Fractionation, dosage and rating of the antioxidant activity of the aqueous extract of Melissa Officinalis from northeastern Morocco

So far, many efforts have been made to discover phytochemical alternatives to chemically synthesized antioxidants. The candidate groups of natural molecules have appeared to be polyphenols and flavonoids. In this study, the amount of phenolic and flavonoid compounds in aqueous extracts of Melissa Officinalis, from North-East Morocco (TAZA), was explored by using two common approaches (Folin Ciocalteu and Aluminum Chloride). Their antioxidant capacity was assessed by DPPH free radical scavenging assay. The results obtained demonstrated that the two fraction of ethyl acetate and diethyl ether were rich in polyphenols (505 ± 26 and 378 ± 16 μg/mg respectively) and had moderate quantities of flavonoids (8 ± 0.1 and 10 ± 0.2 μg equivalent of routine per mg of extract). At 2 µg/ml the antioxidant activities of two fractions appeared to be a lower (70 and 71%) than that of ascorbic acid (83%)

Antioxidant activity of phenols and flavonoids contents of aqueous extract of Salvia Officinalis origin in the North-East Morocco

Oxidative stress is responsible for several diseases. This phenomen has moved researchers into action in looking for new remedies «antioxidants». The aim of this work was to characterize the phenols and flavonoids compounds of extracts of Salvia Officinalis from  North-East Morocco (TAZA) in terms of antioxidant activity.  The antioxidant activityof this aromatic plant was determined according to the DPPH radical scavenging assay to suggest it as a new potential source of natural antioxidants. The quantification of phenolics and flavonoids compounds of solvent extracts (diethyl ether and ethyl acetate) were determined spectrometrically. Furthermore, The DPPH scavenging activity of extracts increased in the order diethyl ether extract < ethyl acetate extract < ascorbic acid. Finally, we suggest that the phenols and flavonoids compounds of Salvia Officinalis has significant potential as a natural antioxidant

Inhibitory effect of Acacia hamulosa methanolic extract on the corrosion of mild steel in 1 M hydrochloric acid

The flora of Saudi Arabia comprises about 18 species of Acacia species including Acacia hamulosa Benth. The methanolic extract of the flowering tops of A. hamulosa was tested for its radical scavenging activity toward 2,2-diphenyl-1-pricylhydrazyl (DPPH) radical and the activity was compared with L-ascorbic acid, quercetin and Trolox as standards. The total phenolic content was determined using Folin-Ciocalteu method. In addition the methanolic extract has been evaluated as a corrosion inhibitor for steel in 1 M HCl solution by means of weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Tafel polarization study revealed that extract of Acacia hamulosa acts as a cathodic type inhibitor. Inhibition was found to increase with increasing concentration of the extract of Acacia hamulosa. Values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS are in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1 M HCl with addition of extract was also studied and thermodynamic parameters were determined and discussed.               KEY WORDS: Acacia hamulosa, Extract, Polyphenols, Antioxidant corrosion, Electrochemical study Bull. Chem. Soc. Ethiop. 2018, 32(2), 323-335.DOI: https://dx.doi.org/10.4314/bcse.v32i2.1

The Palm oil from seed of Phoenix dactylifera (Oil of both Deglet Nour and Kentichi) as a natural antioxidants and Environment-Friendly inhibitors on the Corrosion of mild Steel in HCl 1M

The flora of Republic of Algeria comprises a lot of Palm species, including Phoenix dactylifera. In this work, we used the Palm oil from seed of Phoenix dactylifera (Oil of both Deglet Nour and Kentichi). The objective of this study is divided into two parts. Firstly, determine the antioxidant activity of Palm oil from seed of Phoenix dactylifera (Oil of both Deglet Nour and Kentichi) according to the DPPH radical scavenging assay to suggest it as a new potential source of natural antioxidants, secondly, study the effect of inhibiting Palm oil from seed of Phoenix dactylifera (Oil of both Deglet Nour and Kentichi) on corrosion of mild steel in hydrochloric acid by electrochemical methods. Furthermore, The DPPH scavenging activity of Oil of both Deglet Nour and Kentichi increased in the order, Deglet Nour Oil < Kentichi Oil < ascorbic acid. The results of the polarization curves show that the corrosion current density decreases 577.9 μA/cm2 to 58μA/cm2 and to 59.3 μA/cm2 after addition of the inhibitor (oil of Deglet Nour and Kentichi respectively). The charge transfer resistance increases 21.69 ohm.cm2 to 186.5 ohm.cm2 and to 222.8 ohm.cm2 in the electrochemical impedance spectrum after addition of oil of Deglet Nour and Kentichi respectively. The inhibition of the compound effect is attributed to the formation of a film on the surface of the steel.

Hydrogen effect modeling on Ziegler-Natta catalyst and final product properties in propylene polymerization

Hydrogen, as chain transfer agent, effects on kinetic of propylene polymerization; consequently variation of hydrogen concentration leads to change final product properties and also activates site of used catalyst. This phenomenon is one of the most important process variables is to adjust the final product properties and optimize the operating conditions. This work has attempted to present a mathematical model that cable to calculate the most important indices of end used product, such as melt flow index, number and weight average molecular weight and poly dispersity index. The model can predict profile polymerization rates determining important kinetic parameters such as the activation energy, lumped deactivation reaction initial reaction rate and deactivation constant. The mathematical model was implemented in Matlab/Simulink environment for slurry polymerization in laboratory scale. The modeling approach is based on polymer moment balance method in the slurry semi-batch reactor. In addition, in this work have provided a model that calculating fraction activated sites catalyst via hydrogen concentration. The model was validated by experimental data from lab scale, reactor. The experimental and model outputs were compared; consequently, the errors were within acceptable range.               KEY WORDS: Mathematical modeling, Propylene polymerization, Kinetics study, Hydrogen response, population balance Bull. Chem. Soc. Ethiop. 2018, 32(2), 371-386.DOI: https://dx.doi.org/10.4314/bcse.v32i2.1

Chemical Additives for Corrosion Control in Desalination Plants

The addition of chemical additives has been considered as a standard operation in water treatment systems. This chapter discusses the chemical additives used for the control of corrosion in desalination systems. Specifically, corrosion inhibitors for various metallurgies, biocides, and oxygen scavengers are covered. The pros and cons of the additive chemicals have been highlighted. The need to utilize green corrosion inhibitors based on plants and ionic liquids materials have been emphasized. This class of materials are environmentally friendly, cheap, and readily available

Adsorption proprieties and inhibition of mild steel corrosion in HCl solution by the essential oil from fruit of Moroccan Ammodaucus leucotrichus

International audienceThe essential oil from the fruits of Ammodaucus leucotrichus (AL oil) was studied by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC/MS). 10 components were identified accounting 94.7% of the total oil, which peryllaldehyde (73.5%) and limonene (12.5%) were the major compounds. The inhibitive effect of this essential oil on the corrosion of mild steel in 1M HCl solution was investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. From loss measurements, is clear that inhibition efficiency values increased with increase in inhibitor concentration but decreased with increase in temperature. Polarization measurements showed that the studied inhibitor is mixed type with significant reduction of cathodic and anodic current densities. The results of EIS measurements indicated that the corrosion of steel is mainly controlled by the charge transfer process. Various activation and adsorption thermodynamic parameters are evaluated and discussed. Linearity of Langmuir isotherm adsorptions indicated the monolayer formation of inhibitor on mild steel surface

Evaluation of Pelargonium extract and oil as eco-friendly corrosion inhibitor for steel in acidic chloride solutions and pharmacological properties

International audienceThere is a growing trend in utilizing plant extracts and pharmaceutical compounds as corrosion inhibitors. Accurate identification of the essential oil of aerial parts of Pelargonium was obtained using hydrodistillation, gas chromatography and gas chromatography–mass spectrometry. The oil was predominated by citronellol (22.8 %). The inhibitory effect of essential oil and extract of Pelargonium was estimated on the corrosion of mild steel in 1 M hydrochloric acid (HCl) using weight loss, electrochemical impedance spectroscopy (EIS) and Tafel polarization curves. Inhibition was found to increase with increasing concentration of the essential oil and extractof Pelargonium. The effect of temperature on the corrosion behavior of mild steel in 1 M HCl with addition of essential oil and extract was also studied, and the thermodynamic parameters were determined and discussed. Values of inhibition efficiency were calculated from weight loss, Tafel polarization curves, and EIS. All results are in good agreement. Polarization curves showed that essential oil and extract of Pelargonium behave as mixed type inhibitors in HCl (1 M). The results obtained showed that the essential oil and extract of Pelargonium could serve as an effective inhibitor of the corrosion of mild steel in HCl solution. To avoid any unexpected toxicity, the majority of compounds have been studied by using POM analyses

Synergistic Combination Effect of Salvia officinalis and Lavandula officinalis on the Corrosion Inhibition of Low-Carbon Steel in the Presence of SO42−- and Cl−-Containing Aqueous Environment

The corrosion inhibition of low-carbon steel in 1 M H2SO4 and HCl solutions by the admixture of Salvia officinalis and Lavandula officinalis essential oil extracts was studied through potentiodynamic polarization analysis, coupon measurement and optical microscopy. The carbon steel undergoes severe surface deterioration in H2SO4, while the morphology of the steel from HCl showed selective deterioration with numerous corrosion pits in the absence of the oil extracts. The extracts performed effectively in the acid media with optimal inhibition efficiency of 86.92 and 96.90% in H2SO4, and 84.68 and 97.59% in HCl from potentiodynamic polarization and coupon analysis. The oil extract displayed anodic inhibition properties in H2SO4 due to surface coverage of the steel and cathodic inhibition in HCl due to selective precipitation of extract molecules. Thermodynamic calculations show the extracts adsorbed onto the steel surface, effectively suppressing the corrosion reactions through chemisorption mechanism according to the Langmuir, Frumkin and Freundlich adsorption isotherms