Gravimetric and microstructural assessment of Schiff base inhibitors in Nigerian tar sand processing

Abstract This study presents the first investigation of halogen-substituted aniline-derived Schiff bases (SB1, SB2, SB3) as corrosion inhibitors for mild steel in Nigerian tar sand environments. Key novelty includes introducing inhibition power as a new gravimetric-based performance metric for alkaline conditions where electrochemical methods are limited. Tar sand from Ilubirin was processed with 0.58 M NaOH at 90 °C for 24 h with inhibitors at concentrations of 25–150 ppm. Gravimetric analysis, SEM–EDS, and Langmuir isotherm modelling revealed a significant corrosion rate with effectiveness order SB3 > SB2 > SB1. SB3 achieved 94.4% inhibition efficiency at 150 ppm due to a favourable molecular structure promoting enhanced adsorption. Langmuir analysis confirmed chemisorption (ΔG°ads > − 20 kJ mol−1), while microstructural evaluation demonstrated excellent surface protection. This research demonstrates the effectiveness of inhibition power in assessing corrosion inhibitors using gravimetric data due to the limitations of electrochemical measurement in tar sand environments. The study concludes that Schiff-based compounds offer promising solutions for corrosion control in a harsh alkaline tar sand processing environment.