Kinetics and mechanism of permanganate oxidation of pectin polysaccharide in acid perchlorate media

Zaafarany

2013

Materials

Corrosion inhibition of aluminum (Al) in hydrochloric acid by anionic polyeletrolyte pectates (PEC) as a water-soluble natural polymer polysaccharide has been studied using both gasometric and weight loss techniques. The results drawn from these two techniques are comparable and exhibit negligible differences. The inhibition efficiency was found to increase with increasing inhibitor concentration and decrease with increasing temperature. The inhibition action of PEC on Al metal surface was found to obey the Freundlich isotherm. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated and a suitable corrosion mechanism consistent with the kinetic results is discussed in the paper.

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetics of Corrosion Inhibition of Aluminum in Acidic Media by Water-Soluble Natural Polymeric Pectates as Anionic Polyelectrolyte Inhibitors

Zaafarany

2013

Materials

“…As this reaction of autocatalysis nature, it exhibits the rate law expression

false(A_{t} - A_{\infty} false) = B_{0} e^{- k_{s} t} + P_{0} e^{- k_{f} t . 16},

where k s and k f are the observed first‐order rate constants for the induction and autoacceleration periods, A t and A ∞ are the absorbencies at times t and infinity; whereas B 0 and P 0 represent to the absorbencies change for the slow and fast reacting species, respectively. The analysis of the curves was the same as described earlier . Other reactions involving the permanganate ion as an oxidant were found to exhibit the same kinetic trend .…”

Section: Resultsmentioning

confidence: 90%

“…The analysis of the curves was the same as described earlier . Other reactions involving the permanganate ion as an oxidant were found to exhibit the same kinetic trend . The values of the rate constants were evaluated from the slopes of linear portions of such plots.…”

Section: Resultsmentioning

confidence: 99%

Kinetics and mechanistic aspects on electron‐transfer process for permanganate oxidation of poly(ethylene glycol) in aqueous acidic solutions in the presence and absence of Ru(III) catalyst

Int J of Chemical Kinetics

Sayed

2018

The kinetics and mechanism of oxidation of poly(ethylene glycol) (PEG) by the permanganate ion as a multiequivalent oxidant in aqueous perchlorate solutions at an ionic strength of 2.0 mol dm−3 has been investigated spectrophotometrically. The reaction kinetics was found to be of complex in nature. The pseudo–first‐order plots showed curves of inverted S‐shape, consisting of two distinct stages throughout the entire course of reaction. The first stage was relatively slow, followed by a fast reaction rate at longer time periods. The first‐order dependence in [MnO4−], fractional first‐order dependence in [H+], and fractional first‐order kinetics in the PEG concentration for the first stage have been revealed in the absence of the Ru(III) catalyst. The influence of the Ru(III) catalyst on the oxidation kinetics has been examined. The oxidation was found to be catalyzed by the added Ru(III) catalyst. The First‐order dependence on the catalyst and zero order with respect to the oxidant concentrations have been observed. The kinetic parameters have been evaluated, and a tentative reaction mechanism consistent with the kinetic results is suggested and discussed.

A promising methyl ester of pectic acid polysaccharide in biomedicine and pharmaceutics applications: Oxidation of methyl ester of pectic acid by alkaline hexacyanoferrate(III). A kinetic and mechanistic orientation

Int J of Chemical Kinetics

Ibrahim²

2019

The oxidation of methyl ester of pectic acid (pectin) (PEC) by a hexacyanoferrate(III) ion at a constant ionic strength of 0.1 mol dm−3 has been investigated spectrophotometrically. The oxidation rates were found to increase with increasing the alkali concentration, indicating that the nature of reaction was base catalyzed. The agreement of [pectin] dependence of the rate constants to the Michaelis‐Menten kinetics proves the formation of 1:1 intermediate complex prior to the rate‐determining step. The deviation of the pseudo–first‐order curves from linearity after 65‐70% of reaction completion indicates the interference of some oxidation products during the reaction progression. The oxidation process was proceeding via a free‐radical intervention mechanism. The activation parameters have been evaluated, and a suitable reaction mechanism is suggested and discussed.