Evaluation of [(1E,8E)-9-(4-chlorophenyl)-1,8-bis(2-(2,4-dinitrophenyl) hydrazono)-3,3,6,6-tetramethyl-1,2,3,4,5,6,7,8,9,10-Decahydroacridine] as a Corrosion Inhibitor for Mild Steel in an Acidic Medium
Joachim J. Awaka-Ama
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
Aniedi E. Nyong *
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
Saviour Ekiko
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
Ibagha Isaac
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
Kufre E. Essien
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
Clement Obadimu
Seplat Petroleum Development Company, Onne, Rivers State, Nigeria.
Godwin J. Udo
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
Joshua Felix
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
Joseph Alexander
Department of Chemistry, Akwa Ibom State University, Mkpat Enin, Akwa Ibom State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The corrosion-inhibition behaviour of [(1E,8E)-9-(4-chlorophenyl)-1,8-bis(2-(2,4-dinitrophenyl)hydrazono)-3,3,6,6-tetramethyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine], an acridine-2,4-dinitrophenylhydrazone derivative, was evaluated for mild steel in hydrochloric acid using the gravimetric weight-loss method. Mild-steel coupons were polished, cleaned, weighed, and immersed in uninhibited acid and acid solutions containing selected inhibitor concentrations. Weight loss was recorded at three-day intervals over 30 days, and inhibition efficiency and surface coverage were calculated from the corrosion-rate data. The uninhibited system showed relatively stable weight loss throughout the exposure period, confirming the corrosive nature of the acid medium. The inhibitor reduced weight loss most effectively at 2 ppm, where inhibition efficiency remained between 72.73% and 75.13%. At 6 ppm, inhibition efficiency decreased to 29.27–33.71%, whereas at 10 ppm it decreased further to 14.99–17.34%. Surface-coverage values followed the same pattern, with the highest values at 2 ppm and lower values at the higher concentrations. These findings indicate that the tested compound reduced mild-steel corrosion under the experimental conditions, with the best performance at the lowest tested concentration. Nevertheless, the concentration-dependent decline in performance requires further investigation. Electrochemical measurements, adsorption-isotherm analysis, replicated experiments, and surface-characterisation studies are required to clarify the inhibition mechanism and confirm the reproducibility of the observed behaviour.
Keywords: Mild steel, corrosion inhibition, hydrochloric acid, gravimetric method, weight loss, hydrazone derivative, acridine derivative, surface coverage, adsorption, concentration effect