Thermodynamic, electrochemical and surface studies of dendrimers as effective corrosion inhibitors for mild steel in 1 M HCl

The Corrosion inhibition of mild steel in 1 M HCl has been investigated using three dendrimers by means of gravimetric, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM) and energy dispersive Xray spectroscopy (EDX) techniques. Results showed that inhibition efficiency increases with increasing concentration of dendrimers. Among the studied inhibitors, the DEND_s-G₂ showed maximum efficiency of 96.95% at 25 concentrations. The potentiodynamic study revealed that investigated dendrimers act as mixed type inhibitors. EIS plots indicated that the addition of dendrimers increases the charge-transfer resistance (R_ct), decreases the double-layer capacitance (C_dl) of the corrosion process, and hence increases inhibition efficiency. The adsorption of the dendrimers on the mild steel surface in acid solution obeys the Langmuir adsorption isotherm. Moreover, the thermodynamic activation parameters for the corrosion reaction were calculated and discussed in relation to the stability of the protective inhibitor layer.