Inhibitive effect of Carica papaya seed extract on aluminium in H₂SO₄ medium

The inhibitive effect Carica papaya seed extract (CPSE) on the corrosion behavior of aluminium in sulphuric acid medium of pH 2.3 was investigated by using Tafel polarization and electrochemical impedance spectroscopy (EIS) techniques in the temperature range 30 to 50°C. The concentration of inhibitors used was in the range of 100-400ppm. The surface morphology was studied using scanning electron microscopy (SEM). Inhibition efficiency was found to increase with increase in inhibitor concentration and decrease with increase in temperature. CPSE acted as a mixed type inhibitor. Inhibitor underwent physisorption on the surface of the metal and followed Langmuir adsorption isotherm. The kinetic and thermodynamic parameters were calculated and discussed in detail.. CPSE emerged as a potential, cost effective eco-friendly natural inhibitor for the corrosion control of aluminium in sulphuric acid medium.