American Journal of Chemical Research

  • Thio-ligands in Monomeric Pt(Ii) Complexes – Structural Aspects

    This review includes over three hundred derivatives in which each Pt(II) atom is in a distorted square planar environment with inner coordination spheres of PtS4, PtS3X, PtS2X2, PtSX3, PtS2XY, PtSX2Y and PtSXYZ. There is a wide variety of mono-, bi- , ter- , and tetra-dentate ligands, all incorporating both homo- and hetero-dentate varieties. The most common ligands are dimethylsulphoxide and triphenylphosphine. The chelating ligands create a wide variety of metallocyclic rings, where the effects of both steric and electronic factors are observed. Examples of cis– and trans– isomerism exists in these derivatives as well as distortion isomerism, which is much more common. Ligands exerting the trans– effect in these Pt(II) complexes are stronger in the order: OL, NL < Cl < Br < I < SL < H ~ AsL ~ PL ~ CN. Several relationships between the structural parameters were found and are discussed. The complexes crystallized in five crystal classes: hexagonal (0.4%) < tetragonal (1.5%) < orthorhombic (13.8%) < triclinic (23.7%) < monoclinic (60.7%).

  • Bioactivity of four plant materials against the maize weevil, Sitophilus zeamais Motschulsky

    Fine powders of orange peel (Citrus sinensis), scent leaf (Ocimum gratissimum), morinda leaf (Morinda lucida) and lemongrass (Cymbopogon citratus) were applied against 2-day-old maize weevils, Sitophilus zeamais with a view to identifying non-chemical control agent(s) of the weevils. Growth rate, antioviposition effect, repelling efficacy and mortality due to each powder were determined. It took an average of 35.4 days for weevils to develop from egg to adult and none of the powders had adverse effect on growth rate. The powders repelled maize weevils significantly, being strongest in C. citratus. However, M. lucida did not achieve an effective antioviposition effect like the other three plants. Percent weevil mortality was higher in maize grains treated with C. citratus and M. lucida within the first one week of application but the effect remained stronger in the former beyond this period. The plant materials, especially C. citratus, showed potential for protecting maize grains against the storage pest.

  • Synthesis of graphene oxide using tea-waste biochar and its application

    In the present study, pyrolysis of domestic tea waste was carried out to yield bio-char. The biochar obtained was further used as a substitute for graphite in synthesis of graphene oxide (GO) in the conventional process. GO obtained was further applied for fluoride removal from simulated effluents. The prepared adsorbent was characterized using SEM, XRD and FTIR analysis. Effect of different experimental parameters on the de-fluoridation efficiency of the reported adsorbent was investigated. Data obtained was further used for determination of process isotherms, kinetics and thermodynamics. The regeneration potential of the reported adsorbent was also determined. The experimental results suggested that equilibrium adsorption data was strongly guided by the Langmuir isotherm and pseudo-second-order kinetics. Analysis of process thermodynamics also revealed that the adsorption reaction was spontaneous chemisorption in nature. Significant process parameters including GO dosage, ambient temperature and contact time were optimized using Response surface methodology (RSM) and artificial neural network (ANN). Results of RSM and ANN analysis indicated good correlation between experimentally recorded and theoretically predicted % fluoride removals. Under optimized conditions, fluoride removal efficiency was found to be 98.31%. Therefore, it can be inferred that tea waste derived biochar may be accepted as a sustainable alternative of graphite for GO synthesis. Moreover GO so obtained has immense potential for de- fluoridation of effluents in highly reduced dosage and treatment time.