The Study Of Inhibitory Capability And Inhibitory Mechanisim Of Green Copper Corrosion Inhibitor In Seawater

Making use of corrosion inhibitors in reason is an efficient method to prevent the metal and its alloy from eroding in environmental medium. Corrosion inhibitor technique with favorable effect and high economic benefit had been one of the most abroad anticorrosive techniques applied nowadays such industry as producing and processing petrochemicals, chemical rinse, atmosphere environment, water usage in industry, instrument and meter manufacturing etc. With the advent of oceaic century , corrosion inhibitors have an important function during the course of developing and utilizing seawater. But some poisonous and deleterious inhibitors have been confined or forbidden in use. Research and development of green corrosion inhibitors had been necessitous.According as research and development of green corrosion inhibitors, we developed three-compound inhibitor. The addition ratio was obtained by Latin experiment.Its critical concentration studied by weight loss trials was 250mg/L and inhibitory efficiency was 85.41% at this concentration.Inhibitory capability was tested by weight loss and electrochemistry trials in order to examine its inhibitory effect in different conditions.The results of experiment that filmed on copper beforehand at high inhibitor concentration revealed the inhibitor was type of film-formed inhibitor. Its critical concentration dropped to 200mg/L after filmed beforehand.The inhibitory effect for copper rusted in advance and intermittent marinating was studied by weight loss trials. And inhibitory capability in different medium was tested by weight loss and electrochemistry trials. When the concentration reached 250mg/L, its inhibitory efficiency was 82.65% for intermittent marinating copper. But the inhibitory efficiency was less than 80% for rusted copper at the concentration of 300mg/L. This inhibitor has good inhibitory effect for copper from 20℃to 40℃in seawater and salinity or low velocity of seawater has no effect on inhibitor's function. When the temperature exceeded 50℃the inhibitor's effect as not fine.By comparing with other inhibitors we known the inhibitor mentioned above had best inhibitory capability.Inhibitory mechanism was studied by electrochemistry methods such as polarization curve, EIS and SEM..(1) Results of polarization curve showed that the inhibitor was mix-type inhibitor, which mainly inhibited anodic process. (2) The results were consistent with weight loss experiments'by EIS. (3) The film formed in 1000mg/L inhibitor solution within 48h had short life in blank seawater, shorter than 48h; But this film had long life in the system of 200mg/L inhibitor+seawater, this film had gone intact and firm and had good effect for copper within 168h. These results were consistent with weight loss experiments'. (4) The results showed that three-compound inhibitor could inhibit local corrosion well. Because the inhibitory film could lay over activity points on copper and inhibitor had competitive adsorption with Cl- on copper surface result in the concentration of Cl- on copper surface fell, so that the inhibitor could prevent local corrosion.