THERMODYNAMICS AND ADSORPTION MECHANISM OF Acalypha indica ROOT EXTRACT AS A BARRIER TO REDUCE THE DETERIORATION OF C-STEEL

An ethanolic root extract of Acalypha indica was tested at varying concentrations (50- 300 ppm) after 3 hours of immersion in a medium to evaluate its corrosion inhibition effect on carbon steel in a 0.5N hydrochloric acid solution. This was analyzed using weight loss measurements, Potentiodynamic Polarization, as well as surface morphological methods such as Atomic Force Microscopy and Contact Angle methods. The inhibitor extract was characterized through Gas Chromatography-Mass Spectrometry. Corrosion inhibition behaviour was assessed across a temperature range of 303K to 318 K. The results revealed that inhibition efficiency increased with concentration, reaching a maximum at 200 ppm, followed by a subsequent decline. Additionally, a temperature rise corresponded to a decrease in inhibition efficiency. Thermodynamic parameters were calculated, and adsorption studies identified the Freundlich isotherm as the best fit. Based on experimental results, the root extract of Acalypha indica can be regarded as an effective corrosion inhibitor for carbon steel in a 0.5N hydrochloric acid medium.