(Electro)catalytic oxidation of sulfide and recovery of elemental sulfur from sulfide-laden streams

TL;DR

This study develops a Mo and PANI co-doped MnOx/TiO2 anode for efficient electrochemical desulfurization, enabling stable sulfide oxidation and sulfur recovery from sulfide-rich streams in industrial wastewater.

Contribution

Introduction of a Mo and PANI co-doped MnOx/TiO2 anode that enhances stability and activity for sulfide oxidation in harsh conditions, facilitating sulfur recovery.

Findings

Enhanced anode activity and stability with Mo and PANI doping.

Effective removal of elemental sulfur via chemical dissolution with toluene.

Robust sulfide oxidation performance unaffected by operational parameters.

Abstract

MnxOy coated over TiO2 nanotube array substrate was doped with Mo and polyaniline (PANI) and applied for electrochemical desulfurization of concentrated sulfide (HS) solutions at basic pH, typical of biogas scrubbing solutions and industrial wastewater. Mo and PANI co-dopants significantly enhanced the anode activity towards sulfide oxidation and ensured its complete stability even in highly corrosive sulfide solutions (e.g., 200 mM HS). This was due to the increased electrochemically active surface area, improved coating conductivity and reduced charge transfer resistance. The (electro)catalytic oxidation of HS- demonstrated robust performance with very limited impact of different operational parameters (e.g., dissolved oxygen, anode potential, HS concentration). Due to the formation of elemental sulfur (S0) layer at the anode surface at basic pH, longer term anode usage requires its periodic removal. Chemical dissolution of S0 with toluene allows its rapid removal without affecting the anode activity, and easy recrystallization and recovery of pure sulfur.