Study of Cadmium Complexation with Na-DDTC by Voltammetry and Spectrophotometric Method and its Application in Corrosion Inhibition

Stoichiometry and  of Cd(II)/Na-DDTC complex were herein determined by DPV, employing Lingane's equation in a simple and extended form.Ionic strength was kept constant by using NaClO4 and KNO3 as SE.All measurements were performed at a constant T of 298±1 K.The approximation of all possible Lingane's equations was established.According to obtained results, it was concluded that the equation should be used in its extended form.In KNO3 and in NaClO4, q was found to be 5 and 6, and  logarithms were found to be 21.20 and 24.47, respectively.Spectrophotometric study was also performed to determine stoichiometry and  of Cd(II)/Na-DDTC complex in the same SE.Data indicated that Na-DDTC should be combined with Cd in molar ratios of 1:5 (ML5), in KNO3, and of 1:6 (ML6), in NaClO4. logarithms were calculated to be 22.26 and 23.94, in KNO3 and NaClO4, respectively.IE(%) of Na-DDTC as an ecofriendly CI for CS in 0.5 M H2SO4 medium was also investigated using WL measurements.Experimental results showed that IE(%) increased with higher inhibitor's Ct.The inhibitor's adsorption onto the CS surface obeyed Langmuir's isotherm, and it proceeded by both physisorption and chemisorption modes.ΔGads was determined.The effect of Cd 2+ addition, which formed a complex with Na-DDTC, was also studied.