Formation of Ferrous Sulfide Film from Sulfite on Steel Under Anaerobic Conditions

Abstract

The reactions of carbon steel and sulfite ions were studied by electrochemical experiments in 0.5 M NaCl solution under anaerobic conditions. Sulfite was reduced to sulfide, and a black ferrous sulfide film was formed. The process was monitored as a function of time at different potentials. During film formation, the current density and the intensity of reflected light from the steel surface were recorded. The film formation followed initially a 2-dimensional model and later a 3-dimensional model. The rate of film formation was studied as a function of ionic concentration, electrode rotation speed, potential, and the surface-roughness of the electrode.

Electrochemical Oxygen Removal from Seawater in Industrial Scale Using Silver Cathode

“…Chemical methods, such as addition of oxygen scavengers (sulfites and metasulfites), are mainly used as a backup for the physical process in case of malfunction or in order to remove the last traces of oxygen. Installation of vacuum towers or gas purging facilities has a high capital cost and a large footprint, while the use of sulfite based oxygen scavengers may have a negative impact on the environment and, if overdozed, also gives a high risk of sulfide corrosion of the piplines …”

“…Installation of vacuum towers or gas purging facilities has a high capital cost and a large footprint, while the use of sulfite based oxygen scavengers may have a negative impact on the environment and, if overdozed, also gives a high risk of sulfide corrosion of the piplines. 2 The use of an electrochemical process for the removal of oxygen from seawater is an alternative method that avoids the disadvantages described for the other methods. 3−5 The oxidation of water to yield hydroxium ion and oxygen, and the reduction of oxygen to water are the basis for deoxygenation of water.…”

Experimental Study of Silver Cathode for Electrochemical Deoxygenation of Seawater for Enhanced Oil Recovery

“…Oxygen removal to a concentration less than 10 ppb can be achieved with the use of oxygen scavengers . However, many of the chemicals for oxygen removal are not environmentally friendly, and some chemicals can have a severe negative impact on the occupational safety of the personnel involved in the process, and may in addition increase corrosion when used in too high doses . The scavenging ability of these chemicals depends on pH and temperature, and catalysts might be required in order to have a sufficient reaction rate.…”

State-of-the-art overview of pipeline steel corrosion in impure dense CO2 for CCS transportation: mechanisms and models

“…Moreover, Ruhl and Kranzmann [38] suggested that the inner part of the FeSO 3 · x H 2 O and FeSO 4 · x H 2 O layers changed to iron sulphide (FeS) under ambient pressure. The changing process was characterised by the following equation [123]: When NO x and SO x were present, ammoniojarosite ((NH 4 )Fe 3 (SO 4 ) 2 (OH) 6 ) was found to be the main corrosion product under ambient conditions [36], while Fe(NO 3 ) 3 .9H 2 O and Fe 2 O 3 .H 2 O were detected as the main corrosion products for X65 steel in water-saturated supercritical CO 2 with 1000 ppmv NO 2 [91]. NO 3 – present in the solution might be reduced to ammonium (NH 4 + ) within the aqueous film and in the presence of hydronium ions (H 3 O + ) [37], according to the following equation [124]: …”