A Study of the Inhibiting Action of Benzene Thiols and Related Compounds on the Corrosion of Zinc in Acidic Media

Abstract

The effect of benzenethiol and its methyl, amino, and carboxylic ring substituted derivatives, benzylthiol and thioglycollic acid on the electrochemical and corrosion behavior of zinc in CH3000H, H2SO4, and HCI solutions was studied using the galvanostatic technique. In CH3000H, compounds which function by an adsorption mechanism were found to have inhibitive effects on the corrosion of zinc, while those functioning by surface chelation were ineffective. In H 2SO4 and HCI, with the exception of o-methylbenzenethiol (H 2SO4 and HCI) and benzylthiol (H2SO4 ), all investigated compounds were found to accelerate zinc dissolution. Adsorption of the inhibitors followed the Langmuir isotherm, and the mechanism of both the hydrogen evolution reaction and zinc dissolution were found to be the same in the uninhibited and inhibited states. Experimental Corrosion InhibitorsReagent grade (Fluka AG, Buchs SG Switzerland) benzenethiol ortho, meta, and para methylbenzenethiols, ortho and para aminobenzenethiols, thiosalicylic acid and its methyl ester, benzylthiol and thioglycollic acid were used without further purification. The inhibitor solution was prepared by dissolving the appropriate amount in 10 ml of redistilled methanol. The desired volume was added to the electrolyte (200 ml).Electrolytes 0.5N CH3000H (pH 3.0), 0.5N H 2SO4 (pH 0.8), and 0.1N HCI (pH 1.1) were prepared from the Analar reagent and bidistilled water and were deaerated by 02 free nitrogen for at least 6 hours. The pH of these solutions was adjusted by adding NaOH to the desired value. Zinc SpecimensSpecimens were cut from extra pure zinc rods 0.5 cm in diameter. These were cast from extra pure granular zinc (Merck) by vacuum melting) and were inserted into Teflon mounts so that the flat surface was in contact with solution.

Effect of Orthoaminothiophenol on Nickel in 3% Sodium Chloride Solution

“…3 A comparative study of the inhibition efficiency (E) of some OATP derivatives on the corrosion of iron in hydrochloric acid (HCl) and of zinc and copper in acetic acid (CH 3 COOH) has been performed previously. [4][5] OATP and its dimer have been shown to be efficient inhibitors of corrosion and hydrogen hot air. The counter electrode was a cylindrical platinum grid with a large surface area.…”

Inhibitive effect of salicylidene‐N‐N′‐dimorpholine towards corrosion of zinc in hydrochloric acid

“…Corrosion inhibitors play an important role in controlling the corrosion of metals. Organic compounds studied as inhibitors include imidazole azo derivatives (Ekilik and Grigorev, 1973), thiourea (Shams El Din et al , 1977), benzene thiols and related compounds (Abdel et al , 1981), and Schiff bases of chloroanilines (Desai et al , 1995), and 2‐mercaptobenzimidazole (Wang et al , 2003a). In earlier work, inhibition of the corrosion of zinc in sulphuric acid by Schiff bases of ethylenediamine (Shah et al , 2004), ortho‐substituted aniline‐N‐salicylidenes (Desai et al , 2003), meta‐substituted aniline‐N‐salicylidenes (Talati et al , 2005a), Schiff bases of ethylenediamine/triethylenetetramine with salicylaldehyde (Desai et al , 2008), has been reported.…”

Schiff bases of ethylenediamine/triethylenetetramine with benzaldehyde/cinnamic aldehyde/salicylaldehyde as corrosion inhibitors of zinc in sulphuric acid

“…A survey of literature reveals that there are very few substances that may be considered as highly efficient inhibitors for zinc in non‐oxidizing acids, particularly sulphuric acid. Compounds studied as inhibitors include, benzaldehyde and its derivatives (Grigorev and Ekilik, 1969), quinoline derivatives (Kawai et al , 1971), quaternary salts of pyridine bases (Antropov et al , 1971), alkaloids (Subramanyan and Ramkrishnaiah, 1973), imidazole azo derivatives (Ekilik and Grigorev, 1973), thiourea (Shams El Din et al , 1977), benzene‐thiol and related compounds (Abdel Aal et al , 1981), Schiff bases of chloroanilines and toluidines (Desai et al , 1990) and 2‐mercaptobenzimidazole (Wang et al , 2003). In earlier work, the inhibition of corrosion of zinc in sulphuric acid by Schiff bases of ethylenediamine (Shah et al , 2004), ortho‐substituted aniline‐N‐salicylidenes (Desai et al , 2003), ortho‐, meta‐, and para‐aminophenol‐N‐salicylidenes (Talati et al , 2005a, b), and meta‐substituted aniline‐N‐salicylidenes (Talati et al , 2005a, b), has been reported.…”