mild steel corrosion inhibition in hydrochloric acid using cocoa pod husk-ficus exasperata: extract preparation optimization and characterization

This research aimed at studying the optimization of cocoa pod-ficus exasperate (cp-fe) extract preparation as mild steel anticorrosive agent in hydrochloric acid solution using a central composite design as an optimization tool. the maximum inhibition efficiency of 95.42% was obtained at ethanol volume, extraction time, cp-fe mixing ratio, and cp-fe mass of 500 ml, 48 hr, 5, and 100 g respectively. the coefficient of determination value of 0.9674 between experimental and predicted values suggested that the model developed was exact. the optimum predicted point for cp-fe extract preparation by ccd was 62.02 ml, 9.51 hr, 3.42, and 75.68 g for the ethanol volume, extraction time, cp-fe mixing ratio, and cp-fe mass respectively. sem images revealed an acid attack on the mild steel surface. adsorption of cp-fe extracts on the mild steel surface prevents acid attack. ft-ir revealed the presence of carboxyl (-cooh) and hydroxyl (-oh) functional groups. eds revealed high iron composition on mild steel surface in the presence of cp-fe extracts. loss of fe^2+ into free hcl solution was observed from the aas result. conclusively, mixed cocoa pod-ficus exasperate extracts exhibited effective corrosion inhibitory attributes for mild steel in hcl solution.