The results of the study reveal that the inhibition efficiency of caffeine for CT38 steel corrosion in 1M HCL vary with concentration; the inhibition efficiency of the caffeine - 1%KI system increases compared with only use caffeine and changes is not much when increasing in temperature, extending the trial periods. | Trương Thị Thảo và Đtg Tạp chí KHOA HỌC & CÔNG NGHỆ 96(08): 91 - 96 CORROSION INHIBITION BY CAFFEINE AND CAFFEINE – I - SYSTEM FOR CT38 STEEL IN 1M HYDROCHLORIC ACID SOLUTION Truong Thi Thao*, Hoang Thu Tra College of Sciences - TNU ABTRACT The inhibition efficiency of caffeine and caffeine - KI system in controlling corrosion of CT38 steel immerased in acid 1M HCl solution has been evaluated in the absence and presence of them by weight loss method. Influence of caffeine concentration, temperature and immersion peroid on the inhibition efficiency of the caffeine - 1%KI system has also investigated. The results of the study reveal that the inhibition efficiency of caffeine for CT38 steel corrosion in 1M HCL vary with concentration; the inhibition efficiency of the caffeine - 1%KI system increases compared with only use caffeine and changes is not much when increasing in temperature, extending the trial periods. Thermodynamic consideration reveals that adsorption caffeine on CT38 steel surface is spontaneous and occurs according to Langmuir adsorption isotherm. Physical adsorption mechanism has been proposed for the adsorption of the inhibitor from the trend of the inhibiton efficiency with temperature and the values of some kinetic and thermodynamic parameters obtained. Key words: Corrosion inhibition, steel, Langmuir adsorption isotherm, caffeine, KI INTRODUCTION* Environment friendly inhibitors have attracted the attention of researchers. Non-toxic natural products have been widely used as corrosion inhibitors. Extracts of plants such as green tea, tobaco, café,. have shown good and scale inhibitors [1, 2, 4-7]. These extracts contain caffeine. So that, caffeine was isolated from dry green tea leaves and used as corrosion inhibitor [2]. The present work (i) evaluates the inhibition efficiency of caffeine concentration, of 1g/l caffeine - 1%KI system in controlling corrosion of CT38 steel in 1M HCl acid solution, (ii) examines the .
