A COMPARATIVE STUDY OF INHIBITIVE EFFECTS OF SOME NEW SCHIFF BASES ON COPPER CORROSION IN ACIDIC MEDIUM

Abstract

In this research two new Schiff bases N,N'-bis[(3,4-dihydroxy-5-nitrophenyl)methylidene]thiourea (BDHNPMTU)                and 2-[(3,4-dihydroxy-5-nitrophenyl)methylidene]hydrazine-1-carbothioamide (DHNPMHC) were synthesized by condensation of 3,4-dihydroxcy-5-nitro-benzaldehyde with Thiourea and Thiosemicarbazide. The structures of Schiff bases were fully characterized by elemental analysis, FT-IR and UV–Vis methods. The inhibitive effects of two Schiff bases BDHNPMTU and DHNPMHC towards the corrosion on copper in 0.5M HCl were investigated using weight loss measurement technique. Surface morphology of metal surface in presence and absence of inhibitors were studied by scanning electron microscope (SEM). Results show that both BDHNPMTU and DHNPMHC are an effective inhibitor for copper corrosion in 0.5 M HCl solution. It was found that inhibition efficiency increases with increasing concentration of inhibitor. Adsorption of the inhibitor on the copper surface followed Langmuir adsorption isotherm. SEM study also support the inhibition of corrosion of copper. BDHNPMTU and DHNPMHC show maximum inhibition efficiency i.e. 96% and 95.83% at highest concentration of inhibitor (5X10^-5M). The order of inhibition efficiency of the two Schiff’s bases for Cu metal are BDHNPMTU>DHNPMHC.