Corrosion And Anti-scaling Inhibition Behavior And Mechanism Of Combination With Potassium Sorbate On Q235 Steel In NaCl Solution

Adding corrosion inhibitors to corrosive media was an effective way to slow down the corrosion of metals in corrosive media.Therefore,corrosion inhibitors were mainly used in petrochemicals,chemical cleaning,cooling water and prevention of atmospheric corrosion,etc.However,most of the corrosion inhibitors currently used in the industry were non-environmentally friendly corrosion inhibitors,which had a destructive effect on human health and the environment.Therefore,scientists from all over the world are vigorously researching,looking for and developing new environmentally friendly corrosion inhibitors.Potassium sorbate（PS）is widely used in food as a preservative,in this paper,PS was used as a corrosion inhibitor for NaCl solution,weightlessness method,cyclic voltammetry（CV）,immersion method,potentiodynamic polarization method,electrochemical impedance spectroscopy（EIS）,scanning electron microscope（SEM）and other technologies were used to investigated the corrosion inhibition effect,corrosion inhibition mechanism and main influencing factors of PS,PS and Ce³⁺ compound,PS and hydroxyethylidene diphosphonic acid（HEDP）compound on Q235 steel in NaCl corrosive medium.The following research results are obtained:1.Cyclic Voltammetry（CV）was an effective method for studing metal corrosion.The oxidation peak current of Q235 steel on the CV curve obviously decreases with the increase of PS concentration,indicating that PS inhibits the oxidation reaction on the surface of Q235 steel.The oxidation peak current of Q235 steel increased with the increase of NaCl concentration,indicating that the corrosion inhibition effect of PS on Q235 steel decreased with the increase of NaCl concentration.The scanning speed has a certain influence on the peak current of the CV curve on Q235 steel,the best scanning rate for the CV test of this system is 50 m V/s.The oxidation peak potential of Q235 steel corresponds to the oxidation reaction of iron.2.The results of weight loss test and polarization test showed that the corrosion inhibition effect of NaCl on PS decreased significantly with the increase of NaCl concentration.After PS and Ce³⁺are compounded,the corrosion of Q235 steel can be effectively protected in low-concentration and high-concentration NaCl solution,and the compound corrosion inhibition efficiency was 72.5%.The results of electrochemical impedance spectroscopy showed that PS was adsorbed on the metal surface,preventing the corrosion of Q235 steel by blocking the active sites on the surface of Q235 steel,and mainly controlling the anode reaction,so PS was an anode corrosion inhibitor.Ce³⁺formed a Ce（OH）₃ precipitation film in the cathode area to control the cathode reaction;after PS and Ce³⁺compounded,the impedance spectrum capacitive impedance arc radius increased,and the synergy parameter was greater than 1,indicating that the compound had a synergistic effect.In a high-temperature corrosive environment,the corrosion inhibition efficiency of the compound system decreased with the increase of temperature.SEM results showed that after PS and Ce³⁺compounded,the surface of Q235 steel was smooth and a dense adsorption protective film was formed.3.Regardless of the conditions of normal temperature（20℃）and high temperature（60℃）,PS and HEDP pairing Q235 steel also had a good synergistic effect in different concentrations of NaCl solution,the corrosion inhibition efficiency reached 63.8%at normal temperature（20℃）,and at high temperature（60℃）reached 63.9%.Since HEDP was also a scale inhibitor,the combination of PS and HEDP played an important role in maintaining the stability of the industrial water system.