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We present the use of gentamicin (GENTA) and sulfamethoxazole (SULFA) for carbon steel corrosion protection in HCl solutions using weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization techniques, molecular dynamic simulations plane-wave density functional theory (PWDFT) and the generalized gradient approximation, (GGA). The surface morphologies were examined using scanning electron microscopy (SEM). The potentiodynamic polarization test showed that GENTA and SULFA are mixed-type inhibitors with maximum achievable inhibition efficiency of 90% and 80%, respectively at 500 ppm. SEM analysis further confirmed the inhibitory action of GENTA and SULFA on carbon steel. Molecular simulations reveal two stable adsorption configurations on the Fe (110) surface for GENTA and SULFA which were identified after geometry optimization using PWDFT and the GGA. The presence of the delocalized п-electrons of the aromatic rings provided extra stability to the configurations with flat adsorption orientations on the Fe (100) surface. The inhibitor adsorption energies and electronic properties correlate well with the experimental results. [ABSTRACT FROM AUTHOR]

This work introduces a newly developed kinetic mechanism and thermodynamic study that gives a clear theoretical insight between the iodine and chromium in acid solution. The paper mainly focuses on evaluating kinetic mechanism and thermodynamic properties of the oxidation of iodide by dichromate ion in acidic medium. This study was investigated using iodometric method. The rate has been studied by appropriate choice of concentrated conditions at constant temperature and ionic strength. The kinetic studies revealed half order reaction with respect to dichromate ion, first order for iodide ion and second order for hydrogen ion concentration. The dependence of reaction rate on the temperature was monitored in order to generate some thermodynamic parameters, which can be used in predicting the direction and spontaneity of the reaction. The thermodynamic studies of this reaction revealed negative values for ΔG, ΔS and positive values for ΔH which is an indication that the reaction was spontaneous and endothermic. The oxidant chromium (vi) exist in acidic media as H2CrO4. The effect of ionic strength on the rate of redox reaction was investigated. The ionic strength was adjusted by varying the concentration of the nitrate to maximum. The effect of temperature was also studied to evaluate the thermodynamic parameters. Transition metals should be use as catalyst for future purpose to monitor the rate of redox reaction. The techniques employed on this research are very useful in determining the rate of a redox reaction. [ABSTRACT FROM AUTHOR]

Preparation for the bioremediation of petroleum contaminants is explored to provide a low-cost and capable strategy for biodegradation of contaminants and renewal of soil fertility. In this study, fermented chicken droppings were used as novel in-situ bio-stimulants and bio-augmentation materials. The investigation determines the capability of fermented chicken droppings to biodegrade the residual total petroleum hydrocarbon compounds in-used engine oil contaminated soil – in the case of auto mechanic shops. The soil was collected at 10 cm depth from the ground, air-dried and sieved with 2.5mm mesh. A 4 kg of soil was weighed into 13 perforated buckets to allow aeration and prevent waterlogging. The setup consists of three replicates that were spiked with 150 ml of used engine oil. 500 ml of the fermented chicken droppings were used to irrigate the contaminated soil at ratio 1:8 periodically for every 3 days per irrigation for 21 days. The uncontaminated soil used as the control group was irrigated with normal water. The TPH composition of the contaminated and remediated soil samples was screened using gas Chromatography tandem mass spectroscopy. Results show that the uncontaminated soil (A-group) had C10 - 24.058 ± 0.02 ppm, C12 - 37.327 ± 0.01 ppm, C14 - 28.515 ± 0.02 ppm and C16 - 12.097 ± 0.02 ppm, respectively out of about 35 TPH compounds that ought to be detected from C8 to C40. The Concentration of TPH in Contaminated soil before irrigation with Chicken droppings – positive control (ppm) B-group gave a significant qualitative and quantitative presence of TPHs in contaminated soil at varying concentrations. 36 TPHs were detected out of forty, starting from C10 - 1.836 ± 0.01 ppm to C38 - 50.150±0.01 ppm. Whereas, the Concentration of residual TPH in Contaminated soil after irrigation with Chicken droppings gave varying levels of residual TPHs ranging from C8 - 1.519 ± 0.02 ppm to C38 - 41.487 ±0.02 ppm. This also gave a resultant/differences in the degradation level of TPHs. Differences in TPH Concentration between before the irrigation and after irrigation of contaminated soil were calculated, C8 had - 0.317 ppm while another TPHs concentration varies accordingly. From the results, one can be deduced that despite other environmental factors that influence the degradation of TPHs, fermented chicken d [ABSTRACT FROM AUTHOR]