samples collected at different depths within the sites. The elements were determined by ICP-AES after microwave assisted acid digestion of the samples. Chemical fractionation, mobility and potential bioavailability of some of the toxic and EU priority metals e.g., Pb, Cu, Cd, and Fe were evaluated in the topsoil (0-15 cm) by sequential extraction. There were great variation in the concentrations of the elements in both sites with depth. Speciation analysis showed that Pb and Cd dominated the Fe-Mn oxide fraction while the concentrations of Fe and Cu were higher in the residual fraction in site A. In site B, Pb, Cu and Cd was mainly associated with the Fe-Mn oxide fraction, while Fe was in the residual fraction. Cd has the highest mobility factors, 33.2% (site A) and 29.5% (site B), respectively. The concentrations of most of the toxic heavy metals (e.g., Pb, Zn, Cu, Cr, Cd etc.) exceed that of the control samples and heavy metal baseline values around the world. Thus, proper management of these potentially contaminated sites is imperative to prevent human health risk

Formation, electrochemical and radical scavenging properties of novel ruthenium compounds with N, X-donor (X = O, N) heterocyclic chelators

Herein, we communicate the formation of novel ruthenium compounds with N, X-donor (X = O, N) heterocyclic- derived ligands. A paramagnetic ruthenium(IV) complex, [RuCl(pho)(bzca)(PPh3)](1) (pho = 2- aminophenolate; bzca = 2-carboxylate-1H-benzimidazole) was isolated from the reaction of the ruthenium(II) precursor, trans-[RuCl2(PPh3)3] and 2-((1H-benzimidazole)methylamino)phenol (Hbzap). The 1:1 molar reaction between the same metal precursor and N-(benzoxazole)-2-hydroxybenzamide (H2bhb) led to the formation of cis-Cl, trans-P-[RuIII(Hbhb)Cl2(PPh3)2](2). The dinuclear ruthenium compounds, (l-Htba,Cl)2[RuIICl(PPh3)]2(3) (Htba = N-(thiophene)methyl-benzoxazole-2-amine) and (l-Cl)2[RuIIICl(Hchpr)(PPh3)]2(4) (H2chpr = 2-amino-3-((tetrahydro-2H-pyran-4-ylimino)methyl)-4Hchromen- 4-one) were formed from the equimolar ratio coordination reactions between trans- [RuCl2(PPh3)3] and the respective free-ligands, Htba and H2chpr. These metal complexes were characterized via IR-, NMR- and UV–Vis spectroscopy, molar conductivity measurements and structural elucidations were confirmed by single crystal X-ray analysis. The X-ray studies revealed that all the metallic compounds exhibited octahedral geometries and that the Hbzap free ligand has undergone a unique molecular transformation to afford the pho and bzca bidentate chelators in 1. The electrochemical properties of the respective metal complexes were investigated by voltammetric analysis. The cyclic voltammograms (CVs) of 1–3 showed one redox couple while within the CV of the dinuclear compound 4, two redox couples were observed. The ligands and their metal complexes were also subjected to DPPH radical scavenging studies. The IC50 values showed that all the metallic compounds have higher radical scavenging activities than their corresponding free-ligands and the natural antioxidant, Vitamin C

STUDIES ON THE ANTIBACTERIAL AND ANTICORROSIVE PROPERTIES OF SYNTHESIZED HYBRID POLYURETHANE COMPOSITES FROM CASTOR SEED OIL

Castor seed oil (Ricinus communis) is a prominent feed stock towards the generation of renewable materials for industrial production. The reach presence of ricinoleic fatty acid at 87.5% provides pendant hydroxyl functional groups, which is an essential site for chemical formulations. This paper presents the synthesis, characterization, and evaluations on antibacterial and anticorrosive activities of synthesized hybrid composites from Ricinus communis seed oil. N,N'-bis(2-hydroxy ethyl)-12-hydroxy Ricinus communis oil fatty amide (HERCA) was synthesized via aminolysis polyol formation route. Upon reacting HERCA with succinic acid at a high temperature of about 145 ºC, a polyesteramide (RCPEA) was formed. This ester product undergoes urethanation and subsequently interfaced with modified hybrid material. The synthesized composites were characterized using spectroscopic methods such as FTIR, 1H-NMR, and 13C-NMR. Selected physicochemical parameters were also carried out on the products. Coating performance on cured resins was examined

Ruthenium complexes with lumazine derivatives: structural, electrochemical, computational and radical scavenging studies

In this research study, the formation and characterization of new ruthenium(II) and (III) complexes encompassing multidentate ligands derived from 6-acetyl-1,3, 7-trimethyllumazine (almz) are reported. The 1:1 molar coordination reactions of trans-[RuCl2(PPh3)3] with N-1-[1,3, 7-trimethyllumazine]benzohydride (bzlmz) and 6-(N-methyloxime)- 1,3,7-trimethyllumazine (ohlmz) formed a diamagnetic ruthenium(II) complex, cis-[RuCl2(bzlmz)(PPh3)] (1), and paramagnetic complex, cis-[RuIIICl2(olmz)(PPh3)] (2) [Holmz = 6-(N-hydroxy-N0-methylamino)-1,3,7-trimethyllumazine], respectively. These ruthenium complexes were characterized via physico-chemical and spectroscopic methods. Structural elucidations of the metal complexes were confirmed using single crystal X-ray analysis. The redox properties of the metal complexes were investigated via cyclic voltammetry. Electron spin resonance spectroscopy confirmed the presence of a paramagnetic metal centre in 2. The radical scavenging activities of the metal complexes were explored towards the DPPH and NO radicals. Quantum calculations at the density functional theory level provided insight into the interpretation of the IR and UV–Vis experimental spectra of 1

Coordination of di- and triimine ligands at ruthenium(II) and ruthenium(III) centers: structural, electrochemical and radical scavenging studies

Herein, we explore the coordination of di- and triimine chelators at ruthenium(II) and ruthenium(III) centers. The reactions of 2,6-bis-((4- tetrahydropyranimino)methyl)pyridine (thppy), N1,N2-bis((3-chromone) methylene)benzene-1,2-diamine (chb), and tris-((1H-pyrrol-2-ylmethylene) ethane)amine (H3pym) with trans-[RuIICl2(PPh3)3] afforded the diamagnetic ruthenium(II) complex cis-[RuCl2(thppy)(PPh3)] (1) and the paramagnetic complexes [mer-Ru2(μ-chb)Cl6(PPh3)2] (2), and [Ru(pym)] (3), respectively. The complexes were characterized by IR, NMR, and UV–vis spectroscopy and molar conductivity measurements. The structures were confirmed by single crystal X-ray diffraction studies. The redox properties of the metal complexes were probed via cyclic- and squarewave voltammetry. Finally, the radical scavenging capabilities of the metal complexes towards the NO and 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) radicals were investigate

Ruthenium complexes with Schiff base ligands containing benz(othiazole/imidazole) moieties: Structural, electron spin resonance and electrochemistry studies

Novel ruthenium(II/III) complexes of Schiff bases containing benzimidazole (bz) or benzothiazole (bs) moieties were isolated: the diamagnetic ruthenium complex, cis-[RuIICl2(bzpy)(PPh3)2] (1) was formed from the 1:1 M reaction between N-((pyridine-2-yl)methylene)-1H-benzimidazole (bzpy) and metal precursor, trans-[RuCl2(PPh3)3]. The same metal precursor, when reacted with the benzimidazole-derived Schiff bases [N-(2-hydroxybenzylidene)-benzothiazole (Hbsp) and N-(2-hydroxybenzylidene)-benzimidazole (Hbzp)], afforded the paramagnetic ruthenium(III) complexes [RuCl(bsp)2(PPh3)] (2) and trans-[RuCl(bzp)(PPh3)2] (3), respectively. These metal complexes were characterized via IR, mass and UV–Vis spectroscopy, elemental analysis, single crystal XRD analysis as well as conductivity measurements. Their redox properties were probed by voltammetry and accompanying UV–Vis spectroelectrochemistry experiments. Structural features of complex 1 were further investigated by multinuclear (1H and 31P) NMR spectroscopy

STUDIES ON THE ANTIBACTERIAL AND ANTICORROSIVE PROPERTIES OF SYNTHESIZED HYBRID POLYURETHANE COMPOSITES FROM CASTOR SEED OIL

Castor seed oil (Ricinus communis) is a prominent feed stock towards the generation of renewable materials for industrial production. The reach presence of ricinoleic fatty acid at 87.5% provides pendant hydroxyl functional groups, which is an essential site for chemical formulations. This paper presents the synthesis, characterization, and evaluations on antibacterial and anticorrosive activities of synthesized hybrid composites from Ricinus communis seed oil. N,N'-bis(2-hydroxy ethyl)-12-hydroxy Ricinus communis oil fatty amide (HERCA) was synthesized via aminolysis polyol formation route. Upon reacting HERCA with succinic acid at a high temperature of about 145 ºC, a polyesteramide (RCPEA) was formed. This ester product undergoes urethanation and subsequently interfaced with modified hybrid material. The synthesized composites were characterized using spectroscopic methods such as FTIR, 1H-NMR, and 13C-NMR. Selected physicochemical parameters were also carried out on the products. Coating performance on cured resins was examined

Transesterification of Non-Edible Vegetable Oil for Lubricant Applications in Water-Based Mud: A Review

The deterioration of the environment as a result of the disposal of oil-based mud used in the oil industry in offshore and onshore environment is alarming and preventive measures must be taken to protect it. Vegetable oil as biolubricant in water-base mud has proved to have potentials in formulating drilling mud for oil and gas exploration due to their inherent properties. Nevertheless, the direct usage of this plant oil is limited in application due to their high viscosity, unstable hydrolytic and oxidative effect. These parameters can be improved upon through transesterification process. This paper hereby review the derivable benefits of chemically modifying vegetable oil inorder to improve their physicochemical properties through transesterification reaction process, and the effect it will have when applied to drilling mud

Study of linseed oil, its biodiesel and xylene as flow improver for Nigerian waxy crude oils

In this study, the physicochemical properties of linseed and linseed biofuel were studied and their effect on the flow properties of Nigerian waxy crude oil at different volume fractions was investigated. The Nigerian wax crude oil was characterized for its specific gravity, API gravity, wax content, pour point and cloud point. The properties of the linseed oil and linseed biodiesel investigated include: density, specific gravity, viscosity, pour point, cloud point and flash point. Upon esterification of the free fatty acid (FFA) contained in the linseed oil reduced from 3.5 to 0.75 and the viscosity of the seed oil reduces from 2169 to 362 mm2/s. The linseed oil and its biodiesel exhibited similar trend of reduced viscosity at higher shear rate, however, linseed biodiesel demonstrated the lowest viscosities, cloud points and pour points owing to reduced fatty contents. The effect of the linseed oil and its biodiesel on the pour point and cloud point of the waxy crude oil was determined; and the performance compared to that of xylene. A rapid drop in the pour point and cloud point was observed with the wax crude pre-heated with 0.1 v/v linseed oil, its biodiesel and xylene

Pyrolysis: A Sustainable Way to Generate Energy from Waste

Lignocellulosic biomass is a potentially more valuable renewable resource that can be utilized effusively as a chief source of heat for cooking and can correspondingly subsidize the production of electricity, heat, biofuels and chemicals including solid fuel like char or carbon. Lignocellulosic residues are mixed and burnt with coal to generate electricity. Presently, crude oil is replaced by bioethanol and biodiesel produced from biomass substrate. Some special class of chemicals can be derived from biomass that can subsequently replace the usage of non‐renewable resources of oil and coal. Pyrolysis of woody biomass to obtain pyroliginous acid was started hundreds of years ago, which has versatile applications. The range of products that can be derived from biomass is huge, prompting extent of research using different types of thermal conversion technologies, including pyrolysis, gasification, torrefaction, anaerobic digestion and hydrothermal processing. This chapter provides insights about the stages of reaction during pyrolysis and the outcome of reaction conditions on the products. Technical development and adjustment of process condition can offer a suitable environmentally benign scheme to increase the energy density of the lignocellulosic residues