Study on benzylidine derivatives as corrosion inhibitors for mild steel in 15% HCl medium: Experimental & theoretical investigation

Abstract

Corrosion inhibitors are added to acid solutions used during industrial cleaning and descaling procedures to reduce the metallic corrosion. In the present study, benzylidine Schiff base compounds namely 2-((Z)-(4-((E)-(3,4-dimethoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-ylidene)amino)benzoicacid (DBAB) & (E)N′(4((E)(3,4-dimethoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-ylidene)-2-hydroxybenzohydrazide (DBAH) were prepared and their corrosion inhibition behavior and adsorption properties were studied by using WL (weight loss), PDP (potentiodynamic polarization) along with EIS (electrochemical impedance spectroscopy) methods for mild steel (MS) in 15% HCl solution at different temperatures. The outcomes indicated that DBAH and DBAB offered inhibition efficacy of 96.98% and 94.01% at 120 ppm concentration, respectively. The potentiodynamic polarization studies showed that both inhibitors act as mixed type inhibitor and undergo effective mixed-type adsorption at MS facet. Surface analysis of corroded samples performed by FESEM, AFM and XPS confirmed the establishment of corrosion protective inhibitor film at the MS facet. Additionally, MCS (Monte carlo simulation) and DFT studies support the experimental results obtained by weight loss and electrochemical methods.