Open AccessThermodynamic and Kinetic Parameters of Methanolic Extract of Leaves of Cochlospermum Tinctorium as Eco-friendly Inhibitor for Corrosion of Mild Steel in HCL Medium
Author(s) -
Gloria Adams,
Sylvester O. Adejo,
John U. Ahile,
Joseph A. Gbertyo,
J. O. Ogbodo
Publication year - 2015
Publication title -
nigerian journals of pure and applied sciences (benue online)
Language(s) - English
Resource type - Journals
ISSN - 2705-3997
DOI - 10.46912/napas.12
Subject(s) - adsorption , activation energy , langmuir adsorption model , kinetic energy , corrosion , chemistry , nuclear chemistry , materials science , organic chemistry , physics , quantum mechanics
Thermodynamic, kinetic and adsorptive parameters of methanolic extract of leaves of Cochlospermum tinctorium as eco-friendly inhibitor for the corrosion of mild steel in HCl medium were evaluated through the weight loss method at 303 K and 311 K. The inhibition efficiency, %IE, increased with increase in extract concentration, but found to be better at 303 K than 311 K. The decrease in %IE with increase in temperature with the average value of 81.88 kJ/mol for activation energy, E a , and the values of free energy, ÄG, for the adsorption process are all supportive of physical adsorption mechanism. The values of heat of adsorption, Q ads,, are all negative, an indication that the adsorption process was exothermal. The half-life, t 1/2 , value increased with increase in inhibitor concentration and low at high higher, implying the inhibitor performance increased with increase in the extract concentration and decreased with rise in temperature. The data best fitted the Langmuir adsorption isotherm.