Study of Pyrazolo[3,4-d] pyrimidine Derivative as Corrosion Inhibitor on 904L stainless Steel in Molar H3PO4

The corrosion inhibition of stainless steel type 904 L SS with different concentrations (10 -3 -10 -6 M) of 1,5-diallyl-1H - pyrazolo[3,4-d] pyrimidine (DPP) in acid solutions was investigated by potentiostatic polarization measurements. The effect of temperature (298-353°K) on corrosion parameters was examined. The open circuit potential values in the presence and absence of DPP noted before and after experiments indicated the formation of passive film on the surface of the samples. It was found that corrosion potential (E corr ) increases with increasing DPP concentrations, while, corrosion current (i corr ) decreases. Inhibition efficiency of DPP in 1M H 3 PO 4 . The inhibitor functions through adsorption and follows languimir isotherm in the acid. Activation energy (E a ) for adsorption of DPP is calculated. The values of  ΔG ads decreased (attained more negative values) with increasing temperature.