Role of some thiadiazole derivatives as inhibitors for the corrosion of C-steel in 1 M H2SO4

Abstract

Inhibition of C-steel corrosion by some thiadiazole derivatives (I-VI) in 1 M H 2 SO 4 was investigated by weight loss, potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) techniques. The presence of these compounds in the solution decreases the double layer capacitance, increases the charge transfer resistance and increase of linear polarization. Polarization studies were carried out at room temperature, and showed that all the compounds studied are mixed type inhibitors with a slight predominance of cathodic character. The effect of temperature on corrosion inhibition has been studied and the thermodynamic activation and adsorption parameters were calculated and discussed. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The adsorption of the compounds on C-steel was found to obey Langmuir's adsorption isotherm. The synergistic effect brought about by combination of the inhibitors and KSCN, KI and KBr was examined and explained. The mechanism of inhibition process was discussed in the light of the chemical structure and quantum-chemical calculations of the investigated inhibitors.

An experimental and theoretical investigation of adsorption characteristics of a Schiff base compound as corrosion inhibitor at mild steel/hydrochloric acid interface

“…The high value of these parameters for studied compound indicates stronger and more stable adsorbed layer is formed at mild steel/acid solution interface, which results in the higher inhibition [42]. Furthermore, the values of DG°a ds for the Schiff base compound are negative (Table 3) and these values are consistent with the spontaneity of the adsorption process and the stability of the adsorbed layer on the mild steel surface [43]. Generally, DG°a ds values of -20 kJ mol -1 or higher are associated with an electrostatic interaction between charged molecules and charged metal surface, physisorption; those of -40 kJ mol -1 or lower involve charge sharing or transfer from the inhibitor molecules to the metal surface to form a coordinate covalent bond, chemisorption [44].…”

Inhibiting Effects of Rabeprazole Sulfide on the Corrosion of Mild Steel in Acidic Chloride Solution

“…The higher value of * in presence of RS can be attributed to an increase in the thickness of double layer which increases the * for corrosion process [17]. The * for the corrosion process, both in the absence and presence of inhibitor, is greater than 20 kJ mol −1 and hence the entire process is controlled by surface reaction [30]. These results disclose that the corrosion reaction of mild steel is inhibited by RS.…”

Inhibition study of mild steel corrosion in 1 M hydrochloric acid solution by 2-chloro 3-formyl quinoline

“…The calculated values of K ads and DG 0 ads are reported in Table 3 adsorption process and stability of the adsorbed layer on the mild steel surface. The calculated DG ads values are within -40 and -20 kJ/mol, indicating that the adsorption mechanism of 2-chloro-3-formyl quinoline on surfaces of the mild steel in 1 M HCl solution at 303-333 K temperatures was a combination of both physisorption and chemisorption [21,22]. The increasing value of K ads and DG 0 ads with the increasing temperature as on 303-333 K indicates the consistent and stable adsorption of 2-chloro 3-formyl quinoline on mild steel surface in 1 M HCl solution.…”