Inhibiting effects of some quinolines and organic phosphonium compounds on corrosion of mild steel in 3M HCl solution and their adsorption characteristics

Abstract

2-thiol, triphenylbenzyl,and tetrabenzyl phosphonium chloride on the corrosion of mild steel M. S. MORAD (0•26 wt-%C) in deaerated 3M HCl solution have been studied using the determination of polarisation curves as well as linear polarisation measurements. Adsorption isotherms and thermodynamic parameters for the adsorption process of the inhibitors were also determined and are discussed. Except for benzo(f)quinoline, which acts as an accelerator of corrosion, the other quinolines act as corrosion inhibitors. T he inhibition was found to be predominantly anodic with quinoline and 8-hydroxyquinoline, while quinoline-2-thiol is a mixed inhibitor. T he increase in inhibition eYciency with temperature, the resulting L angmuir adsorption isotherm and the high negative values of the standard f ree energy of adsorption DG°a denoted chemisorption. T riphenylbenzyland tetrabenzyl phosphoniumcompounds were found to be inhibitors of the mixed type. High negative values of the standard free energy of adsorption and the resulting T emkin isotherm indicated chemisorption of the phosphonium compounds. T he positive values of the standard enthalpy and entropy of adsorption indicated that adsorption of the inhibitors is associated with the desorption of H 2 O molecules f rom the electrode surface. High values of the standard energy of activation E* a of the inhibited corrosion process were interpreted in terms of deactivating coverage.

Quantum mechanical and electrochemical investigations on corrosion inhibition properties of novel heterocyclic Schiff bases

“…The difference between the two values gives Rct [18][19][20] . The value of Rct is a measure of electron transfer across the exposed area of the metal surface and it is inversely proportional to rate of corrosion [21][22][23] . Impedance behavior can be well explained by pure electric models that could verify and enable to calculate numerical values corresponding to the physical and chemical properties of electrochemical system under examination.…”

Preparation and Investigation of Some New Pyrazole Derivatives as Corrosion Inhibitors for Mild Steel in Acidic Media

“…Organic inhibitors are very effective way for the reducing of corrosion of metals and alloys due to generate a thin film that controls and prevents access of corrosive agents to the metal surface. The organic inhibitors that used for control corrosion of steel are organic compound containing nitrogen, oxygen and/or sulphur atoms [1][2][3][4][5][6].…”

Study of Some [N-substituted] p-aminoazobenzene as Corrosion Inhibitors for Mild-Steel in 1M H2SO4

“…The selection of inhibitor is controlled by its economic availability, its efficiency to inhibit the substrate material and its environmental side effects. So most of the excellent acid inhibitors for corrosion of steel in acidic medium are organic compound containing nitrogen, oxygen and/or sulphur atoms (5,6) . The inhibition process has been shown to occur via inhibitor adsorption isotherm and the efficiency of the inhibitors strongly depends on the structure and chemical characteristics of the adsorbed inhibitor layer formed under particular experimental conditions (7) .…”