Tryptophan as copper corrosion inhibitor in 0.5 M aerated sulfuric acid

The use of Tryptophan (Trp) as a copper corrosion inhibitor was tested in 0.5 M aerated sulfuric acid (H2SO4) in the 20– temperature range. Its effectiveness was assessed through potentiodynamic (at 1 h, 72 h, 6 months), spectrophotometric (72 h tests) and gravimetric (72 h tests) tests. At 20– (1 h tests) the Trp adsorption followed Bockris–Swinkels' isotherm (x=2). The Trp even underwent over time (six month) a photodegradation, but surprisingly enough this did not affect the inhibition percentage (IP) which was 80% for the solutions kept in the dark as well as those kept in light.