Organic superbase 1,8-diazabicyclo-[5.4.0]-undec-7-ene enhanced adsorption and electrochemical detection of H ₂ S in Deep eutectic solvent

The abstract: In this study, we evaluated the behavior of a new recyclable ternary system composed of 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) mixed with a choline chloride-ethylene glycol-based deep eutectic solvent (ChCl-EGbased DES) for hydrogen sulfide (H 2 S) adsorption and electrochemical detection. The gravimetric absorption capacity was calculated to be 0.278 mmol H 2 S/g-ChCl-EG, which increased to 1.313 mmol H 2 S/g-DBU/ChCl-EG mixtures (1.0:6.0 mole ratio) at 1 bar and 293 K. We compared the electrochemical behaviors of H 2 S at a platinum microdisk electrode in ChCl-EG and DBU/ChCl-EG (1.0:6.0 molar ratio) using cyclic voltammetry. The addition of DBU to ChCl-EG significantly increased the H 2 S absorption capacity through a chemical reaction between DBU and H 2 S. This chemical absorption enhances the electrochemical response of H 2 S, generating electroactive HS - ions that produce an additional and independent anodic peak at approximately 0.70 V vs. Pt, which is suitable for H 2 S detection. Furthermore, cyclic absorption experiments demonstrated that H 2 S gas could be released by bubbling argon (Ar) at 393 K. By measuring the current density change of HS. in the liquid phase, the electrochemical method can investigate the reaction mechanism during the absorption process, exhibiting characteristics of rapid determination and convenient control.