Kinetics of acidic Mn(VII) oxidation of acetaldehyde in aqueous and 5% ethanol-water solvents were studied via pseudo-first order condition at λmax 525nm. The reaction showed a first order dependence with respect to acetaldehyde concentration, [Mn(VII)], fractional order to [H+] and independent on the ionic strength of the solution. Michaelis-Menten plot showed the existence of an intermediate complex and dependence on hydrogen ion is in the form kobs= a + b[H+]. However, oxidation reaction is generally faster in non-aqueous solvent than in aqueous solvent. Product analysis revealed the presence of carboxylic acid and stoichiometric study suggests the consumption of 2 moles of MnO4- by 3 moles of acetaldehyde in both solvents. Thermodynamic parameters of activation were obtained from Arrhenius and Erying’s equations. A plausible associative mechanism in agreement with kinetic and spectroscopic results was proposed.
Additive Manufacturing (AM) is one of several technological breakthroughs that is expected to lead the factories of the future, where conventional equipment will be transformed into smart and flexible systems, run by computers that will allow the fabrication of customized parts. Some authors have called AM the third industrial revolution, as it enables the accurate manufacture of pieces of virtually any shape in different scales, ranging from visual prototypes to specific functional end-use products at relatively short periods of time. Medical applications of AM is one of the key industries driving the innovations in the field, especially because of the possibility to fabricate products individually tailored to the patient’s specific needs. The integration of nanomaterials in the area of AM has a lot of potential and there is a growing interest in academia and industry to explore for new developments. In this section, we examine some successful uses of nanocomposites in additive manufacturing processes.
Evaluation of cassava (Manihot Esculentum) seed waste Activated carbon for kinetic study on methylene blue dye adsorption from aqueous solution
The effect of activation temperature on activated carbon was studied at 400o C, 500oC and 600oC respectively. The characterization properties showed that increased in temperature reduces yield, moisture content, ash content and volatile content but increased fixed carbon, pore volume and porosity. Batch experiment was conducted by varying the dosage of activated carbon (0.2g – 0.6g) and contact time (40 -120 min) on adsorption of methylene blue dye from aqueous solution. The experimental data was fitted to pseudo first and second order kinetics in order to verify the rate controlling mechanism. The pseudo second order model showed a better fit with the highest correlation coefficient of 0.998. The adsorption capacity q computed was found to be 6.561 mg/g and 16.129 mg/g showed deviation from the experimental value of 11.00 mg/g for the both kinetics. The equilibrated isotherm data was also fitted to Langmuir, Freundlich and Dabinin-Radushkevich. Freundlich model has the best fit with R2 = 0.914. The energy of adsorption was calculated using the Dabinin-Radushkevich model and found to be 5.89 kJ/ mol.
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%).
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.
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.