Experimental Studies on Two Isonicotinohydrazide-Based Schiff Bases as New and Efficient Inhibitors for Pipeline Steel Erosion Corrosion in Acidic Cleaning Solution

Abstract

Acidic cleaning solution formulated with HCl (5–15%) corrodes pipeline steel when used for descaling in oilfields. Two isonicotinohydrazide Schiff bases namely, N-(2-hydroxybenzylidene)isonicotinohydrazide (N-2HBI) and N-(5-nitro-2-hydroxybenzylidene)isonicotinohydrazide (N5N-2HBI) were synthesized and tested as alternative eco-friendly and non-toxic corrosion inhibitors for J55 steel in 5% (w/v) HCl at various temperatures. Different experimental techniques were employed to examine the inhibitive performance of N-2HBI and N5N-2HBI on the steel corrosion. Obtained results indicated effective corrosion inhibition by the synthesized Schiff bases on J55 steel dissolution in 5% HCl. Electrochemical impedance spectroscopy (EIS) data reveal that the charge transfer did not only increase on addition of the Schiff bases but the double layer capacitance and the corrosion current decreased as well. Potentiodynamic polarization (PDP) data show the mixed-type behavior of N-2HBI and N5N-2HBI with some dominant anodic effect. The adsorption of N-2HBI and N5N-2HBI on J55 steel surface followed Langmuir’s adsorption isotherm. The thermodynamic adsorption parameters at different inhibitor concentrations were calculated and discussed. Scanning electron microscopy (SEM) analyses revealed a much better morphology of the J55 steel surface in the presence of N-2HBI and N5N-2HBI.