ANTICORROSION PERFORMANCE OF SOME ARYLIDENE-5-PYRAZOLONES FOR MILD STEEL IN SULPHURIC ACID

Abstract

5-Pyrazolone and four of its 4-arylidene derivatives were synthesized from acetoacetic ester, hydrazine hydrate and aromatic aldehydes, and evaluated as corrosion inhibitors for mild steel by weight loss method, gasometry, polarization measurements and impedance studies. Piperonalidene pyrazolone showed the best results among all the compounds tested even at low concentrations. The compounds act as mixed type inhibitors and their adsorption on steel surface obeys the Langmuir isotherm. The effect of temperature on the corrosion behaviour of steel showed that the inhibition efficiency decreases with increase in temperature (303-333K). Ea and ΔG ads were determined. The synergistic effect due to I- ions on one of the aryldene pyrazolone has also been noted.