JUSTIFICATION OF ORDER OF CORROSION INHIBITION KINETICS FOR ESTERS OF CASTOR AND RUBBER SEED OILS

Abstract

The present study centres on the justification of order of corrosion inhibition kinetics for esters of castor and rubber seed oils. Inhibition of mildsteel corrosion was studied in the presence of sulphuric acid medium. The study was justified by the regular misprediction of order of chemical reactions (especially corrosion reaction), due to varying individual perceptions in this regard. While many researchers assume that corrosion reaction kinetics is of first order in most cases, others resolve that it is of zero or even second order. Experimental (gravimetric) data from the mildsteel corrosion inhibition process was used to generate the kinetic data at different experimental conditions of 10g/l (concentration), 40oC (temperature) and 50% stroke (pressure), at different times of 4, 8, 16, 24 and 32hours. Equations of the lines were generated, and coefficient of determination, R2 values for the different (derived) kinetic equations (zero, first and second orders) were obtained. While R2 values for zero order curves fall between 0.9250 – 0.9790, those of first order fall between 0.9740 – 0.9880, and those of second order fall between 0.7820 – 0.9520, which indicates that the R2 values of first order kinetics tend more towards unity than those of zero and second orders. This implies that the corrosion reaction, generally, is governed by the postulations of first order kinetics, followed by the zero order and, then, second order. The results, therefore, justify that kinetics of corrosion reactions is (always) of first order. Keywords: Corrosion inhibition, Justification, Kinetics, Order of reaction.