The inhibition effect of halide ions such as iodide, bromide and chloride ions on the corrosion of iron in 0.5 mol L-1 H2SO4 and the adsorption behaviour of these ions on the electrode surface have been studied by polarization and impedance methods. It has been found that the inhibition of nearly 90% has been observed for iodide ions at 2.5 <FONT FACE=Symbol>´</FONT> 10-3 mol L-1, for bromide ions at 10 <FONT FACE=Symbol>´</FONT> 10-3 mol L-1 and 80% for chloride ions at 2.5 <FONT FACE=Symbol>´</FONT> 10-3 mol L-1. The inhibition effect is increased with increase of halide ions concentration in the case of I- and Br- ions, whereas it has decreased in the case of Cl- ion at concentrations higher than 5 <FONT FACE=Symbol>´</FONT> 10-3 mol L-1. The double layer capacitance values have decreased considerably in the presence of halide ions which indicate that these anions are adsorbed on iron at the corrosion potential.
corrosion inhibition; iron; sulphuric acid; halide ions
