Efficacy of Organoselenium Derivatives as Corrosion Inhibitors
Strategic Research Institute
Published on :
5 Jun, 2023, 5:59 am
A study focusing on organoselenium thiourea derivatives as potential corrosion inhibitors for carbon steel was conducted. The derivatives were characterized using spectroscopic methods and evaluated for their inhibitory performance using electrochemical techniques. The results demonstrated their high inhibition efficiency and revealed insights into their adsorption mechanism and protective abilities. Further theoretical simulations provided valuable information about their interactions with corrosive solutions. This study highlights the promise of organoselenium thiourea derivatives in controlling corrosion and preventing material degradation.
Carbon steel is widely used in various industries, including marine and petroleum sectors, due to its excellent mechanical properties. However, it is highly susceptible to corrosion in acidic environments, particularly in hydrochloric acid used for industrial processes. The economic impact of corrosion-related losses amounts to billions of dollars annually. While several strategies have been developed to prevent corrosion, corrosion inhibitors have proven to be one of the most effective approaches. Corrosion inhibitors possess strong adhesion properties to metallic surfaces and rapidly reduce the corrosion rate upon application.
Organic molecules containing hetero atoms such as sulfur, oxygen, and nitrogen have been extensively employed as corrosion inhibitors for mild steel in aqueous conditions. These organic inhibitors offer cost-effective solutions due to their abundant adsorption centers. The adsorption mechanism between the metal surface and the organic layer significantly hinders both anodic and cathodic corrosion reactions at the metal/solution interface. Electrochemical techniques, including electrochemical impedance spectroscopy and potentiodynamic polarization, provide valuable insights into corrosion rates, while theoretical simulations enable a deeper understanding of the interactions between metals and inhibitors.
Organoselenium (OSe) compounds have recently gained attention for their diverse applications in material and medicinal chemistry. Selenium's unique characteristics, such as its redox properties, have opened up potential applications for OSe agents in various industries. Compared to its analogs sulfur, nitrogen, and phosphorus, selenium exhibits lower electronegativity and larger size, leading to higher polarizability and nucleophilicity. Organoselenium compounds are known for their nucleophilic properties, as well as their potential catalytic and chelating activities. The semiconductor nature of selenium enables its utilization in material science and electronics, including solar cells, sodium-ion batteries, photocells, and light meters.
While numerous corrosion inhibitors have been developed over the years, most are effective only at room temperature and low acid concentrations. Thus, there is a need for inhibitors that can withstand harsh conditions, including high temperatures and concentrated acids (>15 wt% HCl). Thioureas have shown promise in retarding corrosion in various metals, including aluminum, copper, ferrous, zinc, and magnesium, by influencing cathodic and anodic reactions. Their ability to share free electrons with metal templates through nitrogen and sulfur atoms makes them ideal adsorption sites, providing protection against acid corrosion. Organoselenium compounds are considered superior corrosion inhibitors to their organosulfur counterparts due to selenium's greater ability to share outer electrons with metals. However, the anti-corrosive efficacy of OSe agents has been scarcely discussed in the literature.
In recent studies, different organoselenocyanates and diselenide-based water-soluble OSe compounds have been reported as corrosion inhibitors for reinforced steel in simulated concrete pore solutions. OSe-tethered anthranilic acid hybrids and OSe-based tetrazoles have also shown potential as corrosion inhibitors for pipeline steel and steel tubing samples during oil well acidizing. These findings have paved the way for investigating the potential synergy between thiourea and organoselenium compounds to enhance overall corrosion inhibition activity.
In this study, two organoselenium thiourea derivatives, DS036 and DS038, were synthesized and characterized using FTIR and NMR spectroscopy. The inhibitory performance of these compounds on carbon steel corrosion in hydrochloric acid was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The results revealed their exceptional inhibition efficiency, mixed-type corrosion inhibition behavior, and significant changes in polarization resistance and double-layer capacitance upon increasing the inhibitor concentration. Adsorption studies supported the Langmuir isotherm model, indicating the adsorption mechanism of the inhibitors on the steel surface. Field emission scanning electron microscopy (FE-SEM) provided visual evidence of the adsorption and protective abilities of the organoselenium-based inhibitors. The molecular interactions between the inhibitors and corrosive solution anions on the iron surface were explored through in silico calculations using density functional theory (DFT) and Monte Carlo simulations. These calculations shed light on the inhibitors' ability to form a protective surface and control the corrosion rate.