Durability and synergistic effects of KI on the acid corrosion inhibition of mild steel by hydroxypropyl methylcellulose

•Inhibition efficiency increased with inhibitor concentration and temperature.•Addition of KI improved the durability of the inhibitor.•Cathodic and anodic reactions were inhibited but cathodic effect was predominant.•Adsorption of the inhibitor followed Freundlich isotherm.•Glucosidic ring is the s...

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Bibliographic Details
Published in:Carbohydrate polymers 2014-11, Vol.112, p.291-299
Main Author: Arukalam, I.O.
Format: Article
Language:English
Subjects:
Adsorption
Applied sciences
Cellulose and derivatives
Corrosion
Corrosion inhibition
Corrosion prevention
Dielectric Spectroscopy
Electrochemical technique
Exact sciences and technology
Hypromellose Derivatives - chemistry
Metals. Metallurgy
Models, Chemical
Natural polymers
Physicochemistry of polymers
Polymers
Potassium Iodide - chemistry
Quantum Theory
Steel - chemistry
Sulfuric Acids - chemistry
Synergism
Temperature
Thermodynamics
Time Factors
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Summary:•Inhibition efficiency increased with inhibitor concentration and temperature.•Addition of KI improved the durability of the inhibitor.•Cathodic and anodic reactions were inhibited but cathodic effect was predominant.•Adsorption of the inhibitor followed Freundlich isotherm.•Glucosidic ring is the strong adsorption centre for HPMC. The performance of hydroxypropyl methylcellulose (HPMC) as safe corrosion inhibitor for mild steel in aerated 0.5M H2SO4 solution was appraised by weight loss, impedance and polarization measurements. Results indicate that HPMC functions as a good inhibitor in the studied environment and inhibition efficiency increased with increasing concentration of inhibitor and temperature. Time-dependent effect of the inhibition efficiency reveals that inhibition efficiency increased with time up to the fourth day after which it waned, but improved on addition of KI. The synergism parameter evaluated confirmed the synergistic effect of KI and HPMC. Impedance results clearly show that HPMC inhibited the corrosion reaction via adsorption onto the metal/solution interface following Freundlich adsorption isotherm. Polarization results indicate that HPMC acts as a mixed-type inhibitor with predominant cathodic effect. Theoretical study using density functional theory was employed to establish the correlation between the structure (molecular and electronic) and the inhibition efficiency.
ISSN:0144-8617
1879-1344
DOI:10.1016/j.carbpol.2014.05.071