Study of the effectiveness of the new inhibitor in different aggressive media

"The corrosion protection effect of the new S-1 reagent in media with the pH values of 2.0, 4.0, 6.0, as well as carbon dioxide and hydrogen sulfide added separately and combined to the mentioned media, was first tested under laboratory conditions. The protective effect of reagent S-1 was weak in the corrosion medium without hydrogen sulfide and carbon dioxide. However, as the acidity of the medium and the concentration of the reagent increases, the corrosion protection efficiency of the inhibitor also increases. The highest effect is observed at pH = 2.0 and reagent concentration of 30 mg/l. The corrosion protection effect of the reagent reaches 97% under these conditions. In the media with pH = 4.0 and pH = 6.0 without carbon dioxide and hydrogen sulfide, the protective effect of the inhibitor at the optimal concentration of 30 mg/l is 66% and 64%, respectively. In the medium with added carbon dioxide, the protective effect of inhibitor S-1 decreases at pH = 2.0 and, on the contrary, increases at the values of pH = 4.0 and pH = 6.0. Also, as the pressure of carbon dioxide in the medium increases, the protective effect of inhibitor S-1 increases. When hydrogen sulfide is added to the medium, it causes an increase in the corrosion rate and the protection efficiency of inhibitor S-1. However, in the medium without inhibitor, the increase of hydrogen sulfide concentration only up to CH2S = 400 mg/l is accompanied by an increase in the corrosion rate at all values of pH. The addition of 1000 mg/l of hydrogen sulfide to the corrosion medium leads to the decrease in the corrosion rate in the medium without inhibitors and a slight decrease in the protective effect at the concentration of the inhibitor Cinh = 10 mg/l. As the concentration of inhibitor S-1 increases in the medium with the addition of carbon dioxide and hydrogen, its corrosion protection effect also increases. In the range of Cinh = 10–30 mg/l, when PCO2 = 0.5 atm and CH2S = 200 mg/l, the protective effect is estimated at 38–99%, and when CH2S = 1000 mg/l, it is estimated at 17–79%. At PCO2 = 1.0 atm, the value of protective effect is 22–95% and 14–76%, and finally at PCO2 = 2.0 atm, the value of the corrosion protection effect of inhibitor S-1 is estimated at 44–92% and 15–75%, respectively. The coexistence of carbon dioxide and hydrogen sulfide in an aggressive medium leads to an increase in the protective effect of inhibitor S-1 compared to the medium containing only carbon dioxide, and reduces it in comparison to the medium with hydrogen sulfide. An increase in carbon dioxide pressure in the presence of hydrogen sulfide causes a decrease in the protective effect of inhibitor S-1. The protective effect of inhibitor S-1 is lower in the medium with hydrogen sulfide concentration of 1000 mg/l compared to a concentration of 200 mg/l. This case is also observed in the carbon dioxide free medium."