Development,measurement And Investigation Of Two Environmentally Friendly Compound Corrosion Inhibitor

Acid cleaning inhibitor is an important additive on reducing corrosion of the object in the process of cleaning boiler. Acid cleaning inhibitors with good performance provide an important guarantee of successful acid cleaning and the safety of the acid cleaned equipment. Researches are focused on the exploitation of efficient, environment-friendly acid cleaning inhibitors for boilersIn this paper, Following the concept of green chemistry, bis-imidazoline quaternary ammonium and 2-mercapto benzimidazole were used as the main monomers of hydrochloride inhibitor and ethylene diamine tetraacetic acid(EDTA)inhibitor. Efficient, environment-firendly compound corrosion inhibitors CL-1 (hydrochloride inhibitor ) and CL-2 (disodium ethylenediamintertraacetate inhibitor ) were screened by orthogonal tests.The optimal mixture compostion of CL-1 was as follows: 0.05% ( bis-imidazoline quaternary ammonium salt) + 0.006%( EVC-Na ) + 0.008% ( acetone oxime ) + 0.01% (Benzalkonium Bromide ) + 0.02% (disodium EDTA ).When the temperature was 52℃±1℃,static hanging 4 hours and hydrochloric acid concentration 6%(mass percentage) of the medium, the static corrosion rate and inhibition effciency were 0.32 g·m-2·h-1 and 98.39% respectively. The optimal mixture compostion of CL-2 was as follows: 0.01% ( MBI ) + 0.05%( bis-imidazoline quaternary ammonium ) + 0.005% ( acetone oxime ) + 0.08% ( CPB ) + 0.5 mL/L (anhydrous ethanol ). When the temperature 92℃±1℃,static etching 4 hours and EDTA concentration 8%( mass percentage) of disodium EDTA medium, the static corrosion rateand inhibition effciency were 0.33 g·m-2·h-1 and 98.79% respectively.Weight loss method was employed to research the corrosion inhibition properties of CL-1 and CL-2.Factors such as the concentration of the acid cleaning medium inhibitor concentration, acid cleaning temperature, Fe3+ concentration were researched. The Results show that these two inhibitors have a good inhibitory performance a better inhibitory performance under the condition of low concentration, high temperature, high densty. The inhibitors have a good corrosion resistance to Fe3+, and do not appear pitting corrosion in 1500 mg/L.Tafel polarization curves show that the CL-1 and CL-2 are mix-controlled inhibitors in electrochemical reaction process. Electrochemical Impedance Spectroscopy(EIS)show that both CL-1 and CL-2 come forth a"degradation"phenomenon, and exist a high frequency capacitive arc, are adsorption-type corrosion inhibitors compared with the blank solution, the shape of capacitance arc almost identical,the two inhibitors are controlled with the charge transfer. Electrochemical experimental results are basically the same as weight loss method on inhibition effciency.The SEM of the surface treated by inhibitors shows that a well-distributed, compacted corrosion film forms on the surface after treated by one of these two inhibitors.The effciency formula (?) was discovered from inhibition analysis of weight loss method and electrochemical method.CL-1 and CL-2 on the surface of the object satisfied with langmuir adsorption isotherm;CL-1 and CL-2 are geometric covering effect on the surface of the object.