Electrochemically-mediated treatment of sulfur dioxide and purification of carbon dioxide coupled with hydrogen production

Abstract

Sulfur dioxide emissions should be and have been regulated due to adverse effects on the environment, and purification of carbon dioxide from low-concentration sources requires energy-intensive steps. Here, we propose incorporating a NaOH-based absorbent with high pH, in which the two gases are simultaneously absorbed, into an electrochemical system that contributes to: (1) mineralizing sulfur dioxide into sulfate; (2) purifying carbon dioxide; and (3) producing hydrogen. Our electrolysis involves primarily anodic sulfite oxidation, and the hydroxide-consuming (proton-generating) sulfite oxidation coupled with cathodic hydrogen evolution allows to generate CO2 with > 85 % purity from an acidifying anodic chamber, and hydrogen evolution from a cathodic chamber with Faradaic efficiency close to 100 %, all at lower energy cost than water electrolysis. This proof-of-concept study demonstrates the feasibility of our functional electrochemical system as a sustainable solution for air pollution control, carbon neutrality, and energy production.