ELECTROCHEMICAL GRAVIMETRIC AND QUANTUM CHEMICAL COMPARISON OF EXPIRED DRUG AS CORROSION INHIBITORS FOR APIX65 STEEL IN 0.5 M H2SO4

Abstract

The research focused on the effect of expired drug on the corrosion behaviour of APIX65 steel in 0.5 M Tetraoxosulphate (VI) acid (H2SO4). The inhibitor (Isoniazid Tablets) was ground and pulverized to fine particle size which was added to a corroding medium within the range of 0.0 – 0.8 g at interval of 0.2 g. The APIX65 steel samples were subjected to weight loss and electrochemical measurement in 0.5M H2SO4. The scanning electron microscope (SEM) and atomic absorption spectrometer (AAS) was used to identify the microstructural characteristics and access the concentration of iron deposited on the APIX65 steel sample respectively. The quantum chemical investigation of expired drugs for APIX65 steel in 0.5M H2SO4 was determined using Materials Studio DMol^3 version 8.0 software, Density Functional Theory (DFT) calculations on the inhibitor using Becke 3Parameter (exchange), Lee-Yang-Parr (B3LYP). The experimental absorption spectra were compared with the theoretical calculations for the molecule using B3LYP. The SEM results showed that molecules formed on the surface of the steel increases with concentrations. The AAS result show that the concentration of iron deposited in the corrosive environment with and without inhibitor decreases with concentration from 40000 ppm to 13440 ppm, a measure of reduction in corrosion rates. The quantum chemical investigation indicates that the two approaches are in agreement. The electron transfer (-0.01011) is less than 3.6, the inhibition efficiency (94.71%) was found to increase with increasing values of the electron donating ability of the inhibitor. while the value of electron transfer greater than 3.6 indicates a decrease in inhibition efficiency. The magnitude of the obtained adsorption energy from density functional theory (DFT) which is less than -19598.005553 kcal/Mol confirms strong physiosorption of the molecules onto the APIX65 steel surface. This study has revealed that extracts of isoniazid effectively inhibit APIX65 steel corrosion in 0.5 M H2SO4 environment.