The inhibition performance of cysteine for carbon steel of hydrochloric acid corrosion under various temperatures was evaluated by experiments. And the inhibition mechanism was explored by investigation of diffusion inhibition of corrosive particles by inhibitor membrane through molecular dynamics (MD) simulation. Results of static weight-loss experiments indicated that the inhibition efficiency of cysteine decreased from 88.36% to 61.64%, with the increase of temperature from 25 to 65 ℃. MD simulations showed that the free volume of cysteine membrane increased, and the interaction between corrosive particles and inhibitor membrane weakened, with the increase of temperature. While the self-diffusion of cysteine molecules within the membrane increased with temperature rise, and the passive diffusion of corrosive particles by inhibitor membrane enhanced. Analysis of both active and passive aspect of diffusion process reveals that the diffusion ability of corrosive particles in inhibitor membrane increases with temperature. And with temperature rise, the inhibitive efficiency of cysteine membrane for corrosive particles decreases, and diffusion of these particles could be facilitated, which results in decrease of inhibition performance of cysteine.

Key words: cysteine, inhibition efficiency, weight-loss method, molecular dynamics simulation, diffusion coefficient