Novel Water-soluble quinoxaline-2,3-dione-6-sulfohydrazide derivatives as efficient acid corrosion inhibitors: Design, characterization, experimental, and theoretical studies

Abstract

BackgroundThe corrosion of metals results in significant financial losses for the nation and poses a substantial threat to human safety. Few corrosion inhibitors on the market today are water-soluble, so they can't keep up with the growing need for efficient inhibitors. So, many researchers seek to construct efficient and low-cost materials for metal protection. Methods: In the present article, two novel water-soluble quinoxaline-2,3-dione-6-sulfohydrazide derivatives, Qs-HP and Qs-HI, were constructed, synthesized, characterized, and evaluated their activity as anticorrosion inhibitors. The authors confirmed the capacity of both organic compounds to act as corrosion inhibitors for CS alloy by using Potentiodynamic polarization (PP), weight loss, and electrochemical impedance polarization (EIS) studies in 1.0 M hydrochloric acid solution. Significant findingsThe inhibitors, Qs-HP and Qs-HI, demonstrated the highest corrosion protection of 92.06 % and 95.93 %, respectively, at 1000 ppm by the PP method. The results also demonstrated that a higher inhibitor concentration resulted in a more effective inhibition. The PP effect on the condition of mixed adsorption is demonstrated as physical-chemical adsorption (mixed type). Also, Langmuir's adsorption isotherm explains how the CS alloy's surface absorbed the inhibitory materials. EIS results continuously showed that increasing the quantity of injected inhibitor compounds increased charge transfer resistance (Rct), and the electrochemical double layer (Cdl) decreased. Moreover, theoretical studies like EHOMO, ELUMO, diploe moment (µ), and suitable inhibition mechanisms were discussed in detail and used to confirm the donor-acceptor (D-A) system. Finally, all the experimental and theoretical data demonstrate that these derivatives can successfully build a blocking layer and regulate corrosion.